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Overcoming the concrete conquest of aquatic ecosystems
Abstract
In reflecting on the human domination of our planet in the Anthropocene, some have argued that concrete is among the most destructive materials created by humans. Here we explore this idea, specifically in the context of what we consider “the concrete conquest of aquatic ecosystems.” The ubiquitous use of concrete in transportation and building infrastructure has contributed to alterations in freshwater and coastal marine systems. Yet, in some cases, there are no appropriate alternative building materials such that concrete itself is confounded by its application. For example, as the foundation for most dams, concrete fragments rivers and channelizes streams, often creating unnatural systems, yet dams are necessary for hydropower generation and flood control with few alternative materials for construction. In riparian and coastal environments, concrete harbours and inland canal systems are often used to address erosion or reclaim areas for human development. Even when removed (e.g., dam removal, naturalization of shorelines), concrete dust is a major aquatic pollutant. Instances do exist, however, where concrete has been used to benefit aquatic ecosystems – such as the installation of fish passage facilities at barriers or the development of fish-friendly culverts – though even then, there is a movement towards nature-like fishways that avoid the use of harmful materials like concrete. There are also opportunities to achieve conservation gains in the development of seawalls that include more natural and complex features to benefit biota and allow for essential biogeochemical processes to occur in aquatic environments. There have been several innovations in recent years that increase the permeability of concrete, however these have limited application in an aquatic context (e.g., not relevant to dam construction or erosion control but may be relevant in stormwater management systems). We provide a brief overview of the history of concrete, discuss some of the direct and indirect effects of concrete on aquatic ecosystems, and encourage planners, engineers, developers, and regulators to work collaboratively to explore alternatives to concrete which benefit aquatic ecosystems and the services they offer. The status quo of concrete being the default construction material is failing aquatic ecosystems, so we recommend that efforts are made to explore alternative materials and if concrete must be used, to increase structural complexity to benefit biodiversity.
... Silica dust, particularly in the form of crystalline silica, can have a range of environmental impacts when it enters the waterways. As outlined by Cooke et al. (2020), aquatic ecosystems experience several interacting effects, especially the marine and freshwater habitats that are impacted directly through water extraction and pollution during concrete production. ...
This study delves into a crucial yet often overlooked aspect of precast concrete manufacturing in New Zealand—dry grinding. Driven by the need to refine product surfaces, this process generates hazardous silica dust, jeopardizing worker health and environmental integrity. The research responds to industry concerns, particularly in light of the COVID-19 pandemic, by seeking innovative, cost-effective, and worker-centric solutions. It meticulously examines health and safety intricacies, assesses dust contamination repercussions, and presents a comprehensive strategy. The ultimate goal is to transform this research into a practical health and safety business proposal, revolutionizing dry grinding practices while prioritizing worker well-being and environmental responsibility.
... The lower microbial diversity on its surface indicates the slightly toxic nature of this cement to marine bacteria, as previously shown for bacteria in groundwater stored in concrete or earthen ponds, the former being lower in diversity and abundance [114]. Indeed, concrete has been described as having especially deleterious consequences on biodiversity in all aquatic ecosystems [115]; this concords with research suggesting that a relatively mature microbial biofilm on concrete in the marine environment is somewhat generic, differing little from normal structural concrete composition [39][40][41]. ...
Concrete is the most utilized construction material worldwide. In the marine environment, it is subject to chemical degradation through reactions with chloride (the most important ion), and sulfate and magnesium ions in seawater, and to biodeterioration resulting from biological (initially microbiological) activities, principally acid production. These two types of corrosions are reviewed and the failure of attempts to predict the degree of deterioration resulting from each is noted. Chemical (abiotic) corrosion is greatest in the splash zone of coastal constructions, while phenomenological evidence suggests that biodeterioration is greatest in tidal zones. There have been no comparative experiments to determine the rates and types of microbial biofilm formation in these zones. Both chemical and microbiological concrete deteriorations are complex and have not been successfully modeled. The interaction between abiotic corrosion and biofilm formation is considered. EPS can maintain surface hydration, potentially reducing abiotic corrosion. The early marine biofilm contains relatively specific bacterial colonizers, including cyanobacteria and proteobacteria; these change over time, producing a generic concrete biofilm, but the adhesion of microorganisms to concrete in the oceans has been little investigated. The colonization of artificial reefs is briefly discussed. Concrete appears to be a relatively prescriptive substrate, with modifications necessary to increase colonization for the required goal of increasing biological diversity.
... The lower microbial diversity on its surface indicates the slightly toxic nature of this cement to marine bacteria, as previously shown for bacteria in groundwater stored in concrete or earthen ponds, the former being lower in diversity and abundance [112]. Indeed, concrete has been described as having especially deleterious consequences on biodiversity in all aquatic ecosystems [113]; this concords with research suggesting that a relatively mature microbial biofilm on concrete in the marine environment is somewhat generic, differing little with normal structural concrete composition [39]; [40]; [41]. Preprints (www.preprints.org) ...
Concrete is the most utilized construction material worldwide. In the marine environment, it is subject to chemical degradation through reactions with chloride (the most important ion), sulfate and magnesium ions in seawater and to biodeterioration resulting from biological (initially microbiological) activities, principally acid production. These two types of corrosion are reviewed and the failure of attempts to predict the degree of deterioration resulting from each is noted. Chemical (abiotic) corrosion is greatest in the splash zone of coastal constructions, while phenomenological evidence suggests that biodeterioration is greatest in tidal zones. There have been no comparative experiments to determine the rates and types of microbial biofilm formation in these zones. Both chemical and microbiological concrete deterioration are complex and have not been successfully modeled. The interaction between abiotic corrosion and biofilm formation is considered. EPS can maintain surface hydration, potentially reducing abiotic corrosion. The early marine biofilm contains relatively specific bacterial colonizers, including cyanobacteria and proteobacteria; these change over time, producing a generic concrete biofilm, but adhesion of microorganisms to concrete in the oceans is little investigated. The colonization of artificial reefs is briefly discussed. Concrete appears to be a relatively prescriptive substrate, with modifications necessary to increase colonization for the required goal of increasing biological diversity.
... Concrete materials are one of the most widely used structural materials used in urban areas and modern urban drainage systems. Urban runoff drains through concrete drainage structures that include pipes, culverts, gutters and canals [22][23][24]. The widespread use of calcareous concrete urban materials has been termed 'urban karst', which can rapidly weather when exposed to low-pH precipitation [6,19]. ...
The use of recycled concrete aggregates as a construction material is growing and this study was conducted to investigate the potential water quality issues that arise when concrete aggregates are exposed to water. The water used in the study was from a high-conservation-value wetland. It was dilute (17.8 µS cm−1), acidic (pH 5.97) and poorly buffered. The ionic composition comprised sodium, bicarbonate and chloride ions. Water was recirculated for 60 min through a control treatment and three treatments containing recycled concrete aggregates (RCAs) of different fragment sizes (10 mm, 20 mm and 60 mm). The fragment size influenced the final water quality, but the response patterns varied between the attributes tested. Post-recirculation, the RCA treatments increased the electrical conductivity by 6 to 12 times; pH by 2.3 to 3.8 pH units; and concentrations of calcium, potassium, bicarbonate and sulphate. The water exposed to RCA materials also increased the concentrations of several metals (aluminium, arsenic, copper, lead and zinc), resulting in hazardous concentrations for aquatic species according to ecological water quality guidelines. Strontium concentrations in water exposed to RCAs increased by 30 to 120 times background levels. The results from this study added further support to a growing body of evidence that the exposure of concrete materials to water can produce environmentally hazardous water quality.
... Steel and concrete GHG emissions also exceeded those for the life cycle of CCA-treated piles (Bolin and Smith 2012). The production of Portland cement, an essential component of concrete, is highly energy intensive and consequently has a large carbon footprint (Meyer 2009;Cooke et al. 2020). Therefore, each project should consider the surrounding environment and determine an appropriate approach on a case-by-case basis within a system level analysis. ...
Small docks and floats are common in estuaries and coastal waters worldwide. These structures serve a role in coastal recreation by facilitating access to waterways. However, they can impact shoreline ecological function. While individual environmental impacts are generally minor, increasing dock proliferation and overlap with sensitive coastal resources can result in cumulative impacts that pose threats at the ecosystem level. Docks promote changes in habitat and aquatic communities through alteration of environmental conditions. Here, we review the potential environmental impacts of docks on estuarine and coastal flora and fauna and discuss best management practices (BMPs) to avoid or minimize such impacts with a focus on New England. We consider impacts in relation to the structural components of docks: the piles, decking, and floats. Impacts to salt marsh and submerged aquatic vegetation are a particular focus given the important ecosystem services these vegetated habitats provide and their vulnerability to dock-induced habitat alteration. Potential environmental impacts depend on structure size, design, and location, and can include both short-term (e.g., turbidity from pile installation) and long-term (e.g., salt marsh loss from chronic shading) effects. Such effects can be minimized through BMPs (e.g., construction outside sensitive time-of-year periods, designs to reduce shading). As BMPs tend to reduce rather than avoid environmental effects, cumulative impacts also need to be considered in the permitting process. We recommend that managers develop plans or bylaws that identify sensitive habitats where dock construction should be avoided as well as BMPs to make remaining dock proliferation less impactful.
... Ceramic modules with tighter surface-pore densities may reduce biofouling and/or enhance targeted species-specific settlement (Johari et al., 2010). Companies are already creating "ecologically active" concrete materials that modify composition and surface texture to support specific marine fauna and flora (Perkol-Finkel and Sella, 2014), lowers the carbon footprint of artificial habitat construction (Dennis et al., 2018), and addresses the concern of concrete waste in aquatic ecosytems (Cooke et al., 2020). One could even consider expanding and adapting this method to test biofilm or antibiofouling coatings that reduce or promote targeted biotic build-up (Tamburri et al., 2008). ...
Identifying features of biogenic (i.e., living) habitat that attract and retain organisms is a key pursuit in ecological habitat selection research. Here we present an integrative method for creating aquatic artificial habitat modules that allow the user to isolate and flexibly manipulate structural and compositional features of replicated biogenic habitats for a range of habitat selection study designs in aquatic environments: This method combines techniques from engineering (3D scanning and printing), paleontology, and visual art (moulding and casting) into a stream-lined work flow that is likely to perform on par with or better than other techniques widely used to create artificial replicas of biogenic habitats in terms of design accessibility (availability and cost of construction materials and equipment, and training requirements), scalability (durability, ease of deployment, and reproducibility), and the ecology of the artificial habitat module (degree to which structural and compositional features of the habitat elicit appropriate visual, chemosensory, and auditory cues, and impact of the structure on the surrounding environment). This method can be flexibly modified to answer a variety of questions regarding habitat selection cues, for a range of aquatic biogenic habitat types, and can be adapted for theoretical and applied contexts including cue studies and restoration planning.
... The same cannot be said for ocean environments, where comparable manmade barriers to movement that fragment habitats do not exist. While docks and jetties may create obstacles to movement (Cooke et al. 2020), they do not fragment the landscape in the same way as land-based structures which would otherwise restrict or prevent movement. Indeed, the ocean has no fences. ...
Understanding and ultimately predicting how marine organisms will respond to urbanization is central for effective wildlife conservation and management in the Anthropocene. Sharks are upper trophic level predators in virtually all marine environments, but if and how their behaviors are influenced by coastal urbanization remains understudied. Here, we examined space use and residency patterns of 14 great hammerheads Sphyrna mokarran , 13 bull sharks Carcharhinus leucas , and 25 nurse sharks Ginglymostoma cirratum in proximity to the coastal metropolis of Miami, Florida, using passive acoustic telemetry. Based on the terrestrial urban carnivore literature, we predicted sharks would exhibit avoidance behaviors of areas close to Miami, with residency patterns in these urban areas increasing during periods of lower human activity, such as during nocturnal hours and weekdays, and that dietary specialists (great hammerhead) would exhibit comparatively lower affinity towards highly urbanized areas relative to dietary generalists (bull and nurse shark). However, we did not find empirical support for these predictions. Space use patterns of tracked sharks were consistent with that of ‘urban adapters’ (species that exhibit partial use of urban areas). Modeling also revealed that an unmeasured spatial variable was driving considerable shark residency in areas exposed to high urbanization. We propose several hypotheses that could explain our findings, including food provisioning from shore-based activities that could be attracting sharks to urban areas. Ultimately, the lack of avoidance of urban areas by sharks documented here, as compared to terrestrial carnivores, should motivate future research in the growing field of urban ecology.
... In addition, the urbanization and hardening of banks or channels reduced the area of riparian zone and floodplains, made rivers lose ecological resilience, and weakened their functions. The development of cascade power stations damaged the habitats of major fish, and consequently species resources declined [21][22][23]. The channelization of rivers destroyed the living environment of animals and plants and caused the ecological imbalance of the river system. ...
With global warming, urbanization, and the intensification of human activities, great pressures on river ecosystems have caused ecosystem degradation, the decline in habitats and biodiversity, and the loss of function. Ecological restoration technologies (ERTs) in rivers are effective measures for improving habitat and biodiversity, which has the advantage of recovering ecosystems and biodiversity and promoting the formation of healthy rivers. Several applications of ERTs, including ecological water transfer, fish passage construction, dam removal/retrofit, channel reconfiguration, river geomorphological restoration, natural shoreline restoration, floodplain reconnection, revegetation, etc., are summarized. The classifications of ERTs are highlighted, aiming to distinguish the difference and relationship between structure and the processes of hydrology, physics, geography, and biology. The pros and cons of these technologies are discussed to identify the applicability and limitations on the river ecosystem. In the dynamic processes in the river, these interact with each other to keep ecosystem balance. ERTs are more helpful in promoting the restoration of the natural function of the river, which contribute to the management of river ecological health. Some proposals on river management are suggested. Establishing a unified river health evaluation system will help promote positive feedback on rivers and the further development of ERTs.
... The availability of water from groundwater aquifers in the United States has been associated with a trend towards settlement away from surface waters since the industrial revolution (Fang and Jawitz 2019). Increased proportions of individuals living in urban areas may give the illusion of reductions in impacts to surface waters, but in many urban areas such water sources are filled in (wetlands; Davidson 2014, Mao et al. 2018 or constrained in concrete channels (Cooke et al. 2020). Pumping of groundwater has also reduced river flow and depleted wetlands such that development away from the valley will not remove all impacts to the stream (de Graaf et al. 2019). ...
Decades ago, Dr Noel Hynes eloquently summarized the inherent interconnectedness of a stream and its valley and made the case that human alteration of the valley would have direct negative consequences for freshwater systems. Currently, the freshwater biodiversity crisis extends across all continents and demands urgent attention from environmental planners, practitioners, and policymakers to protect streams and their valleys. As we work to slow losses of freshwater biodiversity and restore freshwater ecosystems, it is time to revisit the important messages from Hynes. One of the most obvious and immediate actions that could be undertaken is to “back off”— that is, to limit human activity and new development in floodplain and riparian areas immediately adjacent to freshwater systems, including streams, rivers, lakes, and wetlands, while minimizing impacts and risks in areas with existing development. From reducing erosion and flood damage to maintaining cool water temperatures, filtering pollutants, protecting critical habitats, and enabling lateral connectivity, intact riparian zones mitigate many of the threats that degrade freshwater ecosystems. There has been much research to identify optimal setbacks and buffer-strip widths to protect against harm. As such, in many areas, our ability to protect the stream and its valley is not limited by natural science but rather our failure to consistently apply floodplain and riparian regulations and the absence of political will. We are too quick to trade off the environment for short-term economic development. In areas that are already developed, solutions are more complicated but, in many cases, represent a key priority for healing damaged ecosystems and for addressing economic and social risks of vulnerable development. We need to redefine our relationship with freshwater ecosystems, and the first step is to back off and give freshwater ecosystems the opportunity to heal while ensuring that as-of-yet intact riparian areas continue to support freshwater resiliency. In doing so, we will also gain climate adaptive benefits, given that maintaining intact riparian areas is an effective nature-based solution. Key words: Biodiversity, climate change, floodplain, fresh water, management, riparia © 2022 The Society for Freshwater Science. All rights reserved.
... Steel and concrete GHG emissions also exceeded those for the life cycle of CCA-treated piles (Bolin and Smith 2012). The production of Portland cement, an essential component of concrete, is highly energy intensive and consequently has a large carbon footprint (Meyer 2009;Cooke et al. 2020). Therefore, each project should consider the surrounding environment and determine an appropriate approach on a case-by-case basis within a system level analysis. ...
Small docks and floats are common in estuaries and coastal waters worldwide. These structures serve a role in coastal recreation by facilitating access to waterways. However, they can impact shoreline ecological function. While individual environmental impacts are generally minor, increasing dock proliferation and overlap with sensitive coastal resources can result in cumulative impacts that pose threats at the ecosystem level. Docks promote changes in habitat and aquatic communities through alteration of environmental conditions. Here, we review the potential environmental impacts of docks on estuarine and coastal flora and fauna and discuss best management practices (BMPs) to avoid or minimize such impacts with a focus on New England. We consider impacts in relation to the structural components of docks: the piles, decking, and floats. Impacts to salt marsh and submerged aquatic vegetation are a particular focus given the important ecosystem services these vegetated habitats provide and their vulnerability to dock-induced habitat alteration. Potential environmental impacts depend on structure size, design, and location, and can include both short-term (e.g., turbidity from pile installation) and long-term (e.g., salt marsh loss from chronic shading) effects. Such effects can be minimized through BMPs (e.g., construction outside sensitive time-of-year periods, designs to reduce shading). As BMPs tend to reduce rather than avoid environmental effects, cumulative impacts also need to be considered in the permitting process. We recommend that managers develop plans or bylaws that identify sensitive habitats where dock construction should be avoided as well as BMPs to make remaining dock proliferation less impactful.
... The deterioration of steel reinforcement due to corrosion in the concrete environment leads to frequent maintenance and repair of reinforced concrete (RC) structures, thus adversely impacting the economy [1]. Nevertheless, environmental concerns such as global warming due to increased concrete [2] and steel production and unbalanced river ecosystems due to water consumption [3] are rising international interests. In addition, the coastal infrastructure is a vital factor in a country's economic development. ...
Glass fiber reinforced polymer (GFRP) rebars reinforced in concrete are susceptible to degradation in harsh alkaline environments such as moist reinforced concrete and seawater and sea sand concrete. The residual tensile strength of GFRP rebar is essential in designing guidelines for GFRP reinforced concrete in different codes. The residual tensile strength is reflected as an environment reduction factor (C E) to incorporate long-term environmental exposure effects. For this purpose, an extensive database comprising 715 tested specimens were collected from literature to develop GEP tree-based model. Aging tests of GFRP rebars were carried out in the laboratory to test the trained model. Initially, nine gene expression programming (GEP) tree-based models were initially developed using RMSE, MAE, and RSE as fitness functions while varying the numbers of genes. The models were developed employing a random selection of 70% of the conditioned specimens for the training purpose in accordance with the literature. The trained models were validated using the remaining 30% data. A model was chosen to create a prediction formula evaluated from the GEP-expression trees (ETs) and derived MATLAB model based on a broader range of statistical errors and correlations. The chosen model was tested using 36 experimental accelerated aging results, which yielded a comparable statistical evaluation to training and validation data. Two types of GFRP rebars, Type-I (volume fraction of 0.50) and Type-II (volume fraction of 0.60) of three different rebar sizes, i.e., 9.5 mm, 12.7 mm, and 15.9 mm were investigated for determining tensile strength retention (TSR) and C E. The results concluded that smaller Type-I rebars are more susceptible to degradation as compared to Type-II rebars of larger size. A value of 0.76 is recommended for a uniform C E based on the upper bound of 95% confidence interval for design life of 100 years.
... The deterioration of steel reinforcement due to corrosion in the concrete environment leads to frequent maintenance and repair of reinforced concrete (RC) structures, thus adversely impacting the economy [1]. Nevertheless, environmental concerns such as global warming due to increased concrete [2] and steel production and unbalanced river ecosystems due to water consumption [3] are rising international interests. In addition, the coastal infrastructure is a vital factor in a country's economic development. ...
Glass fiber reinforced polymer (GFRP) rebars reinforced in concrete are susceptible to degradation in harsh alkaline environments such as moist reinforced concrete and seawater and sea sand concrete. The residual tensile strength of GFRP rebar is essential in designing guidelines for GFRP reinforced concrete in different codes. The residual tensile strength is reflected as an environment reduction factor (CE) to incorporate long-term environmental exposure effects. For this purpose, an extensive database comprising 715 tested specimens were collected from literature to develop GEP tree-based model. Aging tests of GFRP rebars were carried out in the laboratory to test the trained model. Initially, nine gene expression programming (GEP) tree-based models were initially developed using RMSE, MAE, and RSE as fitness functions while varying the numbers of genes. The models were developed employing a random selection of 70% of the conditioned specimens for the training purpose in accordance with the literature. The trained models were validated using the remaining 30% data. A model was chosen to create a prediction formula evaluated from the GEP-expression trees (ETs) and derived MATLAB model based on a broader range of statistical errors and correlations. The chosen model was tested using 36 experimental accelerated aging results, which yielded a comparable statistical evaluation to training and validation data. Two types of GFRP rebars, Type-I (volume fraction of 0.50) and Type-II (volume fraction of 0.60) of three different rebar sizes, i.e., 9.5 mm, 12.7 mm, and 15.9 mm were investigated for determining tensile strength retention (TSR) and CE. The results concluded that smaller Type-I rebars are more susceptible to degradation as compared to Type-II rebars of larger size. A value of 0.76 is recommended for a uniform CE based on the upper bound of 95% confidence interval for design life of 100 years.
... This is problematic in many ways: rivers are naturally four-dimensional systems that depend on a high degree of connectivity (Ward, 1989;Auerswald et al., 2019), and there are hardly any free-flowing rivers in the world any more (Grill et al., 2019). Practically all hydropower development depends on the introduction of concrete structures into rivers, resulting in habitat fragmentation; indeed, Cooke et al. (2020) have proposed that the concrete conquest of aquatic ecosystems should cease. The creation of impoundments, urbanization, and catchment land use have been identified as the most important factors affecting fish community composition in streams (Bierschenk et al., 2019a;Mueller et al., 2020a). ...
... For a benthic species, such as a freshwater mussel, this situation should be carefully evaluated and guide the future implementation of nature based solutions (see Palmer et al., 2015). Given the dominance of structures made of concrete in aquatic ecosystems and due to their negative effects on many ecological aspects (for a review, see Cooke et al., 2020), future studies should aim at developing more eco-friendly and sustainable materials. These new materials, including more permeable concrete and fibrous materials such as fuzzy ropes , may not only benefit biota but also humans (e.g. through improved biogeochemical cycling), with lower environmental, social and economic costs (Palmer et al., 2015). ...
Anthropogenic freshwater habitats may provide undervalued prospects for long‐term conservation as part of species conservation planning. This fundamental, but overlooked, issue requires attention considering the pace that humans have been altering natural freshwater ecosystems and the accelerated levels of biodiversity decline in recent decades. We compiled 709 records of freshwater mussels (Bivalvia, Unionida) inhabiting a broad variety of anthropogenic habitat types (from small ponds to large reservoirs and canals) and reviewed their importance as refuges for this faunal group. Most records came from Europe and North America, with a clear dominance of canals and reservoirs. The dataset covered 228 species, including 34 threatened species on the IUCN Red List. We discuss the conservation importance and provide guidance on how these anthropogenic habitats could be managed to provide optimal conservation value to freshwater mussels. This review also shows that some of these habitats may function as ecological traps owing to conflicting management practices or because they act as a sink for some populations. Therefore, anthropogenic habitats should not be seen as a panacea to resolve conservation problems. More information is necessary to better understand the trade‐offs between human use and the conservation of freshwater mussels (and other biota) within anthropogenic habitats, given the low number of quantitative studies and the strong biogeographic knowledge bias that persists.
... For example, mega-nourishments employing waves and currents to naturally redistribute sand along the coast are implemented for coastal safety as well as creating opportunities for ecology and society (e.g. Stive et al., 2013;De Vriend et al., 2015;Cooke et al., 2020). Similarly, many NbS have been tested and implemented in fluvial environments, ranging from catchment-scale natural flood management (e.g. ...
Biogeomorphology has been expanding as a discipline, due to increased recognition of the role that biology can play in geomorphic processes, as well as due to our increasing capacity to measure and quantify feedbacks between biological and geomorphological systems. Here, we provide an overview of the growth and status of biogeomorphology. This overview also provides the context for introducing this special issue on biogeomorphology, and specifically examines the thematic domains of biogeomorphological research, methods used, open questions and conundrums, problems encountered, future research directions, and practical applications in management and policy (e.g. Nature based solutions). We find that whilst biogeomorphological studies have a long history, there remain many new and surprising biogeomorphic processes and feedbacks that are only now being identified and quantified. Based on the current state of knowledge, we suggest that linking ecological and geomorphic processes across different spatio‐temporal scales emerges as the main research challenge in biogeomorphology, as well as the translation of biogeomorphic knowledge into management approaches to environmental systems. We recommend that future biogeomorphic studies should help to contextualise environmental feedbacks by including the spatio‐temporal scales relevant to the organism(s) under investigation, using knowledge of their ecology and size (or metabolic rate). Furthermore, in order to sufficiently understand the ‘engineering’ capacity of organisms, we recommend studying at least the time period bounded by two disturbance events, and recommend to also investigate the geomorphic work done during disturbance events, in order to put estimates of engineering capacity of biota into a wider perspective. Finally, the future seems bright, as increasingly inter‐disciplinary and longer‐term monitoring are coming to fruition, and we can expect important advances in process understanding across scales and better informed modelling efforts.
... For a benthic species, such as a freshwater mussel, this situation should be carefully evaluated and guide the future implementation of nature based solutions (see Palmer et al., 2015). Given the dominance of structures made of concrete in aquatic ecosystems and due to their negative effects on many ecological aspects (for a review, see Cooke et al., 2020), future studies should aim at developing more eco-friendly and sustainable materials. These new materials, including more permeable concrete and fibrous materials such as fuzzy ropes , may not only benefit biota but also humans (e.g. through improved biogeochemical cycling), with lower environmental, social and economic costs (Palmer et al., 2015). ...
Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories, intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions.
For millennia humans have extracted biological and physical resources from the planet to sustain societies and enable the development of technology and infrastructure. Growth in the human population and changing consumption patterns have increased the human footprint on ecosystems and their biodiversity, including in fresh waters. Freshwater ecosystems and biodiversity face many threats and it is now widely accepted that we are in a biodiversity crisis. One means of protecting and restoring freshwater biodiversity is to better manage the exploitation of freshwater biota and aggregate resources (e.g., sand, gravel, boulders). Here we outline the threats arising from such exploitation and identify response options to ensure that methods and levels of extraction are sustainable and allow recovery of over-exploited freshwater biodiversity and ecosystems. The guidance we provide will enable practitioners, policy makers, and resource stewards to embrace effective, sustainable, and evidence-based approaches to resource extraction. Response options for managing species exploitation include strengthening assessment and reporting, using science-based approaches to reduce overexploitation and support recovery, embracing community engagement, and building or tightening legislation. Response options for managing exploitation of freshwater aggregate resources include reducing demand for harvest, strengthening governance, reporting, and monitoring of environmental impacts, and promoting the restoration of degraded ecosystems or compensating for losses. Diverse case studies highlight examples of where various management actions have been implemented in an effort to consider how they can be scaled up and adapted to other contexts. Managing exploitation will be a key aspect of broader initiatives needed to protect and restore freshwater biodiversity around the globe.
India is on development path and construction of various infrastructures work is happening at increasing pace and magnitude. The cement and reinforcement are most essential materials required for a infrastructure projects. Both cement and steel production produce large amount of carbon di oxide and also require large amount of energy for production. This is one main aspect of environmental destruction. Ship building activities are ever increasing in India and so construction of new shipyards and modernization of existing shipyards. Launching of ship is one of the most important operations in the entire ship construction process. Getting permissions for such construction involves various authorities and agencies such as concerned Industrial Development Corporation, River Navigation Department, Caption of Ports, Coastal Regulation Zone Authority, Pollution Control Board to name a few. This paper presents some important aspects of environmentally sustainable, ecologically conservable and economical solution Design and Construction Solution of Ship Side Launching Wharfby substituting conventional RCC piles by rammed stone columns to a large extent and use of gabion walls for closing the face of jetty in place of steel or RCC sheet pile making use of locally available quarry stones.
With 39,400 km2 of coastal and marine areas artificialized and an increasing demand due to the growing global population—9 billion by 2050—it has become necessary to find ways to mitigate futures constructions impacts on biodiversity. This study explores how civil engineering can take further technical measures to enhance marine biodiversity, in a real and valuable “win-win” strategy. The global aim is to integrate eco-engineering practices within coastal projects and include ecological targets (e.g., the diversity and speed of biological colonization) early, at the project design stage, with the same level efforts for technical, social, and economic studies. Concrete is the most useful material for coastal infrastructure construction. Therefore, enhance its positive impact on colonization that is by far one of the key points for developers and coastal managers. To this end, the latest research regarding the bioreceptivity of concrete is reviewed, focusing on the characteristics of the marine environment that affect the colonization of concrete and the organisms involved. From this base of publications, the intrinsic and environmental parameters that can influence the intrinsic and the extrinsic bioreceptivity of concrete have been updated, specifically operating the link with the mechanisms leading to the colonization of concrete and biofilm formation, which hasn't been done before. Based on the persistence of their significant effect (after 78 days of immersion in seawater), the intrinsic parameters that support greater biocolonization are classified from more to less effective in the following order: surface roughness (190%) > chemical composition (slag cement instead Portland cement) (136%) > chemical composition (presence of formwork oil) (106%). Lastly, both the ecological effect and the positive and negative effects of biofilm formation on the durability of concrete were analysed to provide clear and operational results for future concrete coastal construction implementation for decision makers.
Water microorganisms contribute to the key components of ecosystems in dryland waters, which are extremely important for wildlife. However, the distribution patterns of water microbes across different basal water sources are still largely unknown. This study was conducted to compare microorganisms in the water bodies of different types of water sources in the Kalamaili Mountain Ungulate Nature Reserve in China. Bioinformatic analysis revealed that the undirected microbial co-existence network consisted of 15 main modules referring to different water sources, which indicated specific molecular co-existence relationships. It was found that the most dominant phyla (namely Proteobacteria, Patescibacteria, Firmicutes, Bacteroidota, and Actinobacteriota) of the molecular ecological network shared the same structures as the microbial community, which justified the construction of the network via a random network formation. Principal coordinate analysis (PCoA) based on Bray–Curtis distances revealed that there were still considerable variations among different habitats, showing separate sample clusters. Additionally, the different topological roles of subnetworks trimmed to a uniform size indicated different co-existence patterns in the microbiome. The artificially recharged water from concrete pond substrate (ARC) subnetworks had a relatively discrete co-occurrence, while the natural water sources (NRE) and artificially recharged water from earthen pond substrate (ARE) groups were more compact with giant modules. The NRE and ARE groups were also richer in microbial composition and had a higher number of species with low abundance. Consequently, concrete substrates may contribute to dysfunction in water microbiomes. Moreover, the functional diversity of the NRE and ARE groups is due to more intra-module connections and more inter-module connections, indirectly leading to a stable function resilient to external environmental influences. In conclusion, the microecology of the NRE was more stable than that of the concrete substrate, and artificial transportation had less effect on the microbial community.
Increasing frequency of extreme weather events, driven by climate change, coupled with growing population densities, have contributed to an increasing demand for coastal structures to protect and stabilize shorelines. Concrete seawalls are a common category of coastal protection structures, designed with the primary objectives of absorbing wave action, preventing coastline erosion, and alleviating flooding. Much research has been carried out on improving concrete seawall performance. This work is a review of the current state-of-the-art in concrete seawalls focusing on design aspects including wave loading and innovative seawall designs, ecological considerations, and durability performance. Different conventional seawalls and their advantages and disadvantages are reviewed. Wave loads on seawalls have received significant attention; and multiple approaches for the quantification for the different types of loads are presented. However, wave load quantification remains a challenging task, especially for novel designs, and performance under load for such designs must be quantified through testing in wave tanks. Drawing inspiration from natural shorelines, modification of surface complexity at a multitude of scales can improve the otherwise poor ecological performance of seawalls. Ecological performance can also be improved by the incorporation of natural materials or structures in seawalls although the exact influence of concrete and other material chemistry on benthic diversity is unclear. The corrosion of the steel is a major durability concern, and the use of non-corrosive reinforcement can increase seawall durability toward corrosion. Other durability concerns include alkali silica reaction and sulfate attack, which can be mitigated through proper mixture design, including through the use of supplementary cementitious materials. Examples of innovative seawall designs and systems which have the capability to outperform conventional seawalls are discussed. Advances in structural design, ecological engineering, and infrastructure materials science will drive the development of multi-functional seawalls which are sustainable, durable, and resilient.
Hydropower production is one of the greatest threats to fluvial ecosystems and freshwater biodiversity. Now that we have entered the Anthropocene, there is an opportunity to reflect on what might constitute a ‘sustainable’ Anthropocene in the context of hydropower and riverine fish populations. Considering elements of existing practices that promote favorable social-ecological outcomes (i.e., ‘bright spots’) is timely given that there are plans to expand hydropower capacity in previously undammed rivers, intensify dam development in some of the world’s largest river systems, and re-license existing facilities. We approach this from a pragmatic perspective: for the foreseeable future, hydropower will likely remain an important source of renewable electricity. To offer support for moving toward a more ‘sustainable’ Anthropocene, we provide syntheses of best practices during the siting, design, construction, operation, and compensation phases of hydropower development to minimize impacts on inland fish. For each phase, we offer positive examples (or what might be considered ‘bright spots’) pertaining to some of the approaches described within our syntheses, acknowledging that these projects may not be viewed as without ecological and (or) societal detriment by all stakeholders. Our findings underscore the importance of protecting critical habitat and free-flowing river reaches through careful site selection and basin-scale planning, infrastructure designs that minimize reservoir effects and facilitate safe passage of fish, construction of hydropower plants using best practices that minimize long-term damage, operating guidelines that mimic natural flow conditions, and compensation that is lasting, effective, inclusive, and locally relevant. Learning from these ‘bright spots’ may require engagement of diverse stakeholders, professionals, and governments at scales that extend well beyond a given site, river, or even basin. Indeed environmental planning that integrates hydropower development into broader discussions is important for conserving regional biodiversity and ecosystem services.
The rapid global spread of the Anthropocene concept across disciplines, languages, cultures and religions has been extraordinary and is unique in scientific history for a basic concept.
Land use and land cover (LULC) such as agriculture, urbanization, and natural resource extraction are major determinants of water quality worldwide. Shifts from natural landscapes to anthropogenic LULC drive chemical, physical, and biological aspects of water quality through alterations in catchment hydrology, sedimentation and fluvial geomorphology, habitat structure, nutrient availability, and contaminant pollution. These alterations affect the abundances and diversity of aquatic biota in many ways. Conservation approaches including riparian buffers and restoration of streams and wetlands can partially mitigate the effects of LULC change. However, water protection policies and novel management approaches are needed to safeguard water resources in the face of human population growth, climate change, and landscape conversion.
Riparian vegetation along urban streams and wetlands is frequently dominated by invasive weeds. Elevated nitrogen and phosphorous in urban waters and soils are well-known to encourage invasive urban weeds, but this research demonstrates that other urban geochemical contaminants may also be influential. Previous studies have demonstrated that the dissolution of urban concrete is a poorly recognised source of modified water and soil geochemistry, which may enhance the growth of some invasive weeds. This study investigated the relationship between urban water quality and the growth of an invasive urban riparian weed, willow ( Salix spp.) to examine the contribution of concrete materials. The study used water from a wetland in the Greater Blue Mountains World Heritage Area. These wetlands have a unique biodiversity but are fragile and susceptible to degradation from human activity. Many are in urban catchments and are frequently dominated by invasive weeds, including Salix spp. In this study, willow cuttings were grown in a laboratory using four water treatments: pristine, urban, and pristine water exposed to two different concrete materials. The urban and concrete water treatments had higher pH, salinity, calcium, potassium, and higher concentration of several metals and were associated with increased growth of Salix spp. We suggest that the modification of urban water and riparian soil chemistry by urban concrete materials may contribute to the success of invasive species in urban wetlands and riparian zones. Some metals (barium, strontium) were present in urban water and in pristine water exposed to concrete and bioaccumulated in plant tissue.
Increasing frequency of extreme weather events, driven by climate change, has resulted in an increasing demand for coastal structures to protect and stabilize shorelines. Concrete seawalls are a common category of coastal protection structures, designed with the primary objectives of absorbing wave action, preventing coastline erosion, and alleviating flooding. Much research has been carried out on improving the seawall performance. This work is a review of the current state-of-the-art in concrete seawalls focusing on design aspects including wave loading and innovative seawall designs, ecological considerations, and durability aspects. Wave loads on seawalls have received significant attention; however, their quantification remains a challenging task especially for novel designs. Drawing inspiration from natural shorelines, modification of surface complexity at a multitude of scales can improve the otherwise poor ecological performance of seawalls. The corrosion of the steel is a major durability concern, and the use of non-corrosive reinforcement can increase seawall durability towards corrosion. Examples of innovative seawall designs and systems which have the capability to outperform conventional seawalls are discussed. Advances in structural design, ecological engineering, and infrastructure materials science will drive the development of multi-functional seawalls which are sustainable, durable, and resilient.
Urban streams are degraded through multiple mechanisms, including severely altered flow regimes, elevated concentrations of waterborne contaminants, removal of riparian vegetation and the loss of a mosaic of heterogeneous aquatic habitats. Engineering of urban stream reaches using concrete is a widespread and extreme case of deliberate alteration of flow regimes and concomitant habitat simplification. To assess the effect of such engineering practices on stream ecosystems, we compared aquatic macroinvertebrate communities from concrete-lined engineered urban reaches, non-engineered urban reaches with natural substrates and reference reaches flowing through minimally disturbed forested subcatchments and with natural substrates, in the Sydney metropolitan region, Australia. The communities from all urban reaches were impoverished and distinctly different from more diverse communities in forested reference reaches. Despite low aquatic habitat heterogeneity, engineered urban reaches had very high abundances of Diptera and some other tolerant taxa. Diptera and/or Gastropoda were dominant in non-engineered urban reaches. Multivariate community structures were dissimilar between the urban reaches and forested reference reaches and between non-engineered and engineered urban reaches. However, the low family-level richness and SIGNAL scores in both urban reach types indicated they were severely ecological impaired, whether engineered or not. Most macroinvertebrate taxa in the regional pool that were hardy enough to inhabit urban reaches with natural substrates were also present in nearby concreted reaches. The results add weight to the growing evidence that in urban landscapes, regional-scale changes in water quality and flow regimes limit the establishment of diverse macroinvertebrate communities, which cannot be addressed through the provision of increased reach-scale habitat heterogeneity.
Recently, designers have begun to pursue sustainability through the fabrication of materials from living organisms such as bacteria, fungi, and algae in order to address environmental issues. Based on the potential of materials from living organisms, this study has explored a sustainable design application using biocement formed thorough microbially-induced calcite precipitation (MICP), which produces minerals by bacterial metabolic activity. Since most of the studies on MICP thus far have focused on limited fields such as engineering, biotechnology, and geo-technology, this study has focused more on improving the application of biocement in design. We optimized MICP conditions using two parameters (i.e., concentration of urea-CaCl2 and bacterial cell density) through water percolation testing, compressive strength testing, and X-ray diffraction (XRD) analysis. Then, based on the optimized conditions, material compatibility testing and scalability testing were performed, and design application research was conducted as well. As a result, biocement has been identified as a potential sustainable design material, based on its 40% compressive strength compared to conventional concrete, improved material finish, aesthetic aspects, and environmental impact. This paper contributes to the development of biocement applications in the environmental design field through multidisciplinary research ranging from biological experiments to design applications.
The western honey bee (Apis mellifera) is the most frequent floral visitor of crops worldwide, but quantitative knowledge of its role as a pollinator outside of managed habitats is largely lacking. Here we use a global dataset of 80 published plant-pollinator interaction networks as well as pollinator effectiveness measures from 34 plant species to assess the importance of A. mellifera in natural habitats. Apis mellifera is the most frequent floral visitor in natural habitats worldwide, averaging 13% of floral visits across all networks (range 0-85%), with 5% of plant species recorded as being exclusively visited by A. mellifera For 33% of the networks and 49% of plant species, however, A. mellifera visitation was never observed, illustrating that many flowering plant taxa and assemblages remain dependent on non-A. mellifera visitors for pollination. Apis mellifera visitation was higher in warmer, less variable climates and on mainland rather than island sites, but did not differ between its native and introduced ranges. With respect to single-visit pollination effectiveness, A. mellifera did not differ from the average non-A. mellifera floral visitor, though it was generally less effective than the most effective non-A. mellifera visitor. Our results argue for a deeper understanding of how A. mellifera, and potential future changes in its range and abundance, shape the ecology, evolution, and conservation of plants, pollinators, and their interactions in natural habitats.
Concrete is the most-used construction material worldwide. Previous studies on the environmental impacts of concrete production have mainly focused on the materials involved and energy consumption, as well as CO2 emissions; little is known, however, about its water consumption as well as the effective measures to reduce such consumption. We quantify water use of global concrete production in 2012 and project the value to 2050. The results show that concrete production was responsible for 9% of global industrial water withdrawals in 2012 (this is approximately 1.7% of total global water withdrawal). In 2050, 75% of the water demand for concrete production will likely occur in regions that are expected to experience water stress. Among possible ways of mitigating water demand are choosing the appropriate selection of electricity fuel mixes and improved processing of raw materials; however, these strategies may conflict with greenhouse gas emissions reduction goals. This work develops a baseline estimate for water consumption and withdrawal for concrete production and identifies locations for targeted mitigation. Little is known about the water impacts of concrete production. This study quantifies this impact globally for 2012 and projects it to 2050. It also evaluates in which regions the impacts will be more severe, based on the availability of renewable water resources.
Plastics have outgrown most man-made materials and have long been under environmental scrutiny. However, robust global information, particularly about their end-of-life fate, is lacking. By identifying and synthesizing dispersed data on production, use, and end-of-life management of polymer resins, synthetic fibers, and additives, we present the first global analysis of all mass-produced plastics ever manufactured. We estimate that 8300 million metric tons (Mt) as of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt of plastic waste will be in landfills or in the natural environment by 2050.
Biodiversity is essential to human well-being, but people have been reducing biodiversity
throughout human history. Loss of species and degradation of ecosystems are likely to
further accelerate in the coming years. Our understanding of this crisis is now clear, and
world leaders have pledged to avert it. Nonetheless, global goals to reduce the rate of
biodiversity loss have mostly not been achieved. However, many examples of conservation
success show that losses can be halted and even reversed. Building on these lessons to
turn the tide of biodiversity loss will require bold and innovative action to transform
historical relationships between human populations and nature.
Physico-chemical characterisation of industrial effluent is of importance in view of its inherent toxic substances. Effluent from cement plant located in Nigeria was characterised and its impact on the receiving Onyi River was investigated in this study. Effluent, water samples from upstream, discharge point along the river course and downstream location were collected monthly. The river was monitored up to about 1 km downstream from the discharge point for a period of twelve months. The impact of the effluent on the water quality downstream was shown by reduced dissolved oxygen. With respect to upstream, the levels of pH, nitrate, phosphate, total solid, total suspended solids, total dissolved solids, turbidity and biological oxygen demand at downstream were much high, arising from the influx of cement effluent. The cement effluent significantly contributed to the levels of Zn (0.045 ± 0.003 mg/L) and Pb (0.016 ± 0.001 mg/L) downstream such that they exceeded the criteria set by USEPA and WHO respectively. Using Prati method of classification of surface water quality, the Onyi River fell in the class of slightly polluted water. Weight arithmetic water quality index of 85.2 and metal pollution index of 3.46 corroborated the classification. Hence, adequate treatment of downstream water prior to its use for beneficial purposes is required.
Waterlogging is one of the major water issues in most cities of China and directly restricts their urbanization processes. The construction of Sponge City is an effective approach to solving the urban water issues, particularly for the waterlogging. In this study, both the urban issues emerged at the stage of rapid urbanization in China and the demands as well as problems of Sponge City construction related with the water issues were investigated, and the opportunities and challenges for the Sponge City construction in the future were also proposed. It was found that the current stormwater management focused on the construction of gray infrastructures (e.g., drainage network and water tank) based on the fast discharge idea, which was costly and hard to catch up with the rapid expansion of city and its impervious surface, while green infrastructures (e.g., river, lake and wetland) were ignored. Moreover, the current construction of Sponge City was still limited to low impacted development (LID) approach which was concentrated on source control measures without consideration of the critical functions of surrounding landscapes (i.e., mountain, river, wetland, forest, farmland and lake), while application of the integrated urban water system approach and its supported technologies including municipal engineering, urban hydrology, environmental science, social science and ecoscape were relatively weak and needed to be improved. Besides, the lack of special Sponge City plan and demonstration area was also a considerable problem. In this paper, some perspectives on Good Sponge City Construction were proposed such as the point that idea of urban plan and construction should conform to the integral and systematic view of sustainable urban development. Therefore, both the basic theoretical research and the basic infrastructure construction such as monitoring system, drainage facility and demonstration area should be strengthened, meanwhile, the reformation and innovation in the urban water management system and the education system should also be urgently performed. The study was expected to provide a deeper thinking for the current Sponge City construction in China and to give some of suggestions for the future directions to urban plan and construction, as well as urban hydrology discipline.
In the present work, a numerical model based upon the Large Eddy Simulation approach has been set up for predicting the three-dimensional flow around a cylindrical pier, mounted on a flat and fixed bed, a generic case that is relevant for the study of flow and scour around bridge piers. This turbulent flow configuration was studied experimentally by Nogueira et al. (2008) with Particle Image Velocimetry (PIV). The main goal of this paper is a first validation of the numerical model, based upon the available data. The numerical tool is capable to qualitatively reproduce the characteristic flow features around the pier, like e.g. the horseshoe vortex system and the vortex shedding in the wake. The predicted extent of the initial scour hole, based upon the bed shear stress magnitudes, agrees well with the observations at the onset of the souring process during the lab experiments. Further quantitative validation of the numerical model will benefit from additional measurement efforts in the experiments.
Digital fabrication has been termed the “third industrial revolution” in recent years, and promises to revolutionize the construction industry with the potential of freeform architecture, less material waste, reduced construction costs, and increased worker safety. Digital fabrication techniques and cementitious materials have only intersected in a significant way within recent years. In this letter, we review the methods of digital fabrication with concrete, including 3D printing, under the encompassing term “digital concrete”, identifying major challenges for concrete technology within this field. We additionally provide an analysis of layered extrusion, the most popular digital fabrication technique in concrete technology, identifying the importance of hydration control in its implementation.
Demand for fresh water by the construction sector is expected to increase due to the high increase in the growth of construction activities in Jordan. This study aims to evaluate the potential of scale-up of the application of treated domestic wastewater in concrete from bench-scale to a full-scale. On the lab scale, concrete and mortar mixes using Primary and Secondary Treated Wastewater (PTW, STW) and Distilled Water (DW) were cast and tested after various curing ages (7, 28, 120, and 200 days). Based on wastewater quality, according to IS 456-2000, the STW is suitable for mortar and concrete production. Mortar made with STW at curing time up to 200 days has no significant negative effect on the mortar’s compressive strength. Conversely, the PTW exceeded the maximum permissible limits of total organic content and E coli. for concrete mixing-water. Using PTW results, a significant increase in the initial setting time of up to 16.7% and a decrease in the concrete workability are observed. In addition, using PTW as mixing water led to a significant reduction in the compressive strength up to 19.6%. The results that came out from scaling up to real production operation of ready-mix concrete were in harmony with the lab-scale results.
General circulation models predict warming trends and changes in temperature and precipitation patterns that have the potential to alter the structure and function of coastal habitats. The purpose of this study was to quantify the expansion and contraction of mangroves and saltmarsh habitats and assess the impact of climate on these landscape changes. The study was conducted in a mangrove/saltmarsh ecotone in Flagler County, FL, near the northern range limit of mangroves along the Atlantic coast of North America. We used time series of historical aerial photography and high-resolution multispectral satellite imagery from 1942 to 2013 to quantify changes in the extent of mangrove and saltmarsh vegetation and compared these changes to climate variables of temperature and precipitation, temperature–seasonality, as well as historical sea-level data. Results showed increases in mangrove extent of 89% between 1942 and 1952, and a continuous increase from 1995 to 2013. Largest decrease in saltmarsh extent occurred between 1942 and 1952 (-136%) and between 2008 and 2013 (-81%). We found significant effects of precipitation, temperature, seasonality, and time on mangrove and saltmarsh areal extent. The statistical effect of sea-level was rather small, but we speculate that it might have ecological impacts on these two coastal ecosystems. Results also showed a cyclical dynamism as well as a reversal in habitat dominance, which may be the result of complex interactions between plant habitats and several environmental drivers of change such as species interactions, and hydrological changes induced by sea-level rise, in addition to temperature and precipitation effects. Our results on mangrove/saltmarsh expansion and contraction may contribute to the improvement of management and conservation strategies for coastal ecosystems being impacted by climate change.
Ecological Engineering (or Ecoengineering) is increasingly used in estuaries to re-create and restore ecosystems degraded by human activities, including reduced water flow or land poldered for agricultural use. Here we focus on ecosystem recolonization by the biota and their functioning and we separate Type A Ecoengineering where the physico-chemical structure is modified on the basis that ecological structure and functioning will then follow, and Type B Ecoengineering where the biota are engineered directly such as through restocking or replanting. Modifying the physical system to create and restore natural processes and habitats relies on successfully applying Ecohydrology, where suitable physical conditions, especially hydrography and sedimentology, are created to recover estuarine ecology by natural or human-mediated colonisation of primary producers and consumers, or habitat creation. This successional process then allows wading birds and fish to reoccupy the rehabilitated areas, thus restoring the natural food web and recreating nursery areas for aquatic biota. We describe Ecohydrology principles applied during Ecoengineering restoration projects in Europe, Australia, Asia, South Africa and North America. These show some successful and sustainable approaches but also others that were less than successful and not sustainable despite the best of intentions (and which may even have harmed the ecology). Some schemes may be 'good for the ecologists', as conservationists consider it successful that at least some habitat was created, albeit in the short-term, but arguably did little for the overall ecology of the area in space or time. We indicate the trade-offs between the short- and long-term value of restored and created ecosystems, the success at developing natural structure and functioning in disturbed estuaries, the role of this in estuarine and wetland management, and the costs and benefits of Ecoengineering to the socio-ecological system. These global case studies provide important lessons for both the science and management of estuaries, including that successful estuarine restoration is a complex and often difficult process, and that Ecoengineering with Ecohydrology aims to control and/or simulate natural ecosystem processes.
The world's population is concentrated in urban areas. This change in demography has brought landscape transformations that have a number of documented effects on stream ecosystems. The most consistent and pervasive effect is an increase in impervious surface cover within urban catchments, which alters the hydrology and geomorphology of streams. This results in predictable changes in stream habitat. In addition to imperviousness, runoff from urbanized surfaces as well as municipal and industrial discharges result in increased loading of nutrients, metals, pesticides, and other contaminants to streams. These changes result in consistent declines in the richness of algal, invertebrate, and fish communities in urban streams. Although understudied in urban streams, ecosystem processes are also affected by urbanization. Urban streams represent opportunities for ecologists interested in studying disturbance and contributing to more effective landscape management.
Human activity is leaving a pervasive and persistent signature on Earth. Vigorous debate continues about whether this warrants recognition as a new geologic time unit known as the Anthropocene. We review anthropogenic markers of functional changes in the Earth system through the stratigraphic record. The appearance of manufactured materials in sediments, including aluminum, plastics, and concrete, coincides with global spikes in fallout radionuclides and particulates from fossil fuel combustion. Carbon, nitrogen, and phosphorus cycles have been substantially modified over the past century. Rates of sea-level rise and the extent of human perturbation of the climate system exceed Late Holocene changes. Biotic changes include species invasions worldwide and accelerating rates of extinction. These combined signals render the Anthropocene stratigraphically distinct from the Holocene and earlier epochs. Copyright
Restoration of ecological structure and function of urban streams probably requires catchment-scale modification of drainage infrastructure, but such catchment-scale restoration attempts and their assessment are rare. They require stream ecologists to embrace the interdisciplinary challenges of studying the social-ecological systems that are urban catchments. We designed and monitored a catchment-scale experiment that involved the retrofit of urban stormwater infrastructure throughout an urban catchment to restore more natural hydrology, water quality, and consequently, ecological condition in the receiving stream. We worked with government authorities and the catchment community (residents and property owners) over several years to fund and implement 289 stormwater retention systems. The length of the project allowed adaptation of the experimental design to expand the project's breadth and of retention-system design to match community needs and catchment context. Planning provisions are particularly important for such an experiment to ensure that the effect of dispersed experimental treatments is not countered by creation of new connected impervious areas elsewhere in the catchment. Catchment-scale experiments can help to transform policy and practice, but their success requires substantial effort and time to build trust among the numerous, diverse stakeholders of human-dominated urban ecosystems. Researchers need to be prepared to adopt an adaptive approach to the implementation of such experiments and to play the lead role in seeking funds for the implementation of the on-ground works necessary to underpin the experiment.
The geochemical signature of freshwater streams can be used to determine the extent and nature of modification to stream water geochemistry due to urban development. This approach used the Gibbs (1970) diagram as a model for evaluation of changes to ionic composition linked to urban development. In this multi-year study, the geochemistry of 21 waterways in the Georges River catchment, Sydney, were monitored and compared with the level of urban development as measured by sub-catchment imperviousness and directly connected imperviousness. The results reflect a strong relationship between the intensity of sub-catchment urban development and stream geochemistry. All major geochemical attributes increased with escalating levels of urban development. The largest increase was for bicarbonate, which increased 18 times from a mean of 6.4 mg L-1 at non-urban streams to a mean of 118 mg L-1 at urban streams. Similarly, mean concentrations of calcium increased by 14 times (from 2 to 27.9 mg L-1). Mean salinity was enriched in the most urban streams, compared with non-urban streams, by more than 6 times. We attribute this, in part, to the influence of urban geology, notably concrete stormwater infrastructure. Changes in stream geochemistry due to urban development are an important element of the urban stream syndrome.
Rapid coastal population growth and development are primary drivers of marine habitat degradation. Although shoreline hardening, a byproduct of development, can accelerate erosion and loss of beaches and tidal wetlands, it is a common practice globally. Here, we provided the first estimate of shoreline hardening along United States coasts and predicted where existing or future hardening may result in tidal wetland loss if coastal management changes are not made. Our analysis indicated that 22,842 km of continental U.S. shoreline, 14% of the total, has been hardened. We also considered how socioeconomic and physical factors relate to the pervasiveness of shoreline hardening and found that housing density, GDP, storms, and wave height were positively correlated with hardening. Over 50% of South Atlantic and Gulf Coast shorelines are fringed with tidal wetlands that could be threatened by hardening based on projected population growth, storm frequency, and a lack of shoreline hardening restrictions.
The downstream ecological effects of large impoundments have previously been reviewed; however, little is known about the downstream ecological effects of small man-made impoundments. In this review, we examine 94 papers focusing on the effects of small impoundments on stream habitat conditions and macroinvertebrates. Most studies (89.3%) address the effects of small impoundments on physical and chemical habitat conditions, while fewer studies (48.9%) address the effects on macroinvertebrates. In general, most studies report no significant downstream effects of small impoundments on physico-chemical variables, whereas macroinvertebrates richness and abundance increased or decreased. Mean effect sizes (as Cohen’s d) for physico-chemical variables range from −0.82 to 0.68 (small weir: −0.21 to 0.35; run-of-river dam: −0.82 to 0.64; low head dam: −0.49 to 0.68), and from −0.03 to 0.63 for macroinvertebrates abundance and richness. Our assessment of the published literature demonstrates the advantage of combining qualitative and quantitative analyses, and that, while small impoundments may have minimal significant effects on most physico-chemical variables, macroinvertebrates’ richness and density may be affected. This review is relevant for management and scientific communities to identify potential alterations of stream habitats and biota by small impoundments.
Significance
A volcanic ash–lime mortar has been regarded for centuries as the principal material constituent that provides long-term durability to ancient Roman architectural concrete. A reproduction of Imperial-age mortar based on Trajan’s Markets (110 CE) wall concrete resists microcracking through cohesion of calcium–aluminum–silicate–hydrate cementing binder and in situ crystallization of platey strätlingite, a durable calcium-aluminosilicate mineral that reinforces interfacial zones and the cementitious matrix. In the 1,900-y-old mortar dense intergrowths of the platey crystals obstruct crack propagation and preserve cohesion at the micron scale. Trajanic concrete provides a proven prototype for environmentally friendly conglomeratic concretes that contain ∼88 vol % volcanic rock yet maintain their chemical resilience and structural integrity in seismically active environments at the millenial scale.
Eight to 10 percent of the world's total CO2 emissions come from manufacturing cement. The global warming gas is released when limestone and clays are crushed and heated to high temperatures. Green concrete is defined as a concrete which uses waste material as at least one of its components, or its production process does not lead to environmental destruction, or it has high performance and life cycle sustainability. Various efforts have been conducted by researchers to arrive at some alternatives that are able to significantly reduce high energy consumed and environmental impacts during fabrication process of cement, including implementing the concept of industrial ecology and green chemistry as well as nanoengineering that study the behavior of the structure and organization of nanoparticles of cement in the mix for achieving higher performance. The cleaner technologies in concrete production, such as substituting relatively high percentage of cement by fly ash (up to 100%), the use of other natural pozzolans, development of concrete with recycling or waste materials, and developing nanoconcrete by integrating CNT's or self sensing CNT's in the concrete mix for higher performance in terms of strength, stiffness, and durability, have been developed and are addressed in this paper. Several efforts that have been done so far in implementing the concept of green concrete and material development of nanosilica in Indonesia is discussed. Finally, problems in the realization of and potential barriers to green concrete as well as political scenarios that have been adopted by several countries through implementation of various priorities and deregulation in various fields are also discussed.
This overview and synthesis paper focuses on the evolution of urban biogeochemical cycles across time. We synthesize empirical data and review existing literature, including papers in this special issue, and we propose the concept of ''urban evolu-tion.'' The built environment often changes quickly in response to human activities, thus contributing to an urban evolution that affects structure, function, and ecosystem services of human settlements over time. Depending upon management, these changes can result in rapid losses of ecosystem functions/services or progress towards restoration. We explore urban evolution through empirical examples such as: (1) land development and nitrogen inputs within a metropolitan region over half a century; (2) watershed drainage by different forms of stormwater manage-ment over decades; (3) human-accelerated weathering in urbanized watersheds over decades; and (4) global salinization of freshwater across urbanizing landscapes over a century. We also synthesize con-cepts relevant to studying urban evolution of infra-structure and ecosystems including: (1) urban watersheds have challenged our whole notion of the ''watershed approach'' due to complex hydrologic boundaries and flow paths over time; (2) the urban hydrologic cycle evolves due to changing infrastruc-ture and human water use over time; (3) the impor-tance of extending research beyond individual sites using an urban watershed approach over space and time; (4) salinization as a universal tracer of watershed urbanization over time; (5) human-accelerated weath-ering of concrete and construction materials contrib-uting to an ''urban karst'' over time; (6) human alteration of the carbon cycle in urban watersheds over time; and (7) detecting distinct biogeochemical sig-natures across cities globally over time. Our synthesis and this special issue suggest that urban biogeochem-ical cycles have exerted a major influence on the elemental composition of the Earth's surface from local to global scales. A new global research agenda is needed to track the evolution of urban biogeochemical cycles as land development proceeds and infrastruc-ture/management changes so we can better evaluate potential losses in ecosystem services, set realistic watershed and river restoration goals, and formulate effective environmental policy for Earth's growing urban population.
The replacement of natural marine habitats with less structurally complex human infrastructure has been linked to the homogenisation of epibenthic assemblages and associated changes in fish assemblages. To mitigate these impacts, eco-engineering efforts have focussed on increasing the physical and biogenic complexity of artificial structures, in the form of crevices added to seawalls and the seeding of the substrate with habitat-forming organisms such as oysters. While these studies have assessed how these interventions affect epibenthic assemblages, the effect of these strategies on the behaviour, such as feeding and habitat use, of different functional groups of fish (e.g. cryptobenthic and pelagic) remains uncertain. To do this, we manipulated complexity on seawalls by adding concrete tiles with different physical (flat or structured with crevices and ridges) and biogenic (seeding with two common habitat-forming species or naturally recruited fouling) complexities. We assessed pelagic and cryptobenthic fish species composition, abundance, interaction time with the tiles and number of feeding bites on three occasions 8–12 months after deployment. Cryptobenthic fish interacted more with physically complex tiles than flat tiles, regardless of biogenic complexity. In contrast, cryptobenthic fish fed more from flat tiles compared to physically complex tiles, and also appeared to feed more from tiles seeded with oysters. Pelagic fish interacted and fed more from naturally fouled tiles compared to unfouled control tiles, regardless of physical complexity. This study showed that manipulating complexity at the scales used here affects behaviour of fish, but it does not affect fish community. Increasing physical complexity facilitated fish use of seawalls as habitat by providing refuge, while it also hindered fish feeding by providing refuge for their prey. Cryptobenthic fish are important trophic linkages in their ecosystems and we have shown that by changing habitat complexity, we can change the habitat use and feeding activity of these fish, allowing them to fulfil this essential ecosystem role.
Growing human populations are driving the development of coastal infrastructure such as port facilities. Here, we used passive acoustic telemetry to examine the effects of a jetty and artificial light on the rates of predation of flatback turtle (Natator depressus) hatchlings as they disperse through nearshore waters. When released near a jetty, around 70% of the tagged hatchlings were predated before they could transit the nearshore, irrespective of the presence or absence of artificial light. Only 3 to 23% of hatchlings encountered predators at a second study site nearby where there was no jetty and a similar amount of nesting activity. Evidence for predation was provided by rapid tag detachment due to prey handling by a predator or the extensive movement of the tags within the receiver array suggesting that the tag (and hatchling) was inside the stomach of a predator. We found that 70% of the fish predators that consumed tags used the jetty as a refuge during the day and expanded their range along nearshore waters at night, predating on hatchlings in areas adjacent to the jetty with the highest nesting density. Sampling of potential predators including lutjanid reef fishes under the jetty revealed the presence of turtle hatchlings in their gut contents. By providing daytime refuges for predators, nearshore structures such as jetties have the potential to concentrate predators and they may pose a significant threat to populations of vulnerable species. Such effects must be taken into consideration when assessing the environmental impacts associated with these structures.
Stormwater control measures (SCMs) are designed to mitigate the deleterious impacts of urban runoff on the water quality of receiving waters. To assess the cumulative effects of SCMs at the watershed scale, we monitored longitudinal changes in storm discharge and stream water chemistry at high temporal resolution in a suburban headwater stream in Charlotte, NC. SCMs significantly decreased or stabilized instream concentrations of reactive solutes (nitrate, soluble reactive phosphorus, and dissolved organic carbon) relative to the upstream control site. However, SCM outflows minimally influenced concentrations of less reactive solutes (major ions) which increased with urbanization. Additionally, instream concentration variability correlated with antecedent moisture conditions – representative of watershed storage availability – highlighting the role that SCM storage availability plays in the timing of solute delivery to the stream. Our results show that SCMs decrease instream concentrations of biogeochemically reactive solutes but the mitigation potential is temporally dynamic and influenced by antecedent conditions.
In the 12 years since Dudgeon et al. (2006) reviewed major pressures on freshwater ecosystems, the biodiversity crisis in the world's lakes, reservoirs, rivers, streams and wetlands has deepened. While lakes, reservoirs and rivers cover only 2.3% of the Earth's surface, these ecosystems host at least 9.5% of the Earth's described animal species. Furthermore, using the World Wide Fund for Nature's Living Planet Index, freshwater population declines (83% between 1970 and 2014) continue to outpace contemporaneous declines in marine or terrestrial systems. The Anthropocene has brought multiple new and varied threats that disproportionately impact freshwater systems. We document 12 emerging threats to freshwater biodiversity that are either entirely new since 2006 or have since intensified: (i) changing climates; (ii) e‐commerce and invasions; (iii) infectious diseases; (iv) harmful algal blooms; (v) expanding hydropower; (vi) emerging contaminants; (vii) engineered nanomaterials; (viii) microplastic pollution; (ix) light and noise; (x) freshwater salinisation; (xi) declining calcium; and (xii) cumulative stressors. Effects are evidenced for amphibians, fishes, invertebrates, microbes, plants, turtles and waterbirds, with potential for ecosystem‐level changes through bottom‐up and top‐down processes. In our highly uncertain future, the net effects of these threats raise serious concerns for freshwater ecosystems. However, we also highlight opportunities for conservation gains as a result of novel management tools (e.g. environmental flows, environmental DNA) and specific conservation‐oriented actions (e.g. dam removal, habitat protection policies, managed relocation of species) that have been met with varying levels of success. Moving forward, we advocate hybrid approaches that manage fresh waters as crucial ecosystems for human life support as well as essential hotspots of biodiversity and ecological function. Efforts to reverse global trends in freshwater degradation now depend on bridging an immense gap between the aspirations of conservation biologists and the accelerating rate of species endangerment.
Mangroves are tropical and subtropical coastal trees able to resist severe conditions including hurricanes and tropical storms. A potential characteristic of their resilience property is their complex root systems, which can be highly efficient to dissipate tidal energy. To further understand the key hydrodynamic parameters of mangrove trees, we modeled the rigid mangrove root system with a simplified array of circular cylinders (patch) and presented the simulation of the patch wake structure. Five patch porosities ranging from = % % (= −) were considered in numerical simulations with ANSYS Fluent. The complex two-dimensional flow structure of the cylinder wake was captured for various streamwise location including far wake region. In addition, the vorticity, and turbulence intensity contours were computed and analyzed. We compared the wake signature of the patch with a single cylinder of the same diameter. We found that, unlike the canonical cylinder, the vorticity field for the porous patch delays the formation of von Kármán vortex street due to the small vortices in the near wake. An increase in patch porosity gives rise to the delay of vortex street formation and decays the wake vorticity and turbulent kinetic energy. The characteristic of the wake structure behind the patch could be used as guiding reference for coastal protection structures inspired by mangrove roots. Additionally, we present mangrove application in coastal protection.
Surface physical properties, hydrodynamics, biochemical cues, orientation and temporal scales play an important role in invertebrate larval recruitment on artificial substrates. In the present study, invertebrate recruitment on four different substrates (acrylic, stainless steel, ceramic and concrete panels) was investigated in two different orientations (vertical and horizontal) in the central Red Sea. Results showed significant variations in the abundance of benthic invertebrates between the different substrates. While barnacles and bivalves preferred panels placed in vertical positions, the abundance of bryozoans was high on horizontal panels. Artificial panel submersion season plays a significant role in the recruitment of benthic invertebrates on surfaces in the Red Sea. In conclusion, this study supports the overall notion that marine invertebrate recruitment on hard substrates is regulated by a combination of factors which include substrate type, orientation and submersion season.
Disruption of movement patterns due to alterations in habitat connectivity is a pervasive effect of humans on animal populations. In many terrestrial and aquatic systems there is increasing tension between the need to simultaneously allow passage of some species while blocking the passage of other species. We explore the ecological basis for selective fragmentation of riverine systems where the need to restrict movements of invasive species conflicts with the need to allow passage of species of commercial, recreational, or conservation concern. We develop a trait‐based framework for selective fish passage based on understanding the types of movements displayed by fishes and the role of ecological filters in determining the spatial distributions of fishes. We then synthesize information on trait‐based mechanisms involved with these filters to create a multi‐dimensional niche space based on attributes such as physical capabilities, body morphology, sensory capabilities, behavior, and movement phenology. Following this, we review how these mechanisms have been applied to achieve selective fish passage across anthropogenic barriers. To date, trap‐and‐sort or capture‐translocation efforts provide the best options for movement filters that are completely species selective, but these methods are hampered by the continual, high cost of manual sorting. Other less effective methods of selective passage risk collateral damage in the form of lower or higher than desired levels of passage. Fruitful areas for future work include using combinations of ecological and behavioral traits to passively segregate species; using taxon‐specific chemical or auditory cues to direct unwanted species away from passageways and into physical or ecological traps while attracting desirable species to passageways; and developing automated sorting mechanisms based on fish recognition systems. The trait‐based approach proposed for fish could serve as a template for selective fragmentation in other ecological systems. This article is protected by copyright. All rights reserved.
Seawalls made from rock and concrete are engineered to defend coastlines and infrastructure from sea level rise, storm surge and shoreline erosion. However, while they provide a poor substitute for natural intertidal habitat, emerging designs addressing this biodiversity deficit have incorporated eco-engineering concepts with promising results. This study tested whether adding inexpensive household flower boxes (artificial rock pools) to a seawall in a tropical region would support benthic flora and fauna, and whether simple orientation of boxes improves benthic assemblage colonization. Boxes were positioned at mean tide height (1.1 m AHD) along a seawall in tropical Townsville, Australia. Nine boxes were deployed: three positioned vertically on the seawall, while three positioned at 45° facing towards the sea, and three positioned at 45° facing towards the land. Tilting the artificial rock pools at 45° compared overhang walls (simulating rocky shoreline ledge microhabitat) to vertical walls of artificial rock pools. After 12mths, boxes had accumulated (particularly inside on overhang walls compared to outside walls) a greater surface cover of algae and invertebrates. After the second year, box inside walls supported vastly different assemblages compared to outside box walls regardless of orientation, with the most diverse benthic assemblage found on overhang walls, giving support to the conclusion that artificial rock pools on seawalls support more biodiversity (of native species, with no non-indigenous species found) from tilting and creating overhangs. The turbid nature of this coastal region contributed to sediment accumulation at about 25 mm/yr, regardless of box orientation, which may pose maintenance problems (and cost) for managers, and if unchecked could negate any advantages offered by these engineered pool features.
This paper presents the feasibility of wastewater from small scale water treatment plants located in residential buildings as mixing water in Ordinary Portland Cement (OPC). Fourteen water treatment plants were found out in the Narasaraopet municipality region in Guntur district, Andhra Pradesh, India. Approximately, from each plant, between 3500 and 4000 L/day of potable water is selling to consumers. All plants are extracting ground water and treating through Reverse Osmosis (RO) process. During water treatment, plants are discharging approximately 1,00,000 L/day as wastewater in side drains in Narasaraopet municipality. Physical and chemical analysis was carried out on fourteen plants wastewater and distilled water as per [1]. In the present work, based on the concentrations of constituent’s in wastewater, four typical plants i.e., Narasaraopeta Engineering College (NECWW), PatanKhasim Charitable Trust (PKTWW), MahmadhKhasim Charitable Trust (MKTWW) and Amara (ARWW) were considered. The performance of four plants wastewater on physical properties i.e., setting times, compressive strength, and flexural strength of Ordinary Portland Cement (OPC) were performed in laboratories and compared same with reference specimens i.e., made with Distilled Water (DW) as mixing water. No significant change was observed in initial setting time but significant change was observed in finial setting time. No significant change was observed in 90 days compressive strengths in four plants wastewater compared to that of reference specimens. XRD technique was employed to find out main hydration compounds formed in the process.
Paulo J. M. Monteiro, Sabbie A. Miller and Arpad Horvath provide an overview of the challenges and accomplishments in reducing the environmental burden of concrete production.
The covering of native soils with impervious surfaces (e.g. roofs, roads, and pavement) prevents infiltration of rainfall into the ground, resulting in increased surface runoff and decreased groundwater recharge. When this excess water is managed using stormwater drainage systems, flow and water quality regimes of urban streams are severely altered, leading to the degradation of their ecosystems. Urban streams restoration requires alternative approaches towards stormwater management, which aim to restore the flow regime towards pre-development conditions. The practice of stormwater infiltration—achieved using a range of stormwater source-control measures (SCMs)—is central to restoring baseflow. Despite this, little is known about what happens to the infiltrated water. Current knowledge about the impact of stormwater infiltration on flow regimes was reviewed. Infiltration systems were found to be efficient at attenuating high-flow hydrology (reducing peak magnitudes and frequencies) at a range of scales (parcel, streetscape, catchment). Several modelling studies predict a positive impact of stormwater infiltration on baseflow, and empirical evidence is emerging, but the fate of infiltrated stormwater remains unclear. It is not known how infiltrated water travels along the subsurface pathways that characterise the urban environment, in particular the ‘urban karst’, which results from networks of human-made subsurface pathways, e.g. stormwater and sanitary sewer pipes and associated high permeability trenches. Seepage of groundwater into and around such pipes is possible, meaning some infiltrated stormwater could travel along artificial pathways. The catchment-scale ability of infiltration systems to restore groundwater recharge and baseflow is thus ambiguous. Further understanding of the fate of infiltrated stormwater is required to ensure infiltration systems deliver optimal outcomes for waterway flow regimes.
This chapter introduces important problems related to crude oil, the main feedstock of most polymer-based materials. These problems include interstate wars and environmental disasters. The latter is the most worrisome, such as the recent Deep Water Horizon oil spill that released approximately 780. million liters of crude oil on the Gulf of Mexico. Some historical examples on the use of bio-admixtures in construction materials are presented. The importance of biopolymers and biotech admixtures for eco-efficient construction materials is summarized. A brief review on the role of promising biotech-based materials, like cellulose nanocrystals for eco-efficient construction, is given. An outline of the book is also given.
Wood coating experts are concentrating to manufacture waterborne UV coatings so as to protect wood and keep them natural along with fulfilling the demands of the latest chemistry and curing technology. They are working constantly on cutting-edge technical solutions by collaborating with leading coating system manufacturers thereby formulating waterborne and UV products to meet a wide range of requirements within the industrial coatings industry. The waterborne coatings offer the advantage of producing a dry film that can be applied using a variety of techniques, over standard waterborne or solvent borne coatings. Certain other benefits of these deployed coatings include excellent chemical and physical features but require high initial costs of investment in equipment and materials for UV coating users. The wood industry especially is facilitated with increased productivity along with marked reductions in solvent emission through the development of these waterborne UV coatings.
The strength of concrete is its heterogeneous composition. It is a system that is formed by the chemical process of hydration, producing crystalline and amorphous reaction products interlocking and binding the aggregates together. The material grows in time, resulting in a resilient system that is sufficiently strong to carry loads but can also respond to environmental conditions. Crack initiation and crack growth at the various scale levels govern the mechanical tensile response of the heterogeneous concrete material. Therefore, the fracture mechanics principles of strength and energy criteria help in understanding and modelling the response mechanisms. The internal stress conditions and defect distributions are at (i) meso-level, governed by the aggregate grading, mortar and bonding (ITZ) properties, and at (ii) micro-level, defining the mortar properties (aggregates-cement matrix, ITZ and capillary pore system). The structure at micro/nano-level (cement matrix and micro-pore system) gives the sub-scale condition for the mortar. In this chapter we will describe the concrete system and the material structure from the material science point of view at the microscopic and mesoscopic levels, respectively. It provides general background information for the chapters that follow.
A variety of patented approaches have been devised in efforts to halt shoreline erosion. Commonly termed ‘alternative’ or ‘innovative’ technologies, these are typically variations on the traditional approaches. A categorization of these approaches is presented that identifies devices placed in the water and devices placed on the beach. These categories are further subdivided. Despite their innovative nature and the claims of their inventors and promoters, these devices suffer from a variety of weaknesses when deployed in the real world. We present a non-exhaustive list of 110 devices for which US patents were awarded since 1970.
The view of success of ‘alternative’ devices often differs between reports made by the developer and those of the end-user and only in a few cases have objective assessments been made. Using a variety of sources we review experiences with artificial surfing reefs and beach drainage systems. We conclude that ‘alternative’ devices offer the same range of shortcomings as traditional shoreline stabilization approaches because of the inherent inability to control such a dynamic sedimentary environment and the failure to address the underlying causes of shoreline recession (sea level rise, sediment supply, other engineering structures, and the presence of infrastructure in the active coastal zone).
Ecological engineering is a relatively unfamiliar, cost-effective strategy for tackling the "second generation" of water resource problems. It can be defined as the design, construction, operation, and management of landscape/aquatic structures and associated plant and animal communities to benefit humanity and nature. It is introduced by comparing it with "conventional" engineering, including case studies with cost and performance data. Ecological engineering can offer important potential advantages: better performance, less cost, multiple benefits, and better acceptance by the public and regulators. It can cost less because structures are sometimes not as highly engineered and are durable and self-maintaining. Natural energy sources and self-regulating processes reduce operation and maintenance costs. The ancillary benefits can be ecological, recreational, or economic. Case studies include a treatment of wetland to remove nitrogen from wastewater, a lakeshore stabilization project, and stream and riparian restoration via beaver reintroduction. The investigation concludes with a discussion of obstacles and caveats for ecological engineering.
Urban drainage systems that use concrete gutters, pits and pipes have been adopted worldwide by drainage engineers. This study tested the hypothesis that treating a concrete pipe with a coating of epoxy resin is an effective method to reduce the concrete mineral leaching and associated contamination of water carried within the pipe. Four 20 litre samples of rainwater were individually circulated through the untreated and epoxy treated portions of the pipe for 100 minutes. After recirculation through the untreated portion of the pipe pH increased by almost two units, electrical conductivity doubled and there were significant increases in bicarbonate, calcium and other ions. In contrast, rainwater circulated through the epoxy treated portion of the pipe showed a minimal pH increase (0.32 pH units) but no other significant increases in any other water chemistry attributes. The epoxy resin greatly reduced mineral contamination of recirculated water, supporting the hypothesis.
The potential for enhancing fish abundance, species richness, and biomass on artificial reefs was examined by attaching floating attractants and manipulating structural complexity of small concrete reefs each approximately 1.3 m in diameter, 1 m high. Experimental design consisted of a comparison of fish assemblages among three treatments (10 replicate, hemisphere-shaped reefs each): 10-m floating line attached (Streamer); concrete block in the central void space (Block); and no floating line or concrete block (Control). Reefs were deployed on sandy substrate at 20-m depth off Fort Lauderdale, Florida, USA. Divers recorded fish census data on slates 18 times over 24 months. Species composition, numbers of individuals per species, and estimated total length (TL; by size class: 20 cm) for all fishes within 1 m of each reef were recorded. Size classes were used to calculate fish biomass. There was a significant difference among treatments. Block reefs had higher numbers of individuals, species, and biomass than Streamer or Control reefs (p 0.05). These results highlight the importance of structural complexity in artificial reefs designed to enhance fish recruitment, aggregation, and diversity. Copyright 2002 Published by Elsevier Science Ltd on behalf of the International Council for the Exploration of the Sea.
In 1992, a UN conference on Environmental Development held in Rio de Janeiro reintroduced the concept of "sustainability"(advanced by the United Nations Commission on Environment and Development [UNCED] in 1987) and defined it as: "Development that meets the needs of the present without compromising the ability of future generations to meet their own needs." A year later the U.S. Green Building Council was established to formalize this concept by developing a green rating system — "Leadership in Energy and Environmental Design" (LEED), applicable to new and renovated buildings. The system utilizes 69 certification points dealing with sustainable sites, water efficiency, energy and atmosphere, materials and resources, air quality and innovation. Recently, several investigators, including this author, extended the applicability of sustainability to environmental science and engineering studies. This paper deals with sustainable port development and operation. During the last two decades, several ports introduced "Green Ports" programs to promote environmental stewardship. The paper depicts several examples and shows how these and more advanced programs can be made to fit a sustainability framework. Eight specific port operational topics (dredging, ballast water, habitat restoration, air quality, water conservation, energy conservation, material conservation and waste handling) are discussed using a sustainability perspective. It is believed that employment of a holistic approach and adaptive management built around a sustainability framework can promote innovative thinking, collaboration, consensus building and streamline regulatory mandates. While incorporation of some sustainability elements can increase initial costs, they can yield substantial life cycle savings resulting from lower energy and water consumption and wastewater and emissions production, lower O&M costs and savings from increased productivity and health. The paper cites port initiatives advanced by the Port of New York and New Jersey to show how this approach can be propagated to create a clean and green system that is self-pollinating and rewards heavily. Sustainability is an ideal stewardship-driven alternative to the reactive and piecemeal regulatory-driven modes of yesteryear.
This paper presents the use of artificial reef structures as submerged breakwaters, providing both wave attenuation for shoreline stabilization, and habitat for biological and environmental enhancement. The interactions between the coastal process and the reefs and submerged breakwaters are discussed, and examples of natural reefs and man-made submerged breakwaters are shown.