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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.

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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.
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The pyroclastic aggregate concrete of Trajan's Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime-volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium-aluminum-silicate-hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8-0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45-0.75. Dense clusters of 2- to 30-μm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.
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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.
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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.
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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.
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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.
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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.
Conference Paper
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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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).
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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.
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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.
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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.
Conference Paper
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.
Conference Paper
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.