Ecological Engineering

Published by Elsevier BV

Print ISSN: 0925-8574


Considerations in miniaturizing simplified agroecosystems for advanced life support
  • Literature Review
  • Full-text available

February 1996


73 Reads

Tyler Volk
Miniaturizing the Earth's biogeochemical cycles to support human life during future space missions is the goal of the NASA research and engineering program in advanced life support. Mission requirements to reduce mass, volume, and power have focused efforts on (1) a maximally simplified agro-ecosystem of humans, food crops, and microbes; and, (2) a design for optimized productivity of food crops with high light levels over long days, with hydroponics, with elevated carbon dioxide and other controlled environmental factors, as well as with genetic selection for desirable crop properties. Mathematical modeling contributes to the goals by establishing trade-offs, by analyzing the growth and development of experimental crops, and by pointing to the possibilities of directed phasic control using modified field crop models to increase the harvest index.

Fig. 1. ( Continued ) 
Fig. 1. Major experimental events, (a) planting; (b) vegetative stage; and (c) harvest maturity. 
Fig. 1. (Continued) (3.2 g MJ − 1 , Tubiello et al., 1997), but about 40% higher than those reported for optimal field conditions under ambient CO 2 (2.0-2.2 g MJ − 1 Gallagher and Biscoe, 1978). The IAB RUE might have been high partly because PAR intensity in the IAB was low during the experiment compared to typical field conditions. Under low light environments, canopy leaves are seldom light-saturated and thus can photosynthesize more efficiently (Norman and Arkebauer, 1991). In addition, previous studies suggest that a high ratio of diffuse-to-direct light enhances crop RUE (Sinclair et al., 1992). Thus, diffuse light inside the IAB-due to the space-frame structure, as well as elevated CO 2 levels-might also have contributed to increase crop RUE with respect to field values. In fact, additional model simulations indicated that low light levels in the IAB could alone explain more than half (about 55%) of the discussed 40% increase in RUE with respect to field conditions. In those simulations, elevated CO 2 contributed about 30% to such increase, while diffuse light was responsible for to the remaining 15%. Finally, because CO 2 levels varied significantly during the day, by as much as 300 ppmv by the end of the growing season, it is difficult to interpret our data from a 
Table 5 Phenology, experiment and simulation results
Table 6 Crop Production, experiment and simulation results


Growing wheat in Biosphere 2 under elevated CO2: Observations and modeling

February 1999


376 Reads



Ty Morton




Bruno D.V Marino
Spring wheat (Triticum aestivum L., cv. Yecora Rojo) was grown in the intensive agricultural biome (IAB) of Biosphere 2 during the l995-l996 winter/spring season. Environmental conditions were characterized by a day/night temperature regime of 27/17 degrees C, relative humidity (RH) levels around 45%, mean atmospheric CO2 concentration of 450 ppmv, and natural light conditions with mean intensities about half of outside levels. Weekly samples of above-ground plant matter were collected throughout the growing season and phenological events recorded. A computer model, CERES-Wheat, previously tested under both field and controlled conditions, was used to simulate the observed crop growth and to help in data analysis. We found that CERES-Wheat simulated the data collected at Biosphere 2 to within 10% of observed, thus suggesting that wheat growth inside the IAB was comparable to that documented in other environments. The model predicts phenological stages and final dry matter (DM) production within l0% of the observed data. Measured DM production rates, normalized for light absorbed by the crop. suggested photosynthetic efficiencies intermediate between those observed under optimal field conditions and those recorded in NASA-Controlled Ecological Life-Support Systems (CELSS). We suggest that such a difference can be explained primarily in terms of low light levels inside the IAB, with additional effects due to elevated CO2 concentrations and diffuse light fractions.

Large-Scale Controls on Potential Respiration and Denitrification in Riverine Floodplains

May 2012


641 Reads

Restoration measures of deteriorated river ecosystems generally aim at increasing the spatial heterogeneity and connectivity of these systems in order to increase biodiversity and ecosystem stability. While this is believed to benefit overall ecological integrity, consequences of such restoration projects on biogeochemical processes per se (i.e. ecosystem functioning) in fluvial systems are rarely considered. We address these issues by evaluating the characteristics of surface water connection between side arms and the main river channel in a former braided river section and the role and degree of connectivity (i.e. duration of surface water connection) on the sediment biogeochemistry. We hypothesized that potential respiration and denitrification would be controlled by the degree of hydrological connectivity, which was increased after floodplain restoration. We measured potential microbial respiration (SIR) and denitrification (DEA) and compared a degraded floodplain section of the Danube River with a reconnected and restored floodplain in the same river section. Re-establishing surface water connection altered the controls on sediment microbial respiration and denitrification ultimately impacting potential microbial activities. Meta-variables were created to characterize the effects of hydrology, morphology, and the available carbon and nutrient pools on potential microbial processing. Mantel statistics and path analysis were performed and demonstrate a hierarchy where the effects of hydrology on the available substrates and microbial processing are mediated by the morphology of the floodplain. In addition, these processes are highest in the least connected sites. Surface water connection, mediated by morphology regulates the potential denitrification rate and the ratio of N2O to N2 emissions, demonstrating the effects of restoration in floodplain systems.

Modeling mosquitofish (Gambusia holbrooki) responses to Genapol OXD-080, a non-ionic surfactant, in rice fields

February 2001


65 Reads

An ecotechnological approach to control crayfish (Procambarus clarkii) infestation in rice fields of the Lower Mondego River Valley (Central Portugal) has recently been investigated. The application of the biodegradable non-ionic surfactant Genapol OXD-080, a fatty alcohol polyglycol ether, in rice paddies at a given concentration (50 mg/l) has been considered as a non-harmful chemical method to mitigate damage caused by crayfish digging activities to rice crops. Therefore, an important requirement regarding the ecological viability of this approach is that populations of non-target species are not significantly affected. A simple mosquitofish (Gambusia holbrooki) population model, in which the relationships with its main food prey were considered, was developed to assess the potential risk to a non-target key species of contaminating the irrigation channels following surfactant application. The model is based on data concerning mosquitofish life cycle and population dynamics, as well as mosquitofish diet and interactions with its main prey species. Quantitative information regarding the acute and sublethal effects of Genapol OXD-080 on mosquitofish and other non-target organisms was obtained from laboratory experiments. Three concentrations of Genapol OXD-080 (0.75, 1 and 2.5 mg/l) were used to simulate a small amount of contamination in irrigation channels. If contamination occurred, the mosquitofish population would tend to decline dramatically, even when submitted to a very small concentration of Genapol OXD-080 (e.g. 0.75 mg/l, 66.7 times lower than the concentration planned to be used in rice paddies). Thus, Genapol OXD-080 could potentially cause vast damage to local mosquitofish populations, and therefore should not be used without taking all precautions to avoid contaminating important biological reservoirs, such as the rice field irrigation channels.

Fate of 15N-Nitrate in Unplanted, Planted and Harvested Riparian Wetland Soil Microcosms

October 2002


297 Reads

Riparian wetlands are important for the protection of river water quality in agricultural landscapes by intercepting and removing nutrients, such as nitrate (NO3−), in runoff. However, limited information is available on the relative importance of biological NO3− removal processes in these ecosystems. In this study the fate of 15N-NO3− was investigated for 32 days in three types of wetland soil microcosm (unplanted, planted, and planted with shoot harvest) in order to identify the key processes responsible for NO3− removal, elucidate the role of the wetland plant and determine the effect of shoot harvest. 15N-NO3− solution (7.9 mg N l−1, 99 at.% 15N) was added to each microcosm at a rate of 0.5 μg N g−1 soil every 2 days. In both types of plant-inhabited microcosm, similar proportions of added 15N-NO3− were denitrified (61–63%), soil-immobilised (24–26%), plant-assimilated (11–15%) and reduced to ammonium (NH4+) (<1%). However, in unplanted microcosms, 49% was reduced to NH4+, 29% denitrified and 22% immobilised. Elevated denitrification in the presence of the plant, glaucous sweetgrass (Glyceria declinata), was attributed to a higher degree of soil oxidation, which is considered to be the principal regulator of NO3− partitioning between denitrification and DNRA. Shoot harvest did not affect the fate of 15N-NO3−, but it decreased new shoot production (by a factor of 3.9), inhibited new root production, and increased the NO3− assimilation capacity of shoots (by a factor of 5.2). Although this study lasted for only 1 month, the results have important implications for riparian ecosystem management, restoration and design. The water quality protection afforded by riparian wetlands might be substantially enhanced by maximising vegetation cover with plants like G. declinata that promote high denitrification nitrogen (N) losses. In contrast, shoot harvest as a mechanism of permanent N loss may be much less important.

Adsorptive removal of fluoride from aqueous phase using waste fungus (Pleurotus ostreatus 1804) biosorbent: Kinetics evaluation

September 2007


333 Reads

This contribution presents results pertaining to the adsorptive studies carried out on fluoride removal using waste fungal biomass (Pleurotus ostreatus 1804) derived from laccase fermentation process. Batch sorption studies were performed and the results revealed that biosorbent demonstrated the ability to adsorb fluoride from aqueous phase. The sorption interaction of fluoride onto non-viable fungal species obeyed the pseudo-first-order rate equation. Isothermal data fitted well with the Langmuir isotherm adsorption model. Fluoride sorption was found to be dependent on the aqueous phase pH and the fluoride uptake was observed to be greater at lower pH. The fluoride sorption phenomena on fungal biosorbent might be attributed to the chemical type of interaction. In order to gain the practical utility of the studied biosorbents, batch studies were performed to evaluate their viability for real field application using eight water samples collected from the fluorsis-affected area.

Sustainability at the U.S. Environmental Protection Agency: 1970–2020

May 2007


95 Reads

Perhaps reflecting the minor role that sustainability plays in EPA's statutory mission, the agency has adapted to changing environmental issues in an often slow and uneven manner to make sustainability a key element of its environmental policy. This article uses the words of past and present EPA administrators to identify major themes contributing to sustainability and assesses how a regulatory agency created to address pollution control has evolved to face new problems resulting from population increases, urbanization, and global economic growth. EPA can enhance its role in promoting sustainability by redefining relationships with the regulated community, defining and measuring sustainable outcomes, using science to support sustainable decision-making, and promoting stewardship and collaborative problem solving. Between now and 2020, as key environmental questions relate ever more closely to sustainability, EPA can draw upon the best of its experience, knowledge, and resources to play a central role in leading the public and private sectors towards sustainability.

Watershed modelling of nonpoint nitrogen losses from arable land to the Swedish coast in 1985 and 1994

April 2000


21 Reads

Eutrophication problems in the Baltic Sea have drawn attention to the contribution of nutrients from surrounding countries. By using the HBV-N model in southern Sweden (145 000 km2) daily nitrogen leaching, reduction in rivers and lakes, net transport to the sea and source apportionment have been calculated in 3725 subbasins for the period 1985–1994, with calibration at 722 sites against measured time series. On average, 48% of the nonpoint losses from agriculture were reduced during the transport towards the sea, which left about 33 500 tonnes in annual mean net transport. This represents 45% of the total land-based load. Land cover and emissions for the years of 1985 and 1994 were used in two separate simulations of the 10-year period. The normalized gross leakage from arable land in 1985 was estimated to 29 kg N ha−1 year−1, which corresponds to 15 kg N ha−1 year−1 in net leakage to the sea. In 1994 these transports were reduced by 20 and 15%, and thereby the total load on the sea was decreased by 7%. This is still far from the Swedish goal of 50% reduction. The article presents the spatial variation of nitrogen leakage and retention within the southern half of Sweden, and emphasizes the importance of allocating measures where down-stream retention is low in order to achieve efficiency with respect to the sea. It is shown that the model approach may be used in the decision making process for best management practices in watersheds.

A review of published wetland research, 1991–2008: Ecological engineering and ecosystem restoration

August 2010


2,622 Reads

An effective bibliometric analysis based on the Science Citation Index (SCI) published by the Institute of Scientific Information (ISI) was carried out to identify wetland research between 1991 and 2008. The objective was to conduct a quantitative and qualitative analysis for global trends of wetland-related research. The characteristics related to publications were analyzed. The results showed the significant wetland research issues in the SCI database. From 1991 to 2008, the annual number of journal articles published and the number of articles cited to wetland research increased more than sixfold and ninefold respectively. The USA produced the most single-country articles and international collaborative articles, followed by Canada and UK. The results also showed the significant wetland research issues in SCI database. The most frequently used words were: “water” (or “water quality”), which ranked 3rd, 7th, and 3rd according to the word in article title, author keyword, and keyword plus analysis, respectively. Constructed wetland biodiversity became more active in wetland research. The keywords “constructed wetland” and “constructed wetlands” ranked 58th and 12th in 1991–1996, while they ranked 5th and 4th in 2003–2008; the author keyword “biodiversity” ranked 45th in 1991–1996, while it ranked 23rd in 1997–2002, and 14th in 2003–2008; and keyword plus “diversity” ranked 93rd in 1991–1996, while it ranked 20th in 1997–2002, and 17th in 2003–2008. Moreover, it was proved that article title, author keyword, and keyword plus analysis methods were effective approaches for mapping wetland research. Popular wetland research issues and wetland research changes were also identified by statistical analysis.

Fig. 1. Biospherian crew time tasks inside Biosphere 2. Averages are based on data from March 1992– February 1993 (Nelson and Dempster, 1996). 
Fig. A.1. Schematic of data acquisition and monitoring systems in Biosphere 2. 
Overview and Design Biospherics and Biosphere 2, mission one (1991–1993)

June 1999


3,300 Reads

This paper outlines concepts, construction and operation of Biosphere 2, the large glass closed life facility in the mountains of southern Arizona, USA. Plans used concepts of systems ecology and biospherics from the early writings of V.I. Vernadsky, work of the Russian space program on closed ecological life support systems and other leading proponents of a total systems approach to ecology. Mission one was the first experimental closure of Biosphere 2 with eight crew members for 2 years, 1991–1993.

The 1994 experimental opening of the Bonnet Carre Spillway to divert Mississippi River water into Lake Pontchartrain, Louisiana

August 2001


160 Reads

A diversion of Mississippi River water into Lake Pontchartrain, Louisiana, USA by way of the Bonnet Carre Spillway has been proposed as a restoration technique to help offset regional wetland loss. An experimental diversion of Mississippi River water into Lake Pontchartrain was carried out in April 1994 to monitor the fate of nutrients and sediments in the spillway and Lake Pontchartrain. Approximately 6.4×108 m3 of Mississippi River water was diverted into Lake Pontchartrain over 42 days. As water passed through the Bonnet Carre Spillway, there were reductions in total suspended sediment concentrations of 82–83%, nitrite+nitrate (NOx) of 28–42%, in total nitrogen (TN) of 26–30%, and in total phosphorus (TP) of 50–59%. 3.9±1.1 cm of accretion was measured in the spillway. Nutrient concentrations at the freshwater plume edge in Lake Pontchartrain compared to the Mississippi River were lower for NOx (44–81%), TN (37–57%), and TP (40–70%), and generally higher for organic nitrogen (−7–57%). The Si:N ratio generally increased and the N:P ratio decreased from the river to the plume edge. Nutrient stoichiometric ratios indicate water at the plume edge was not silicate limited, suggesting conditions favoring diatomic phytoplankton.

Spatial evaluation model for assessing and mapping impacts on threatened species in regions adjacent to Natura 2000 sites due to dam construction

August 2010


195 Reads

The main purpose of this study was the development of an impact evaluation model to effectively assess and map possible ecological impacts due to a dam construction on habitats and species from the nearest Natura 2000 sites. A new approach has been developed in order to assess and map possible impacts on habitats due to a dam construction at both construction and operation phase. This methodology includes procedures in order to assess impacts and by calculating evaluation scores. Using Geographical Information Systems (GIS) evaluation scores were assigned to grouped habitat regions at construction and operation dam phase. The construction may affect the presence of the species Lutra at the site near the river but will have no effect at the area where the dam basin and the Natura 2000 site intersect. The other species are not expected to be affected from the dam construction. During the operation phase, the presence of water will influence species like Bombina in a very positive way. The dam operation itself will not have negative effects on the rest of habitats but due to the presence of water, factors like a possible increase on traffic and population may affect negatively the habitats especially near the village areas. The proposed methodology offers an alternative point of view on impact assessment and it is expected to serve as become a valuable tool for decision makers to evaluate potential impacts to threatened species and habitats due to a technical project at construction and operation phase.

Corrigendum to “Improving revegetation of gypsum slopes is not a simple matter of adding native species: Insights from a multispecies experiment” [Ecol. Eng. 30 (2007) 67–77]

December 2007


113 Reads

A common practice in the revegetation of motorway slopes is to hydroseed broad-purpose, fast-growing, usually exotic species, without particular attention to soil, climate and general features of each site. The importance of using native species is becoming widely acknowledged and restoration projects are gradually considering native species for the hydroseeding mixture, particularly under adverse climatic and soil conditions. However, the selection of species may not take into account the competitive interactions among commercial and native species, which can dramatically affect the outcome of the hydroseeding. We carried out a multispecies controlled experiment simulating eight different communities with species typically used in the revegetation of gypsum motorways slopes in Mediterranean Spain. The effect of the presence, relative density and emergence time of Lolium rigidum, a fast-growing and highly competitive introduced grass, on the growth and cover of each community and on the performance of six individual gypsum species was assessed. Survival and performance of the gypsum species was always hindered by L. rigidum. Mean height of the gypsum species was maximal at the combinations without L. rigidum and the same was true for aboveground biomass. Same kind of significant effect, although reduced in extent, was obtained when L. rigidum was sown 1 month after the emergence of the gypsum species. On the contrary, mean height, aboveground biomass, root biomass, and cover of the whole community (gypsum species + L. rigidum) was higher at the combinations with more individuals of L. rigidum, due to the fast growth of the latter. Our results showed that fast-growing commercial species outcompeted slow-growing gypsum species even on real gypsum soils and even if the community gets started with less individuals of commercial than of gypsum species, or if the former is sown 1 month after the germination of the latter. These results suggest that the inclusion of native species in the hydroseeding mixture may not improve the revegetation of gypsum slopes in Mediterranean conditions if used in combination with commercial, fast growing species, which can quickly cover the ground during the spring but are not likely to survive over the summer drought. Further studies should focus on the suitability of using herbaceous species tolerant of gypsum soils, as their growth rate is likely to be higher and could be used together or even instead commercial species.

Erratum to “Effect of soluble and particulate organic compounds on microfauna the community in subsurface flow constructed wetlands” [Ecol. Eng. 29 (2007) 280–286]

September 2007


38 Reads

The effect of particulate and soluble organic load on experimental subsurface flow constructed wetlands was evaluated by means of changes in the microfauna community. Two experimental constructed wetlands with a length of 0.93 m, a width of 0.59 m and a wetted depth of 0.3 m were monitored for a period of 5 months with both physical–chemical and biological analyses carried out on a weekly basis. The results obtained suggest that there are no relevant differences in terms of pollutant removal efficiency when particulate or soluble organic matter is supplied. However, the microfauna composition appears to be highly dependent on the source of organic matter supplied. Specifically, when the wetland was supplied with particulate matter, the ciliates represented more than the 60% of the total microfauna abundance at the initial section of the system, whereas when it was supplied with soluble matter, the heterotrophic microflagellates represented more than the 95%. Furthermore, the increase in particulate organic load doubled the ciliate abundance in the system, whereas the increase in soluble organic load caused a hundred fold decrease of microflagellate abundance.

Nutrient removals by 21 aquatic plants for vertical free surface-flow (VFS) constructed wetland

March 2007


175 Reads

An attempt was made to investigate the removal of high nutrient contents from polluted water. This study focused on the comparisons between nitrogen and phosphorus removal rates by area-based calculation and biomass-based calculation using various kinds of aquatic plants (18 emergent and 3 floating plants). Results showed that all floating plants performed maximum nutrient removal rates based on plant weight calculation while most emergent plants performed maximum nutrient removal rates based on planted area calculation. The reason is that the weights of rooted mass by emergent plants are heavier than their shoots, resulting to low nutrient removal efficiencies in terms of their total weight. The study suggests that the planted area and the plant's geometries (such as roots and shoots) should be considered for the effective design in aquatic plant treatment systems.

Simulated acid azo dye (Acid black 210) wastewater treatment by periodic discontinuous batch mode operation under anoxic–aerobic–anoxic microenvironment conditions

December 2007


122 Reads

Treatment of simulated acid azo dye (C.I. Acid black 210) wastewater was studied in periodic discontinuous batch mode operation employing sequencing batch reactor (SBR) with suspended growth configuration under anoxic–aerobic–anoxic microenvironment. The performance of the reactor was evaluated at two organic loading rates (0.56 kg COD/m3-day and 0.75 kg COD/m3-day) with a total cycle period of 24 h [fill phase: 30 min; react phase: 23 h; settle phase: 15 min; decant phase: 15 min] at room temperature. The performance of SBR was assessed by monitoring both COD and colour (OD-617 nm) concentrations. Periodic discontinuous batch mode operation feasibility for dye colour removal along with simultaneous substrate (COD) removal. The performance efficiency of the system was found to depend on the operating organic loading rate. Induced anoxic microenvironment during cycle operation and persistent anoxic microenvironment in the internal layer of suspended biomass may be probable reasons for dye mineralization/reduction. Rapid startup period and non-inhibited performance at higher loading rate are some of the advantages observed in the SBR operation.

Impact of heavy oil-polluted soils on reed wetlands. Ecological Engineering, 29, 272-279

March 2007


57 Reads

The impacts of heavy oil-contaminated soils on a reed wetland were studied during a 3-year field experiment in China's Liaohe Oilfield. Contaminated soils with a 30% heavy oil concentration were spread in the reed wetland in April of the first 2 years with 0.2, 2, 6, 18, and 0 kg of oil-polluted soil m−2 for 4 reed beds and a control. In the third year no polluted soil was spread in the wetland. Results indicated that removal efficiencies in 0–80 cm soil layers were between 88 and 92% in the first 2 years, and up to 96% in the third year. The soil profile analysis pointed out that in the third harvest season, there was little residual heavy oil in soil layers 60–80 cm deep, with most of heavy oils removed in the 0–20 cm surface layer, thus avoiding additional pollution of the deep soil layer. Furthermore, contaminated soils had beneficial impacts on soil physiochemical indices of chloride (Cl−), pH, and organic matter in the 0–20 cm surface layer, as well as allowing total nitrogen (TN) and total phosphorus (TP) in the 0–20 cm surface layer to recover within the last 2 years of operation. At the end of this experiment, all these indices in the soil profile (0–80 cm) followed the same trend as those in normal soil. During the first harvest season, reed biomass in the wetland increased with increasing heavy oil pollution loading. In the last two harvest seasons, reed biomass followed the same trend, i.e., at the highest and lowest contaminated soil levels (18 and 0.2 kg oil-polluted soil m−2 soil, respectively), reed biomass in reed beds increased with time, and resulted in levels higher than in the control. In contrast, at middle contaminated soil levels (2 and 6 kg oil-polluted soil m−2 soil) reed biomass followed an inverse trend similar to that experienced by the control. Reed health results suggested that contaminated soils had no obvious adverse effects on reed height and number of leaves, and no significant effect on the eco-physiological indices of reeds, including cellulose, pentose, lignose, length and width ratio of cellulose, and width of cellulose. There was also no effect on germination percentages from below-ground rhizomes, but some inhibition on the germination process. In order to analyze heavy oil uptake and distribution within reeds, a 14C-hexadecane tracer experiment was conducted in 2003. Results indicated that after a growing season, heavy oil concentrated mainly in the below-ground root of reeds.

Evaluation of physical fish habitat quality enhancement designs in urban streams using a 2D hydrodynamic model

October 2010


145 Reads

Creating a habitat for a variety of forms of life, such as riparian plants and various fish, is a necessity for stressed river ecosystems. In this study, the hydraulic characteristics of a fish habitat in an urban channel were analyzed using River2D, which is a two-dimensional (2D) depth-averaged finite element hydrodynamic model, to improve the habitat of two target fish in the Daejeon Stream, Korea. These species are Pseudopungtungia nigra, which is an endangered species in the Daejeon Stream, and Zacco platypus, which is a dominant species. In addition, changes in the weighted usable area (WUA) were compared and reviewed as boulders were placed in the stream. The best method for improving the P. nigra's habitat is proposed. A simulation analysis was performed on urban rivers for fish habitats. As a result, a straight and monotonous urban river flow was found to be an appropriate habitat environment for Z. platypus. The WUA for Z. platypus was about 20 times greater than that for P. nigra. Three different fish habitat enhancement methods were evaluated by calculating the WUA for the target fish in the study channel. By calculating the WUA to create fish habitats, the V-type riffle method was found to increase the usable area of the habitat environment for P. nigra by 360%, and the step stone method and single boulder method did so by 60% and 8%, respectively. For the single boulder method, boulders were placed in the channel bed at 3.5-m intervals, which significantly increased habitat availability. Moreover, centralizing the flow pattern in the channel among several types of boulder placements greatly expanded the habitat for P. nigra. Thus, an appropriate placement interval and boulder location that considers the characteristics of the riverbed and target fish species should be researched and implemented.

Evaluation of relative importance of different microbial reactions on organic matter removal in horizontal subsurface-flow constructed wetlands using a 2D simulation model

August 2008


54 Reads

In this study, we used a two-dimensional (2D) mechanistic mathematical model in order to evaluate the relative contribution of different microbial reactions to organic matter removal (in terms of COD) in horizontal subsurface-flow constructed wetlands that treated urban wastewater. We also used the model to analyse the effect of increasing or decreasing the organic loading rate (changing the hydraulic loading rate (HLR) at a constant influent organic matter concentration, or changing the organic matter concentration at a constant HLR) on both the removal efficiency and the relative importance of the microbial reactions. The model is based on the code RetrasoCodeBright, which we modified to include the main microbial processes related to organic matter and nitrogen transformations in the wetlands: hydrolysis, aerobic respiration, nitrification, denitrification, sulphate reduction and methanogenesis. The model was calibrated and validated with data from two wetlands (each with a surface area of 55 m2) located in a pilot plant near Barcelona (Spain). According to the simulations, anaerobic processes (methanogenesis and sulphate reduction) are more widespread in the wetlands and contribute to a higher COD removal rate (60–70%) than anoxic (denitrification) and aerobic reactions do. These model results are confirmed by experimental observations. In all the cases tested, the reaction that most contributed to COD removal was methanogenesis (33–52%). According to our simulations, decreasing the HLR (for example, from 40 to 25 mm/d) while maintaining a constant COD influent concentration has a clear positive impact on COD removal efficiency (which increases from 65% to 89%). Changing influent COD concentration (for example, from 290 to 190 mg/L) while maintaining a constant HLR has a smaller impact, causing efficiency to increase from 79% to 84%. Changes in influent COD concentration (at a constant HLR) affect the relative contribution of the microbial reactions to organic matter removal. However, this trend is not seen when the HLR changes and the COD influent concentration remains constant.

Ecological compensation of the impacts of a road. Preliminary method for the A50 road link (Eindhoven-Oss, The Netherlands)

December 1996


109 Reads

After years of efforts to avoid or reduce the impact of infrastructure projects on nature, the principle of ecological compensation has been incorporated in Dutch governmental policy. Ecological compensation aims to recover those ecological functions and natural values that still remain affected after maximum effort has been made to reduce the impact of the intervention (mitigation). The accepted aim of current policy is thus no-net-loss of area and quality by means of mitigative and compensatory measures. As part of the planning process for construction of a stretch of road in The Netherlands, viz., the A50 road link in the province of North Brabant, a Nature Compensation Plan (NCP) was required to be drawn up. This work has recently been completed by the Regional Directorate of Public Works and Water Management, the initiator of the intervention. The NCP, initially presented as a Draft Plan, was drawn up by the Regional Directorate using a preliminary method designed by the Centre of Environmental Science of Leiden University for deriving compensatory measures. After an opportunity for public comment, the Draft Plan was revised to form a Final NCP. This article describes, firstly, the preliminary method for deriving ecological compensatory measures. The method starts by quantifying the effects of habitat loss, habitat disturbance (by changes in noise emissions, in the water table and in outdoor recreational patterns), barrier action and fauna casualties. Following mitigation of impacts on nature, compensation for non-mitigable effects focuses successively on area size, derived from the impacts on breeding birds, and on area quality, derived from the habitat requirements of the vegetation and fauna groups affected by the road. Guidelines for identifying appropriate locations for compensation are also formulated. Secondly, the compensation method is applied to calculate the mitigative and compensatory measures for the A50 trajectory between Eindhoven and Oss. Thirdly, two comparisons are made: the Draft NCP is compared with the results of the preliminary method, and the Draft and the Final NCP are compared with one another in order to identify the role of the interest groups that played a major role in commenting on the Draft Plan. Finally, realization of the compensatory measures and development of the preliminary method itself are discussed. On the basis of the experience with the A50 case study, a more robust compensation method for road projects is to be developed.

Towards calcareous wetland creation in flooded abandoned aggregate quarries: A 3-year field mesocosm study

April 2010


31 Reads

The purpose of this study was to demonstrate the feasibility of the rehabilitation of abandoned aggregate quarries to calcareous wetlands through a growth experiment at the quarry floor. We tested the effects of planting substrate (fine screenings, coarse rock, transplanted peatball, and topsoil addition to screenings) and springtime water depth (+15, 0, and −15 cm relative to ground surface) on the growth of Carex aquatilis over 3 years. Survival rate of the transplanted material was 100%. Minimal growth was observed after the first growing season, but by the end of the third growing season the transplanted material had added on average 80, 4, and 3 shoots in the topsoil-amended, intact peatball, and coarse rock treatments, respectively, but lost on average 4 shoots in the fine screenings treatment. The addition of topsoil significantly increased final aboveground biomass (285 ± 49 g per plot) compared to the peatball (40 ± 16 g), rock (36 ± 11 g) and screenings (35 ± 21 g) treatments, which were not significantly different. The effect of water depth did not lead to overall significant differences, as Carex aquatilis ramets were capable of growing in springtime water levels from 15 cm above to 15 cm below ground surface. Our data demonstrate that some flooded abandoned aggregate quarry floors represent suitable sites for conversion to calcareous wetlands, even with a strategy of minimum maintenance, and that wetland species are capable of growth in these largely inorganic settings.

Economic returns from environmental problems: Breeding salt- and drought-tolerant eucalypts for salinity abatement and commercial forestry

November 2007


122 Reads

Remediation of agricultural landscapes affected by salinity requires modification of land use practices to re-establish water balance at the catchment scale. Forest plantations established throughout the landscape, from recharge to discharge areas, have the potential to play an important role in this regard given their deep rooting habit, high perennial water use and low leakage of rainfall below the rootzone relative to annual crops. However, areas affected by salinity in Australia often present environmental conditions challenging to commercial growth. In 1996, the XylonovA R&D Syndicate commenced a collaborative breeding program to combine the salt and drought tolerance of Eucalyptus camaldulensis, with the growth rate, stem form and wood properties of the commercial species Eucalyptus grandis and Eucalyptus globulus. These hybrids exhibited heterosis under saline irrigated conditions, with the mean stem volume of hybrids at 85 months exceeding the best pure species parent by 140–252%. Gains in stem volume based on the mean of a commercial selection of hybrid clones ranged from 287 to 481%. Gains were more modest under non-saline, medium to low rainfall conditions (531–707 mm/year). Hybrid population means were similar to alternative pure species, but the hybrids were more stable across sites. Gains in mean stem volume from selection of the top 10% of hybrid clones over the best performing pure species ranged between 40 and 45%. The opportunity for commercial plantations of improved eucalypt hybrids integrated with agriculture in medium to low rainfall areas to address salinity and sustainability is discussed.

Nursery practices and field performance for the endangered Mediterranean species Abies pinsapo Boiss

September 2006


85 Reads

In the nursery production of Abies pinsapo there have been changes in container, growing media types, and fertilization in the last 10 years. In this research, five types of standard A. pinsapo planting stock were raised under different cultivation periods (2 and 3 years), growing media (soil–peat–organic soil mixture), and fertilizer applications (234, 339 and 397 mg of N). At the end of the nursery cultural treatments, the five planting stock types from the different treatments were morphologically and physiologically different.Five years after outplanting, seedlings grown from 3-year-old containerized stock were the tallest (averaging 38 cm) and had an excellent survival (85–90%). However, 2-year-old containerized stock also showed a very high survival (80–100%) with similar height growth (averaging 32 cm). In the split-plot analysis, survival was positively related to subsoil percentage in the growing media and fertilization. In term of morphological attributes of planting stock, height, diameter and height: diameter ratio seems to be negatively correlated to mortality. The results indicate that, in terms of field performance and seedling cost, containerized 2-year-old seedlings, 40% peat media and moderate level of N fertilization may enhance the field performance of A. pinsapo plantations and be a good initial point for new research to improve planting stock.

Central-European mountain spruce (Picea abies (L.) Karst.) forests: Regeneration of tree species after a bark beetle outbreak

August 2004


310 Reads

In the 1990s, a bark beetle (Ips typographus) outbreak caused a dieback of semi-natural mountain spruce (Picea abies) forests in the Šumava National Park (Czech Republic). Two different approaches were applied to the attacked forests: (1) a small portion of the stands in the core zone of the national park was left without intervention, relying upon natural regeneration, and (2) traditional technical measures were adopted, in which attacked trees were felled and removed. Under the dead canopy of the stands left without intervention, there was a good regeneration of spruce and rowan (Sorbus aucuparia) and, sporadically, beech (Fagus sylvatica). In clear-cut areas, the numbers of spruce and rowan were significantly lower than under the dead canopy. Pioneer species such as willow (Salix aurita), birch (Betula pubescens), and aspen (Populus tremula) appeared in the clear-cut areas. The dependence of spruce regeneration on the availability of suitable microhabitats was found: decaying wood and spruce litter was found as the most favourable. The results confirmed that the original tree species of the mountain spruce forests regenerate well under dead canopy. The bark beetle outbreak does not result in the complete loss of the forests and could even be considered as a tool for the restoration of their natural character.

Evaluating vertical-slot fishway designs in terms of fish swimming abilities

August 2006


905 Reads

One of the major problems in fishway design is that optimal parameters depend on an interplay of hydraulic and biological variables. This study presents a methodology for evaluating fishway designs in terms of the swimming capabilities of the target species. Specifically, we have evaluated two vertical-slot designs whose hydraulic properties were empirically characterized in a previous study. In view of these empirical data, for each design we have estimated (a) minimum discharges giving minimum fish-acceptable depths; (b) maximum pool sizes ensuring flow velocities low enough to be overcome by the fish; (c) maximum pool sizes ensuring turbulence low enough to be acceptable to the fish. These design constraints are calculated for different slopes (∼6 or ∼10%), different water temperatures (10, 15 or 20 °C), and different fish lengths. This methodology constitutes an effective means of taking fish swimming capabilities into account at the fishway design stage.

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