Ecological Engineering

Published by Elsevier
Online ISSN: 0925-8574
Publications
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
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. 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
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.
 
Article
In the French Southern Alps, erosion-control experiments have been conducted since spring 2002 in marly catchments subjected to a mountainous and Mediterranean climate. Bioengineering works, installed in the gully beds and constituted as vegetation barriers, have been efficient in trapping sediment, thus creating sediment deposits upstream of each barrier. Natural colonization of these deposits by vegetation, which could enhance soil protection against erosion, have therefore been observed. From 2003 to 2005, we investigated the abiotic and biotic factors influencing plant establishment after restoration on 29 bioengineering works constructed in two experimental marly gullies. On the sediment deposits upstream of each structure, we identified the standing vegetation, measured species richness and abundance, and also evaluated vegetation cover on the gully sides. The results indicate that colonization by plants may be influenced by abiotic factors such as the presence of vegetation on the gully sides and climatic conditions. In addition, the ability of the bioengineering works to retain water seems to have an impact on the success of vegetation establishment. Finally, we highlighted changes in growth form proportions over time that may result from biotic factors such as plant–plant interactions. These results allow us to hypothesize on how vegetation evolves over the medium term after ecological restoration of eroded marly gullies in a mountainous and Mediterranean climate.
 
Article
Constructed wetlands for wastewater treatment in the Czech Republic are commonly planted with reed canarygrass (Phalaris arundinacea). Phalaris is a fast-growing grass which may be cut several times during the growing season. During 2005, the experiments were carried out at horizontal sub-surface flow constructed wetland Břehov to evaluate whether multiple harvest may increase the amount of 23 trace elements removable via mowing. The plants were cut in mid-June and re-harvested in mid-August. The single harvest was carried out at the end of July during the peak standing crop of this species. The biomass of Phalaris cut once and twice during the year was nearly identical but analyses of the biomass indicated that the amount (standing stock) of trace elements varied. For 13 elements (As, Ba, Co, Cr, Cu, Fe, Ga, Hg, Mn, Ni, Pb, Sb and U) the standing stock was higher for single harvest, indicating that these trace elements are transported to the aboveground biomass later in the growing season. Standing stock found in the biomass harvested at the peak standing crop as percentage of the cumulative standing stock from two harvests was highest for Hg (385%), Pb (249%) and U (244%). On the other hand, for 10 elements (Al, Cd, Li, Mo, Rb, Se, Sn, Sr, Tl and Zn) cumulative standing stock was higher than the standing stock for one harvest, indicating high accumulation during the early growth stages. For those elements, multiple harvest could be beneficial for element removal from wastewater.
 
Article
Phragmites australis (common reed) grew well in the presence of high concentrations of NH4+-N (300 mg/1), BOD (300 mg/1), Fe (30 mg/1), Mn (1.5 mg/1) and K (500 mg/1). Other metals were not particularly elevated with the pH of the landfill leachate being 7-7.2. Reed standing crop continued to increase in the two years after leachate applications began, ranging to about 1100, 100, and 1000 g/m2 dry wt. for shoots, roots and rhizomes, respectively. Nutrient elements like N, K, Ca, and Mg were absorbed to normally sufficient levels, while tissue P was low at 0.04%. Metals were not translocated to and accumulated by shoots or rhizomes, but exhibited elevated levels in roots. Fe, Cu, Zn, Pb, and Cd were at levels of 3700, 65, 45, 12 and 0.2 mg/kg respectively, but the roots acted as effective filters for transport of metals to the shoots and rhizomes. Only P and Zn accumulation by plants approached total amounts in leachate entering the constructed beds. SEM and X-ray microanalysis showed Fe accumulation on root surfaces, with Fe and other metals at lower concentrations inside the root tissue. The rhizosphere may provide a particularly effective, locally oxidized environment for metal precipitation and adsorption outside the root.
 
Article
Constructed and estuarine wetlands, influenced by wastewater treatment plants, were investigated, with respect to microbial activity in terms of functional genes. The density and abundance of three denitrifying genes coding for nitrate (narG), nitrite (nirS), and nitrous oxide (nosZ) reductases, in sediment soil samples from wastewater effluent-fed and estuarine wetlands, were quantified using the SYBR green-based real-time polymerase chain reaction (PCR). To assess seasonal effects (i.e., winter (average temperature ∼2 °C) versus spring (average temperature ∼20 °C)), the densities of denitrifying genes, with respect to the abundance of functional genes, for the two different wetlands were determined. The three functional genes for all the sampling sites ranged from 1.0 × 106 to 1.0 × 109 copies/g of soil. Without considering seasonal variation, the nitrite-reducing functional genes were dominant over the other two genes in the effluent-fed wetland samples. However, nitrate and nitrite-reducing functional genes were dominant in relatively cold and warm seasons, respectively, in the estuarine wetland samples. Even though robust patterns and conclusions could not be obtained from the limited investigations, patterns with certain trends and needs for potential future research directions were obtained.
 
Article
In the post-mining landscape of Lower Lusatia (eastern Germany), four mining areas were studied with respect to distribution and abundance of terrestrial Heteroptera. Colonization dynamics and formation of species communities in devasted open areas with different environmental conditions were investigated. In total, 127 species were found in 30 sampling sites, representing about 30% of all species of the state of Brandenburg. The ratio between purely phytophagous and mainly zoophagous species in younger (<20 years) and older sites (>20 years) did not differ much; the ratio between purely macropterous and partly brachypterous species was higher in younger sites. Macropterous species are able to colonize the sites more rapidly. Correspondence and cluster analyses revealed that community patterns are mainly determined by the architecture of the vegetation. Herb cover, grass cover, vegetation density and height, relation of grass versus herb dominance explained most of the community variances, while soil parameters and age of sites were of minor importance. Species number of Heteroptera is also strongly influenced by the plant species composition of sites. Except of young pioneer stages no significant differences in species number between undisturbed and disturbed sites were detected. Younger and older sites differed only slightly in species number of Heteroptera. Colonization by numerous species takes place rather rapidly, depending on the formation of special features of the vegetation and on the species pool of the surrounding area.
 
The relationship between important aspects of fodder trees within the study site in the context of livestock carrying capacity. The units are in SSU maintained per ha for three months. Farm boundaries are for small farms only.
Article
Multiple land-use designs are becoming increasingly necessary in semi-arid Africa as growing populations focus numerous production systems onto spatially limited arable lands. Engineering distinct land uses into a single area ideally requires that land-use components complement each other, and operate in predictable magnitudes. Quantitative evaluations of components to be included in multiple land-use designs are necessary to determine both how components would ‘fit’ together, and how these would serve populations participating in distinct production systems.With data gathered in Somalia, this study considers a design in which fodder-producing trees and irrigated agriculture could be integrated. Following a discussion of the benefits of such an integration, this analysis focuses on a quantitative examination of potential livestock carrying capacity from Acacia albida trees in an irrigated area. Comparisons are made with observed livestock numbers in order to determine if such a design could accommodate the seasonal influx of nomadic herds. The land-use elements that comprise carrying capacity are themselves examined to see which elemens might be managed to offset or take advantage of those which are not easily managed.
 
Article
‘Ecological engineering’ is relatively recent. It resembles chemical, hydrological and other engineering where the title indicates another discipline specialisation (ecology, chemistry, hydrology) is closely associated. Differently, civil, mechanical, or electrical engineering titles indicate engineering subdivisions based on areas of application. The ecological engineering title is twice asymmetric: it indicates a kind of engineering, not science (engineering ecology); and only part of ecological science has as yet been included in ecological engineering. The ‘civil’ engineering descriptor is defined by its context, rather than this area being defined by its descriptor. Civil engineering includes a specialisation with another inappropriately undescriptive title—environmental engineering. Ecological and environmental engineering are readily confused by the public, ecologists, and other engineers. There have recently been laudable efforts by engineers, ecologists, economists, writers, and many others to move society towards more sustainable living. Young engineers can be encouraged in this by greater understanding of ecology and sustainability in their academic and professional formation. The desirable formation of ecological engineers remains unclear. Meanwhile, many approaches exist to introducing ecological understanding and principles of sustainability into other engineering academic curricula. Some approaches are discussed in this paper, in the context of developing appropriate education and training in ecological engineering.
 
Article
Horizontal flow constructed wetlands are engineered systems capable of eliminating a wide range of pollutants from the aquatic environment. Nevertheless, poor hydrodynamic behavior is commonly found resulting in preferential pathways and variations in both (i) the hydraulic residence time distribution (HRTD) and, consequently, (ii) the wetland's treatment efficiency. The aim of this work was to outline a methodology for wetland design that accounts for the effect of heterogeneous hydraulic properties of the porous substrate on the HRTD and treatment efficiency. Biodegradation of benzene was used to illustrate the influence of hydraulic conductivity heterogeneity on wetland efficiency. Random, spatially correlated hydraulic conductivity fields following a log-normal distribution were generated and then introduced in a subsurface flow numerical model. The results showed that the variance of the distribution and the correlation length in the longitudinal direction are key indicators of the extent of heterogeneity. A reduction of the mean hydraulic residence time was observed as the extent of heterogeneity increased, while the HRTD became broader with increased skewness. At the same time, substrate heterogeneity induced preferential flow paths within the wetland bed resulting in variations of the benzene treatment efficiency. Further to this it was observed that the distribution of biomass within the porous bed became heterogeneous, rising questions on the representativeness of sampling. It was concluded that traditional methods for wetland design based on assumptions such as a homogeneous porous medium and plug flow are not reliable. The alternative design methodology presented here is based on the incorporation of heterogeneity directly during the design phase. The same methodology can also be used to optimize existing systems, where the HRTD has been characterized with tracer experiments.
 
Article
Sediment profiles from four sites of the middle Ebro River (NE Spain) were examined to describe total organic carbon (TOC) and total nitrogen (TN) accretion patterns during the last century. Such patterns were related to the potential of floodplain substrates to act as C and N sinks. Two oxbow lakes with different hydroperiods and two patches of riparian forest at different successional stages were selected to represent permanently and intermittently flooded habitats, respectively. Total organic carbon (TOC) and total nitrogen (TN) stocks were estimated, whereas Cs-137 dating and aerial photographs were used to determine historical accretion rates. Our results indicate that TOC and TN accretion patterns have been modified during the last century as a result of human impact on natural river processes at both basin and site scales. Since 1963, sediment deposition at the study sites has diminished, regardless of their hydrological connectivity, indicating a reduction in the potential of the middle Ebro floodplains to act as TOC and TN sinks. Although TOC and TN concentrations are markedly higher in recent sediments, accretion rates between 1927 and 1963 still exceed those of recent years. Despite such recent human-induced changes at basin and habitat scale, the middle Ebro floodplains presented relatively high TOC and TN accretion rates, a fact that should be considered in future basin management plans. Based on those results, suggestions to maximize TOC and TN accretion through ecological restoration are provided. Specific actions include the rehabilitation of fine-grained (<2 mm) sediment delivery, land reclamation or dyke reconfiguration.
 
Article
This study reports on the response of a tidal, freshwater forested wetland ecosystem to long-term input of secondarily treated municipal effluent from the City of Mandeville, LA. Measurements of hydrology, nutrients, and aboveground net primary productivity were made from September 1998 through March 2002. Accretion measurements were made in October 2000 and October 2004. The major hydrologic inputs to the system were the effluent, precipitation, and back water flooding from Lake Pontchartrain. Nutrient levels were generally low except in the immediate vicinity of the outfall. Mean net primary production of the freshwater forest system was significantly higher downstream of the effluent discharge (1202 g m−2 yr−1) compared to the control site (799 g m−2 yr−1). Downstream of the outfall, accretion rates were double the rate of relative sea level rise in the area. Removal efficiencies of N and P were as high as 75% and 95%, respectively. The relatively constant flow of secondarily treated municipal effluent buffered the downstream area from salinity intrusion during a region-wide drought. Re-direction of nutrient-enhanced effluents from open water bodies to wetland ecosystems can maintain plant productivity, sequester carbon, and maintain coastal wetland elevations in response to sea-level rise in addition to improving overall surface water quality, reducing energy use, and increasing financial savings.
 
– Location and sampling map of the study area. WTP means Wastewater Treatment Plant. Site 1 is the point before any water mass from WTP discharged to Kehli Stream. Site 2 is the line of filtrate of primary settled solids. Site 3 is Kehli Stream just after Site 2. Site 4 is the effluent discharging line. Site 5 is by-pass line. Site 6 is Kehli Stream that contains the Sites 2, 4, and 5. Site 7 is filtrate line from sludge drying beds. Site 8 is Kehli Stream that contains all effluents of WTP, and point at a distance of about 2 km from Site 1. Site 9 is just before the point where Kehli Stream falls into Keban Dam Lake.  
-Operation conditions for ICP-MS
– Average Zn, Ni, Cu and Pb concentrations in roots and leaf of Typha latifolia together with water and sediment concentrations.  
Article
Typha latifolia L. from aquatic plants is widely found throughout Kehli Stream (Elazig, Turkey). This study examined the uptake of some metals by T. latifolia and the transfer from roots to other plant parts. The accumulation of Mn in T. latifolia L. can be suggested as a tolerance strategy due to its transfer factor higher than 1.0. The enrichment coefficients in the leaves of T. latifolia L. were higher than 1.0 for Zn and Mn and often lower than 1.0 for other metals. Similarly, the enrichment coefficients of all metals, except for Cr, in roots of T. latifolia L. were higher than 1.0. This study demonstrated that T. latifolia L. could be considered as either a bio-indicator or a bio-accumulator for sediments and water polluted by metals.
 
Article
Recent advances in peatland restoration techniques have succeeded in establishing Sphagnum moss on the remnant cutover peat surface following peat extraction; however, evaluating restoration success remains a key issue. We argue that a Sphagnum-dominated peatland can only be considered functionally ‘restored’ once organic matter accumulation has achieved a thickness where the mean water table position in a drought year does not extend into the underlying formerly cutover peat surface. Here we monitor the spatio-temporal development of organic matter accumulation in a new peat layer for the first 8 years following the restoration of a Québec peatland and couple a simple acrotelm carbon accumulation model and ecohydrological model to assess peatland restoration success.We determined that organic matter accumulation increased from 2.3 ± 1.7 cm 4 years post-restoration to 13.6 ± 6.5 cm 8 years post-restoration. For comparison, at an adjacent non-restored section of the peatland organic matter accumulation was significantly lower (p < 0.001 for all years), with mean thicknesses of 0.2 ± 0.6 and 0.8 ± 1.2 cm for 24 and 28 years post-extraction, respectively. Given the mean summer water deficit at the site (−64 mm), our ecohydrological modeling results suggest that a 19-cm-thick moss layer would be required to offset the water table decrease induced by the summer water deficit. Given the current rate of organic matter accumulation, net primary productivity and the new peat layer decomposition rates determined using litter bags, we estimate it will take 17 years post-restoration to accumulate a 19-cm moss layer. Consequently, we argue that successful peatland restoration may be achieved in the medium-term and that our simple modeling approach can be useful in assessing the long-term impact of restoration on atmospheric carbon dioxide sequestration.
 
Article
Reconstructing landscapes after open pit mining of the Canadian oil sands presents enormous challenges. Freshwater peatlands dominate the pre-disturbance landscape; however, elevated salinity in the post-disturbance landscape will exclude the use of many freshwater vegetation species for reclamation. Successful reclamation will require plants to grow and accumulate peat despite elevated salinity. We evaluated the potential of salt-tolerant plants to accumulate peat by integrating plant production and decomposition rates in natural and oil sands wetlands across a salinity gradient. These wetlands were dominated by marsh-like vegetation with relatively rapid decomposition, especially of the belowground plant material. Aboveground production was high enough to compensate for rapid decomposition, resulting in mean annual organic matter accumulation of 307 g m−2. Thus, both natural wetlands (which despite the elevated salinity had peat deposits >35 cm) and the oil sands wetlands accumulated organic matter during the study. There is potential for peat to accumulate in future oil sands wetlands, although long-term accumulation rates may be slower than in undisturbed freshwater fens and bogs. A reliable water supply and a host of other factors will be required for wetlands to accumulate organic matter, and eventually peat, in the post-mining landscape.
 
Article
Aquatic plants are used as a practical and effective method to remove toxic elements from secondary-treated municipal wastewater. In this study, Lemna gibba was investigated for its capacity to remove uranium, arsenic, and boron from secondary effluents. L. gibba was collected from a natural lake in Elazığ, Turkey, then acclimatized to the effluent in situ. The concentration of toxic elements in the plant material was monitored as a function of time for 7 days. L. gibba significantly accumulated the toxic elements, particularly in the first 2 days. Arsenic, uranium, and boron were accumulated in the highest concentrations (133%, 122%, and 40%, respectively). However, in the following days, accumulation levels showed both increases and decreases, most probably due to L. gibba reaching saturation levels.
 
Article
Metal accumulations in sediments and plants of constructed and natural wetlands were compared in two wetlands constructed by the Tennessee Valley Authority (TVA) for the treatment of acid mine drainage and a natural wetland. Load rates and removal efficiencies of most metals were generally greater in the constructed wetlands than in the natural wetland. There were similar sediment and plant metal concentrations between one constructed wetland and the natural wetland and greater metal concentrations in the sediments and plants in the other constructed wetland compared to the natural wetland. Data indicate that Mn, Zn, Cu, Ni, B, and Cr are being accumulated in the plants at all three wetlands, although accumulation of metals by these plants accounts for only a small percentage of the removal of the annual metal load supplied to each wetland.
 
Article
Phytoextraction is a remediation technology that uses plants to remove heavy metals from soil. Effective implementation requires an understanding of plant processes that control uptake and translocation of metals from the soil. These processes are poorly understood. The purpose of this work is to gain insights on the plant mechanisms that control uptake and translocation of lead (Pb) from the soil and how these mechanisms interact to control levels of Pb accumulation in the plant. A mechanistic system dynamics modeling approach was used, simulating extraction and translocation of Pb by a maize plant. Confidence in the model structure was achieved through application of classical system dynamics validation procedures. Results of model simulations suggest that precipitation of Pb as a Pb-phosphate is one of the most important mechanisms in this system. Maximum saturable uptake rate of Pb and effective root mass may also be key plant parameters. The model may also be used to test phytoextraction management scenarios, two of which were tested in this study.
 
Article
Constructed wetlands have shown a substantial capacity for wastewater treatment under a wide range of conditions, but removal efficiency of nitrogen (N) and phosphorus (P) has been inconsistent and is often low. Models designed to predict N and P removal in wetlands include complex numerical efforts and empirical models, both of which have shortcomings. In this paper we present a simple mechanistic model capable of predicting N and P removal by detritus accumulation in constructed wetlands. Implications of the simplifications made in this model are explored through simulation modeling. Preliminary validation with one system suggests that the model holds promise. The dominant role of refractory organic matter suggests that more research is needed on this topic.
 
Article
In this study, the bioaccumulation of Cu and Zn by the earthworm Lumbricus terrestris L. and Cu and Zn fractions in casts and surrounding soil of soil amended with different doses of sewage sludge have been explored. The total and fractions of Cu and Zn contents were increased by sewage sludge amendments at all doses. Thirty days after sewage sludge amendment, the soil, cast, and earthworm bodies receiving the highest dose (400 g kg−1) showed significantly higher Cu and Zn content than the non-amended soil. In particular exchangeable (EX)-Zn and organically complexed (OM)-Cu contents of casts and surrounding soil were higher than the other fractions at all sewage sludge amended soils.
 
Article
Typha latifolia plants, commonly known as cattails, were grown in a mixture of sewage sludge compost, commercial compost and perlite. Four groups (A, B, C and D) were irrigated (once every 2 weeks) with a solution containing different concentrations of Cd, Cu, Ni, Pb and Zn, where in the fifth (group M) tap water was used. At the end of the 10 weeks experimental period the mean concentration of Ni, Cu and Zn in the roots and leaves of the plants in the four groups was significantly larger to that of the plants of group M. A linear regression test satisfactorily correlated the metals’ concentrations in the irrigation solutions with the metals concentration in the leaves and roots of groups A, B, C and D. The concentration of total chlorophyll, chlorophyll a (chla) and chlorophyll b (chlb) in the leaves of the developing plants was also monitored in 2 weeks intervals. Groups A, B, C and M presented an increasing concentration of total chlorophyll, with time. In group D (stronger solution), the mean total chlorophyll concentration was reduced from 1080.69 μg/g fresh weight (f.w.) in the 8th week to 715.14 μg/g f.w., in the 10th week, a probable evidence of inhibition. When statistically tested, it was suggested that there was no significant difference between the mean chlorophyll values of the groups in each set of samples, concluding that no significant toxic action was imposed in the plants by the metals. However, when similar statistical analysis was implemented in the ratios of chla and chlb, there was significant reduction of the ratios in groups D plants, suggesting some increase in chlorophyll hydrolysis due to the metals accumulation (toxic effect) in comparison with the other groups.
 
– Schematic view of an aerated unit planted with Typha.  
– Average nitrogen mass flow measured between inlet and outlet of the mesocosms (n = 15). Other N forms include particulate TKN, urea, and every other form except N-NH 4 . Repeated measures ANOVA was used to test differences between the aerated and non-aerated CWs (F(1, 6) = 46.4, p < 0.001) and among macrophyte treatments (F(2, 6) = 25.8, p < 0.001). Capital letters denote significant differences between aerated and non-aerated CWs, and lower case letters denote significant differences between macrophyte treatments within aerated or non-aerated conditions, using a Tukey HSD test.  
– Annual solids accumulation rate (in dry matter) in the CWs units (In and Out: inlet and outlet cores), average of two replicates.  
– Biological parameters and activities recorded in solids sampled from various locations (inlet, outlet; top, bottom) in the aerated and non-aerated CWs. Results are the average of two replicates for each mesocosm. In and Out: inlet and outlet zones.  
Article
In constructed wetlands, solids accumulation may have two consequences with opposing effects on treatment efficiency: it decreases the longevity by reducing void space and it enhances biological activity by favoring biofilm development. The goal of our study was to estimate the effect of plants (presence and species) and artificial aeration on solids accumulation (volatile and inorganic). The horizontal and vertical distribution of solids was sampled using solids traps in 12 constructed wetland mesocosms (5 years old). Microbial density and activity were estimated in the biological fraction of the sampled solids. The effect of plant presence reduced accumulated solids by 26% and sulphide content by 50% sulphide content. There was more solids accumulation in Typha angustifolia units than in Phragmites australis. Also, T. angustifolia generated more biological activities at the surface and close to the inlet while conditions were more homogeneous throughout P. australis units. Aeration (1) stimulated biofilm development at the inlet of planted beds, (2) seemed to reduce mineral matter accumulation and (3) generated the same pattern of activities in planted beds enabling to reach a total nitrogen removal rate of up to 0.65 g N m−2 d−1.
 
Article
Application of sewage sludge and fly ash (FA) to soil is gaining practice and has become an alternative to chemical fertilizers in many countries. The present study aimed to assess the potential of fly ash–tannery sludge (TS) mixture in two ratios {4 (TS):1 (FA), denoted as A and 4 (TS):2 (FA) denoted as B} and different amendments were made with soil to study the yield and metal availability and their uptake by Brassica campestris L. (cv. Pusa Jaikisan). Experimental data showed that increase in dry matter yield and oil content of B. campestris was noted in lower amendments of soil with mixture A. However, total chlorophyll content of the leaf increased significantly, whereas carotenoid content showed non-significant increase in all the amendments with mixtures A and B as compared to control. The translocation of most of the tested metals (Pb, Mn, Cd, Ni, and Fe) in the shoot of the plant was found higher except Cr, Cu, and Co. Overall, experimental results showed that mixture A (≥10%) was found to be suitable due to better yield and less accumulation of metal in the seed of B. campestris.
 
Article
The aim of this study was to verify under lab conditions the reliability, repeatability and accuracy of the falling head method (FHM) for hydraulic conductivity measurements. The FHM is a reliable procedure that has slight variations (less than 10%) in repeated measurements and turns out to be a reliable technique to record the hydraulic conductivities typically described for clogged and unclogged subsurface-flow constructed wetlands (from 4 to ca. 360 m/day). The accuracy of the method is acceptable considering difficulties in the measurement of hydraulic conductivity in highly conductive media. Accordingly, results show measurement deviations of 20% when compared with a laboratory constant head method for highly conductive media (higher than 250 m/day), and 80% for media with low hydraulic conductivity (lower than 50 m/day). The main conclusion of the present paper is that of the FHM is a reliable and repeatable technique for hydraulic conductivity measurements and it is accurate enough for on-site clogging assessment in full-scale constructed wetlands.
 
Article
Flooded lignite pits (Tagebaurestseen) in Lusatia, Germany, are acidic (pH 2.5–4) with high concentrations of iron. Mesocosms (total volume 20 l) were set up with water and sediment from a Tagebaurestsee (Koschen, pH 3.1, Fe 20 mg l−1, acidity (KB8.2) 2.45 mM) to assess the effects of phosphate and organic amendments under natural light and low temperature. Chemical and biological parameters were observed over a 9-month period. Phosphate rock addition (300 mg l−1) resulted in sustained reduction in acidity (H+ and Fe3+) in the water column and induced the growth of Chlamydomonas spp. (Chlorophyceae) near the water surface and Lepocinclis teres (Euglenophyceae) in a band above the sediment. Addition of potatoes to mesocosms resulted in the generation of near-anoxic conditions above the sediment, and phosphorus, ammonium and carbon (organic and inorganic) were released as the potatoes decomposed. A pH>6 was attained with 5.1 g (dry weight) of potatoes and pH>8 with 34 g (dry weight). In both mesocosms, more than 90% of total acidity was removed. Algal growth, mainly of small, coccoid Chlorophyceae, Ulothrix sp. (Chlorophyceae) and Eunotia exigua (Bacillariophyceae), was observed throughout the water column.
 
Article
Pit lakes in the Lausitz lignite-mining district of Germany are diverse in size and morphometry. Many are extremely acidic with pH ≤ 3 and high iron concentrations. Productivity in most of the lakes is low and they support only simple food webs. Various methods are being investigated to remove acidity from the lake waters. The microcosm experiment described here employs controlled eutrophication to enhance element cycling and sediment-bound alkalinity generating processes. Sixty-litre microcosms with water and sediment from Lake Grünewalde (pH 3.0, Fe 14 mg L−1, acidity (KB8.2) 2 mmol L−1 and phosphorus 4 μg L−1) were set-up under laboratory conditions. The addition of nutrients (organic carbon and phosphorus) led to dramatic increases in primary production associated with blooms of green algae (Chlamydomonas sp.) and diatoms (Eunotia exigua) but no substantial removal of acidity. Generation of temporary anaerobic conditions, through the addition of potatoes, led to the removal of 85% of acidity, all detectable dissolved iron, and an increase in pH from 3 to 7. These conditions were maintained with this treatment for the remainder of the 8-month observation period following removal of iron and protons from the water column.
 
Article
The environment in former open-pit brown coal dumps differs from natural conditions. This paper gives the most likely scenario of the long-term progression of streams planned in the re-deposited lowlands in Lusatia, Germany. The scenario is based on observations of streams in old abandoned mines. The stream's progression is controlled by non-cohesive virgin soils, extremely acidic iron-rich water, specific stream and bank vegetation, and incomplete in-stream decay of plant litter and wood. The scenario differs from progression of natural streams. It is a sequence from an open-land stream to a woodland stream and finally to a wetland stream. Key processes responsible for these transitions are strong deposition of iron oxyhydroxides, incomplete decay of leaves and wood, and reduced vitality of riparian trees. Uncertainties of the scenario and management conflicts that may emerge from undirected stream progression are briefly discussed.
 
Top-cited authors
William J Mitsch
  • Florida Gulf Coast University
Jan Vymazal
  • Czech University of Life Sciences Prague
Ülo Mander
  • University of Tartu
Hans Brix
  • Aarhus University
Robert Kadlec
  • Independent Researcher