查看更多>>摘要：? 2021The loss of N from aquaculture has caused eutrophication of freshwater systems. A multistage surface flow constructed wetland (SFCW) with Myriophyllum (M.) aquaticum was engineered to treat lagoon swine wastewater from a large-scale hoggery. The mean removal efficiency of TN and NH4+-N were 9.92 and 7.64 g·m?2·d?1, respectively. The plant and sediment absorption were 1.89 and 1.96 g·m?2·d?1, respectively. The dynamics of the NO3?-N concentrations and the abundance of nitrifiers (AOA and AOB) and denitrifiers (nirK and nirS) revealed strong nitrification and denitrification processes occurring in the SFCW, with a mean N removal of 6.07 g·m?2·d?1. Moreover, AOB and nirK could be the main participants for nitrifiers and denitrifiers, respectively. The combination of quantitative polymerase chain reaction (qPCR), the potential nitrification rate (PNR), and the potential denitrification rate (PDR) showed that the microbial abundance and activity was significantly positively with N concentrations and water temperature (P < 0.05). Factors like PDR, DO, plant N uptake, sediment N adsorption, and pH may play an important role on N removal. These results showed that the M. aquaticum SFCW can efficiently treat swine wastewater and reduce the discharge of pollutants downstream in situ.
查看更多>>摘要：? 2021The loss of longitudinal connectivity in regulated rivers, both up- and downstream, has been detrimental for biodiversity worldwide. While progress has been made regarding upstream fish passage solutions, many questions remain unanswered regarding downstream passage alternatives. To address these knowledge gaps, we used Atlantic salmon (S. salar) smolts to experimentally assess the guidance efficiency and passage rates produced by several common screen-and-bypass fish guidance systems. Vertical screens with horizontally oriented bars extending across a turbine intake channel at a shallow angle (angled guidance screens), combined with a single, full-depth bypass entrance at their downstream end, were on average 20% more effective and produced passage rates that were 10 times higher than screens which extended perpendicularly across a turbine intake channel with vertically oriented bars that rose gradually towards the surface (inclined guidance screens) and with a bypass at the surface, on either side of the screen. Among inclined screens, gap width was negatively associated with guidance efficiencies and the smallest gap width (15 mm) exhibited a 41% greater guidance efficiency than the largest (30 mm). Among angled screens, performance was more closely linked to construction material as metal racks produced passage rates over three times faster than flexible Kevlar netting. Overall, passage through the guidance screens, and therefore into a tentative turbine intake area, was positively associated with gap width and was twice as prevalent among the inclined relative to angled guidance screens. Ultimately, an angled guidance screen with a 30 mm gap width produced the highest guidance efficiency and passage rates (a 30% improvement over the next best screen), while an inclined screen with a 30 mm gap width produced the lowest guidance efficiencies and passage rates. These results have implications for the suitability and performance of downstream fish passage solutions at both large- and small-scale hydropower plants where passage solutions are currently lacking or inadequate.
查看更多>>摘要：? 2021 Elsevier B.V.The amount of solid waste generated by the industrial processes increased tremendously due to rapid industrialization. This waste contains hazardous material and unscientific disposal leads to land degradation and environmental pollution. Therefore, it must be managed carefully to reduce adverse environmental effect and restore ecosystem function. The study aims to evaluate the potential of grass (Pennisetum pedicellatum) and legume (Stylosanthes hamata) revegetation to restore the soil fertility of a steel and iron ore solid waste dump in central India. A field experiment was carried out at the reclaimed site without seeding (control), 1-year and 5-year after direct seeding of grass-legume mixture to assess the changes in soil fertility and biomass production. Soil samples (0–10 cm and 10–20 cm) were collected by laying random quadrats and analyzed for physicochemical and biological properties. Plant biomass and nitrogen (N) mineralization potential of accumulated mulch were measured along the age chronosequence. Soil fertility in terms of organic matter (SOM; 1.61%), organic carbon (SOC; 1.03%), Av. N (132.1 mg kg?1), and enzyme activity (dehydrogenase; 5.32 μg TPF g?1 h?1 and urease; 7.11 μg NH4+ g?1 h?1) at the 5-year-old revegetated site was significantly greater than that of the control site. Plant biomass (32.5–45.8 Mg ha?1) and mulch density (11.4–28.0 Mg ha?1) increased after 1- to 5-year of revegetation. Biomass C:N ratio was higher in grass while cumulative N-mineralization by legume was three times higher than in the grass. Soil moisture, SOM, microbial biomass carbon (MBC) and nitrogen (MBN), and mineralizable N increased with the mulch thickness (3–12 cm). The study concludes that direct seeding of grass-legume mixture potentially recuperates the soil fertility and increase biomass production that help ecosystem restoration. Direct seeding of the grass-legume mixture can be a promising ecological restoration tool to combat land degradation and to achieve UN sustainable development goals.
查看更多>>摘要：? 2021 Elsevier B.V.Floating treatment wetlands are an innovative wetland design to passively improve water quality and remove pollutants from reservoirs with limited infrastructure modification or construction as compared to traditional treatment wetlands. However, design recommendations remain limited. Therefore, the objectives of this study were: 1. Determine nitrate-N removal rates in two floating treatment wetland vegetation designs entering a second growing season and 2. Evaluate nitrate-N removal performance in floating treatment wetland designs following the addition of two carbon amendments during the growing season. Three floating treatment wetland mesocosm experiments were conducted during the summer of 2019, where nitrate-N removal was evaluated. Two floating treatment wetland plant designs (Rush species and Diverse species) and three carbon conditions (no amendment, spent coffee grounds, and barley straw) were assessed in replicates of three. Floating treatment wetland vegetation design (Rush versus Diverse) was found to have significant (P < 0.05) effects on nitrate-N removal performance with Diverse floating treatment wetlands removing nitrate-N at more than twice the rate of Rush floating treatment wetlands (491 to 695 mg N m?2 d?1 and 1547 to 1937 mg N m?2 d?1, respectively). However, impacts of nitrate-N removal following carbon amendments were insignificant compared to no amendment Controls. Diverse wetland species should be considered in floating treatment wetland design while alternative methods to add carbon amendments to floating treatment wetland mats should be further explored.
查看更多>>摘要：? 2021 Elsevier B.V.Planting engineer species is widely used to restore coastal dune ecosystems, but the success of this nature-based practice is often low. Increasing nutrient availability through fertilization and using plant density promoting facilitative plant-plant interactions are increasingly advocated to improve dune restoration. However, how fertilizer application (homogeneous or heterogeneous spatial distribution) influences plant interaction intensity in dune species is still poorly known. We conducted a field-mesocosm experiment assessing the effects of spatial nutrient distribution and planting density on functional traits and intraspecific interactions in two dune plants with contrasting clonal growth architecture. Fragments of Calamagrostis arenaria (phalanx architecture) and Sporobolus virginicus (guerrilla architecture) were grown in monoculture either at low or at high density with the same total supply of fertilizer applied either heterogeneously or homogeneously. We hypothesized that these species would respond differentially to nutrient distribution and plant density. C. arenaria allocated less biomass below- than aboveground under homogeneous than heterogeneous conditions and produced less shoots at low than high density. Conversely, under homogeneous conditions, S. virginicus plants grown at low density had a greater rhizome, root, and total biomass than those at high density. For C. arenaria, intraspecific interactions on aboveground, root, and total biomass shifted from positive to neutral under heterogeneous conditions while those on rhizome biomass switched from neutral to negative. S. virginicus intraspecific interactions on all biomass variables shifted from negative to neutral. Our results demonstrate that nutrient distribution affected functional traits and intraspecific interactions differentially in phalanx and guerrilla species. Notably, in nutrient homogeneous substrates high planting density increased phalanx species performance but reduced that of guerrilla species due to competition. Instead, in heterogeneous substrates both species performed similarly at low and high density. These findings may help restoration practitioners in identifying suitable fertilization/planting schemes and implementing effective dune restoration programs.
查看更多>>摘要：? 2021 Elsevier B.V.The objective of this study is to make a comparison between two 3D CFD platforms: OpenFOAM (free and open-source CFD software) and FLOW-3D (closed source commercial CFD software), focusing on vertical slot fishways, one of the most widespread solutions to facilitate the fish migration through transversal obstacles in rivers. Considering previous comparative studies, our initial hypothesis is that both OpenFOAMs' multiphase solver and FLOW-3D provide good comparable results. In this study, in contrast to previous comparative studies, turbulence was addressed using LES approach and the volume of fluid method was used to model the multiphase interface (air-water). Mesh independency was assessed through LES IQ index and the numerical models' accuracies were evaluated comparing representative hydraulic variables (velocity, its components, and turbulence kinetic energy) with ADV experimental data and discussing results in previous studies. Both platform codes reproduced the scenario under study, concurred with experimental data and offered a superior performance on flow structure velocity simulation than turbulent kinetic energy. Results validate the use of the free and open platform OpenFOAM as a viable alternative to commercial ones in the domain of fishway design and assessment. While OpenFOAM provides a reliable free alternative, FLOW-3D has a faster setup and makes the simulating experience apt for beginners.
查看更多>>摘要：? 2021 Elsevier B.V.Mountain grassland restoration success may be hampered by limited seed dispersal and poor soil seed banks of many grassland species. These constraints can be overcome by actively introducing propagules from nearby non-degraded communities. We tested different restoration techniques in order to understand the mechanisms favouring target species seedling recruitment and establishment. In five degraded mountain grasslands, we analysed (i) the effect of two techniques increasingly used in ecological restoration to overcome low seed dispersal: transfer of brush-harvested seed material and hay transfer, and (ii) the potentially facilitative effect of a temporary plant cover (common wheat) on the recruitment of transferred brush-harvested propagules. We found that both propagule transfer techniques were successful in establishing plant species of the donor community with an increase of plant species richness, cover and abundance of transferred species. Hay transfer was more efficient in transferring species of the donor grassland than brush-harvested material transfer. Brush-harvested material transfer only increased abundance and cover of donor grassland species when sown together with wheat. The results indicated that hay mulch favoured seedling recruitment of target species, and that propagule transfer without hay mulch needs to be compensated by additional temporary plant cover in order to create favourable conditions for seedling recruitment. A comparison with best reference communities for each restoration grassland confirmed that hay transfer and brush material transfer with wheat sowing were successful in driving plant community composition towards the desired reference state. In conclusion, restoration of mountain grasslands with shallow and stony soils clearly benefits from a facilitative effect of dead (hay) or living (wheat) vegetation cover.
查看更多>>摘要：? 2021 Elsevier B.V.Landfills remain widely used for waste disposal, despite their negative impact on human health and environment. Adverse impact is mainly due to gas and leachate emissions. Leachates are liquids that are characterized by high variability in composition, high ammonia and chloride content, and presence of toxic and non-biodegradable compounds. In recent years there has been growing interest in issues related with the reactions of living organisms to pollution - biomonitoring. However, bioindicative methods are not fully used in landfill studies and are still rarely applied. The aim of this work is finding the relationship between the composition and leachate seepage points and determining the possibilities of their practical utilization for the assessment of the applied mineral sealing of landfill surfaces. Additionally, detailed analysis of leachate composition was made. The hypothesis is that some species indicating natural salinity will also indicate landfill sites with the occurrence of leachate seepage, which increase salinity. Physico-chemical analysis of the leachate were carried out. Moreover, vegetation assessment was conducted by phytocoenological relevés. The landfill has different habitats in places where leachate seepage is observed. The results indicate that the presence of leachates alters the plant species composition. The composition shows increasing representation of species tolerant to salinization and a decreasing share of glycophytes in leachate seepage points. Based on the relation of glycophytes to plant species tolerant to salinization, a work procedure and index of leachate vegetation were created, which provide a fast identification of leachate seepage points. The presented results confirm the diagnostic potential of plants for the assessment and location of leachate seepage points. The results may be applied in the reclamation works on landfills.
查看更多>>摘要：? 2021 The AuthorsThere is an increasing call for tools that provide insight into the complex field of land-use systems, especially considering the broad range of sustainability issues related to policy intervention, technological innovation and continuous changes in environmental conditions. Stakeholders ranging from farmers, community leaders to national policy decision makers often fail in managing land due to various reasons, such as imperfect information, lacking awareness of ecosystem service provision and externalities, risk aversion, management quality and skills. To make better informed land-use decisions, they demand information about socio-economic and environmental properties of land-use systems and how they respond to changes in external stimuli and shocks such as climate change. Bioeconomic modelling has been positioned as an integrative approach able to deliver advice to sustainability related problems. This review describes bioeconomic models applied to land-use decisions, with a particular focus on the provision of ecosystem services. For this review, we have considered the main two brands of modelling, empirical (or econometric) and mechanistic, to analyse how mutually exclusive applications as well as newer combinations of both approaches have been implemented in the field to guide decision making towards sustainable land-use management. With the development of new computer-based techniques, bioeconomic modelling has become more complex, accurate and comprehensive in the range of alternatives they are able to evaluate. From previous models limited to a reduced number of decision factors, we see a tremendous evolution towards integrated modelling based on multiple-goal and spatial applications. This step forward in bioeconomic modelling enables it to incorporate multiple time and spatial scales. Despite the undeniable advance achieved by the improved performance of bioeconomic models, we found that their transfer to stakeholders and their expected evolution towards policies and other decision instruments appear to be underperformed, evidence suggests that the gap between science and decision making is still wide To reduce the gap, scientists need to integrate stakeholders during the modelling process, and improve communication platforms.
查看更多>>摘要：? 2021 Elsevier B.V.Constructed wetlands (CWs) are a promising sustainable water-management measure where hydrology plays a fundamental role as the basic driver of mass and energy. Various designs of CWs exist, and these have unique hydrological characteristics that are distinct from those of natural wetlands. However, there have been few reviews of the hydrology and responses of CWs, such that not enough is known of the possible responses of hydraulic, water quality and biology to changing hydrological conditions, especially for different CWs systems. Thus, this paper commences with a review of the basic features of common CWs and their different hydrological conditions. This is followed by the responses of CWs to the hydraulic parameters hydraulic retention time (HRT), hydraulic loading rate (HLR) and water depth that control the changing hydrological conditions of CWs. It is shown that water quality responses are highly related to HRT and HLR and thus a simple method is proposed to predict the responses to the changes of HRT and HLR through a statistical analysis of previous studies. While water depth and inflow patterns appear to have a greater influence on biological responses and some suitable water depths for different species are summarized from papers. Future researchers should pay more attention to the regional ecohydrological patterns of CWs. Long-term hydrological and biological management of CW systems will require the development of frameworks based on an index system for monitoring the responses of interventions.
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