Alkali and Transition Metals In Macrophytes of a Wetland System (original) (raw)
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Role Of Detritus On Trace Metals In Wetland-Terrestrial Systems: A Review
Mass settling of the detritus through the overlying water column results in their accumulation at the bed surface of aquatic bodies (wetlands, lakes, ocean etc.). This review attempts brief description about the processes that start soon after the deposition of detrital matter resulting in formation of relatively stable end product, the humus that plays a major role in pedochemical processes. This review discusses the interaction (Complexation) between humus (Natural organic matter in soil/sediments) and trace metals, which determines their fate in aquatic systems, specifically wetlands. The activities of metal ions at the binding sites, the common methods used to study complexation of humic substances with metal elements are also talked over. The limitations of the instrumental methods in studying the complexation process and its possible solutions are focussed in this section. In this context certain aspects of trace metal(Bio) availability, distribution and mobility are also discussed. In addition, this review provides a brief overview of chemical speciation of trace metals in the system.
Alkali and alkaline earth metals in decomposing macrophytes in a wetland system
Acta Ecologica Sinica
The background concentration of selected alkali and alkaline earth metals (sodium, potassium, calcium and magnesium) in some macrophytes was explored in the wetland system of Keoladeo National Park, Bharatpur, India. Changes in the concentration of these elements in the course of macrophyte decomposition were also studied. The species selected were Paspalum distichum, Paspalidium punctatum, Cyperus alopecuroides, Pseudoraphis spinescens, Ipomoea aquatica, Neptunia oleracea and Hydrilla verticillata, which dominate the aquatic vegetation of the Park. Litterbag decomposition experiments were carried out with nylon bags of two different mesh sizes (0.14 and 0.375 mm) in the laboratory and in the field. Among the macrophytes, Hydrilla was the fastest decaying species with the lowest half-life (12.65 days) and Paspalidium the slowest with the highest half-life (385.08 days). Overall, the grasses had low decay rate and high half-life. Background concentration of Na, K, Ca and Mg varied among the plant species. During decomposition and towards the end of the experiment, Na, K and Ca gradually declined whereas Mg increased. The variation was significant (ANOVA, P <0.05) among metals and macrophytes. Na showed no correlation with the weight loss of decomposing macrophytes in the field or in the laboratory tanks. In the field, the K concentration, in contrast with the observations in the tanks, was negatively correlated with the biomass and positively correlated with Ca content. Ca concentration in the biomass was negatively correlated with the weight of the remaining biomass, while Mg was positively correlated with the biomass in the litterbags.
Environment International, 2004
Marshes have been proposed as sites for phytoremediation of metals. The fate of metals within plant tissues is a critical issue for effectiveness of this process. In this paper we review studies that investigate the effects of plants on metals in wetlands. While most of these marsh plant species are similar in metal uptake patterns and in concentrating metals primarily in roots, some species retain more of their metal burden in belowground structures than other species, which redistribute a greater proportion of metals into aboveground tissues, especially leaves. Storage in roots is most beneficial for phytostabilization of the metal contaminants, which are least available when concentrated below ground. Plants may alter the speciation of metals and may also suffer toxic effects as a result of accumulating them. Metals in leaves may be excreted through salt glands and thereby returned to the marsh environment. Metal concentrations of leaf and stem litter may become enriched in metals over time, due in part to cation adsorption or to incorporation of fine particles with adsorbed metals. Several studies suggest that metals in litter are available to deposit feeders and, thus, can enter estuarine food webs. Marshes, therefore, can be sources and well as sinks for metal contaminants. Phragmites australis, an invasive species in the northeast U.S. sequesters more metals belowground than the native Spartina alterniflora, which also releases more via leaf excretion. This information is important for the siting and use of wetlands for phytoremediation as well as for marsh restoration efforts.
Marshes have been proposed as sites for phytoremediation of metals. The fate of metals within plant tissues is a critical issue for effectiveness of this process. In this paper we review studies that investigate the effects of plants on metals in wetlands. While most of these marsh plant species are similar in metal uptake patterns and in concentrating metals primarily in roots, some species retain more of their metal burden in belowground structures than other species, which redistribute a greater proportion of metals into aboveground tissues, especially leaves. Storage in roots is most beneficial for phytostabilization of the metal contaminants, which are least available when concentrated below ground. Plants may alter the speciation of metals and may also suffer toxic effects as a result of accumulating them. Metals in leaves may be excreted through salt glands and thereby returned to the marsh environment. Metal concentrations of leaf and stem litter may become enriched in metals over time, due in part to cation adsorption or to incorporation of fine particles with adsorbed metals. Several studies suggest that metals in litter are available to deposit feeders and, thus, can enter estuarine food webs. Marshes, therefore, can be sources and well as sinks for metal contaminants. Phragmites australis, an invasive species in the northeast U.S. sequesters more metals belowground than the native Spartina alterniflora, which also releases more via leaf excretion. This information is important for the siting and use of wetlands for phytoremediation as well as for marsh restoration efforts. D
Editorial: Wetland Biogeochemistry: Response to Environmental Change
Frontiers in Environmental Science, 2020
Editorial on the Research Topic Wetland Biogeochemistry: Response to Environmental Change Wetlands around the world are increasingly impacted by a shift in environmental conditions due to climate change, land use development, resource extraction, urbanization, and sea level rise, to name a few external pressures (Meng et al., 2016; Walpole and Davidson, 2018). These environmental changes can alter the hydrological regime, impacting the biogeochemical processes that govern important wetland ecosystem services, such as carbon sequestration and water storage. Biogeochemical processes in wetlands are highly dynamic (Reddy et al., 2010; Jackson et al., 2014) and involve complex interactions between hydrological processes, mineralogical transformations, bacterial and vegetation communities, and soil stores of carbon and nutrients (Cherry, 2011; U.S. EPA, 2015). Currently, our understanding of biogeochemical properties of wetlands are derived from mechanistic and statistical links between biological, geological, and chemical processes. However, how climatic and hydrological processes interact with wetland biogeochemical functions is still not well-understood. Wetland ecosystems maintain a fragile balance between soil, water, plant, microbial, and atmospheric processes, which regulates water flow and water quality (Reddy and Delaune, 2008). Even minor gradients (naturally or anthropogenically induced) in hydrological and climatic parameters (e.g., wetting and drying, flooding, freezing, and thawing, groundwater-surface water interactions, etc.) can change the ecology and (bio)geochemistry of wetlands. These changes can have profound impacts on globally important processes, such as greenhouse gas emissions. Within a wetland, there is a high degree of spatial and temporal heterogeneity of chemical properties, temperature, and water-saturation that regulates the transport and transformation of carbon, nutrients, and redox-active elements (Reddy et al., 2010; Cherry, 2011; Jackson et al., 2014). The heterogeneity results in both spatial and temporal pulses of biogeochemical activity, primarily associated with aerobic or anaerobic microbial respiration. Thus, wetlands are considered "biogeochemical hotspots" in the landscape, with an enhanced cycling of nutrients, carbon and trace metals (Megonigal, 2008; Reddy et al., 2010; Cherry, 2011). Quantifying the variability in process intensity remains challenging but is, however, critical to unravel the linkages between forcing environmental boundary conditions and biogeochemical responses. This Research Topic brings together wetland (bio)geochemists, hydrologists, biologists, ecologists, and soil scientists to share research in various areas of wetland biogeochemistry
The fate of selected heavy metals and arsenic in a constructed wetland
Journal of Environmental Science and Health, Part A, 2019
The fate of Cd, Pb, Cu, Zn, Ni, Cr, and As in a horizontal subsurface flow-constructed wetland was studied. The concentrations of the risk elements in treated municipal wastewater, wetland sediments, and Phragmites australis biomass were determined. Most of the studied elements were removed from the wastewater with fair efficiencies. On the other hand, As was released to treated water in the wetland bed. The removal efficiencies obtained for the individual elements were as follows: 64.2, 48.7, 70.0, 93.9, 63.6, 63.8, and-236.2%, respectively. The concentrations measured in sediments were the highest for samples taken 1 m from the inflow zone. They were 4.11, 2.01, 6.01, 4.85, 3.39, 9.30, and 3.17 times higher as compared to the samples taken in the distance of 10 m. The pollutants were preferentially deposited at the front part of the wetland bed where anaerobic conditions predominated and sulfate reduction took place. There were no significant differences in the concentrations of the studied elements in the aboveground biomass (Phragmites australis) samples taken in the distances of 1, 5, and 10 m from the inflow zone. However, the concentrations measured in the belowground biomass samples were significantly higher for samples taken at the front part of the wetland bed. The individual element concentration ratios between the below-and aboveground biomass measured for samples taken 1 m from the inflow zone were 4.
Elemental composition of native wetland plants in constructed mesocosm treatment wetlands
Bioresource Technology, 2005
Plants that accumulate a small percentage of metals in constructed treatment wetlands can contribute to remediation of acidic, metal contaminated runoff waters from coal mines or processing areas. We examined root and shoot concentrations of elements in four perennial wetland species over two seasons in mesocosm wetland systems designed to remediate water from a coal pile runoff basin. Deep wetlands in each system contained Myriophyllum aquaticum and Nymphaea odorata; shallow wetlands contained Juncus effusus and Pontederia cordata. Shoot elemental concentrations differed between plants of deep and shallow wetlands, with higher Zn, Al, and Fe concentrations in plants in shallow wetlands and higher Na, Mn, and P concentrations in plants in deep wetlands. Root and shoot concentrations of most elements differed between species in each wetland type. Over two seasons, these four common wetland plants did help remediate acidic, metal-contaminated runoff from a coal storage pile.
Use of Wetland Plants in Bioaccumulation of Heavy Metals
Soil Biology, 2013
Environmental pollutants due to dispersal of industrial and urban wastes generated through anthropogenic activities have become a major global concern. Most of the pollutants once enter into the environment get accumulated in soils and aquatic environments, creating wide spread contamination that vary in composition and in concentration. Several factors are responsible for the migration of contaminants like controlled and uncontrolled disposal of organic and inorganic wastes, accidental and process spillages, inadequate residue disposal, mining, and smelting of metalliferous ores, sewage sludge application to agricultural soils, etc. (Ghosh and Singh 2005; Kavamura and Esposito 2010). Steady deterioration of the environment due to pollution and its ailing effects to mankind is among the major concerns worldwide.