Results and discussion
3.1 Effect of the CW on HM removal from the YR water
A summary of the concentrations of the major contaminations in the water samples from the YR and CW is given in Table 1. The concentration of the HMs in the water from the CW system were much lower than that from the YR throughout the experimental period. The average removal rates (RRs) in the CW were 86.2%, 61.7%, 82.9%, and 76.7% for Cd, Cu, Pb, and Zn, respectively, (that is, in the order Cd>Pb>Zn>Cu), showing that the CW removed the HMs from the YR water efficiently. Importantly, the concentrations of all of the HMs studied were decreased by the CW to below the permissible limits defined in the level III guidelines in the Chinese Surface Water Environment Quality Standard (GB 3838-2002). Our results agreed with previously published results [19], confirming that CWs are effective at removing HMs from contaminated wastewater, and that the RRs are different for different metals. Moreover, it could be seen from the present results that the removal efficiency of CW on HMs would be differernt due to the status of the water pollution in the YR as well as the growth cycle of the cattails. That is, during stages III-V, the removal efficiency was relatively lower than stages I-II, this was attributed to the relative slowly growth of the cattailss which would in turn produce less biomass. This has been confirmed by previous studies (Rousseaua et al. 2008; Si et al. 2011).
The Cd, Cu, Pb, and Zn concentrations in the wetland substrate samples from the YR and CW are shown in Table 2. The HM concentrations were significantly higher in the YR sludge samples than in the CW substrate samples, except for Pb, and moreover, no significant variations in the YR water concen...
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The first mitigation banking guidance was released in 1995 by the EPA and Corps of Engineers. The most recent wetland mitigation banking guidance was released in 2008. The idea behind both wetland mitigation banking and conservation banking is to provide compensation for unavoidable impacts to resources prior to the environmental impact taking place (FWS, 2003). Based on the rules set forth in section 10 of the Rivers and Harbors Act and section 404 of the Clean Water Act, wetland impacts are reduced by using the following sequence of steps: avoiding impacts, minimizing impacts, and as a last resort, mitigating for impacts. Although the Corps has enforced a mitigation policy to reg...
Office of Water (2006) Wetlands: Protecting Life and Property from Flooding, Washington: Environmental Protection Agency
In the area of the Great Lakes, eastern Georgian Bay houses thousands of miles of marshlands and wetlands. These areas are some of the most threatened habitats in the world because they form where human development is highly concentrated, near the coast. Yet, the uninhabited wetlands are sometimes taken over by beaver dams. The water chemistry of these marshes depends on their location and connection with other bodies of water. Scientists Amanda Fracz and Patricia Chow-Fraser hypothesized that open wetlands
Due to industrial waste ,domestic wastes and agriculture wastes entering into water source, Chinese government reporting that nearly 60 percent of China’s groundwater is polluted. It also leads the decrease in water quality. A large amount of water cannot be used and thus foster the water scarcity problem in China.
There are many ways pollutants can enter lakes and rivers: agricultural and urban runoff, industrial outfalls, migration through groundwater, through the food chain, and many more. Many p...
Human activity is one of the leading causes of the disappearance of coastal wetlands. As the human population increases in coastal cities so does the demand for more land. Urbanization is causing enormous amounts of devastation to the existing wetlands. Unrestricted development is causing the erosion of soil, which is dumping foreign sediments into the wetlands polluting the water and disturbing the ecosystem. According to Lee et al. (2006) “Urbanization is a major cause of loss of coastal wetlands. Urbanization also exerts significant influences on the structure and function of coastal wetlands, mainly through modifying the hydrological and sedimentation regimes, and the dynamics of nutrients and chemical pollutants”. Restrictions on the development...
According to the U.S. Environmental Protection Agency, zinc ores contain only 3% to 11% metallic zinc. Along with the zinc, the ores usually contain other metals, including toxic metals like cadmium and lead. In addition, zinc itself, though necessary in small amounts, is harmful in high doses to both humans and animals. All these toxic metals can contaminate water, soil, and plants in the area surrounding the
wetlands. In order to do this, the NWI developed and utilizes a wetland classification system based on Cowardin et al. (1979). Utilizing this system, image analysts identify and classify wetlands and deepwater habitats from aerial photograph interpretation coupled with field-verification to ensure method accuracy. This information was formally only available as paper maps or transparent overlays, but data is now available through online mapping tools and standardized GIS information.
Between 300 and 400 million people worldwide live in areas near wetlands and depend on them. Wetlands are mechanisms for treatment of wastewater are extremely efficient because they absorb chemicals and filter pollutants and sediments. Half the world's wetlands have disappeared due to urbanization and industrial development. The only way to achieve sustainable development and poverty reduction will be through better management of rivers and wetlands, and the land they drain and drain as well as through increased investment in them.
The heap leaching method used to extract gold uses cyanide as part of the process. This can be “toxic to fish and wildlife” and is therefore an environmental concern with the mining of gold (Bartlett 79). Some other concerns taken into consideration when dealing with gold mining and heap leaching are “preventing bird poisoning on wet heaps and solution storage ponds […as well as amounts of] wind blown dust and other air contaminants [which] can be serious” problems spreading throughout the environment (Bartlett 79). Contamination of surface and ground waters is a major concern as a side effect of heap leaching (Bartlett 79). There has been action taken in order to reduce the possibility of any of these environmental considerations taking place during and after the process of heap leaching.
Wetlands are highly productive ecosystems. Wetlands include marshes, estuaries, bogs, fens, swamps, deltas, shallow seas, and floodplains. Wetland habitats support a vast range of plant and animal life, and serve a variety of important functions, which include water regime regulation, flood control, erosion control, nursery areas for fishes, fish production, recreation, plant production, aesthetic enjoyment, and wildlife habitat. Wetlands account for about 6% of the global land area and are among the most valuable environmental resources.
However, when the pH levels reach a certain stage, the iron can then precipitate out, coating sediments with the characteristic yellow, red or orange colourings (D.E.P. 2, 2002; U.S.G.S. ; U.S.E.P.A., 2002). The rate that A.M.D. advances is also influenced by the presence of certain bacteria (Doyle; U.S.G.S). A.M.D. that has dissolved heavy metals such as copper, lead and mercury can contaminate ground and surface water.
"Protecting Water Quality from Agricultural Runoff." Home. EPA, Mar. 2005. Web. 9 Mar. 2012. .
Most people think they know a wetland when they see one, but the delineation of wetlands for the purpose of granting permits has proven enormously controversial. According to the Environmental Protection Agency (EPA), an area is defined as a wetland when a combination of three technical criteria are met: Wetland hydrology (land that is saturated within 18 inches of the surface for more than seven days per year), Hydrophytic vegetation (a list of plants that will thrive in wet areas), and Hydric soil (mucky and peat-based soil). The continual destruction of these valuable lands is due mainly to farmers, oil and mining interests, and development groups (Russel, p.36). It is estimated that 30-40% of the original wetlands in the United States have been lost, and about 300-400,000 acres are destroyed each year (Hollis, p. 36). Recent concern has led to an increase in wetland restoration and creation to reduce the impacts of activities in or near wetlands, compensate for additional losses, and to restore or replace wetlands already degraded or destroyed (Nicholas, p. 39).
Water pollutants are of different types such as oxygen demanding wastes, disease causing agents, synthetic organic compounds, plant nutrients, inorganic chemicals and minerals, oils, thermal discharge and radioactive wastes. Of all these water pollutants, heavy metals and synthetic organic compounds cause majority of water pollution. Industries like paper and pulp, tanneries, textiles and coke ovens, pha...