Polluted sites

Table I. Concentrations of halogenated hydrocarbons in organisms, (ng d.w.). The first number represents samples from the non-poUuted site, the second from polluted site...

In the last few years, detection, characterization, and handling of pollution sites have grown into a new discipline with its specific technology, initially drawn from other disciplines such as statistics, then customized to meet the specificity of pollution control. 

The landfill liner, cover, and hydraulic barrier all belong to the subsurface pollutant engineered containment system. The liner is designed at the bottom of a landfill to contain downward leachate. The cover is designed at the top of a landfill to prevent precipitation from infiltrating into the landfill. The hydraulic barrier, or cutoff walls, is a vertical compacted earthen system to contain horizontal flow of plume. The ultimate purpose of these barriers is to isolate contaminants from the environment and, therefore, to protect the soil and groundwater from pollution originating in the landfill or polluted site. 

Phytoremediation is considered a low-cost remediation alternative for low-depth contamination, offering a permanent solution and improving the aesthetics of the polluted site. It is well-suited for use in the following situations ... 

Limitations need to be carefully considered before selecting this method for site remediation. These include the depth of contamination, the total length of time required for cleanup to below accepted limits, potential contamination of vegetation and the food chain, and difficulty in establishing and maintaining vegetation at some polluted sites.8... 

Natural attenuation relies on natural processes to clean up or attenuate pollution in soil and ground-water. Natural attenuation occurs at most polluted sites. However, the right conditions must exist underground to clean sites properly. If not, cleanup will not be quick enough or complete enough. Scientists monitor or test these conditions to make sure natural attenuation is working. This is called monitored natural attenuation (MNA)94-96... 

Li Y, Huo X, Liu J, Peng L, Li W, Xu X (2010) Assessment of cadmium exposure for neonates in Guiyu, an electronic waste pollution site of China. Environ Monit Assess 177 343-351... 

Bainy ACD, Saito E, Carvalho PSM, Junqueira VBC (1996) Oxidative stress in gill, erythrocytes, liver and kidney of Nile tilapia (Oreochromis niloticus) from a polluted site. Aquat Toxicol 34 151-162... 

Fleck, L. C., Bicca, F. C. and Ayub, M. A. Z. (2000). Physiological aspects of hydrocarbon emulsification, metal resistance and DNA profile of biodegrading bacteria isolated from oil polluted sites, Biotechnol. Lett., 22, 285-289. 

Comprehensive information on contamination by all of the POPs is not available for China. However, some monitoring information is available. For example, information on PCBs indicates that contamination is greatest in the industrialized areas of the coast. Sediments in the Pearl River and its estuary, Dalian Bay and the Songhua River had relatively high levels of PCBs. There were also some areas, mainly the industrial pollution sites or PCB equipment storage locations, which remain seriously polluted with high PCB residue levels. (Xing et al., 2005 See list of published papers.)... 

Species firom this family are often found on salt or heavy metal polluted sites. Since they accumulate little biomass they are not used for phytoremediation, but their presence is taken as an indicator of pollution. 

The above examples have shown that laboratory studies carried out under eontrolled conditions are important for gaining an understanding of the processes and mechanisms involved in plant acclimation to environmental stresses. The results of these studies, besides being of academic interest, can also inform the development of phytoremedation technology. We anticipate seeing the cultivation of plants not only for aesthetic and landscape architecture reasons, but also for the rescue of polluted sites. 

Cell components or metabolites capable of recognizing individual and specific molecules can be used as the sensory elements in molecular sensors [11]. The sensors may be enzymes, sequences of nucleic acids (RNA or DNA), antibodies, polysaccharides, or other reporter molecules. Antibodies, specific for a microorganism used in the biotreatment, can be coupled to fluorochromes to increase sensitivity of detection. Such antibodies are useful in monitoring the fate of bacteria released into the environment for the treatment of a polluted site. Fluorescent or enzyme-linked immunoassays have been derived and can be used for a variety of contaminants, including pesticides and chlorinated polycyclic hydrocarbons. Enzymes specific for pollutants and attached to matrices detecting interactions between enzyme and pollutant are used in online biosensors of water and gas biotreatment [20,21]. 

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