Soil contaminant primary sources

The demands for assessing the potential impact of radionuclides produced by military and nuclear power supply applications on environmental quality and human and the desire to remediate radionuclide-contaminated site have triggered an intensive and wide range of research activities. Soil chemical reactions are critical to both environment and human health and to successful remediation. This chapter s aim is to briefly describes the physical and chemical characteristics of the most important radioactive nuclides likely to be found in soils. The primary sources of these radionuclides include the fallout from atmospheric weapon tests, release from fuel processes facilities, nuclear material storage facilities, biomedical applications, and, of course, naturally-occurring radioactive elements. The forms and interactions of the radionuclides in soil environment are subsequently discussed. 

Table 1 indicates primary pollutant sources and waste modes, and Table 2 indicates the primary and secondary sources and associated pollutants. The primary sources of soil contamination include land disposal of solid waste sludge and waste-water industrial activities and leakages and spills, primarily of petroleum products. The solid waste disposal sites include dumps, landfills, sanitary landfills, and secured landfills. 

PRIMARY SOURCES OF SOIL CONTAMINATION AND ASSOCIATED POLLUTANTS... 

The primary sources of PCP in humans include direct intake by way of diet, air, or water and through contact with PCP-contaminated materials (Uhl et al. 1986). It is now established that PCP is taken up by female rhesus monkeys via the skin from PCP-contaminated soils. Monkeys accumulated up to 24% of the PCP in contaminated California soils over a 24-h period (Wester et al. 

On May 17, 1993, two underground storage tanks (USTs) at the Artesia Yard failed tank-tightness tests. A representative of the New Mexico Environment Department (NMED) confirmed the release on August 2, 1993, when the tanks were removed (Fig. 2). In addition to removing the tanks and associated piping, which were the primary sources of contamination, the excavation contractor removed approximately 100 yards of hydrocarbon-contaminated soil from the former tankhold. 

Toxoplasmosis is a recurrent, potentially blinding, disease caused by the obligate intracellular parasite Toxoplasma gondii. Toxoplasmosis affects millions of people worldwide. Cats are the definitive host for the parasite but not the primary source of human infection. Environmental contamination of the soil, water, fruits and vegetables, and infection in other animals cause most human infections. Human infection may be either congenital or acquired, and acquired disease appears to be the most prevalent. 

POPs are pervasive in our environment. They are present virtually everywhere in the world including the Arctic environsFood is the primary source of human exposure to POPs. As discussed in Chapter 9, they are taken up in plants grown in contaminated soil. I2 For example, alpha-endosulfan, beta-endosulfan, and endosulfan sulfate were absorbed by lettuce growing in soil contaminated with these pesticides J3 ... 

The primary sources of bacteria in water are human and animal wastes, seepage or discharge from septic tanks, sewage treatment facilities, and natural soil and plant bacteria. Pathogenic organisms can cause intestinal infections, dysentery, hepatitis, typhoid fever, cholera, and other illnesses. The EPA requires that aU public water suppliers regularly test for coliform bacteria and deliver water that meets the EPA standards. The EPA Maximum Contaminant Level (MCL) for coliform bacteria in drinking water is zero total cohforms per 100 mL of water (56). 

Atmospheric testing of nuclear weapons has been the main source of plutonium dispersed in the environment. Accidents and routine releases from weapons production facilities are the primary sources of localized contamination. Consumer and medical devices containing plutonium are sealed and are not likely to be environmental sources of plutonium (WHO 1983). Plutonium released to the atmosphere reaches the earth s surface through wet and dry deposition to the soil and surface water. Once in these media, plutonium can sorb to soil and sediment particles or bioaccumulate in terrestrial and aquatic food chains. 

Anthropogenic (man-made) releases of plutonium are the primary sources of plutonium to the atmosphere. Atmospheric testing, fires involving plutonium-containing materials, and routine releases due to normal activities at processing and generating plants are all potential sources of airborne plutonium. Resuspension of plutonium sorbed to contaminated surface soils via fugitive dust emissions is an indirect pathway by which plutonium may be re-released into the atmosphere (Harley 1980). 

It seems a reasonable assumption that a primary source of contamination in urban parklands will be fallout from air pollution, although the much higher variance for copper, lead and zinc in urban soils suggests that contributions from other sources, such as pockets of old refuse within the soil, cannot be ruled out. 

The primary source of rare earths for agricultural use in China are soluble extracts of mineral ores, that were originally known as Nongle (=happy farmer) but have recently been re-named Changle (=happiness forever). These compounds have usually been extracted with nitric acid and are said to contain an equivalence of 38% RE oxide. As well as the rare earths they also contain a number of elements essential to plant growth (table 8). Trace element deficiencies are common in China, particularly those of B, Fe, Mn, Mo and Zn (Liu et al. 1983, 1984). Many of these soils are also low in REE (Zhu and Liu 1986) and it remains possible that some of the reported effects of rare earths may be due to other trace elements, especially Mo, present in Changle as contaminants. The... 

Important environmental sources and pathways of lead still remain, with lead-based paint and lead-contaminated dusts and soils as the primary sources and pathways of lead exposure for children. In addition, children continue to be exposed to lead through air, water, and food, as well as occupations and hobbies ofparents and caretakers. The focus ofprevention efforts must therefore expand... 

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