Discharge anthropogenic

Finally, some authors have computed metal loading to the enviroranent from specific human activities, such as discharges of waste-water, and compared these with natural release rates. While the details of the computations and conclusions vary, the general observation for many metals is that anthropogenic contributions to metal ion transport rates and environmental burdens are approaching and in many cases have already exceeded natural contributions. A few such comparisons are provided in Tables 15-1-15-4. 

Once the anthropogenic release rates of metals are established, the next critical step is to evaluate their fate upon discharge to receiving... 

About 2.47 million kg of silver are lost each year to the domestic biosphere, mostly (82%) as a result of human activities. As discussed later, the photography industry accounts for about 47% of all silver discharged into the environment from anthropogenic sources. In 1990, about 50% of the refined silver consumed domestically was used to manufacture photographic products 25% in electrical and electronic products 10% in electroplated ware, sterlingware, and jewelry 5% in brazing alloys and 10% in other products and processes. 

Arsenic geochemistry in Chesapeake Bay, Maryland, depends on anthropogenic inputs and phytoplankton species composition (Sanders 1985). Inputs of anthropogenic arsenic into Chesapeake Bay are estimated at 100 kg daily, or 39 tons/year — probably from sources such as unreported industrial discharges, use of arsenical herbicides, and from wood preservatives (Sanders 1985). The chemical form of the arsenic in solution varies seasonally and along the axis of the bay. Arsenic is present only as arsenate in winter, but substantial quantities of reduced and methylated forms are present in summer in different areas. The forms and distribution patterns of arsenic... 

Today, the most important environmentally damaging anthropogenic radiation comes from atmospheric testing of nuclear weapons conducted 20 to 30 years ago, authorized discharges to the sea from nuclear reprocessing plants, and from the Chernobyl accident in 1986 (Aarkrog 1990). 

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