[USGS] 지하수질 변동 맵 발간

지난 20년 간 미국 지질조사소(USGS)가 미국 내 지하수질의 변동을 평가한 결과에 따르면 염화물 및 질산염 오염물질이 증가하고 있으며, 비소농도는 같거나 다소 떨어진 것으로 조사됐다.

현재 1억4천만 명 이상의 미국인은 주요 식수원으로 지하수를 이용하고 있으며, 이들 중 4천500만 명의 사람들은 오염물질에 특히 취약한 개인 우물을 이용하고 있다. 지하수질지도는 농약, 질산염, 중금속, 가솔린 첨가제, 기타 화학물질 등의 증감 변동을 보여준다. 연방과학기관(federal science agency)은 이러한 결과를 담은 상호작용적 온라인 맵을 발간했으며, nawqatrends.wim.usgs.gov/Decadal에서 확인할 수 있다.

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USGS Map highlights groundwater quality concerns

A U.S. Geological Survey assessment of changes in the nation’s groundwater quality in the last two decades shows chloride and nitrate concentrations are rising and arsenic levels are holding steady or falling. The federal science agency published the results in an interactive online map, available at nawqatrends.wim.usgs.gov/Decadal.

More than 140 million people in the United States use groundwater as their primary source of drinking water. Of that group, some 45 million people use private wells, which are particularly vulnerable to contamination, as they are not subject to the same quality standards as water utilities.

The groundwater quality map shows whether concentrations of pesticides, nutrients, heavy metals, gasoline additives, and other chemicals are rising or falling. The map tracks contaminants such as chloride and nitrate, where there is a clear upward trend nationally. According to the map, uranium is rising in California’s Central Valley and in the Southwest.

The study is part of the USGS’s National Water Quality Assessment, whose purpose is to identify long-term changes in the quality of rivers and aquifers. It is part of a revamped effort at the federal level to understand the nation’s groundwater resources. The national groundwater monitoring network, being developed by the USGS in partnership with local agencies, was recently granted $US 3.6 million for the 2016 fiscal year. Additionally, the first national assessment of brackish groundwater in more than 50 years will be published in September.

The data for the groundwater quality map was collected once between 1988 and 2000 and again between 2001 and 2012. Federal scientists and colleagues at state agencies collected water samples from roughly 5,000 wells in the first period. They then resampled some 1,500 wells in 67 regions of the country. Sampling was conducted at the same time of year so as to measure the same seasonal conditions.

[출처 = Water World / 2016년 6월 8일]