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首页> 外文期刊>Environmental Science & Technology >Contemporary Trends in the Acid-Base Status of Two Acid-Sensitive Streams in Western Maryland
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Contemporary Trends in the Acid-Base Status of Two Acid-Sensitive Streams in Western Maryland

机译：马里兰西部两条酸敏感流的酸碱状态的当代趋势

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Recovery of streamwater acid neutralizing capacity (ANC) resulting from declines in regional acid deposition was examined using contemporary (1990-2005) data from two long-term monitoring stations located on the Appalachian Plateau in western Maryland, U.S. Two computational methods were used to estimate daily, monthly, and annual fluxes and discharge-weighted concentrations of ANC, sulfate, nitrate, and base cations over the period of record, and two statistical methods were used to evaluate long-term trends in fluxes and concentrations. The methods used to estimate concentrations, as well as the statistical techniques, produced very similar results, underlining the robustness of the identified trends. We found clear evidence that streamwater sulfate concentrations have declined at an average rate of about 3 μeq L~(-1) yr~(-1) at the two sites due to a 34% reduction in wet atmospheric sulfur deposition. Trends in nitrate concentrations appear to be related to other watershed factors, especially forest disturbance. The best evidence of recovery is based on a doubling of ANC (from 21 to 42 μeq L~(-1)) at the more acid-sensitive site over the 16-year period. A slowing, or possible reversal, in the sulfate, nitrate, and SBC trends is evident in our data and may portend a decline in the rate of-or end to-further recovery.
机译：使用来自美国马里兰州阿巴拉契亚高原的两个长期监测站的当代（1990-2005年）数据，研究了由区域酸沉降减少导致的溪水酸中和能力（ANC）的恢复，使用了两种计算方法进行估算记录期内ANC，硫酸盐，硝酸盐和碱性阳离子的日，月和年通量和放电加权浓度，并使用两种统计方法评估通量和浓度的长期趋势。用于估算浓度的方法以及统计技术产生了非常相似的结果，突显了已识别趋势的稳健性。我们发现明确的证据表明，由于湿大气中硫的沉积减少了34％，两个地点的溪流硫酸盐浓度平均下降了3μeqL〜（-1）yr〜（-1）。硝酸盐浓度的趋势似乎与其他流域因素有关，尤其是森林干扰。最好的恢复证据是在16年的时间内对酸敏感度更高的部位的ANC翻倍（从21μeqL〜（-1）增加到42μeqL〜（-1））。硫酸盐，硝酸盐和SBC趋势的减缓或可能逆转在我们的数据中很明显，并且可能预示着或最终回收率的下降。

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