Fölster Jens, Wilander Anders
Department of Environmental Assessment, Swedish University of Environmental Sciences, Uppsala.
Environ Pollut. 2002;117(3):379-89. doi: 10.1016/s0269-7491(01)00201-9.
Sulphur deposition in Sweden has decreased to less than half of the levels recorded in 1970 and now signs of recovery from acidification of surface waters are beginning to appear. We investigated time trends of water chemistry between 1985 and 1998 in 13 streams draining small forested catchments with generally shallow acid sensitive soils. At nine of the catchments, bulk deposition was monitored as well. Sulphate concentrations decreased in both stream water and deposition, although with somewhat smaller trends in stream water compared with deposition. The magnitude of the trends in sulphate increased from north to south, following a gradient of increasing industrial influence. Five sites in the southern half of the country showed weak signs of recovery from acidification in terms of increasing concentrations of acid neutralising capacity and decreasing concentrations of hydrogen ions, corresponding to annual increases of 0.01 pH units. Changes in stream discharge and concentrations of marine salts and organic acids could not explain the observed decrease in acidity and the results were interpreted as recovery from anthropogenic acidification. For the northern half of Sweden, any changes in water chemistry could be attributed to natural variation in climate and marine influence, and the effect of anthropogenic acidification was negligible.
瑞典的硫沉降已降至1970年记录水平的一半以下，现在地表水酸化的恢复迹象开始显现。我们调查了1985年至1998年间13条流经小型森林集水区的溪流的水化学时间趋势，这些集水区的土壤普遍浅薄且对酸敏感。在其中9个集水区，还监测了总沉降量。溪流水和沉降中的硫酸盐浓度均有所下降，不过溪流水浓度下降的趋势与沉降相比略小。硫酸盐浓度下降趋势的幅度从北向南增大，这与工业影响增强的梯度一致。该国南部一半地区的5个地点在酸中和能力浓度增加和氢离子浓度降低方面显示出从酸化中恢复的微弱迹象，相当于每年pH值增加0.01个单位。溪流流量、海盐和有机酸浓度的变化无法解释观察到的酸度下降，结果被解释为人为酸化的恢复。对于瑞典的北部一半地区，水化学的任何变化都可归因于气候和海洋影响的自然变化，人为酸化的影响可以忽略不计。
