贵州省六冲关流域大气沉降和地表水化学特征

对比贵州六冲关森林小流域1992─1994年和2001─2005年2个时期穿透水沉降(TF)和地表水的化学组成,以分析大气沉降对森林小流域生物地球化学过程的影响. 结果表明:2001─2004年硫沉降量较1992─1994年有显著下降,但自2005年起硫沉降量又显著增加. 六冲关流域无机氮(尤其是NH₄+-N)沉降量较历史时期显著增加,说明贵阳市大气污染正在由硫酸型向硫酸-硝酸混合型过渡. 长期的大气沉降导致地表水中SO₄2-和NO₃-等阴离子质量浓度的增加,加剧了Ca,Mg和K等营养元素的流失,使地表水的酸中和能力在2002年为负值. 长期观测发现,地表水酸中和能力与穿透水中Ca和Mg的沉降通量密切相关,说明大气沉降已经对六冲关流域的相关生物地球化学过程造成了潜在的影响. 

Chemical Characteristics of Atmospheric Deposition and Surface Water in Liuchongguan Catchment, Guizhou Province

To fully understand the influences of atmospheric deposition on biogeochemical processes of forest catchements, chemical composition of throughfall deposition and surface water were studied based on field monitoring over two periods (1992-1994 and 2001-2005), in Liuchongguan (LCG) forest catchement, Guizhou Province. The data show a clear decrease of sulfur deposition in 2001-2004 due to strict control policies compared to that in 1992-1994 in Guizhou Province. However, sulfur deposition increased again in 2005 because of higher sulfur emissions from power plants. Inorganic nitrogen, especially NH₄⁺-N deposition, was higher than 1992-1994, which indicated a transformation of air pollution from sulfur type to sulfuric-nitrous mixed type in Guiyang. Long-term atmospheric deposition resulted in higher concentrations of SO₄^2- and NO₃^- in the surface water, which accelerated the losses of nutrient elements such as Ca, Mg and K. A negative acid neutralizing capacity(ANC) was observed in 2002. The ANC of the surface water was significantly related with Ca and Mg fluxes in the throughfall, showing the potential effects of atmospheric deposition on the biogeochemical processes in Luchongguan catchment.