Li Rui, Xiao Qiong, Liu Wen, Guo Fang, Pan Mou-cheng, Yu Shi
Huan Jing Ke Xue. 2015 Aug;36(8):2877-86.
To reveal the temporal and spatial variation pattern of groundwater chemistry in Lihu Lake and explore the causes for the change of water quality through analysis of sulfur isotope and nitrogen-oxygen isotope, so as to provide scientific basis for reasonable exploitation and protection of karst water resources. Several groundwater samples, collected from January to December in 2010 and May, October in 2014 were monitored to analyze the chemical composition of conventional water and the characteristics of delta34S-SO4(2-), and delta15N-NO3-. The results showed that: (1) The hydrochemical type of the underground water was HCO3-Ca type and effected by the seasonal precipitation and human activity, the temporal and spatial variation of the main cations was obvious. (2) The sulfur concentration in the underground river was slightly decreased since the operation of the sewage plant, however, the sulfur concentration was still high. The nitrate pollution aggravated in the year 2014 compared to 2010. Impacted by human activity, the concentration of sulfur and nitrate was higher in the upstream Nandan river, Layi cave and the midstream Liangfeng cave, and Gantianba than in the downstream Xiaolong cave. (3) The delta34S-SO4(2-) value ranged from -4.12%o to -0.93%o. It was inferred that the emission of sulfur oxides through burning coal resulted in the rainwater acidification, which input a large amount of SO4(2-) into the underground water in the form of acid rain. (4) The delta15N-N03- value ranged from 0.26%o to 11.58%o, with an average value of 7.61%o, the delta18O-NO3- value ranged from -2.33%o to 21.76%o, with an average value of 9.38%o. In combination of the composition analysis of nitrogen-oxygen isotope of nitrate, it was believed that soil organic nitrogen, manure and sewage were the main sources of nitrate in the groundwater and the main causes for aggravation of nitrate pollution of the underground water.
揭示里湖地下水化学特征的时空变化规律，通过硫同位素和氮氧同位素分析，探究水质变化原因，为岩溶水资源合理开发与保护提供科学依据。采集了2010年1月至12月以及2014年5月、10月的多个地下水样本，监测常规水化学成分以及δ34S-SO4(2-)和δ15N-NO3-特征。结果表明：(1) 地下水水化学类型为HCO3-Ca型，受季节性降水和人类活动影响，主要阳离子的时空变化明显。(2) 污水处理厂运行后地下河硫浓度略有下降，但仍处于较高水平。2014年硝酸盐污染较2010年加重。受人类活动影响，南丹河上游、拉易洞、凉风洞中游以及甘田坝的硫和硝酸盐浓度高于下游小龙洞。(3) δ34S-SO4(2-)值在-4.12‰至-0.93‰之间。推测燃煤排放的硫氧化物导致雨水酸化，以酸雨形式向地下水中输入大量SO4(2-)。(4) δ15N-N03-值在0.26‰至11.58‰之间，平均值为7.61‰，δ18O-NO3-值在-2.33‰至21.76‰之间，平均值为9.38‰。结合硝酸盐氮氧同位素组成分析，认为土壤有机氮、粪便和污水是地下水中硝酸盐的主要来源，也是地下水硝酸盐污染加重的主要原因。
