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随着城市化的快速发展,大量生活废水的排放严重影响岩溶地下水质。本文尝试利用重庆南山老龙洞流域2012年每月地下水、雨水和生活污水的水化学数据与环境同位素~(87)Sr/~(86)Sr、δ~(34)S-SO_4~(2-)和δ~(13)C_(DIC)来研究城市发展对岩溶地下水质的影响,结果表明:1)城市化过程带来的硫酸改变了岩溶地质过程,不同月份碳酸溶蚀碳酸盐岩对地下水中(Ca~(2+)+Mg~(2+))和HCO_3~-的贡献率分别变化于38%~68%(平均贡献率为53%)和55%~81%(平均贡献率为68%),而硫酸溶蚀碳酸盐岩对地下水(Ca~(2+)+Mg~(2+))和HCO_3~-的贡献率分别变化于32%~62%(平均贡献率为47%)和19%~45%(平均贡献率为32%);2)生活废水的输入改变了流域地下水锶同位素的地球化学特征,地下水~(87)Sr/~(86)Sr变化于0.70800~0.70900,明显高于雨水和石灰岩溶解来源的~(87)Sr/~(86)Sr值,而低于生活废水的~(87)Sr/~(86)Sr值,表明流域地下水质受水-岩作用和污水输入的共同影响;3)地下水δ~(34)S-SO_4~(2-)变化于7.8‰~12.0‰之间,SO_4~(2-)主要来源于生活污水和雨水的输入与石膏的溶解;4)地下水δ~(13)C_(DIC)变化于-11.2‰~-7.3‰之间,且地下水(Ca~(2+)+Mg~(2+))/HCO_3~-摩尔比率介于0.60~0.71,流域地下水质一方面受控于CO_2对碳酸盐岩溶解的自然过程,另一方面则受城市化过程产生的硫酸对碳酸盐岩溶解的控制。
With the rapid development of urbanization, the discharge of a large amount of domestic wastewater seriously affects the quality of karst groundwater. This paper attempts to make use of monthly chemical and environmental isotopes of (87) Sr / ~ (86) Sr, δ ~ (34) S-SO_4 ~ (2-) in groundwater, rainwater and domestic sewage in Laolongdong Valley of Nanshan in 2012, And δ ~ (13) C_ (DIC) were used to study the impact of urban development on karst groundwater quality. The results show that: 1) Sulfuric acid brought by urbanization changed the karst geologic process; carbonate dissolution in different months affected groundwater (Ca 2+ + Mg 2+) and HCO 3+ varied from 38% to 68% (average contribution rate was 53%) and 55% to 81% (average contribution rate was 68% %), While the contributions of sulfate-dissolved carbonate rocks to groundwater (Ca2 + Mg2 +) and HCO3- vary from 32% to 62% (with an average contribution of 47%) And 19% -45% respectively (average contribution rate was 32%). 2) The input of domestic wastewater changed the geochemical characteristics of strontium isotopes in the groundwater. The change of 87 Sr / 86 Sr in groundwater varied from 0.70800 to 0.70900, (87) Sr / ~ (86) Sr, which is lower than that of ~ (87) Sr / ~ (86) Sr in domestic wastewater, indicating that the groundwater quality in the basin is affected by water-rock And the combined effect of sewage input; 3) the groundwater δ 34 S-SO 4 2- changes from 7.8 ‰ to 12.0 ‰ SO (4) The change of δ ~ (13) C_ (DIC) in groundwater is between -11.2 ‰ and -7.3 ‰, and the groundwater (Ca ~ (-)) is mainly from the input of domestic sewage and rainwater and the dissolution of gypsum. 2 +) + Mg ~ (2 +) / HCO_3 ~ - molar ratio range from 0.60 to 0.71. The groundwater quality in the basin is controlled by the natural process of carbon dioxide dissolution of carbonate rock on the one hand and the urbanization process Sulfuric acid produced controls the dissolution of carbonate rocks.