【摘要】：為探討人為來源的硫酸和硝酸進入地下河系統(tǒng)后產(chǎn)生的水-巖作用時空差異,以受城鎮(zhèn)排污和工農(nóng)業(yè)活動影響的廣西南丹縣里湖地下河流域為研究對象,分別于2014年5月、10月及2015年1月、7月對里湖地下河水化學進行監(jiān)測并分析其δ~(13)CDIC組成,結(jié)果表明:1里湖地下河流域為HCO_3-Ca型,受控于碳酸鹽巖的自然風化溶解和人為產(chǎn)生的城鎮(zhèn)污水、工業(yè)廢水和農(nóng)用肥料的影響,各離子濃度在旱季大于雨季,空間上從上游到下游整體呈現(xiàn)波動下降的趨勢;2地下水[Ca~(2+)+Mg~(2+)]/[HCO_3~ ]當量比值在1.12~1.56之間,[SO_4~(2 )+NO_3~ ]/[HCO_3~ ]比值在0.11~0.50之間,揭示硫酸、硝酸參與了水-巖作用;3根據(jù)水化學方法計算得出碳酸溶蝕碳酸鹽巖的比例介于28.04%~78.55%之間,平均為50.01%,溶解能力最強為下游的小龍洞處,季節(jié)上,在2014年5月其溶蝕能力均較弱,受多種因素影響,在流域的不同區(qū)域,碳酸溶蝕的最大強度出現(xiàn)在不同季節(jié);硫酸和硝酸溶蝕碳酸鹽巖的比例介于21.45%~71.96%之間,平均為49.71%,在農(nóng)業(yè)活動的影響下,其溶蝕能力最強出現(xiàn)在2014年5月,受人類活動強度和水體自凈作用的綜合影響,其溶蝕強度總體上表現(xiàn)為中游農(nóng)業(yè)活動區(qū)域上游城鎮(zhèn)和工業(yè)排污區(qū)域下游人為活動較少干擾區(qū)域;4地下水δ~(13)C_(DIC)分布在 10.74‰~ 4.34‰之間,平均為 7.36‰,由δ13CDIC估算出的碳酸溶解碳酸鹽巖形成的DIC的比例在34.32%~84.96%之間,2014年5月的農(nóng)耕季節(jié)所占比例較低,與水化學方法估計出的結(jié)果一致,共同指示了農(nóng)業(yè)活動對碳酸溶解碳酸鹽巖的干擾�？臻g上,在流域水體CO_2脫氣和水生植物代謝過程的擾動下,兩種估算結(jié)果的響應受到干擾,還應根據(jù)具體情況,將水化學劃分方法和同位素混合比例方法相結(jié)合,相互檢驗。
[Abstract]:In order to study the space-time difference of water-rock interaction between the water and rock in the underground river system after the anthropogenic sulfuric acid and nitric acid enter the underground river system, the underground river basin of Lihu in Nandan County, Guangxi, which is affected by urban sewage discharge and industrial and agricultural activities, is taken as the research object. Chemical monitoring and analysis of 未 ~ (13) CDIC composition of Lihu underground river were carried out in May, October, and January, 2015 and July, respectively. The results show that: 1) Lihu underground river basin belongs to HCO_3-Ca type. Controlled by the natural weathering dissolution of carbonate rocks and the effects of man-made municipal sewage, industrial wastewater and agricultural fertilizers, the concentrations of ions in dry season are greater than in rainy season. (2) the ratio of [Ca~ (2) Mg~ (2)] / [HCO_3~] in groundwater is between 1.12 and 1.56, and the ratio of [SO_4~ (2) NO_3~] / [HCO_3~] is between 0.11 and 0.50. (3) according to the calculation of hydrochemical method, the ratio of carbonated carbonate rock is between 28.04% and 78.55%, with an average value of 50.01. The dissolution capacity of carbonate rock is the strongest in the lower reaches of Xiaolong Cave, and in season, the dissolution capacity of carbonate rock is weak in May 2014. Under the influence of many factors, the maximum strength of carbonate solution appeared in different seasons in different regions of the basin, and the ratio of sulphuric acid and nitric acid dissolved carbonate rock was between 21.45% and 71.96%, with an average of 49.71%, which was affected by agricultural activities. Its dissolution capacity was strongest in May 2014, and was affected by the intensity of human activities and the self-purification of water body. Generally speaking, the dissolution intensity of groundwater is less disturbed by human activities in the upper reaches of towns and industrial sewage areas in the middle reaches of agricultural activities, and (4) the distribution of 未 ~ (13) C _ (DIC) in groundwater ranges from 10.74 鈥，

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