石漠化治理对岩溶地下水水化学和溶解无机碳稳定同位素的影响

• 作 者: 肖时珍 熊康宁 蓝家程 张晖 杨龙
• 机 构: 贵州师范大学中国南方喀斯特研究院,西南大学地理科学学院,国家喀斯特石漠化防治工程技术研究中心,
• 出 处: 环境科学
• 发表日期: 2015年05期
• 关键词: 石漠化治理 水井湾 土地利用 碳酸盐岩 岩溶地下水 稳定同位素 岩溶石漠化 溶解无机碳 饱和指数 岩溶作用

以贵州关岭-贞丰花江岩溶石漠化综合治理示范区不同土地利用类型和不同石漠化治理模式的5个泉点为研究对象,分析泉水水化学特征及溶解无机碳(DIC)稳定同位素(δ13CDIC)的分布和变化,揭示石漠化治理的岩溶效应和水质效应.结果表明,研究区地下水水化学类型为重碳酸-钙型(HCO3-Ca),人类活动干预相对较少的水井湾、戈贝和毛家湾泉水的水质较好,而受农业活动影响较多的吊井和谭家寨泉水主要离子浓度和电导率都较高,水质相对较差;泉水p H值、方解石饱和指数(SIc)和二氧化碳分压(p CO2)对土地利用或石漠化治理反应敏感,表现为水井湾、吊井、谭家寨和戈贝泉水中的p H值和SIc小于毛家湾泉水,相反p CO2明显大于毛家湾泉水;水井湾、毛家湾、戈贝泉水中的(Ca2++Mg2+)/HCO-3当量比接近1∶1,以碳酸风化碳酸盐岩为主,吊井和谭家寨泉水中(Ca2++Mg2+)相对HCO-3明显偏高,主要是因为受到农业活动强烈影响,可能有硫酸和硝酸参与了碳酸盐岩的溶蚀;此外,雨季由于生物旺盛,泉水中的δ13CDIC值较旱季偏轻;不同泉水中δ13CDIC平均值大小顺序为吊井(-12.79‰)<水井湾(-12.48‰)<戈贝(-10.76‰)<毛家湾(-10.30‰)<谭家寨(-6.70‰),反映了石漠化和农业施肥影响下的地下水的δ13CDIC值偏重,石漠化治理后泉水的δ13CDIC值则偏轻. Taking five springs of different land use types and different rocky desertification control models of Guanling - Zhenfeng Huajiang karst rocky desertification integrated control demonstration area as the research object, the chemical characteristics of spring water and the stable isotopes of dissolved inorganic carbon (DIC) (δ13CDIC) in the study area and reveal the karst effect and water quality effect of the rocky desertification control.The results show that the hydrochemical types of groundwater in the study area are HCO3-Ca (HCO3-Ca), relatively few wells , The water quality of the springs of Gobe and Maojiawan is better, while that of the wells and Tanjiazhai springs that are more affected by agricultural activities are higher and the water quality is relatively poorer; the p H value of spring water, the saturation of calcite The index (SIc) and the partial pressure of carbon dioxide (p CO2) are sensitive to land use or desertification control. The p H value and SI c in Shuijingwan, Shajing, Tanjiazhai and Geobeichu springs are less than those in Maojiawan spring water (P <0.05). On the contrary, p CO2 was obviously higher than that of Maojiawan spring water. The equivalent ratio of (Ca2 + + Mg2 +) / HCO3 in Shuijingwan, Maojiawan and Gebei springs was close to 1: The hanging well and Tanjiazhai spring water (Ca2 + + Mg2 +) relative HCO-3 was significantly higher, mainly Sulfuric acid and nitric acid may be involved in the dissolution of carbonate rocks because of the strong agricultural activities. In addition, the δ13CDIC values ​​in spring water tend to be lighter than those in the dry season due to bio-exponential weather during the rainy season. The average δ13CDIC values ​​in different springs are in the order of -12.79 ‰)