农业活动对表层岩溶泉水化学特征及溶解无机碳损失量的影响

摘要

以重庆市南川区不同农业活动强度下的3个表层岩溶泉为例,通过分析泉点水化学变化特征来估算不同泉点的DIC损失量(△DIC)和探讨农业活动对岩溶碳汇的影响.研究结果表明:柏树湾泉水温变幅较小,电导率、pH值相对兰花沟泉、后沟泉较低.由于农业活动的影响,兰花沟泉、后沟泉Ca-2+浓度偏高,而HCO3浓度偏低.NO(L)、SO(:) 浓度也因农业活动干扰,表现出后沟泉、兰花沟泉远大于柏树湾泉.随农业活动强度的增加,△DIC也逐渐增大,表现为:柏树湾泉(1.64 mmol/L)＜兰花沟泉(4.28 mmol/L)＜后沟泉(4.36 mmol/L).△DIC与(SO(i)+NO(i))呈正相关,表明农业活动越强烈,DIC损失量越大,岩溶碳汇的损失也随之增大.%Abstract:In this study,three epi-karst springs under different intensity agricultural activity in Nanchuan area,Chongqing have been investigated to discuss the impact of agricultural activity on karst carbon sink by analyzing hydro-chemical characteristics and estimating the △DIC of water samples in different springs.The results show that compared to the Lanhuagou spring and the Hougou spring,the amplitude of variation in temperature in the Baishuwan spring is relatively small; EC and pH are relatively low.Because of the impact of agriculture activity,the Lanhuagou spring and the Hougou spring have a higher Ca2+ concentration and lower HCO3-concentration that are not consistent with Ca2+.The concentrations of NO3-and SO24-in the Lanhuagou spring and the Hougou spring are far higher than that in the Baishuwan spring for the same reason.With the enhancement of agricultural activity,the △DIC increases as follows,1.64 mmol/L in the Baishuwan spring ＜ 4.28 mmol/L in the Lanhuagou spring ＜ 4.36 mmol/L in the Hougou spring.The △DIC represents positive correlation with the concentration of (SO24-+ NO3-) among the three different springs.It can be inferred that the more intensity of agricultural activity,the larger amount of △DIC,which means the less amount of CO2 sink.