摘要
土壤CO2与土下岩溶作用密切相关。了解不同土地利用类型下土壤CO2的时空变化特征及来源,将有助于准确揭示岩溶碳循环规律。2018年1-5月,在柏树湾和后沟2个岩溶泉域不同深度土壤中插入PVC管,并通过注射器抽取土壤CO2样品,通过对比土壤CO2浓度及其δ13C的变化特征分析岩溶作用与土壤CO2之间的关系,并对土壤CO2的来源进行示踪。结果表明,(1)柏树湾土壤CO2浓度(1812-18654μmol·mol^−1)大于后沟(507-9975μmol·mol^−1)。2个泉域上覆土壤的δ13C相近,但柏树湾和后沟土壤CO2的δ13C分别为−22.4‰-−17.03‰和−16.33‰-−11.45‰。土壤CO2的δ13C接近其上覆植被,说明上覆植被差异是造成柏树湾土壤CO2浓度大于后沟的主要原因。(2)柏树湾土壤CO2浓度最大值出现在4月,并在5月降低;后沟除20 cm处土壤CO2浓度最大值出现在5月外,其他深度土壤CO2浓度最大值也出现在4月,并且在3月和5月分别出现了降低的趋势。土壤CO2浓度的时间变化受温度和降水共同影响,过多的降水量可能对土壤CO2产生抑制作用。(3)在垂向变化上,1-3月柏树湾和后沟土壤CO2浓度均未出现双向梯度,而是同非岩溶区一样,表现为随土壤深度的增加而增加。这可能是由于1-3月降水减少导致土壤含水量降低,从而限制了岩溶作用对底部土壤CO2的消耗造成的。而随着降水增加,土下岩溶作用增强,促进了底部土壤CO2的消耗,土壤CO2浓度的垂向变化由单向梯度转为双向梯度。另外,各泉域不同深度土壤CO2的δ13C差异较小,并且具有相似的季节变化规律,证实H2SO4和HNO3溶蚀碳酸盐岩产生的CO2对土壤CO2的影响较小。
Soil CO2 is closely related to the karstification under covered karst.Understanding the spatio-temporal variation characteristics and the sources of soil CO2 under different land use types will help to accurately reveal the rule of karst carbon cycle.From January to May 2018,PVC pipes installed at different depths of soil were used to collect soil CO2 from Baishuwan(BSW)and Hougou(HG)spring catchments.Soil CO2 samples were drawn off using syringes to analyze its concentration andδ13C values,and also the relationship between soil CO2 and karst carbon cycle as well as the source of soil CO2 were discussed in this study.The results showed that,(1)The soil CO2 concentration at BSW ranging from 1812 to 18654μmol·mol^−1 was higher than it at HG which ranged from 507 to 9975μmol·mol^−1.Theδ13C values of soil organic carbon were similar among two catchments,while theδ13C value of soil CO2 ranged from−22.4‰to−17.03‰at BSW and ranged from−16.33‰to−11.45‰at HG,respectively.Theδ13C value of soil CO2 was close to theδ13C of overlying vegetation,indicating that vegetation was the main factor to induce the difference of soil CO2 concentration between two catchments.(2)The maximum soil CO2 concentration occurred in April and then dropped in May at BSW.For HG,maximum value of soil CO2 concentration at 20 cm depth appeared in May,while it appeared in April at other depths and showed a decreasing trend in March and May.It indicated that temporal variation of soil CO2 concentration was affected by both temperature and precipitation which the increasing precipitation may inhibit the production of soil CO2.And(3)for vertical change,bi-directional gradient did not occurre,instead,the soil CO2 concentration increased with soil depths as that in non-karst area at both catchments from January to March,which may be resulted from the low soil water content limiting the consumption of bottom soil CO2 by karstification.With the precipitation increasing,the enhanced karstification promotes the consumption of bottom
作者
赵瑞一
李建鸿
董莉莉
刘畅
张灵艺
ZHAO Ruiyi;LI Jianhong;DONG Lili;LIU Chang;ZHANG Lingyi(Key Laboratory of Karst Dynamics,MLR&GZAR/Institute of Karst Geology,CAGS.Guilin 541004,China;College of Architecture and Urban Planning,Chongqing Jiaotong University,Chongqing 400074,China)
出处
《生态环境学报》
CSCD
北大核心
2020年第1期81-87,共7页
Ecology and Environmental Sciences
基金
国家重点研发计划项目（2018YFD1100104）
自然资源部/广西壮族自治区岩溶动力学重点实验室开放课题（KDL201707）
重庆市教育委员会科学技术研究项目（KJ1705127
KJQN201800710）
