喀斯特地区水库夏季溶解性有机碳来源解析及输入通量估算

In the background of the“karst effect”,investing the migration and transformation of dissolved organic carbon(DOC)in karst reservoirs will help to improve the understanding of the process and mechanism of the organic carbon cycle. We used the two-carbon isotope method(δ¹³C-Δ¹⁴C)to trace the sources of DOC in an open reservoir(Aha reservoir)and a closed reservoir(Guanshan Lake)in summer,and assess its sources(biospheric and petrogenic DOC from rivers,i.e. DOC_bio and DOC_petro,respectively). The results showed that the DOC in Aha Reservoir((5.39 ± 0.39)mg.L^-1) was lower than that in Guanshan Lake((6.29±0.47)mg.L^-1). In the Aha reservoir,the inflow rivers were the largest contributor of DOC,which accounted for 55%±22%,followed by the algae(29%± 10%),and the last was sediment(16%±7%). While in the Guanshan Lake,the algae played as the largest contributor(60%±15%). In the open reservoir,the inflow rivers transported about 0.24 t.km^-2.mon^-1 DOC_petro and 0.43 t.km^-2.mon^-1 DOC_bio. Hence there exists a significant difference between open and closed reservoirs regarding the migration and transformation of DOC in karst areas,and the open reservoirs played as a huge sink for“old carbon”derived from rocks.