[Concentration Variations and Flux Estimation of Dissolved Carbon in Karst Spring of a Typical Karst Area].

Dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) are two important indices for studying karstification, carbon sinks, and the carbon cycle. In order to further understand the migration characteristics of DIC and DOC in karst springs in small watersheds and improve the estimation accuracy of carbon flux under conditions of discrete and limited water quality monitoring data, the concentration variations of DIC and DOC were studied in karst outlet springs of Chenqi small watershed in Puding County, Guizhou Province, China. The flux estimation regression equations of DIC and DOC were established by the LOADEST model, and the carbon sink intensity in Chenqi karst spring basin was estimated.

[Elution of endosulfan from contaminated soil by surfactants and their combination].

The elution efficiency and dynamic characteristic of endosulfan from the contaminated soil were studied using non-ionic surfactants and anionic/non-ionic surfactants in the presence or absence of Na2SiO3 with batch experiment and parallel desorption experiment. The results showed that the elution percents of alpha-, beta-endosulfan followed a decreasing order of Tween 80/SDS, Tween 80 and Triton X-100 in the absence of Na2SiO3, while that by Triton X-100/SDS at low concentration (100-500 mg x L(-1)) and high concentration (800-1000 mg x L(-1)) were lower and higher than those by the corresponding concentrations of Triton X-100, respectively. The elution efficiencies for four elution modes obviously increased in the presence of Na2SiO3, and the elution percents of alpha-, beta-endosulfan followed a decreasing order of Tween 80/SDS, Tween 80, Triton X-100/SDS and Triton X-100, and that of alpha-endosulfan were as 1.