贵州草海颗粒物和沉积物有机碳氮同位素特征及来源研究

颗粒物和沉积物作为湖泊污染物的重要载体，其同位素可以有效示踪污染物来源。本研究选取贵州草海作为研究对象，于2023年3月采集湖泊及入湖河流的悬浮颗粒物和表层沉积物，进行了有机碳同位素（δ13C）、有机氮同位素（δ15N）、C/N及总有机碳（POC、TOC）和总氮（PON、TON）的测定，结合MixSIAR同位素模型分析了湖泊有机碳氮来源及贡献率。结果表明：草海悬浮颗粒物的δ13C变化范围为-27.56‰～-23.64‰，其中湖区＞入湖河流，δ15N的变化范围为3.12‰～10.93‰，其中湖区＜入湖河流，颗粒物有机碳主要来源于大气沉降（21.1%）和水生植物（20.7%），氮来源主要为土壤有机质（25.6%）和水生植物（25.3%）；表层沉积物的δ13C介于-28.18‰～-20.53‰，其中湖区＞入湖河流，δ15N介于1.70‰～6.58‰，其中湖区＜入湖河流，沉积物有机碳主要来源于大气沉降（34.4%）和水生植物（33%），氮主要来源于化肥（24%）；其中入湖河流对两者有机碳氮来源影响较小；颗粒物与沉积物亦没有显著相关性，两者之间有机氮来源的差异反映出土壤有机质和水生植物来源的有机氮易降解，而化肥来源的氮则易沉积。本研究揭示了草海颗粒物和沉积物有机碳氮来源，为草海保护治理提供了科学依据。

Organic Carbon and Nitrogen Isotope Characteristics and Sources of Particulate Matter and Sediment in Caohai Lake, Guizhou Province

Particulate matter and sediment are important carriers of lake pollutants, and their isotopes can effectively trace the sources of pollutants. In this study, Caohai Lake, Guizhou Province was selected as the research object. Suspended particulate matter and surface sediments from lakes and rivers were collected in March 2023, and the organic carbon isotopes (δ13C), organic nitrogen isotopes (δ15N), C/N, total organic carbon (POC, TOC) and total nitrogen (PON, TON) were determined respectively. Combined with MixSIAR isotope mode, the sources and contribution rates of organic carbon and nitrogen in lakes were analyzed. The results show that: The δ13C of suspended particulate matter in Caohai Lake ranges from -27.56‰ to -23.64‰, and the lake area is greater than that of the river entering the lake. the δ15N ranges from 3.12‰ to 10.93‰, The δ15N of suspended particulates in lake area is less than that in the river entering the lake. The organic carbon of suspended particulate matter in lakes and rivers is mainly derived from atmospheric deposition (21.1%) and aquatic plants (20.7%). The main sources of nitrogen were soil organic matter (25.6%) and aquatic plants (25.3%). The δ13C of surface sediments ranges from -28.18‰ to -20.53‰, and the δ13C of lakes is greater than that of rivers entering lakes. and the δ15N ranges from 1.70‰ to 6.58‰, the lake area is smaller than the river entering the lake. The δ13N of surface sediments is mainly from atmospheric deposition (34.4%) and aquatic plants (33%), and nitrogen is mainly from chemical fertilizer (24%). The influent rivers have little effect on the sources of organic carbon and nitrogen. There was no significant correlation between particulate matter and sediment. The difference of organic nitrogen sources between the two reflects that the organic nitrogen from soil organic matter and aquatic plants is easily degraded, while the nitrogen from fertilizer is easily deposited. This study revealed the organic carbon and nitrogen sources of particulate matter and sediment in Caohai Lake, which provided a scientific basis for the protection and treatment of Caohai Lake.