岱海沉积物营养盐时空分布特征及污染评价

Temporal and Spatial Distribution Characteristics and Pollution Assessment of Nutrients in Sediments of Daihai Lake

为了揭示岱海沉积物中营养盐的时空分布特征,分别于2021年1月(冬季)、4月(春季)、7月(夏季)、9月(秋季)共采集了36个岱海沉积物样品,该文研究并分析岱海沉积物中总氮(TN)、总磷(TP)、有机质(OM)含量的时空分布特征。根据C∶N原子比判断沉积物中有机质的来源,并采用有机氮(ON)、有机指数(OI)和综合污染指数评价其污染程度。结果表明:TN含量在1.69~2.79 g/kg之间,平均值为(2.10±0.28)g/kg;TP含量在159.84~306.91 mg/kg之间,平均值为(213.73±33.95)mg/kg;OM含量在29.99~48.16 g/kg之间,平均值为(38.63±5.19)g/kg。空间上TN和OM空间分布相似,湖心区>西北部>东部,TP空间分布呈现西部>东部>湖心区;时间上,TN和TP在冬季最高,秋季、春季最低,OM在夏季最高、冬季最低。岱海沉积物中C∶N原子比在8.30~13.53之间,平均值为(11.24±1.35),表明岱海沉积物中有机质主要来自于内源污染,浮游动物、浮游植物及藻类是沉积物中有机质的重要来源。有机氮和有机指数结果表明,岱海沉积物所有点位属于有机氮污染等级,有机指数以尚清洁等级为主;单项污染指数与综合污染指数结果显示,岱海沉积物所有点位TN单项污染指数和综合污染指数属于重度污染等级,TP单项污染指数以清洁等级为主。岱海沉积物氮负荷较高,具有潜在的内源氮释放风险。

In order to reveal the spatial and temporal distribution characteristics of nutrients in Daihai Lake sediments,36sediment samples were collected in spring,summer,autumn and winter of 2021,and the spatio-temporal distribution characteristics of total nitrogen(TN),total phosphorus(TP)and organic matter(OM)were studied and analyzed,and the source of organic matter in sediments was judged according to the C∶N atomic ratio,and the degree of pollution was evaluated by organic nitrogen,organic index and comprehensive pollution index.The results showed that the TN content was between 1.69 and2.79 g/kg,and the average value was(2.10±0.28)g/kg;the TP content was between 159.84 and 306.91 mg/kg,and the average value was(213.73±33.95)mg/kg;the OM content was between 29.99 and 48.16 g/kg,and the average value was(38.63±5.19)g/kg.Spatially,TN and OM spatial distribution are similar,the lake center area>the northwest>the east,the TP spatial distribution shows the western>the eastern>lake center area;in time,TN and TP are the highest in winter,the lowest in autumn and spring,and OM are the highest in summer and lowest in winter.The C∶N atomic ratio in the sediments ranged from 8.30 to 13.53,with an average value of(11.24±1.35),indicating that the organic matter in Daihai Lake sediments was mainly contaminated endogenously,and zooplankton,phytoplankton and algae were the main sources of organic matter in the sediments.Organic nitrogen and organic index show that all points of sediment belong to the organic nitrogen pollution level,and the organic index is mainly clean;The comprehensive pollution index results show that the TN pollution index and comprehensive pollution index of all points of the sediment belong to the heavy pollution level,and the TP pollution index is mainly clean.Daihai Lake sediment nitrogen load is high,with potential endogenous nitrogen release risk.