Characteristics of nutrient profiles in sediments and pore water of Lake Chaohu
巢湖近代沉积物及其间隙水中营养物的分布特征

The nutrients in lake sediment and pore water play an important role in the bio-geochemical cycles of lake nutrients and lake trophic history. In this study, the nutrient profiles and their relationships in sediments and pore water from recent sediment cores of eastern and western Lake Chaohu were investigated. The concentrations of nutrients in pore water in west lake region (Cores C1 and C3) generally were higher than that in east lake region (Core C16). The content of nutrients in the sediment cores decreases with increasing depth. At a depth of 0~15 cm, TOC (total organic carbon), TN (total nitrogen), TP (total phosphorus) and Pi (inorganic phosphorus) exhibited a distinct spatial variation, gradually reducing from the western to eastern lake region, C1>C3>C16. At a depth of 15~30 cm in the sediment cores, TOC, TN and TP at three sites were practically constant, approximately 5 mg·g-1, 0.5 mg·g-1 and 0.45 mg·g-1, respectively. The spatial variations of Po (organic phosphorus) were opposite to the changes of TP in sediment cores, and the order was C16>C3>C1. The nutrient profiles in pore water and sediments show similar spatial variations. The results also suggested that nitrogen, phosphorus and silicate in pore water vary collaboratively and the contents of nitrogen and phosphate in pore water were closely related with N and P in sediments, except in the eastern lake region where P in pore water was not significantly related with P in sediments. Furthermore, the fact that the nutrient concentrations in surface pore water were higher than the overlying water indicated that the nutrients preserved in the sediments are one of the main sources of nutrients in the water column.