巢湖近代沉积物及其间隙水中营养物的分布特征

湖泊沉积物及其间隙水中的营养盐对于研究湖泊营养盐的生物地球化学和湖泊营养状态的历史变化具有重要的作用.系统研究了巢湖东、西湖区沉积物和间隙水中营养盐的剖面分布特征及其营养盐之间的相互关系.结果表明,巢湖近代沉积物中营养盐含量总体上随着深度的增加而降低,上层沉积物(1～15cm)中TOC(总有机碳)、TN(总氮)、TP(总磷)和Pi(无机磷)的含量都表现出明显的区域差异性,从西到东逐渐减小,含量的大小顺序为C1C3C16;东、西湖区下层沉积物(15～30cm)中TOC、TN和TP的含量差异不明显,分别在5mg.g-1、0.5mg.g-1和0.45mg.g-1左右变化;Po(总有机磷)在整个剖面上的分布则相反,总体上从西向东逐渐增大,含量大小顺序为C16C3C1.沉积物间隙水中的营养盐在空间上的分布规律与沉积物相似,西湖区两个点(C1、C3)沉积物间隙水中的营养物浓度总体上高于东湖区的C16点,大小顺序为C1C3C16,间隙水中的氮、磷酸盐、硅酸盐处于协同变化.间隙水中的氮与沉积物总氮含量密切相关;西湖区间隙水中的磷与沉积物磷含量密切相关,但在东湖区相关性不显著.表层沉积物间隙水中营养盐浓度都明显高于上覆水体,表明沉积物中的营养盐是水体营养盐的主要来源之一.

Characteristics of nutrient profiles in sediments and pore water of Lake Chaohu

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.