黄大湖沉积物营养盐分布及来源解析

在黄大湖设置13个采样点,采集表层及柱状沉积物样品,对沉积物中总氮(TN)、总磷(TP)和有机质(OM)浓度进行测定,分析黄大湖沉积物营养盐的空间及垂直分布,研究黄大湖沉积物营养盐来源,并对沉积物污染程度进行评价。结果表明:黄大湖表层沉积物中TN浓度为1 112~3 277 mg/kg,平均值为2 016 mg/kg;TP浓度为547.19~784.43 mg/kg,平均值为651.84 mg/kg;OM浓度为5.21%~11.21%,平均值为8.6%;TN、TP和OM浓度空间分布较为一致,主要表现为西北部>东南部>湖心中部,浓度垂直变化趋势总体表现为随深度增加而下降;沉积物中TN和OM污染比TP严重,且三者污染程度空间分布与浓度空间分布一致。Pearson相关性分析表明,TN和OM显著正相关,二者具有同源性;TP和OM无显著相关关系,二者同源性较差;沉积物中碳氮比(C/N)平均值为25.43,OM主要来自外源颗粒有机物的输入,柱状沉积物-20 cm以上碳磷比(C/P)和氮磷比(N/P)的增加表明沉积物中营养盐受近年来周边人类活动的影响较大。

Distribution and source analysis of nutrients in sediments of Huangda Lake

In order to study the source of nutrients in the sediments of Huangda Lake, the surface sediments and columnar sediments were collected from 13 points in Huangda Lake. Total nitrogen (TN), total phosphorus (TP) and organic matter (OM) contents were measured, the spatial and vertical distribution of nutrients in the sediments of Huangda Lake analyzed, and the sediment pollution degree assessed. The results showed that TN concentration of the surface sediments in Huangda Lake varied from 1 112 to 3 277 mg/kg with an average value of 2 016 mg/kg, TP concentration varied from 547.19 to 784.43 mg/kg with an average value of 651.84 mg/kg, and OM concentration varied from 5.21% to 11.21% with an average value of 8.6%. The spatial distribution of TN, TP and OM showed consistency, mainly in the northwest> southeast> middle of the lake center, and the vertical concentration of TN, TP and OM generally showed a decline with depth. The pollution caused by TN and OM was more serious than that of TP, and the spatial distribution of pollution degree was consistent with the spatial distribution of TN, TP and OM. Pearson correlation analysis showed that TN and OM were significantly positively correlated, indicating that they were homologous; TP and OM were not significantly correlated, suggesting that they were poorly homologous. The average C/N ratio of the sediment was 25.43, indicating that OM in the sediment mainly came from exogenous particulate organic matter. The increase of C/P ratio and N/P ratio in the upper 20 cm of the columnar sediments indicated that nutrients in the sediment were greatly affected by human activities surrounding Huangda Lake in recent years.