卫河新乡段底泥-间隙水-上覆水中营养盐的分布特征

Nutrient Distribution in the Sediment,Interstitial Water and Overlying Water in the Xinxiang Section of Weihe River

为研究卫河新乡市区河段底泥-间隙水-上覆水中营养盐的时空分布特征,分别于2013年1、4、7、10月对卫河新乡段上游(S1)、人口密集区(S2)、人工拓宽河道形成的牧野湖入湖水口(S3)、湖岸静水区(S4)、湖心处(S5)和湖区下游(S6)共计6个样点进行采样分析。结果表明:(1)S1和S2底泥中总氮(TN)、氨氮(NH^+_4-N)含量呈现随深度增加而上升的趋势,除S3外,各样点底泥中总磷(TP)含量的垂向分布在15~20 cm处比表层含量低,但并无明显规律性;(2)S2、S3、S4样点在4月时底泥(干重)中的TN含量达到最大值,分别为5.8、2.2、1.7 g/kg,10月时TP含量达到最大值,分别为0.88、0.22、0.21 g/kg,除S3号样点外,其余各样点底泥NH+4-N的含量均在7月出现最大值,按样点号依次为25.42、37.19、14.23、12.28、34.11 mg/kg;(3)间隙水中TN和NH^+_4-N含量的垂向分布与底泥中的分布相似,间隙水和底泥中的TN、NH^+_4-N之间呈显著的正相关,TP之间无明显相关性;(4)间隙水和上覆水中的各营养盐之间均无明显相关性。

Nutrient exchange between sediment,sediment interstitial water and the overlying water is significant for nutrient loading and eutrophication of lacustrine waters. The Weihe River flows across Xinxiang City from west to east. In 2009,an artificial lake（ Muye Lake） was constructed in the lower reach of the Weihe River with an area of 28 hm2 and an average depth of 3. 5 m. A rubber dam separates Muye Lake from the Weihe River channel,decreasing water flow and increasing siltation from the upper Weihe River and severely impacting ecosystem function.Characterizing nutrient distribution in Weihe River sediments and its influence on overlying water is basic for understanding and managing eutrophication in Muye Lake. The spatial-temporal variation of nutrients in the sediments,interstitial water and overlying water in Weihe River were investigated during January,April,July and October in2013,aiming to supply scientific data for water quality protection and sediment dredging in Muye Lake. Six sampling sites（ S1- S6） were selected for the study： the Weihe River entering Xinxiang City（ S1）,a densely populated area（ S2）,Muye Lake inlet（ S3）,static water area near the shoreline（ S4）,the open area of Muye Lake（ S5）,and the downstream river（ S6）. Sediments（ 0- 20 cm） and water samples were collected at the six sites for determination of TN,TP and NH＋4-N in sediments,interstitial and overlying waters,with three or four replicates at each site. Concentration of TN and NH＋4-N in sediments from S1 and S2 increased with depth. The TP content of sediment at 15- 20 cm was lower than at 0- 5 cm,except for at S3,and there was no obvious regularity in vertical distribution. Temporally,TN concentrations in sediments collected at S2,S3 and S4 were highest（ 5. 8 g / kg,2. 2 g / kg,1. 7 g / kg） in April,while TP concentrations were highest（ 0. 88 g / kg,0. 22 g / kg,0. 21 g / kg） in October. Except for S3, NH＋4-N concentrations were highest（ 25. 42 mg / kg,37. 19 mg / kg,14. 23 mg / kg,12. 28 mg / kg,and 34. 11 mg / kg） in July. The vertical distribution of TN and NH＋4-N in interstitial water was similar to that in sediment. There was a significant positive correlation between TN and NH＋4-N concentrations in interstitial water with those in the sediment,but no similar correlation between TP concentrations. Additionally,no obvious correlation was observed in the nutrient content of interstitial water and the overlying water.