洱海罗时江湿地表层沉积物氨氮释放特征及影响因素  

Release characteristics and influencing factors of ammonia nitrogen in the surface sediment of the Luoshijiang Wetland upstream of the Erhai Lake

作　　者：王化 宝冬润 梁启斌[1] 王艳霞[1] 李晓琳[1] 侯磊[1] WANG Hua;BAO Dongrun;LIANG Qibin;WANG Yanxia;LI Xiaolin;HOU Lei(College of Ecology and Environment,Southwest Forestry University,Kunming,650224,China)

机构地区：[1]西南林业大学生态与环境学院,昆明650224

出　　处：《环境化学》2024年第10期3416-3424,共9页Environmental Chemistry

基　　金：国家自然科学基金(22066023,41663016).

摘　　要：以洱海上游的罗时江湿地为研究对象,基于为期半年的野外监测,弄清湿地水体和表层沉积物中氨氮(NH_(3)-N)的时空分异规律,借助摇瓶试验法探究湿地入口沉积物NH_(3)-N的释放特征及水体离子强度(IS)和pH的影响.结果表明:(1)罗时江湿地上覆水和表层沉积物NH_(3)-N浓度变化范围分别为0.14-1.45 mg·L^(−1)和0.23-8.89 mg·kg^(−1),干湿季差异均不显著(P>0.05);上覆水和表层沉积物NH_(3)-N浓度均沿水流方向显著下降(P<0.05),出水口NH_(3)-N平均浓度分别是入水口的59.2%和49.9%,湿地对水体NH_(3)-N有截留效果.(2)模拟试验条件下,沉积物NH_(3)-N累积释放量的变化范围为412.9-653.7 mg·kg^(−1),随提取次数的增加单次释放量逐渐降低;NH_(3)-N累积释放量湿地入口显著高于其他样点,干季高于湿季.(3)上覆水IS升高促进沉积物NH_(3)-N的持续释放,增加快速释放NH_(3)-N占比;上覆水处于弱酸条件下更利于沉积物NH_(3)-N的持续释放,同时提高快速释放NH_(3)-N占比.研究结果显示,表流湿地入水口沉积物是NH_(3)-N的主要富集场所,水化学条件变化导致NH_(3)-N向上覆水释放可能引起二次污染.The Luoshijiang Wetland,located in the upstream of the Erhai Lake,was selected as the research object.The spatiotemporal variations of ammonia nitrogen(NH_(3)-N)in the water body and surface sediment of the wetland were clarified based on the half-year field monitoring,and the release characteristics of NH_(3)-N in the wetland inlet sediment and the effects of water ionic strength(IS)and pH were explored via flask-shaking test.The results showed that:(1)The NH_(3)-N concentrations in the overlying water and surface sediment of the Luoshijiang Wetland varied from 0.14 mg·L^(−1)to 1.45 mg·L^(−1)and 0.23 mg·kg^(−1)to 8.89 mg·kg^(−1),respectively,with no significant difference in dry and wet seasons(P>0.05).The NH_(3)-N concentrations in the overlying water and surface sediment decreased significantly along the flow direction(P<0.05),and the average NH_(3)-N concentration at the outlet was 59.2%and 49.9%of that at the inlet,respectively.The wetland showed a retention effect towards NH_(3)-N in the water body.(2)Under the simulated test conditions,the cumulative release amount of NH_(3)-N from sediment varied from 412.9 mg·kg−1to 653.7 mg·kg^(−1),and the single release amount gradually decreased with the increase of extraction times.The cumulative release amount of NH_(3)-N at the wetland inlet was significantly higher than that at other sample sites,and was higher in the dry season than in the wet season.(3)The increase of IS in the overlying water promoted the continuous release of NH_(3)-N from sediment and increased the proportion of rapid release NH_(3)-N.The weak acid condition of the overlying water facilitated the continuous release of NH_(3)-N from sediment,and the proportion of rapid release NH_(3)-N was also increased.The results indicated that the sediment at the inlet of the surface flow wetland was the main enrichment site of NH_(3)-N,and the change of water chemical conditions might lead to the release of NH_(3)-N to the overlying water,resulting in potential secondary pollution.

关 键 词：表流人工湿地 沉积物氨氮 释放特征 上覆水 PH 和离子强度影响. 

分 类 号：X-1[环境科学与工程] O6[理学—化学]