海口美舍河沉积物化学性状时空分布特征

通过2018年4月和9月对海口市美舍河湿地上、中、下游底泥沉积物进行取样,研究沉积物化学性状的时空分布特征,并对重金属污染进行评价,以期为美舍河湿地公园的管理与湿地功能的维持提供科学依据。结果表明：（1）美舍河沉积物整体偏酸性,pH为6.58;4月份下游pH显著高于中游、上游Ⅰ和上游Ⅱ,而9月份各采样断面间无显著差异;9月份上游Ⅱ的pH显著高于4月份,增幅为13.0%,而9月份下游pH则显著低于4月份,降幅为16.6%。（2）4月份下游有机碳（SOC）含量显著高于其他采样断面,9月份上游Ⅰ和下游的SOC显著高于上游Ⅱ和中游,同时上游Ⅰ在两次采样间存在显著差异,9月份较4月份显著增加65.4%;（3）全氮（TN）和全磷（TP）含量以及重金属铜（Cu）、铅（Pb）和锌（Zn）含量整体上由上游至下游呈增加的趋势,其中中游TP含量和下游Cu含量在两次采样间存在显著差异,9月份TP含量较4月份显著增加76.9%,9月份Cu含量较4月份显著降低13.0%。（4）相关性分析结果表明,pH与Cu及Zn含量之间存在极显著正相关关系（P<0.01）,SOC、TN及TP含量与各重金属含量均呈极显著正相关关系（P<0.01）。综合分析沉积物的污染系数以及潜在风险发现,美舍河沉积物属清洁水平、较低潜在风险;同时,美舍河富营养化较轻,总体未受重大污染,具有较优质的环境,底泥符合农用标准;此外,需加强上游的污染源控制。

Temporal-spatial Distribution Characteristics of Chemical Properties of Meishe River in Haikou,Hainan, China

By sampling the sediments in the upper, middle and lower reaches of the Meishe River wetland in Haikou City in April and September 2018, the temporal and spatial distribution characteristics of the chemical properties of the sediments were studied, and the heavy metal pollution was evaluated to provide scientific basis for the management and maintenance of wetland functions of Meishe River Wetland Park. The sediment of Meishe River was generally acidic with pH value of 6.58. The pH value of the downstream in April was significantly higher than that in the midstream, upstream I and upstream II, but there was no significant difference among sampling sections in September. The pH of the upstreamⅡin September was significantly higher than that in April, with an increase of 13.0%, while that of the downstream in September was significantly lower than that in April, with a decrease of 16.6%. In April, the content of organic carbon (SOC) in the downstream was significantly higher than that in other sampling sites. In September, the SOC of the upstream I and downstream was significantly higher than that of the upstream II and midstream. At the same time, there was a significant difference in the upstream I between the two sampling time, with a significant increase of 65.4% in September compared with April. The contents of total nitrogen (TN), total phosphorus (TP) and heavy metals copper (Cu), plumbum (Pb) and zinc (Zn) increased from the upstream to downstream. The content of TP in the midstream increased by 76.9% and the Cu contents decreased in the downstream by 13.0% in September compared with April. Correlation analysis showed that there was a significant positive correlation between pH and Cu and Zn contents, and SOC, TN and TP contents were significantly positively correlated with heavy metal contents (P<0.01). A comprehensive analysis of the pollution coefficient and potential risks of sediments revealed that Meishe River sediments are clean and have low potential risks. In summary, the Meishe River is lighter in eutrophication, generally not subject to major pollution, has a relatively high-quality environment, and has a silt composite agricultural standard. In addition, it is necessary to strengthen upstream water pollution control.