天津围海造陆区吹填土氮磷的分布特征

Spatial Distribution of Nitrogen and Phosphorus in Dredger Fill at Tianjin Reclamation Land Area

天津临港经济区地处滨海,完全是由填海造陆形成的人工陆地。土壤是港口航道清淤淤泥、近海海沙吹填围海造陆后形成的吹填土,其性质特殊,研究吹填土壤中氮磷空间分布对了解该区域环境状况有重要意义。研究发现：天津临港吹填土整体含氮量较低,按土层深度分布,平均质量分数为161.73~240.09mg/kg;含磷量相对丰富,平均质量分数为355.54~443.27mg/kg;总氮变异系数较大,总磷变异系数较小,氮、磷质量分数主要受不同区域吹填土性质影响。吹填土中有机磷质量分数较少,平均仅占总磷的3.83%,吹填土中磷大多以无机磷形式存在,其相对质量分数从大到小为：钙结合磷（Ca-P）〉铁结合磷（Fe-P）〉铝结合磷（Al-P）〉闭蓄态磷（Oc-P）〉碎屑磷（De-P）〉交换态磷（Ex-P）。研究表明,临港吹填土氮、磷质量分数水平对近海环境有潜在富营养污染威胁。

Tianjin Lingang Economic Area is located in the coastal region which is formed by land reclamation.The soil is dredger fill formed by silt and sand.The characteristics,spatial distribution of nitrogen and phosphorus in the dredger fill of Tianjin Lingang Area is important information for figuring out the eutrophication of the region.Nitrogen and phosphorus contents were measured using the samples collected from the dredger fill of Lingang.The results indicated that soil nitrogen content in Lingang Economic Area was quite low,which was 161.73-240.09 mg/kg in average.However,the phosphorus content was relatively rich among 355.54 and 443.27 mg/kg.The horizontal variation coefficient of total nitrogen distribution was greater than the total phosphorus.The nitrogen and phosphorus contents of dredger fill in different regions were related to the characteristics itself.Dredger fill in part of the region was resulted by artificial interferences,which caused the increments of nitrogen and phosphorus contents.Predictable,the level of nitrogen and phosphorus contents may bringeutrophication to the coastal environment near Lingang.