上海滨岸沉积物、上覆水中N含量及时空变化

SPATIAL AND TEMPORAL VARIATION IN CONCENTRATION OF NITROGEN IN SEDIMENTS AND OVERLYING WATER COLUMNS FROM SHANGHAI COASTAL AREA

综合分析了上海滨岸潮滩表层沉积物及上覆水中营养盐N的含量 ,结果显示 ,表层沉积物中NH+ 4 N的含量在 8月、2月及 11月均很高 ,占 5 0 %～ 98% ,在 11月份NH+ 4 N和NO-3 N含量均显著增加 ;在空间分布上 ,长江口南岸无机氮含量普遍高于杭州湾北岸 ,其中NH+ 4 N含量峰值出现在SDK和BLG ,NO-3 N的沿程分布与NH+ 4 N较为一致 ,二者均受到排污及长江入海径流输入的影响。上覆水中在 2月和 8月NO-3 N含量普遍高于NO-2 N和NH+ 4 N ,而在 11月NH+ 4 N的含量则明显增加 ,并超过了NO-3 N ;无机氮沿程分布呈现较大地区差异的特点 ,而且NO-3 N含量普遍高于NH+ 4 N(SDK、WSK、LC除外 ) ,这受污水排放和所在沉积环境等多因素控制。在对比分析从2 0世纪 80年代至 2 0 0 0年近 2 0年间上海滨岸带无机氮含量的变化趋势 ,发现上海滨岸水体及沉积物总体质量在不断下降。其中滨岸水体若以国家海水水质标准进行评价 ,发现各采样点无机氮含量均超过四类海水的标准 ,而且最大超标幅度达到了 9.5 4倍 。

Based on the analysis of N concentration in surface sediments and overlying waters, the result shows that the concentration of NH\++\-4 is high in August, February and November, occupying for 50%～98% of total inorganic nitrogen. In November both NH\++\-4 and NO\+-\-3 obviously increased. On spatial distribution, the concentration of inorganic nitrogen in the south bank of Yangtze estuary is commonly higher than in the north bank of Hangzhou bay. Both BLG and SDK have the maximum concentration of NH\++\-4. The spatial distribution of NO\+-\-3 is consistent with NH\++\-4, and both are influenced by the sewage discharges and the nutrient inputs from the Yangtze River. In overlying water, the concentration of NO\+-\-3 is commonly higher than NO\+-\-2 and NH\++\-4 in February and August, but in November the concentration of NH\++\-4 obviously increased, and exceeded NO\+-\-3. Inorganic nitrogen in overlying water is characterized by greater regional variation, showing the control of sewage discharge and depositional environments. In comparison with nitrogen concentration levels and developing trend from 1980's to 2000's, the findings show that the environmental quality of waters and sediments decreases with time. And water quality is lower than Grade Ⅳ of Marine Water Quality Standard. Maximum value is up to \{9.54\} times higher than the standard. The trend becomes severe.