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滩涂湿地在吸收、转化和滞留氮、磷等营养元素方面具有重要功能。选取江苏东部沿海典型滩涂区,分别对垦殖时间为0、3、6、17、30、60a的沿海滩涂进行采样,对相应的土壤氮总转化速率指标进行实验测定。结果表明,滩涂垦殖后,表征氮素活化过程的指标,如总矿化率、总硝化率、净矿化率和净硝化率等有所增加,而有利于氮固持的铵态氮同化率指标无显著变化,硝态氮同化率指标变慢;围垦期限超过30a后,各氮总转化速率指标渐趋稳定。相关性分析表明,净矿化率、总矿化率、铵态氮同化率、净硝化率、总硝化率与围垦年限呈显著正相关(p<0.01),相关性系数分别为0.966、0.929、0.819、0.800、0.798;硝态氮同化率与围垦年限呈显著负相关(p<0.01),相关性系数为-0.685;除铵态氮外,全氮、硝态氮、pH值、有机碳均与各氮总转化速率指标呈显著相关关系(p<0.01)。滩涂垦殖后土壤理化性质指标的改变带来土壤氮总转化速率的变化,一定程度上破坏了土壤氮生态系统平衡。
Tidal flat wetlands have an important function in absorbing, transforming and retaining nutrients such as nitrogen and phosphorus. A typical beach area along the eastern coast of Jiangsu Province was selected. Coastal beaches with reclamation time of 0, 3, 6, 17, 30, 60a were sampled. The corresponding total nitrogen conversion rate was measured experimentally. The results showed that after the reclamation of tidal flats, the indexes of nitrogen activation, such as total mineralization rate, total nitrification rate, net mineralization rate and net nitrification rate increased, but the indexes of ammonium assimilation rate No significant change, the index of nitrate nitrogen assimilation slowed down; reclamation period of more than 30a, the total nitrogen conversion rate gradually stabilized. Correlation analysis showed that net mineralization rate, total mineralization rate, ammonium assimilation rate, net nitrification rate, total nitrification rate and reclamation age had a significant positive correlation (p <0.01), the correlation coefficients were 0.966,0.929, 0.819, 0.800 and 0.798 respectively. There was a significant negative correlation between the assimilation rate of nitrate nitrogen and the reclamation age (p <0.01), and the correlation coefficient was -0.685. In addition to ammonium nitrogen, total nitrogen, nitrate nitrogen, pH value, organic carbon And total nitrogen conversion rate was significantly correlated (p <0.01). Changes in soil physical and chemical properties after the tidal flats reclamation led to changes in the total nitrogen conversion rate, and to a certain extent, destroyed the soil nitrogen ecosystem balance.