缢蛏扰动对柱状沉积物中氮形态及其含量影响的实验室模拟研究

本文采用底栖生物缢蛏的室内培养实验，研究生物扰动对柱状沉积物中氮形态及其含量的影响。实验设置了两个生物栖息密度（99 ind./m2、249 ind./m2）和空白对照，在水温为23 ℃，盐度为26，pH为8的条件下，进行了20 d的室内模拟生物扰动培养。实验结束后将柱状沉积物从上到下分层切割，提取氮形态并测定其含量。结果表明，扰动后沉积物中总氮（TN）含量增加，其中不可转化态氮（NTN）含量增加了30.94%，可转化态氮（TTN）含量降低了20.57%。有机态和硫化物结合态氮（OSF-N）是TTN的主要赋存形态，占TN的9.31%，碳酸盐结合态氮（CF-N）的含量最低，占TN的2.77%，离子交换态氮（IEF-N）和铁锰氧化态氮（IMOF-N）分别占TN的3.39%和3.06%。综上所述，缢蛏扰动促进了沉积物中OSF-N向其他形态的转化以及TTN向NTN的转化。

A laboratory experimental research into the bioturbation effects of Sinonovacula constricta on the content of nitrogen forms in columnar sediments

The bioturbation effects of Sinonovacula constricta on the transformation of different forms of nitrogen in sediments were studied based on a laboratory experiment in this study. Two treatment groups and a control group were set up according to different biological densities (99 ind./m2, 249 ind./m2), and a 20-day laboratory experiment was carried out in the condition of water temperature 23 ℃, salinity 26 psu, and pH8. The columnar sediments were stratified and cut from top to bottom, and the changes of different forms of nitrogen content in the sediment were analyzed. Results showed that the content of total nitrogen (TN) in the sediment increased after the bioturbation of S. constricta. The content of non-transferable total nitrogen (NTN) increased by 30.94%, and the content of transferable total nitrogen (TTN) decreased by 20.57%. The content of organic-sulphide form (OSF-N) was the highest among the four forms, accounting for 9.31% of TN, which was the main form of TTN. The content of carbonate form (CF-N) was the lowest and only 2.77% of TN. The ion exchange form (IEF-N) and the iron manganese oxide form (IMOF-N) accounted for 3.39% and 3.06% of TN, respectively. Above all, the bioturbation of S. constricta promoted the conversion of OSF-N to other forms, as well as the conversion of transferable total nitrogen to non-transferable total nitrogen.