乳山湾外低氧海域沉积物中有机碳、氮、磷及其形态特征分析

Characteristics of different forms of nitrogen and phosphorus and organic carbon in the sediments of low-oxygen zones in adjacent Rushan Bay

根据2009年8月在乳山湾及其毗邻海域的综合调查,分析了该海域表层沉积物中有机碳、氮、磷含量及其组成形态的变化,初步探讨了影响底质理化参数变化的原因及对乳山湾外近岸底层低氧形成的影响。结果表明,乳山湾外近海为粉砂质岸滩,以细颗粒为主;底质中有机碳含量介于0.49%～0.93%,平均值为0.69%;总氮含量介于382～1 020 mg/kg,平均值为671 mg/kg;可溶性总氮含量介于23.0～60.0 mg/kg,平均值为44.0 mg/kg,其中可溶性有机氮和氨氮分别占可溶性总氮的58.8%和38.8%;总磷含量介于138～769 mg/kg,平均值为356 mg/kg,有机磷是占有绝对优势的磷形态(62.5%)。研究区域沉积物中总氮和湾内相当,有机碳、总磷含量普遍低于乳山湾内,但均明显高于南黄海区域,且呈还原性状态。调查区域内沉积物中相对较高的有机碳、氮、磷可能是在潮流作用下乳山湾与外海的物质交换所致,其耗氧过程是导致底层溶解氧亏损的重要原因,值得进一步关注。

A comprehensive survey of Rushan Bay and its adjacent area was carried out in August, 2009. The content and forms of organic carbon, nitrogen and phosphorus in surface sediments were analyzed. Fine sediment is the major components of the sediment in this area. The contents of organic carbon, total nitrogen and phosphorus in the marine sediments range from 0.49% to 0.93%, from 382 to 1020 mg/kg and from 138 to 769 mg/kg, with their av- erage value of 0.69%, 671 mg/kg and 356 mg/kg, respectively. In addition, dissolved organic and ammonia nitrogen account for 58.8% and 38.8% of the total dissolved nitrogen. The organic phosphorus is the dominant part of the total phosphorus （62.5%）. The concentration of total nitrogen is equal to that in Rushan Bay, The organic carbon and phosphorus concentrations are lower than those in Rushan Bay, but higher than those in the South Yellow Sea. The relatively high content of organic carbon, nitrogen and phosphorus in the sediments might due to the material exchange between Rushan Bay and the open seas. The sediment oxygen consumption may be the major cause of loss of dissolved oxygen in the bottom water, which needs further research.