南极普里兹湾表层沉积物中磷的形态分布特征

摘要

Speciation of phosphorus ( P) in surface sediments collected during several Chinese National Antarctic Re-search Expedition cruises in Prydz Bay was investigated .The sequential extraction method was used to separate and quantify the following five sedimentary P reservoirs:exchangeable phosphorus ( ExP) , iron phosphorus ( FeP) , au-thigenic phosphorus ( AuP) , detritus phosphorus ( DeP) , and organic phosphorus ( OP) .DeP and AuP were the major types of phosphorus in surface sediments , with an average of 37.5% and 25.8%, respectively, of total P. Obvious positive relationships between both OP and AuP , and organic carbon and biological silica indicated that they might originate from the same source , that is , marine biogenic matter .DeP was positively correlated with alu-minum and sandy sediments , which suggests that this form of P was derived from land-based sources and carried to the sea ice in ocean currents .The content and distribution of P in sediments were mainly influenced by the sources of P, but the grain size of sediments and other physical factors , such as sea ice and current , were also involved . ExP was related to the grain size of sediments , while FeP was related to iron.In addition, both ExP and FeP were small components of total P , accounting for only 8.9%and 6.5%, respectively.Bioavailable P was concentrated in central and eastern Prydz Bay , with an average content of 37.2%of total P.%针对多次南极考察中雪龙号在普里兹湾海域获取的表层沉积物样品，分析了该海域沉积物中各形态磷的含量，并讨论了其分布特征和控制因素。结果表明，表层沉积物总磷含量介于416．1×10－6—676．3×10－6之间，平均为543．5×10－6，主要由碎屑磷（平均为209．9×10－6）和自生磷（平均为137．7×10－6）组成。自生磷、有机磷呈现从湾东部至西部逐渐降低的分布趋势，这种分布与有机碳、生物硅等生源要素的分布以及上层水体生产力的高低相吻合，指示了其海洋生源属性；碎屑磷在湾西部含量较高，其分布与沉积物中铝、砂质的分布模式一致，表明其主要来自堆积在西部浅滩区域冰山携带的陆源砂质碎屑。可交换态磷（平均为36．0×10－6）和铁结合磷（平均为47．1×10－6）在沉积物中含量较低，分别受沉积物粒度和铁含量的控制，仅在湾东部和中心个别站位含量较高。生物可利用磷在湾东部和中心区域含量较高，可能与上述区域较高的生源颗粒物沉降速率有关，同时这些颗粒物可能吸附了水体中的磷进入沉积物中，导致对应底层海水磷酸盐浓度相对降低。