河口潮滩沉积物磷的季节性累积和生物有效性

Seasonal accumulation and bioavailabilities of phosphorous in the tidal flat surface sediments from the Yangtze estuary

对长江口潮滩表层沉积生磷的赋存形态和含量的研究表明,碎屑态磷为沉积物中磷的主要形态,约占总磷的62.52%;铁结合态磷和有机磷次之,分别占总磷的18.06%和14.69%;自生磷灰石加钙结合态磷和吸附态磷最少。综合研究区内的各种理化条件,指出弱吸附态磷、铁结合态磷和有机磷是长江口潮滩潜在生物可利用磷,约占总磷的33.16%,是导致水体富营养化的潜在因素。上覆水的盐度效应是影响沉积物铁结合态磷含量的关键性因子;而自生磷灰石加钙结合态磷的含量变化则与上覆水的温度、溶氧量及沉积物有机质的分解有关;有机磷在时间和空间尺度上都存在较大变化,主要与潮滩生物动态过程,即磷的再矿化有关。

The species and contents of phosphorus were studied in the tidal flat surface sediments of the Yangtze estuary. The results showed that detrital apatite contributed 62. 52% of total phosphorus, which is the main speciation of phosphorus. Iron-bound phosphate and organic phosphate respectively made up 18.06% and 14.69% of total phosphorus. While authigenic apatite plus calcium bound phosphate and loosely adsorbed phosphate occupied the least of total phosphorus. According to all kinds of physico-chemical conditions in the study area, only loosely adsorbed phosphate, iron-bound phosphate and organic phosphate should be considered as the potential factors for eutrophication, which represented mean proportion of 33. 16% of the total phosphorus. Salinity effect on the overlying waters was the key factor to the content of iron-bound phosphate, and authigenic apatite plus calcium-bound phosphate is relative to the water temperature, dissolved oxygen and decomposition of sedimentary organic matters. Organic phosphate was the only form to exhibit significant spatiotemporal variations, which were linked to the remineralization of phosphorus.