黄河表层沉积物中磷的分布特征及磷的生物可利用性

采用改进的七步连续提取法分别对黄河中下游流域5个不同段位表层沉积物中总磷(TP)、有机磷(OP)及各种无机磷形态进行了分析,研究并探讨了沉积物中磷的分布特征及其对河海町能产生的影响,为预测黄河乃至渤海流域的营养状况、预防及科学管理等提供理论依据.结果表明,所测黄河表层沉积物中TP含量范围为240.71~576.59 μg·~(-1).以无机磷(IP)为主,占TP含量的85.73%～98.48%;OP含量占TP的1.52%～14.27%.受陆地河流和海流注入的影响,所研究沉积物样中TP、IP和0P含量的最大值均出现在靠近黄河口的渤海浅海区,其次是黄河口.IP分为6种形态磷.即交换态磷(Ex-P)、铝结合态磷(AI-P)、铁结合态磷(Fe-P)、闭蓄态磷(Obs-P)、自生钙结合磷(Ca-P)和原生碎屑磷(De-P),其中以De-P为主,其次是Ca-P,分别占TP的52.47%～73.67%和18.32%～38.20%,Ex-P、Fe-P和Al-P含量均相对较低,Obs-P含量最低.各形态磷的空间分布均与调查区沉积物粒径有一定相关性,粒径小于0.063 mm的沉积物样中TP和IP含量均最高.Ex-P、Al-P、Fe-P、Or-P和部分Ca-P作为黄河表层沉积物中潜在的生物可利用磷,其总量至少占TP的6.09%～24.46%.

Distribution Characteristics and Bioavailability of Phosphorus in Surface Sediments from the Yellow River

Phosphorus( P) is one of the foundational nourishing elements on which the marine life rely for existence, limiting nutrient in the ecosystem, and its form distribution and bioavailability are affecting the primary productivity of the waters directly. Total P(TP), organic P (OP), and different forms of inorganic P(IP) were analyzed by using the seven-step sequential extraction method in different sediments from the Yellow River. Distribution characteristics of P in different sections and its impact on the natural water column were discussed, aiming to understand the importance of P cycling between the river and sea and the trophic status of the waters. The results indicated that the contents of TP in all samples ranged from 240.71 to 576.59 μg·g~(-1) and IP was its dominant portion, occupying 85.73%～98.48% of TP. OP content was 1.52%～14.27% of TP. Their maximums all appeared in the shallow sea of the Bohai sea near the Yellow River estuary and the next ones were at the Yellow River estuary. IP included six form phosphorus: exchangeable+loosely-bound P(Ex-P), aluminum-bound P (Al-P), iron-bound P(Fe-P), obstinate-bound P(Obs-P), authigenic+biogenic apatite+calcium carbonate-bound P(Ca-P ) and detrital apatite+ other remaining inorganic P(De-P), De-P and Ca-P were found to be the major components of IP whose contents were 52.47%～73.67% and 18.32%～38.20% of TP, respectively. Contents of Ex-P、Fe-P、Al-P were all lower and that of Obs-P was the lowest. The spacial distribution of various form P was correlated with the grain size of sediments. Contents of TP and IP were all maximums in sediments of the grain size less than 0.063 mm from different sections. Ex-P、Al-P、Fe-P、OP and part of Ca-P, acting as the bioavailable P, accounted for 6.09%～24.46% of TP at least.