Study of chemical forms of phosphorus and their bioavailability in the sediments

Chemical forms of phosphorus in the sediments of the Daya Bay, the Zhujiang River estuary , and the Xiamen Bay are measured with extraction solutions of MgCl2, NaOH, and HC1. Their availabilities to Chlorella sp. and Isochrysis galbana are estimated by using sediments as the sole source of P in the bioassays. The results show that the contents of total phosphorus (TP) in these sediments are 449.3, 650.1 and 643.9 mg/kg, respectively. The contents of non-apatite inorganic P (NAIP) extracted with MgCl2 and NaOH from 3 sediments are 168.8, 146.6 and 118.1 mg/kg, respectively, and account for 18.3% -32.6% of TP. The phosphorus extracted with HC1 solution is greater than that extracted with NaOH solution and the lowest extracted P is MgCl2-extractable P. The greatest relative growth rates of Chlorella sp. and Isochrysis galbana cultured with sediments are in the range of 4.3% -26.9%. The increasing biomasses of these algae correspond to NAIP and AAPP (the estimated algal-available particulate P). AAPP accounts for 42.4% -78.2% of NAIP, 21.1 % - 27.1% of total inorganic P, and 11.8% - 20.3% of TP, respectively.

Organic Phosphorus in Shallow Lake Sediments in Middle and Lower Reaches of the Yangtze River Area in China

Thirteen sediment core samples(0-10 cm) were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus(P) fractions in the sediments of the shallow lakes in the area.The organic P fractions in the sediments were in the order of moderately labile organic P(MLOP) > moderately resistant organic P(MROP) > highly resistant organic P(HROP) > labile organic P(LOP),with average proportional ratios of 13.2:2.8:1.3:1.0.LOP,MLOP,and MROP were significantly related to the contents of total organic carbon(TOC),water-soluble P(WSP),algal-available P(AAP),NaHCO3-extractable P(Olsen-P),total P(TP),organic P(OP),and inorganic P(IP).However,HROP was significantly related to OP and weakly correlated with TOC,WSP,AAP,Olsen-P,TP or IP.This suggested that organic P,especially LOP and MLOP in sediments,deserved even greater attention than IP in regards to lake eutrophication.In terms of organic P,sediments were more hazardous than soils in lake eutrophication.Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment,LOP and MLOP were higher in the heavily polluted sediment,which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.

沉积物中磷的存在形态及其生物可利用性研究

用MgCl2,NaOH和HCl对大亚湾的大鹏澳、南海的珠江口、厦门湾的胡里山沉积物进行了逐级提取和总磷分析,并以这3种沉积物为惟一磷源培养小球藻和球等鞭金藻,估算了藻类对沉积物中磷的可利用量.结果表明,3种沉积物总磷含量分别为449 3,650 1和643 9mg/kg;MgCl2和NaOH提取的生物可利用的非磷灰石无机磷分别为168 8,146 6和118 1mg/kg.非磷灰石无机磷占总磷的18 3%～32 6%.3种提取剂对3种沉积物提取的磷是HCl提取相最大,NaOH提取相次之,MgCl2提取相最小.小球藻和球等鞭金藻在3种沉积物中的最大相对生长率为4 3%～26 9%,两种藻在3种沉积物中的生长与非磷灰石无机磷和藻类可利用的颗粒磷量相对应.颗粒磷占非磷灰石无机磷的42 4%～78 2%,占沉积物中总无机磷的21 1%～27 1%,占总磷的11 8%～20 3%.

武夷山五夫荷塘底泥重金属赋存特征及其生物有效性

研究武夷山市五夫镇白莲荷塘底泥中7种重金属(Hg、As、Cd、Pb、Cr、Cu和Zn)的全量和形态分布,运用风险评价编码(RAC)法及次生相与原生相分布比值(RSP)法评价元素生物有效性、判断元素的主要来源,并利用相关系数分析重金属形态受土壤理化性质的影响。结果表明:部分荷塘底泥样品的Hg、Cd全量超出NY/T5010—2016《无公害农产品种植业产地环境条件》的标准限值,且均值分别为福建省土壤背景值的3.09、5.37倍,富集较为严重。其中,Hg的残渣态占总量的80.79%,RAC值和RSP值较小,生物有效性较低且以自然来源为主;Cd以离子交换态、碳酸盐态和残渣态三种形态为主,RAC值和RSP值最大,生物有效性最高且受人为污染最为严重;Pb和Cu以残渣态为优势形态,但RAC值和RSP值较大,一定程度受人为来源的影响;As、Cr和Zn以残渣态为主,基本为自然来源。研究区荷塘底泥重金属形态分布在不同程度上受土壤基本理化指标(有机质和p H值)的影响。本研究可为合理地防治武夷山土壤重金属污染提供科学依据。

胶州湾表层沉积物中磷的形态及特征研究

于2016年9月和11月在胶州湾采集表层沉积物样品,应用改进后的SEDEX法对沉积物中的弱吸附态、铁结合态、钙结合态、碎屑态、惰性有机态以及增加了活性有机态共6种形态的磷进行了分步提取和测定,研究了它们的含量和分布特征,以进一步加深对近岸海域磷循环和生物可利用性的认识。结果表明,无机磷是胶州湾沉积物中磷的主要形态,有机磷仅占较小比率。其中碎屑态磷含量最高,活性有机态磷含量最低。湾东部及东北部表层沉积物中弱吸附态磷、铁结合态磷以及钙结合磷含量较高,推测为受陆岸输入的影响;其它形态的磷含量较均衡,无明显的分布差异。活性有机磷含量约占沉积物总磷的4%,对有机磷的贡献率约14%,为生物可利用磷的组成的19%,其性质活泼,受陆岸输入影响较小,推测主要与生物循环有关。生物可利用磷约占沉积物总磷的20%,并以铁结合态磷为主。表层沉积物中总磷的分布受生物可利用磷含量的影响,在一定程度上可体现活性磷形态的贡献。