微波消解法是水体沉积物中重金属测定的一种重要前处理方法。本研究通过对水体沉积物重金属检测前处理中微波消解方法的消解剂的比较,选择常用的4种消解多元酸配比,对上海黄浦江沉积物样品进行消解,分析消解液浓度来检验方法的差异性,选定一种消解方法用标准沉积物样品进行检验。结果表明,测定不同的元素适用不同的消解方法,采用9 mL HNO_3+3 mL HF+3滴HClO_4多元酸体系对0.25 g水体沉积物样品检测,其方法重现性较好的元素最多,符合元素平行样测定结果最大相对标准偏差满足率的最高要求,是一种适合于河道沉积物中大部分重金属元素检测的方法。
为了深入研究复合生物净化槽内脱氮除磷的微生物种类及特性,以培养基为单位进行初筛、以脱氮除磷试验进行复筛,得到了3株优势菌株A-1、B-5、C-2。运用离子色谱法和营养液培养法综合分析菌株的脱氮除磷产物,并采用革兰氏染色法对菌株进行初步判定,另外还建立了3种菌株的系统树,研究了3种菌株的基因序列。对菌株理化指标的分析表明,菌株A-1、B-5、C-2分别符合奇异变形杆菌、门多萨假单胞菌、枯草杆菌的特征;通过16S r DNA基因序列进行对比分析,发现3种菌株与上述对应菌种的同源性分别可达到99%、98%、98%。最后,运用Monod方程和Lineweaver-Burk图解法建立了3种菌株的反应速率方程式。
The concentration and spatial distribution of persistent toxic substances (PTS) in the river sediment in Chaohu City, China were investigated. A total of nine surface sediments were collected and the selected PTS pollutants including six heavy metals and nineteen polybrominated diphenyl ethers (PBDEs) were analyzed. The mean heavy metal concentrations (in mg/kg, dry weight) ranged within 0.18-1.53 (Hg), 50.08-200.18 (Cu), 118.70-313.65 (Zn), 50.77-310.85 (Cr), 37.12-92.72 (Pb) and 13.29-197.24 (As), and Cu, Zn and As have been regarded as the main metal pollutants. The levels of PBDEs (1.2-12.1 ng/g) and BDE-209 (2.4-30.5 ng/g) were at the middle level of the global range. BDE-209 was the predominant congener (67.0%-85.7%), which agrees with the fact that technical deca-BDE mixtures are the dominant PBDE formulation in China. The relative high level of PTS pollutants in the western part of the city is probably owing to the intensive agricultural activities and lack of sewerage system there. The ecological risk assessment with the sediment quality guidelines (SOGs) indicates that the urban river sediments in the city have been heavily contaminated by heavy metals with probable ecotoxicological impacts on freshwater organisms and the main toxic pollutants are Hg and As. The results of current study imply that the city, and perhaps many other small cities in China as well, requires immediate pollution control measures with emphasis on not only conventional organic pollutants but also on PTS such as heavy metals and PBDEs.
