Fe3+固定浓缩混合酸消化测定土壤水溶性硒

由于水溶性有机态硒及有机质的存在,准确测定土壤水溶性硒宜经浓缩、消化处理后进行.采用在适量硝酸存在的条件下,以Fe3+作为固定剂,沸水浴浓缩土壤水提取液,再经硫酸-硝酸混合消化,用氢化物原子荧光光度计测定硒.结果认为:在适量Fe3+和硝酸存在条件下,土壤水提取液经浓缩、消化处理后,硒测定值较未作处理的提高40%以上,加标回收率在98%～102%之间,变异系数≤0.3%;浓缩和消化过程中,根据水提液有机质的含量,适量地使用硝酸和硫酸对保证测定的精密度具有重要意义.

Abstract：

As soil water extract contains much water-soluble organic selenium and organic matter, the determination of soil water-soluble selenium should be concentrated and digested beforehand. Water extracts from the soil was concentrated in boiling bath under the presence of nitric acid and with added Fe3+ as fixative, and then digested with mixed acid before selenium content was determined by a hydride atomic fluorescence spectrometer. The results showed that the determination values were raised by 40% or more than those of the untreated soil, the recoveries were between 98 ～ 102%, and the variation coefficient was ≤0.3 %. In the process of enrichment and digestion, suitable use of nitric acid and sulfuric acid to ensure the accuracy according to the dissolved organic matter content is of great significance.     

重庆地区酸性紫色土锌有效性及其影响因素研究

以重庆地区紫色土为对象,研究了重庆地区酸性紫色土Zn有效性及主要影响因素。结果表明:供试紫色土全Zn含量为40.2～89.6mg/kg,有效Zn含量在0.2～4.2mg/kg之间;用直线、幂函数和指数函数回归方程对影响有效Zn的主要土壤因素进行回归拟合,土壤有效Zn与土壤全Zn、有机质、全N含量呈极显著正相关关系,相关系数依次为0.5243**、0.5308**、0.5097**;而与全P含量相关性显著(r=0.4637*);与土壤pH值呈极显著负相关关系(r=-0.5698**);通径分析表明,土壤理化性质对有效Zn的直接作用系数大小次序为全Zn全NpH,土壤全Zn对Zn有效性的直接作用最为明显。     

重庆土壤铅含量污染评价及其影响因素分析

对重庆市8个区县160个表层土壤样品进行铅（Pb）含量分析,探讨土壤Pb含量特点及其影响因素,并运用地积累指数法对各区县表层土壤Pb污染作出评价。结果表明：全部供试土壤样品的Pb浓度几何平均值为37．30mg／kg,显著高于重庆市土壤Pb背景值（22．20mg／kg）,表现出一定的积累趋势。pH值是影响土壤全Pb含量的重要因素,当pH≤6．5和pH≥7．5时,随着pH值的增大,土壤全Pb含量增加;而6．5〈pH〈7．5时,随着pH值的增大,土壤全Pb含量减少。在供试样品有机质含量范围内,随着有机质含量的增加,土壤全Pb含量呈线性增加。总体上看,重庆市8个区县表层土壤Pb污染为轻度至中度,其中秀山县Pb污染最严重,达到中度污染水平。