Comparative evaluation of residual and total metal analyses in polluted soils

Abstract

Two digestion procedures, employing aqua regia‐HF (ARHF) and HNO₃‐HCIO4‐HF (HHH), were used to analyze residual metals (following a chemical fractionation scheme) and total metal content of two soils, one moderately polluted by municipal sludge applications and the other a grossly‐contaminated sample (20.8% Pb) from a battery recycling site. Although commonly used in sequential extraction analyses, the ARHF method solubilized only 53% (significant at p = 0.05) of the HHH‐determined residual Pb in the battery soil. For the sludge‐amended soil, residual Cd, Pb, and Zn were not statistically different by the two methods. For the battery soil, a single ARHF extraction also underestimated total Pb and Cu relative to HHH, but both methods gave statistically‐similar total Cd, Cu, Pb, and Zn for the sludge‐amended soil. As the sample metal concentration increased, the ability of ARHF to solubilize HHH‐equivalent metal quantities generally decreased. Since the degree of contamination is often unknown for environmental samples, the HHH method is more reliable for assessing residual and total metals in polluted soils     

滇池周边农田中拟除虫菊酯农药残留研究

为探明滇池周边农田土壤中拟除虫菊酯农药残留污染状况,用气相色谱法(ECD)对采自该区土壤样品进行了5种拟除虫菊酯农药残留检测.结果表明,在蔬菜和花卉地中,5种拟除虫菊酯农药的检出率,以氯氰菊酯和三氟氯氰菊酯最高,分别为66.7％～100％,52.9％～100％,氟氯氰菊酯和氰戊菊酯次之,溴氰菊酯最低;检出浓度平均值以氟氯氰菊酯最高,蔬菜地土壤中达44.9 μg/kg;春、秋两季,5种农药在花卉地的残留量高于蔬菜地,而夏季和冬季则相反.大棚和露地中,大棚的残留量显著高于露地.不同土层中,除氯氰菊酯在表层(0～20cm)中的残留量明显高于下层,其他4种农药在0～60 cm土层中残留量差异不显著.由于目前没有制定拟除虫菊酯农药土壤中残留环境质量标准,无法判定实验区土壤中拟除生菊酯农药残留超标率及土壤环境等级,但其在环境中的残留问题应引起重视.     

水田土壤剖面磷素分布特征

对水田土壤剖面分层采样分析，研究了磷素在水田土壤剖面中的分布特征。结果表明水田土壤剖面各层中全磷、有机磷、速效磷均有一定量的积累，并且表现出土壤剖面下层磷素增加的趋势；秋季土壤剖面中有机磷占全磷的比例有高于春季比例的特点。     

四川山丘区不同利用方式土壤磷吸附特性

[目的]研究四川山丘区11种不同利用方式土壤磷的吸附特性,为生态沟渠底质的选择提供科学依据。[方法]针对生态沟渠中的底质,选取四川山丘区11种不同利用方式的土壤为研究对象,对磷的吸附特性进行研究。[结果]等温吸附时,磷的最大吸附量Qm、吸附平衡常数K、最大缓冲容量MBC均与黏粉粒含量呈正相关,但K和MBC与p H呈负相关;适宜的淹水条件能增加土壤黏粉粒含量,促进非晶质氧化铁的形成,从而有利于土壤对磷的吸附。土壤磷吸附动力学试验表明,在接触时间2 h内吸附反应速率较快,这是磷向沟渠底质转移的主要阶段;去除水体中多余的磷素,应选取黏粉粒含量高的土壤作为生态沟渠的底质。[结论]该研究对生态沟渠底质的合理选择具有重要的实际应用价值。     

土壤表面电荷测定的两种方法之比较

用返滴定法和Mehlich法研究测定了我国不同地带土壤 (砖红壤、红壤、黄棕壤、暗棕壤、黑土 )无机胶体的表面电荷。结果表明 :( 1 )两者的测定结果有较大的差异 ,其主要的原因是返滴定法和Mehlich法分别基于不同的衡量标准 ,从不同的侧面反映了土壤表面的电荷性质 ;( 2 )返滴定法与Mehlich法各有其优点 ,但在具体的测定过程中都有些环节可能需要改进。     

General Chemical Properties of Brown Forest Soils Developed from Different Parent Materials in the Submontane Zone of the Kanto and Chubu Districts, Japan

It is essential to analyze chemical properties including the amount of various materials and the soil colloid characteristics in forest soils to forecast wood production and the distribution of and variations in the environmental functions of forest soils, such as conservation of stream water and carbon sequestration. Approximately 70% of the forest soils in Japan consists of Brown Forest Soils (BFS), which are considered to be typical zonal soils under the humid-temperate and warm-temperate regime of Japan. BFS were subclassifled into several groups according to the soil moisture environment along the slope and morphological properties. However, even the same type of soil may display different properties depending on the climatic conditions, parent materials and vegetation types. In the present study, the variations in the carbon content, nitrogen content, cation exchange capacity and some properties depending on the parent materials, were clarified by using 34 sola of BFS, and 3 sola of black soils (BLS) for comparison, which were distributed in the submontane zone of the Kanto and Chubu districts in central Japan under the same climatic conditions. We observed differences in the pH, cation exchange capacity, base saturation and clay content among BFS samples derived from various parent materials. The BFS derived from volcanic ash contained obviously larger amounts of carbon and nitrogen than the BFS derived from other parent materials. However, the BFS derived from volcanic ash differed from the BLS derived from volcanic ash in the vertical distribution pattern of carbon and nitrogen. Thus, even in the submontane zone of the Kanto and Chubu districts, the chemical properties of BFS varied considerably with the parent materials. It was concluded that the classification of BFS by the parent materials was useful for evaluating the ability of the BFS, that cover 70% of the forests in Japan, to store various materials.     

Extraction of DNA from soil

There is an increased interest in the extraction of nucleic acids from various environmental samples, since molecular techniques allow less biased access to a greater portion of uncultivable microorganisms. Two strategies have been developed to improve DNA recovery in terms of yield, purity and unbiased representation of the microbial diversity. The first approach consists of the direct extraction of nucleic acids from soil through in situ cell lysis followed by DNA purification. The alternative approach is based on the separation of bacteria from the soil particles followed by cell lysis and then DNA purification. Several published methods describe the recovery of highly purified nucleic acids that are well-suited for molecular purposes even though a new challenge concerns the recovery of large bacterial DNAs essential for functional investigation of gene clusters and biosynthetic pathways. This review presents an overview of the available methods to achieve this challenging objective.     

Heavy metal accumulation by two earthworm species and its relationship to total and DTPA-extractable metals in soils

The concentrations of Zn, Cd, Pb and Cu in earthworm tissues were compared with the total and DTPA-extractable contents of these heavy metals in contaminated soils. Samples were taken from a pasture polluted by waste from a metallurgic industry over 70 y ago. Three individuals of Aporrectodea caliginosa and Lumbricus rubellus and soil samples were collected at six points along a gradient of increasing pollution. Total metal contents of earthworms, soil, and metals extracted by DTPA from the soil were measured. Total heavy metal contents of the soils ranged from 165.7 to 1231.7 mg Zn kg⁻¹, 2.7 to 5.2 mg Cd kg⁻¹, 45.8 to 465.5 mg Pb kg⁻¹ and 30.0 to 107.5 mg Cu kg⁻¹. Their correlations with metals extracted by DTPA were highly significant. Contents of the metals in earthworm tissues were higher in A. caliginosa than in L. rubellus, with values ranging from 556 to 3381 mg Zn kg⁻¹, 11.6 to 102.9 mg Cd kg⁻¹, 1.9 to 182.8 mg Pb kg⁻¹ and 17.9 to 35.9 mg Cu kg⁻¹ in A. caliginosa, and from 667.9 to 2645 mg Zn kg⁻¹, 7.7 to 26.3 mg Cd kg⁻¹, 0.5 to 37.9 mg Pb kg⁻¹ and 16.0 to 37.6 mg Cu kg⁻¹ in L. rubellus, respectively. Correlations between body loads in earthworms with either total or DTPA-extractable contents of soil metals were significant, except for Cd in L. rubellus and Cu in A. caliginosa. Considering its simple analytical procedure, DTPA-extractable fraction may be preferable to total metal content as a predictor of bio-concentrations of heavy metals in earthworms. Biota-to-Soil Accumulation Factor (BSAF) of these four metals are Cd>Zn>Cu>Pb, with range of mean values between: Cd (6.18-17.02), Zn (1.95-7.91), Cu (0.27-0.89) and Pb (0.08-0.38) in A. caliginosa, and Cd (3.64-6.34), Zn (1.5-6.35), Cu (0.29-0.87) and Pb (0.04-0.13) in L. rubellus. The BSAF of Ca, Fe and Mn are Ca>Mn>Fe, with mean values of: Ca (0.46-1.31), Mn (0.041-0.111), Fe (0.017-0.07) in A. caliginosa and Ca (0.98-2.13), Mn (0.14-0.23), Fe (0.019-0.048) in L. rubellus, respectively. Results of principal component analysis showed that the two earthworm species differ in the pattern of metal bioaccumulation which is related to their ecological roles in contaminated soils.     

Determining fertilizer-induced NO emission ratio from soils by a statistical distribution model

To reduce uncertainties in the highly variable estimates of NO emission from N fertilizer, we compiled and analyzed available reports of field measurements on fertilizer-induced NO emission. Three statistical distribution models, lognormal, gamma and Weibull, were used to fit the observation data. Results show that while all three models fit the observation data statistically, the lognormal model is not applicable to this data set. A mean fertilizer-induced NO emission ratio of 0.71% was derived from a Weibull distribution, which is the besting fitting model.     

云南省新构造运动与土壤形成及分布的关系

 云南在高原面及若干河谷高阶地上,有富铝化作用甚强的古红土,且纬度愈高,分布的海拔愈高,这与常理不符,它与各地新构造运动上升量的差异有关.新构造运动观点可圆满解释: 红色盆地的分布状况、红色盆地内紫色土的淋溶程度差异、无量山主峰的形成,昆明山字型构造对土壤发育的影响、砖红壤与燥红土等土壤的形成规律等等.云南全境受新构造运动影响深刻,导致土壤分布复杂,本文对此做了"土壤四度空间分布"概念的分析.