土壤弹尾目昆虫Folsomia candida对铜污染的急性毒理初步研究

随着土壤环境重金属污染的加剧,有关重金属污染土壤的风险评估受到关注.对土壤质量评价的方法长期以来集中在检测重金属污染物质在土壤中的浓度及化学形态等方面,而对于重金属、土壤和生物之间的相互作用很少考虑,因而难以全面评估重金属对土壤环境的生态毒性效应[1].重金属污染土壤的生物评价是对化学评价的有效补充和相互验证.土壤弹尾目昆虫(跳虫)作为土壤动物群落中的优势物种之一,是土壤环境的重要指示生物,在对污染环境的生态评估研究中得到越来越多的重视[2-5].     

土壤有机质含量测定方法的改进研究

通过研究改进了土壤有机质含量的测定方法。首先称取适量土壤置于长管消解系统中进行消解,然后采用全自动电位滴定仪进行滴定,直接获得土壤的有机质含量。使用该方法测定的土壤标准样品的有机质含量均在保证值以内,同时对实际样品进行精密度测试,得到相对标准偏差为1.03%。该方法降低了土壤有机质含量检测的实验成本,减少了环境污染,同时提高了实验数据的准确度与精密度,值得推广。     

基于质量法的土壤水溶性盐总量测定方法改进

  目的  利用现有常规测定方法批量测定土壤水溶性盐总量时存在浸提液用水质量不统一、浸提液获取慢、浸提液吸液量大、蒸干时间长导致测试效率低等突出问题。因此,探究基于质量法对土壤水溶性盐总量的测定方法进行改进。  方法  试验利用不同盐分水平的土壤对现有常规土壤盐分含量测定方法中的浸提方式、浸提液用量及试验用水质量进行改进研究。  结果  在中度及以下盐化土壤条件下,将浸提方式由抽滤改为离心,并将离心参数设置为转速4000 r min?1,离心8 min即可保证测试结果准确度,提高测试效率;无论浸提液盐分含量高低,当浸提液的吸液量由50 ml或100 ml降为20 ml时均可保证盐分测定结果的精密度和准确度,有效缩短蒸干时间;蒸馏水可以替代去CO₂的蒸馏水或超纯水作为土壤水溶性盐测定用水,既避免了进一步制水的时间消耗,又可以进一步降低测试成本。  结论  试验所得中度盐化及以下土壤含盐量测定方法可在保证改良方法合理性及应用效果条件下,从试验准确度、效率和成本等方面对现有方法进行了有效改进。     

土壤中砾石含量的测定方法研究进展

石质土壤中含有大量砾石,大量砾石的存在会影响土壤理化特性和水力特性。土壤中砾石含量的研究会影响土石介质的生产力评估、水文及风化过程的研究水平。本文主要介绍了国内外土壤中砾石含量的现有测定方法,对环刀取样法、挖坑法、Viro插钎法,γ射线法、探地雷达及电阻率断层扫描技术的实际应用进行了讨论。在实际研究中应根据实际情况选择合适的砾石含量测定方法。土壤中砾石含量的测定应该引起国内相关研究的重视,为土壤研究提供重要信息并为土壤学研究水平的提高提供帮助。     

植物吸收污染土壤中镉的规律

选取黑麦草和羽衣甘蓝两种植物进行盆栽试验,并对25、50、75、100、125、150 mg/kg 6个浓度等级下两种植物地上部分镉含量进行了测定与分析,结果表明:黑麦草吸收、富集镉的能力较弱,羽衣甘蓝在土壤中镉浓度超过125 mg/kg时,地上部分镉含量超过100 mg/kg,但其富集系数和转运系数均小于1,两种供试植物均不是理想的修复镉污染土壤的超积累植物。     

土壤中水分和镉供应量对油菜器官中镉分布特征的影响

为探究油菜作为镉(Cd)污染农田修复植物的可行性,本研究以德油5号为试验材料,采用全生育期土培盆栽试验,设置高、中、低3个水平的土壤水分及4个水平的土壤镉含量,研究不同土壤水分条件下油菜对镉的吸收和富集规律。结果表明,土壤水分与镉浓度对油菜的吸镉能力影响显著,且其吸收量随着土壤水分与镉浓度的增加而增大;油菜不同器官的镉含量差异较大,其地上部分吸镉量为土壤总镉含量的0.41%～1.17%,叶片镉含量为总吸收量的46.4%～72.6%;不同水分条件下,油菜器官的镉富集量差异明显,高水、中水处理下油菜各器官的镉富集表现为叶>茎>根>角果壳>籽粒,低水处理下表现为叶>根>茎>角果壳>籽粒。综上,油菜整体具有较强的吸镉能力,但镉离子不溶于菜籽油,说明油菜可吸收土壤中的镉,又不影响菜籽油食用,是修复镉污染农田土壤的理想植物。本研究为利用油菜进行重金属土壤综合治理提供了理论依据。     

粉煤灰对污染土壤中铜镉的稳定化

采用批衡量吸附和室内培养实验,考察了粉煤灰对Cu和Cd的吸附等温线及0.2%、0.5%、1%和2%用量的粉煤灰对土壤pH、有效态Cu和Cd、以及5种化学形态Cu和Cd分布的影响。结果表明:粉煤灰对Cu和Cd的吸附等温线均可以用Langmuir和Freundlich方程进行拟合,其对Cu的最大吸附量(9.90 mg/g)高于对Cd的最大吸附量(9.43 mg/g)。随着粉煤灰用量的增加,土壤pH显著增加,有效态Cu和Cd显著降低。同时,粉煤灰处理显著降低了离子交换态Cu和Cd含量,增加了铁锰氧化物结合态Cu和Cd含量,降低了Cu和Cd活性,使活性态Cu和Cd逐渐向潜在活性态和非活性态转化。其中培养60天后,2%处理的粉煤灰处理较对照pH提高了0.44个单位,离子交换态Cu和Cd分别降低了35.7%和35.9%。因此,粉煤灰能够有效吸附Cu和Cd,显著降低土壤有效态和离子交换态Cu和Cd的含量,在重金属稳定化修复应用中具有较好的应用前景。     

土壤中含钾测定方法(J.L.Smith法)的改进

以碳酸鈣、氯化銨混合体,来熔化土壤中鉀矿物的方法^{[Lawrence Smith(史密司)法]}是分析化学上通用了最久的方法之一^[1]。这个方法,显然具有分解作用比較彻底的优点,而土壤及岩石中某些原生鉀矿物又为一般酸液所不能溶解。分析化学家在最近20-30年以来,企图用各种混合酸液(特别是氟氫酸——过氯酸——硫酸)来代替史密司的冗长熔化步驟^[2],但是在对待某些富有Al、Ti、Ba等合鉀矿物的土壤时,显然沒有达到完全分解的目的。     

土壤全硫测定方法的改进及其在燃煤电厂周边土壤分析中的应用

为了提高硫酸钡比浊法测定土壤中全硫含量方法的准确性,对其进行改进,考察了乙酸和硝酸镁添加量对比浊液吸光度的影响,并对某燃煤电厂周边土壤样品进行测定。结果表明:乙酸溶液(1∶1)和硝酸镁溶液(308 g/L)的最佳添加量分别为 15、5 mL。改进后的方法具有较高的准确度和精确度。某燃煤电厂周边土壤全硫的含量范围为 95.71～ 1 102.03mg/kg,平均值为 412.48mg/kg,总体平均含量未超过全国一般水平,但有 32%的样品高于全国一般水平,说明该燃煤电厂周边土壤的硫发生了一定程度的蓄积,需引起重视。     

污染土壤中镉活性提取剂的选择

通过综合分析比较九种活性提取剂对２１个污染土壤镉的提取能力，土壤基本性状对提取量的影响，以及提取量与土壤中镉赋存形态的关系，提出了以０．０５ｍｏｌ／ＬＣａＣｌ２作为评价污染土壤活性镉的最佳提取剂。     

Evaluation of a rapid microwave digestion method for determination of total organic carbon in soil

Precise measurement of soil organic carbon (SOC) is essential for constructing regional inventories, developing best agricultural management practices, and modeling purposes. Currently, the automated dry combustion method is considered standard, but the method is both costly and time-consuming. There is a need for a simple, easy to use and cost-effective method of organic C determination in soil. A simple method of total organic carbon (TOC) determination in soil that involved wet digestion of K₂Cr₂O₇-H₂SO₄-soil mixture in a commercial microwave oven followed by spectrophotomteric measurement of Cr (III) was evaluated. The method was compared with automated dry combustion and two other wet digestion methods. The method showed close agreement with dry combustion method (R² = 0.90; root mean square error = 0.70) and the TOC measured with the two methods did not differ for a range of soils drawn from lowland and upland land-uses and varying in pH (6.2–9.3), TOC (2.8–14 g kg^?1), and calcium carbonate content (0–6.7%). The recovery of the added organic C by the microwave method was 98.6 ± 4.2%. The results suggested that microwave-spectrophotometric method could be easily adopted in routine soil analysis as it is not only precise, rapid, and cost-effective but also produced small volume of reagent waste.     

Microwave Digestion for Colorimetric Determination of Total Si in Plant and Mineral Samples

A new method for determining the soluble silicon (Si) concentrations in nonliquid plant and mineral samples was developed using sodium hydroxide (NaOH)–hydrogen peroxide (H₂O₂) matrix for microwave digestion (MWD-Na) followed by colorimetric Si testing. MWD-Na was compared with autoclave-induced digestion and alkali fusion. The data have shown no significant difference between these three methods. HNO₃–H₂O₂ or HNO₃?–H₂O₂?–HF microwave technique results in Si loss. The reduction of the total Si can be realized via low solubility of Si in the acid solutions or silicon tetrafluoride formation. The Mullen and Riley method for colorimetric testing of Si in a solution that uses ascorbic acid to reduce the silicomolybdate complex formed under acid conditions to an intensely blue complex was modified using iron sulfate. The combination of MWD-Na and modified colorimetric blue method provides cheap and valid data on determining the total Si in both plant and mineral samples.     

Near-infrared spectroscopy for determination of soil organic C,microbial biomass C and C and N fractions in a heterogeneous sample of German arable surface soils

Visual and near-infrared spectroscopy (vis-NIRS) is an established method to estimate soil properties. However, only limited information is available to estimate C and N fractions in a heterogeneous sample. The objectives of our study were to determine estimation accuracies of vis-NIRS using two software for soil organic carbon (SOC), total nitrogen (N_t), pH, texture, and C and N fractions (light (LF), mineral (MF), labile, intermediate and passive fractions) in a heterogeneous sample (consisting of 51 units with different mineralogy) and to compare these results with those obtained by mid-infrared spectroscopy (MIRS). Analyzing vis-NIRS spectra and the mentioned properties showed a possibility to distinguish between high and low values for SOC (residual prediction deviation (RPD) = 1.90) and N_t (RPD = 1.93). Sand and clay could be estimated, whereas pH and silt could not. No useful estimation was possible for N-LF, passive C, intermediate C or intermediate N. C-LF, C-MF and N-MF could be differentiated between high and low values, whereas for passive N the estimation was approximate quantitative. MIRS reached one or two times higher estimation categories than vis-NIRS for SOC, N_t, pH and texture, suggesting that MIRS has a higher potential to estimate soil properties in a heterogeneous sample.     

A simplified procedure for the determination of total mercury in soils

Abstract

A saraimplified procedure for the measurement of total mercury in soils and some preliminary results for Saskatchewan are presented. Soil samoles were digested in aqua regia at low temperatures, followed by determination of Hg with a simplified flameless atomic absorption technique. Hg levels in soils analyzed ranged from 0.003 to 0.071 ug/g.     

小麦籽粒中微量铅的快速测定技术(简报)

为建立一种快速测定粮食中微量铅的新方法,以南阳彩色小麦为材料,用微波压力消解技术快速处理样品,对测定条件进行优化,并与国家颁布标准方法(GB/T5009.12-2003)进行比较。结果表明:加标回收率为92.5%～96.8%,相对标准偏差RSD(Relative Standard Deviation)为0.67%～1.7%(n=11),铅的最低检出限为0.0099mg/L,测定的线性范围为0.850～206.0mg/L,相关系数为0.996,电极斜率为24.160。样品用该法与国标方法对照测定并进行显著性检验证明,该方法具有直观、快速、简便、灵敏、准确、适于现场进行测定的显著优点。     

A comparison of wet oxidation methods for determination of total phosphorus in soils

For 15 soils with widely different extractability of phosphorus (P) two newly introduced digestion techniques for determining total P (P_t) were compared with the standard perchloric acid digestion procedure. The two digestion techniques were: (1) concentrated H₂SO₄ plus 30 % H₂O₂ at 360 °C, (2) concentrated HCl plus concentrated HNO₃ in the ratio 3:1 (aqua regia) at 140 °C. Almost equal amounts of P_t were extracted by the two methods (mean = 188.7 mg kg^—1 for H₂SO₄/H₂O₂ and 188.4 mg kg^—1 for aqua regia) which were slightly higher than the standard method (mean = 183.8 mg kg^—1). However, there is no statistical difference among the three digestion methods, suggesting that the tested methods should be useful for estimating P_t in soils with high content of organic C, eliminating the danger of explosion when hot concentrated HClO₄ is used.     

Premixed digestion salts for Kjeldahl determination of total nitrogen in selected forest soils

Abstract

Estimates of total soil nitrogen by a standard Kjeldahl procedure and a modified procedure employing packets of premixed digestion salts were closely correlated (r² = 0.983). The modified procedure appears to be as reliable as the standard method for determining total nitrogen in southern alluvial forest soils.     

Threshold levels of cadmium for soil respiration and growth of spring wheat (Triticum aestivum L.), and difficulties with their determination

Summary Inconsistent results were obtained from comparative studies on the impact of increasing Cd contamination in three soils on growth of spring-wheat plantlets and soil respiration. With identical soil Cd loads, plant growth was increasingly inhibited in the following sequence: Neutral sandy hortisol (pH 7.0) < phaeosem (pH 6.9) < acidic cambisol (pH 5.6), suggesting a strong dependence on pH. In contrast, oxidation of a glucose-glutamate mixture by these soils was increasingly inhibited in the sequence: Acidic cambisol < neutral sandy hortisol < phaeosem. Inhibition of plant growth was correlated with the extractability of Cd from soils by 0.1 M CaCl₂. However, comparison of dose-response curves with dose-extractability and dose-uptake curves suggested the presence of a soil factor that modified plant uptake of available Cd. This factor, possibly the concentration of antagonistic cations, was apparently also active within the plants. The inconsistency in the responses of plant growth and of soil respiration with respect to the soil Cd load was ascribed to microbiological soil properties exceeding the importance of Cd availability. Relatively high in vitro sensitivity of prokaryotes and their biochemical interdependence together with relatively high diversities of streptomycetes and fungi were paralleled by a relatively strong inhibition of soil respiration.     

Use of ferrous hydroxide for determination of nitrate in soil extracts

Abstract

A simple steam distillation method of determining nitrate is described that is not subject to interference by substantial amounts of phosphate or silicate. It involves use of FeSO₄ and MgO for reduction of nitrate to ammonia. The method is rapid and precise, and tests reported show that it is satisfactory for nitrate analysis of soil extracts.