Effect of Sulfate on Adsorption of Zinc and Cadmium by Variable Charge Soils *1

SO 4 2- and Zn 2+ or Cd 2+ were added to three variable charge soils in different sequences. In one sequence sulfate was added first, and in the other, Zn 2+ or Cd 2+ first. The addition of sulfate to the system invariably caused an increase in adsorption of the heavy metal added, with the effect more remarkable when the soil reacted with the sulfate prior to the metal. The shift in pH 50 for both Zn and Cd adsorption was also comparatively larger in the first sequence of reactions. It was suggested that the increase in negative charge density and the resultant negative potential of the soil were the primary cause of the pronounced effect of sulfate on adsorption of Zn or Cd, and the formation of the ternary surface complex S SO 4 M might also play a role in the effect.

Sufficiency and Deficiency Indices of Soil Available Zinc for Rice in the Alluvial Soil of the Coastal Yellow Sea

To determine the sufficiency and deficiency indices of soil available Zn by the Agro Services International （ASI） method （ASI-Zn） for Zn fertilizer recommendation in rice production in the alluvial soil of the coastal Yellow Sea, the relationship between relative rice yield and soil available ASI-Zn concentration was analyzed from a ten-field experiment with various soil test classes ranging from low to high fertility in 2005 and 2006, and nine Zn fertilizer application rates （0, 7.5 15, 22.5, 30, 37.5, 45, 52.5 and 60 kg Zn/ha） arranged at random with three replications in each field. There was a significant quadratic relationship between soil available ASI-Zn and rice yield, and a significant linear relationship between soil available ASI-Zn concentration and Zn fertilization rate. For rice variety Wuyujing 3, soil available ASI-Zn was deficient when the value was at lower than 1 mg Zn/L, low at 1 to 2 mg Zn/L, sufficient at 1 to 2 mg Zn/L, excessive at higher than 7.5 mg Zn/L. Thus, Zn fertilizer recommendation could be done according to the sufficiency and deficiency indices of soil ASI-Zn. For most of alluvial soils of the coastal Yellow Sea in the study, the available ASI-Zn was lower than 1 mg Zn/L, and then the optimum application rate of Zn fertilizer was about 20 kg Zn/ha.

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine, Middle Benue Trough, Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (<10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leaves>cassava tubers>peelings. In the same plant species, metal levels decreased in the order of Zn>Fe>Mn>Cu>Pb>Cr>Cd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.

Pig Compost Use on Zinc and Copper Concentrations in Soils and Corn Plants

The use of pig compost (PC) in agricultural land has increased in Chile in the last years. This organic amendment is a valuable nutritional source for crops, but its applying must be done in a controlled manner since it exhibited high copper (Cu) and zinc (Zn) concentrations. A short-term field experiment was conducted out to study the effects of increasing PC rates on the production and quality corn crop in two soils located at south central Chile. Five treatments were evaluated: control without fertilization (C), conventional fertilization (CF) (350 kg N ha-1), and three increasing PC rates (15.33, 30.65, and 61.31 Mg&middotha-1, corresponding to 350, 700, and 1400 kg N ha-1, respectively) in a split plot design with four replicates. The overall results indicated that dry matter production, grain yield, and plant Zn and Cu concentrations were similar among fertilization sources and rates. Extractable soil Zn concentration exhibited a rate-related increase of PC in both locations, while Cu concentration exhibited this behavior only at the soil located in Chillan. Nevertheless, the values obtained were below of those considered phytotoxic levels. Therefore, the contribution of Zn and Cu through PC applying at different rates to the soils studied showed a slight affect in soil extractable Zn and Cu values without negatively effects on quantity and quality corn crop. The organic amendment applied can be a good and cheaper substitute to conventional fertilization, although further monitoring of Zn and Cu soil levels should be carried out to avoid any environmental risk.

Zinc Soil Deficiency Affected Human Health

Calcareous formations and low soil organic carbon induced low Zn concentration and high phytic acid to zinc ratio in consumed plants and human nutrition materials.Zinc is essential in minor amounts for human body,but have major role in vital activities. Zinc role is as structures membranes maintenance and nervous systems construction.Zinc deficiency has

Release behavior of copper and zinc from sandy soils

The concentrations and chemical forms of copper(Cu) and zinc(Zn) in surface soils directly influence the movement of Cu and Zn. In this study, thirteen sandy soil samples with a wide range of total Cu and Zn concentrations were collected for evaluating the relationships between Cu and Zn release and extraction time, ratio of soil to water, pH and electrolyte types. The results indicated that Cu released in batch extraction that represents long-term leaching was mainly from exchangeable, and carbonate bound Cu fractions, and Zn released in the batch extraction was mainly from its carbonate bound fraction. However, the Cu and Zn leached from the soils using the column leaching that represents short-term leaching were mainly from their exchangeable fractions. Soil column leaching at different pH values indicated that the amounts of leached Zn and Cu were greatly affected by pH. The Cu and Zn release experiments with varying extraction times and ratio of soil to water suggest that long-term water-logging in the soils after rain may increase contact time of the soils with water and the release of Cu and Zn to water from the soils, and total amounts of Cu or Zn released from the soils increase, but the Cu or Zn concentration in the surface runoff decrease with increasing rainfall intensity. The increased Ca concentration in soil solution increased stability of organic matter-mineral complexes and might decrease the dissolution of organic matter, and thus decreased the release of Cu-binding component of organic matter. However, high concentration of Na in the soil solution increased the dispersion of the organic matter-mineral complexes and increased dissolution of organic matter and the release of Cu from the soils.

Corrosion behaviors of arc spraying single and double layer coatings in simulated Dagang soil solution

Three kinds of single layer coatings of Zn,Zn15Al,316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to protect the metal ends of prestressed high-strength concrete(PHC)pipe piles against soil corrosion.The corrosion behaviors of the coated Q235 steel samples in the simulated Dagang soil solution were investigated by potentiodynamic polarization,electrochemical impedance spectroscopy(EIS) and natural immersion tests.The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn,Zn15Al, Zn+316L and Zn15Al+316L coatings.The corrosion rate value of Zn15Al coated samples is negative.The corrosion products on Zn and Zn15Al coated samples are compact and firm.The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time,and the latter are more outstanding than the former.But the corrosion resistance of 316L coated samples is decreased quickly with the increase in immersion time.When the coatings are sealed with epoxy resin,the corrosion resistance of the coatings will be enhanced significantly.

Effects of Different Nitrogen Fertilizer Levels and Native Soil Properties on Rice Grain Fe, Zn and Protein Contents

Deposition of protein and metal ions （Fe, Zn） in rice grains is a complex polygenic trait showing considerable environmental effect. To analyze the effect of nitrogen application levels and native soil properties on rice grain protein, iron （Fe） and zinc （Zn） contents, 32 rice genotypes were grown at three different locations each under 80 and 120 kg/hm2 nitrogen fertilizer applications. In treatments with nitrogen fertilizer application, the brown rice grain protein content （GPC） increased significantly （1.1% to 7.0%） under higher nitrogen fertilizer application （120 kg/hm2） whereas grain Fe/Zn contents showed non-significant effect of nitrogen application level, thus suggesting that the rate of uptake and translocation of macro-elements does not influence the uptake and translocation of micro-elements. The pH, organic matter content and inherent Fe/Zn levels of native soil showed significant effects on grain Fe and Zn contents of all the rice genotypes. Grain Zn content of almost all the tested rice genotypes was found to increase at Location III having loamy soil texture, neutral pH value （pH 6.83） and higher organic matter content than the other two locations （Locations I and II）, indicating significant influence of native soil properties on brown rice grain Zn content while grain Fe content showed significant genotype × environment interaction effect. Genotypic difference was found to be the most significant factor to affect grain Fe/Zn contents in all the tested rice genotypes, indicating that although native soil properties influence phyto-availability of micronutrients and consequently influencing absorption, translocation and grain deposition of Fe/Zn ions, yet genetic makeup of a plant determines its response to varied soil conditions and other external factors. Two indica rice genotypes R-RF-31 （27.62 μg/g grain Zn content and 7.80% GPC） and R1033-968-2-1 （30.05 μg/g grain Zn content and 8.47% GPC） were identified as high grain Zn and moderate GPC rice genotypes. These results indicate that soil property and organic matter content increase the availability of Fe and Zn in rhizosphere, which in turn enhances the uptake, translocation and redistribution of Fe/Zn into rice grains.

An Integrated Geochemical and Mineralogical Approach for the Evaluation of Zn Distribution in Long-Term Sludge-Amended Soil

This research work was designed to compare the Zn distribution in a long-term sludge-amended soil with that in a control soil. Two complementary approaches were performed: 1) a geochemical approach at the metric scale of the bulk soil horizons and 2) a mineralogical approach at the micrometric scale of the primary minerals weathering microsites. The geochemical approach revealed that Zn in the control soil was inherited from the weathering parent-rock. Its concentration was always lower than in the amended soil where Zn was supplied at the surface by the spread sludges and moves downwards. The mineralogical approach showed that the clay minerals, produced by the weathering of the primary minerals (amphiboles and plagioclases), or filling the fissure network were made up of smectites (saponite and montmorillonite) at the bottom and kaolinite at the top of the two soil profiles. Each clay mineral, with its specific sorption capacity, controlled the Zn distribution within the soil: the smectites produced by the amphiboles had high sorption capacity and favored Zn retention in the upper horizons of the soil. Conversely, the kaolinites produced by the plagioclases had lower sorption capacity, did not retain Zn in the surface horizons, and allowed it to migrate to deeper horizons where it was sorbed onto the montmorillonites.

典型铅锌矿区周边土壤-稻米重金属污染特征及健康风险评价

为了掌握黔西北典型铅锌矿区周边稻田土壤重金属污染状况,分别采集98个土壤样品和稻米样品,运用单因子污染指数法、内梅罗综合污染指数法和潜在生态危害指数法对研究区稻田土壤中八种重金属(Cr、Ni、Cu、Zn、Cd、Pb、Hg、As)进行污染特征分析和风险评价,并采用健康风险评估模型对研究区稻米进行健康风险评价。结果表明:研究区稻田土壤受到重金属不同程度污染,整体处于中度污染水平(P_(N)=2.61),但Cu为重度污染(P_(Cu)=3.13);土壤生态风险总体处于中等水平(RI=279),最主要生态风险因子为Hg,其生态风险危害程度为很强(E_(Hg)=179);研究区稻米中重金属平均含量未超标,但有部分点位样品重金属含量超标;食用研究区种植的稻米不会对成人和儿童引起单一重金属健康风险,但长期食用,多种重金属复合污染会对成人和儿童健康产生负面影响(THQ_(成人)=2.41,THQ_(儿童)=2.48)。

电感耦合等离子体发射光谱法测定土壤中铜、锌含量的不确定度评定

采用电感耦合等离子体发射光谱法对土壤标准物质(GSS-38)中的铜、锌含量进行测定,并对测量结果进行不确定度评定。分析整个检测过程中产生不确定度的来源,发现检测不确定度的来源主要包括样品称量、标准溶液配制、校准工作曲线拟合、试液定容、仪器误差及实验室重复性等分量,并计算了各分量的相对标准不确定度。研究发现测量结果不确定度主要来源于测定溶液定容、标准曲线稀释配制、测量重复性等。采用置信概率为95%,包含因子k=2,电感耦合等离子体光谱法测定土壤中铜含量的测定结果为(176.9±4.8)mg/kg,锌含量的测定结果为(507.8±10.6)mg/kg。

铅锌冶炼重金属重污染土壤稳定化研究

针对部分铅锌冶炼场地遭受严重重金属污染的问题,采用基于铁的稳定化材料FeCl_(3)+CaCl_(2)+NaOH+Ca(OH)_(2),FeCl_(3)+CaCl_(2)+NaOH+Ca(OH)_(2)+Na_(2)S及FeCl_(3)+Na_(2)HPO_(4)进行修复。根据TCLP浸出法评估效果,选出最佳组合为FeCl_(3)+Na_(2)HP0_(4),该组合在3个场地中使Pd浸出浓度分别下降96%,63%,61%,显著减少重金属迁移。研究突显了合适材料的选择对有效土壤稳定化的重要性。

旱地小麦锌吸收转移与籽粒锌含量的关系

【目的】黄土高原旱地小麦籽粒锌含量较低,明确土施锌肥引起的小麦花前花后锌吸收转移和籽粒锌含量的变化,及其与土壤锌形态及有效性关系,为优化旱地小麦锌营养强化技术提供科学依据。【方法】基于2017年在黄土高原旱地石灰性土壤上开始的定位试验,于2021—2022和2022—2023年两个小麦生长季取样,研究锌肥用量对土壤有效锌及锌形态、小麦花前花后锌吸收转移及籽粒锌含量的影响。【结果】施用锌肥对小麦产量无显著影响,但两季小麦籽粒锌含量分别提高44.7%和38.2%,施锌25.6 kg/hm^(2)时,籽粒锌含量最高达33.6 mg/kg,花前锌吸收量分别提高38.8%~83.7%和13.4%~49.0%,花后锌转移量分别提高36.0%~73.9%和13.0%~39.6%;施锌对小麦花后锌吸收量的影响因年份而异。表层0—20和20—40 cm土壤有效锌含量分别提高11.6和11.3倍,最高分别达9.20和3.57 mg/kg,深层40—60、60—80和80—100 cm土壤有效锌含量分别提高4.4、1.8和1.9倍,最高分别达0.54、0.28和0.29 mg/kg。施用锌肥显著提高了土壤各形态锌含量,0—20和20—40 cm土层水溶态锌分别提高54.5%和75.0%,达0.17和0.14 mg/kg;松结有机态锌分别提高214.9%和90.8%,达5.70和3.11 mg/kg;碳酸盐结合态锌分别提高1178.0%和551.7%,达5.24和1.89 mg/kg;氧化锰结合态锌分别提高345.9%和183.9%,达15.52和9.37 mg/kg;紧结有机态锌分别提高91.5%和34.4%,达1.13和0.86 mg/kg;残渣态锌分别提高23.7%和24.3%,达56.57和56.80 mg/kg。【结论】施锌显著提高了土壤松结有机态、碳酸盐结合态和氧化锰结合态锌含量,并通过其向水溶态锌转化,维持了施锌后表层土壤有效锌提升和施入土壤的肥料锌的有效性,促进了小麦花前锌吸收,实现了花后地上部锌向籽粒的转移及籽粒锌含量提升,但干旱缺水影响了旱地小麦花后锌吸收,抑制了施锌后籽粒锌含量进一步提升。

淹水培养下紫云英对紫潮泥锌有效性及形态转化的影响

采用90d的紫云英室内培养试验,探究了石灰性水稻土紫潮泥锌(Zn)有效性及形态转化对不同紫云英添加量的响应。结果表明:添加紫云英促进了紫潮泥中难以被植物吸收利用的矿物残渣态锌(Min-Zn)和氧化锰结合态锌(OxMn-Zn)、潜在有效的碳酸盐结合态锌(Carb-Zn)向易被植物吸收利用的松结有机态锌(Wbo-Zn)和交换态锌(Ex-Zn)转化,从而提高紫潮泥Zn的生物有效性。在整个研究期间,紫潮泥Zn平均转化比率T1处理(添加1.50t/hm^(2)紫云英)最低(-116.40%),T2处理(添加2.25t/hm^(2)紫云英)最高(-19.57%)。到试验结束,添加紫云英处理均提高了紫潮泥Zn转移因子,T2处理最高(1.56%);降低了Zn分配指数,T2处理最低(96.9%);表明紫潮泥土壤Zn向有效态组分发生了转化。不同紫云英添加量处理中,紫潮泥Zn有效性和形态转化之间存在差异,2.25t/hm^(2)紫云英添加量最有利于紫潮泥Zn有效性的提高。研究结果将为以种植紫云英绿肥为手段提高紫潮泥Zn的有效性提供科学依据。

广西横州市岩溶与非岩溶区耕层土壤Zn通量特征

以广西横州市岩溶区和非岩溶区为研究区,针对耕层土壤Zn的输送途径和年输送通量密度进行对比研究.结果表明,受成土母质影响,岩溶区表层土壤Zn含量明显高于非岩溶区,岩溶区和非岩溶区土壤Zn的输入量受人类活动影响较大,主要输入途径均为大气沉降,年输入通量密度均值分别为494.15和484.99g/(hm^(2)·a);主要输出途径为农作物收割,年输出通量密度分别为490.63和580.12g/(hm^(2)·a),受铁锰结核和灌溉水影响,非岩溶区年输出通量密度略高;研究区年净输入通量整体表现为Zn累积状态.

石膏钙源微生物固化/稳定化锌污染粉土试验研究

微生物固化/稳定化重金属污染土时,反应速率过快和高浓度盐离子对细菌活性的抑制作用是阻碍单次搅拌工艺应用的关键问题。采用低溶解度的石膏(二水硫酸钙)作为钙源,以钙盐掺量和锌污染浓度为控制变量,进行微生物单次搅拌固化/稳定化锌污染粉土试验,研究固化/稳定化锌污染粉土的强度、锌离子浸出浓度和形态的变化规律。试验结果表明,锌污染浓度为500 mg/kg的污染粉土固化强度较处理前提高了77.3%,锌离子浸出浓度较处理前降低了87.3%;固化/稳定化后,锌污染粉土强度大幅提升,重金属锌迁移性明显降低;固化/稳定化锌污染粉土中有碳酸钙、碳酸锌和碱式碳酸锌生成,碳酸盐晶体聚集形成多孔簇状团聚体。研究结果表明,基于石膏钙源的单次搅拌微生物矿化处理能够有效固化/稳定化锌污染粉土,具有良好的应用潜力。

水泥固化淤泥质锌离子污染土强度特性试验研究

以人工制备的淤泥质锌离子(Zn^(2+))污染土为研究对象,采用室内试验与理论分析相结合的方法对不同锌离子浓度、水泥掺量及养护温度下的水泥固化污染土无侧限抗压强度进行分析,提出了相应固化土强度变化预测的经验模型。结果表明:Zn^(2+)污染会导致土体强度发生劣化,当Zn^(2+)浓度小于0.2%时,土体无侧限抗压强度显著下降,当Zn^(2+)浓度大于0.2%时,土体无侧限抗压强度下降不明显;采用水泥固化锌离子污染土可有效提高土体强度,固化土强度变化规律符合指数函数模型;养护温度对固化土强度变化规律单独发挥作用,锌离子浓度对两者之间的关系影响较小。

昆明市植烟土壤有效锌时空变异特性及驱动因子分析

探明昆明市植烟土壤有效锌含量时空变化规律,为优质烟区土壤锌污染阻控和耕地质量提升提供依据。2018—2020年用GPS定位采集昆明市8个县(区)烟田耕层(0~20 cm)土壤样品共3347个,分析土壤有效锌时空变化特征,并利用回归拟合及提升回归树模型探究影响土壤有效锌变化的主控驱动因素。结果表明:2020年昆明市植烟土壤有效锌平均值为2.53 mg/kg,变异系数89.55%,变异程度较高,且丰富和极丰富等级占比较大(75.83%),属于偏高和丰富水平。2020年土壤有效锌含量与2019年相比相对稳定,但其均值较2018年下降0.85 mg/kg,变异增大,处于丰富和极丰富等级分布频率降低15.01%,而适宜水平的样点比例增加8.34%。2020年8个县土壤有效锌均值变幅1.84~4.19 mg/kg,变异系数55.22%~93.37%,富民变异最大,各烟区均值高低为:寻甸>安宁>嵩明>富民>禄劝、晋宁>宜良>石林。与2019年相比,2020年富民、禄劝、嵩明、寻甸土壤有效锌含量下降0.11~0.69 mg/kg,安宁、晋宁、宜良和石林土壤有效锌含量相对稳定;2020年土壤有效锌较2018年平均降低0.23~1.65 mg/kg,其中富民、嵩明、寻甸降幅最大。2020年各县土壤有效锌属于丰富、极丰富级别合计占比较2019年和2018年分别下降0.16%~15.03%、5.88%~23.20%,以宜良降幅最高,嵩明降幅最小。利用Pearson、回归拟合和提升回归树分析,发现造成土壤Zn空间尺度上差异的主导因子是年均降雨,其次是年均温、年蒸发量、土壤类型、土壤质地,以及土壤pH、水解性氮、有机质、速效钾、有效磷含量等指标;最后是氮、钾、磷肥投入。昆明植烟土壤有效锌含量总体偏高,但近2 a呈持续逐渐下降趋势。今后应继续减氮控磷钾,控制施用含锌有机肥和化肥,降低锌素投入;调节部分烟区土壤酸度或阻控土壤酸化,改善锌形态,进而降低土壤高浓度有效锌对烤烟、土壤潜在的污染风险。

螯合锌肥对小白菜生长、品质、吸收镉铅及土壤酶活性的影响

以小白菜为供试作物,研究了不同螯合锌肥及螯合锌添加量(1%、3%和5%)对Cd和Pb复合污染土壤上小白菜的生长、品质及吸收镉铅的影响。结果表明,乙二胺四乙酸二钠螯合锌肥(EDTA-Zn)和聚天门冬氨酸螯合锌肥(PASP-Zn)均明显促进了小白菜的生长和品质(维生素C、可溶性糖和叶绿素含量均提高),而三聚磷酸钾螯合锌肥(KTPP-Zn)则抑制了小白菜的生长和品质。除PASP-Zn1、PASP-Zn3外,其余处理的小白菜硝酸盐含量均显著增加,增幅为3.23%~16.27%。大部分处理的小白菜根部和地上部中Cd和Pb含量均增加,其中EDTA-Zn5和PASP-Zn5处理显著增加了小白菜根部Pb含量,增幅分别为44.65%和35.29%。3种螯合锌肥均表现为螯合锌添加量为5%时的小白菜根和地上部的Cd和Pb含量最高,说明螯合锌肥添加量越高促进了小白菜对土壤中重金属Cd和Pb的富集。此外,总体上3种螯合锌肥均促进了土壤过氧化氢酶、蔗糖酶、脲酶和酸性磷酸酶活性,其中PASPZn和KTPP-Zn对土壤酶活性的促进作用要大于EDTA-Zn。本研究为螯合肥在重金属污染土壤上的施用提供了重要的指导意义。