Geochemical Fractionation and Adsorption Characteristics of Zinc in Thai Major Calcareous Soils

Zinc (Zn) is a vital plant nutrient that is widely deficient in Thai cultivated calcareous soils. The chemical fractionation and adsorption of Zn are among the most important solid- and liquid-phase interactions that determine the retention of Zn in the soils. This study aimed to investigate the fractionation and adsorption isotherms of Zn in cultivated Thai calcareous soils. The results of sequential extractions showed that Zn is mainly distributed in residual fractions followed by organic-bound, iron and manganese oxides-bound, carbonate-bound, and exchangeable Zn, respectively. Zinc adsorption was well fitted by the Langmuir and Freundlich isotherms. Thai calcareous soils had high Zn adsorption capacity. Soil pH, organic carbon, calcium carbonate, cation exchange capacity, and extractable calcium were the major soil properties that affected the Zn adsorption isotherms in these soils. Zinc hydroxide was the solid precipitate and the Zn hydroxide ion (ZnOH⁺) was the dominant Zn ion in alkaline equilibrium solution.     

岚皋县岩石、土壤和农产品中硒分布规律研究

[目的]探讨岚皋县岩石、土壤和农产品硒含量分布特征及其相互关系,揭示岚皋县岩石、土壤和农产品硒的分布规律.[方法]采集岚皋县岩石、土壤和农产品样本,测定样本中总硒含量.[结果]岚皋县岩石硒含量范围0.006～43.38 mg kg-1,均值4.15 mg kg-1,震旦系和寒武系地层岩石硒含量显著高于其他地层;土壤硒含...     

黑龙江省土壤硒分布及其影响因素研究

黑龙江省处于全国缺硒带的始端,为研究黑龙江省土壤全硒(Se)的含量、分布及其与土壤性质的关系,在全省采集400余个农业土壤0~20 cm耕层样品及主要类型土壤剖面样品(共21个剖面各发生层次土样71个),分析了土壤全硒含量、分布规律及其影响因素。结果表明,黑龙江省土壤全硒含量变幅为0.008~0.660 mg kg~(-1),平均值为0.147 mg kg~(-1),总体上处于缺硒及潜在缺硒土壤范畴,几乎不存在高硒土壤与硒毒土壤。不同类型土壤中以盐碱土含硒量最低(0.097 mg kg~(-1)),而泥炭土最高(0.273 mg kg~(-1));硒在土壤剖面中主要呈现表聚型分布,也有少数呈现双峰型和心土聚集型分布;不同区域以大兴安岭地区为最低(0.115 mg kg~(-1)),小兴安岭山地最高(0.198 mg kg~(-1));不同行政市以大兴安岭地区最低(0.115 mg kg~(-1)),黑河市为最高(0.228 mg kg~(-1))。回归分析表明:土壤全硒含量与土壤有机碳(SOC)、黏粒含量具有极显著正相关关系,与pH呈极显著负相关。研究区表土层土壤SOC、黏粒含量与pH是影响土壤硒含量的主要因素,此外土壤母质也是影响硒分布的重要因素;而土壤SOC含量对硒在土壤剖面中的分布与富集起到了至关重要的作用。     

新乡市寺庄顶污灌区土壤中重金属的形态分布及生物有效性研究

对长期电池废水灌溉的新乡市寺庄顶污灌区和对照区土壤重金属进行取样分析,结果表明,对照区土壤中Cd,Ni,Zn,Cu和Cr含量都能达标,污灌区土壤中Cr含量能达标,Cd,Ni,Zn和Cu的含量超标,其平均含量分别为65.31,1 196.64,2 799.25,145.78 mg/kg,是国家土壤环境质量二级标准的108.85,19.94,9.33和1.46倍。形态分析结果表明,污灌区污染最严重的Cd主要以铁-锰氧化物结合态存在,所占比例平均为56.84%;Ni主要以铁-锰氧化物结合态和残余态存在,所占比例平均为37.44%和39.55%;Zn主要以残余态存在,所占比例平均为78.24%;Cu主要以有机结合态存在,所占比例平均为57.70%;Cr主要以有机结合态和残余态存在,所占比例平均为45.55%和34.18%。与对照相比,污灌降低了Cd,Ni,Zn,Cu和Cr残余态所占比例,提高了重金属迁移能力和生物有效性。在4种超标重金属中Cd可交换态所占比例最高,平均为24.54%,由于其生物有效性最高,Cd迁移能力和植物毒性最值得关注。     

安康南部大巴山区硒过剩土壤分布及来源研究

为了查明安康市南部大巴山区硒过剩土壤分布特征和来源，为安康富硒土壤安全、合理开发和规划打下基础，采集了研究区岩石、土壤样品，测定了硒含量，分析了岩石、土壤硒含量分布特征及其相互关系。结果表明：研究区土壤硒含量在0.000 07 ~ 36.69 mg/kg，均值0.84 mg/kg，变幅大，呈现两条NW—SE向高硒区，高硒土壤面积占73.09%，硒过剩土壤以斑块、斑点状分布，面积占0.91%；岩石硒含量范围0.005 ~ 68.75 mg/kg，均值5.83 mg/kg，变幅大，处于深水沉积环境下的震旦系上统灯影组和两期大规模海侵阶段的寒武系下统鲁家坪组和志留系下统斑鸠关组岩石硒含量均值明显高于其他岩组，板岩、硅质岩、白云岩、正长斑岩硒含量较高，尤其黄铁矿和石煤硒含量更高；岩石、土壤硒含量表现出强烈的正相关性。硒过剩土壤以斑块、斑点状分布于紫阳县双安镇、汉王镇、焕古镇、洞河镇、蒿坪镇、瓦庙镇、麻柳镇、毛坝镇、高滩镇、界岭镇，岚皋县佐龙镇、城关镇，镇坪县城关镇。土壤硒主要来源于岩石，震旦系上统灯影组含硒量高的碳质板岩，寒武系下统鲁家坪组含硒量高的黄铁矿、含碳板岩、碳质板岩、硅质板岩、含碳硅质岩、硅质岩和志留系下统斑鸠关组硒量高的石煤、含碳板岩、含碳硅质板岩是硒过剩土壤的主要来源。     

Selenium Distribution for Soils Derived from Mancos Shale in Gunnison and Uncompahgre River Basins,West-Central Colorado

Selenium (Se) is an essential micronutrient for humans and animals and can be toxic when present in high concentrations in soil and water. Many soils in Gunnison and Uncompahgre River Basins in West-Central Colorado are formed from deposits derived mainly from weathered Mancos shale that have high concentration of Se and salts. Elevated concentrations of Se and salts were detected in streams and rivers in this area. The objectives were to determine the amount and distribution of different forms of Se and relationships with physical and chemical properties for soils derived from Se-rich Mancos shale. The information may help to improve land management practices and minimize the environmental impact on natural water resources. A total of 48 topsoil samples and soils from horizons in 9 pedons were investigated. The total and water-soluble Se and other elements as well as physical and chemical properties were determined in soils. The total Se ranged from 330 to 5,673 µg/kg with a mean of 2,224 µg/kg. The water-soluble Se ranged from a minimum of 4.95 µg/kg to a maximum of 2,415 µg/kg and a mean of 338 µg/kg. A highly significant correlation was detected between the total and water-soluble Se in soils. Both the total organic carbon (TOC) and CaCO₃% had significant positive correlations with the total Se. A highly significant correlation was also found between the water-soluble Se and electric conductivity (EC), as well as with the water-soluble chloride, sulfate, nitrate, molybdenum, and sodium in soils. For the pedons tested, in general, both the total and water-soluble Se increased with depth. However, the water-soluble Se concentrations were greater in shallow than deep pedons where most Se was removed from soils with drainage water. It could be concluded that Se leaching from topsoils and that dissolving from Se-rich parent materials would be a major source of elevated Se concentrations in streams/rivers for the West-Central Colorado area. To minimize the impact on water quality, an appropriate land/water management practices should be followed to minimize Se leaching from soils derived from Mancos shale.     

虱螨脲在土壤中的降解、吸附和移动特性

采用室内模拟试验方法,研究了虱螨脲在3种土壤中的降解、吸附和移动特性。结果表明：25℃下,虱螨脲在江西红壤中的降解半衰期为101d,属于中等降解农药;在太湖水稻土和东北黑土中的降解半衰期分别为74.5d和55.5d,属于较易降解农药。土壤有机质含量是影响虱螨脲降解速率的主要因素;3种土壤对虱螨脲具有较强的吸附性,且土壤有机质含量越高,对虱螨脲的吸附性越强;3种土壤对虱螨脲的吸附自由能变化均小于40kJ·mol^-1,属于物理吸附;虱螨脲在土壤中不易移动,正常条件下不会造成地下水的污染。     

哒螨灵农药在土壤中的降解吸附和移动特性

采用室内模拟试验方法,研究了哒螨灵在3种土壤中的降解、吸附和移动特性。结果表明,25℃下,哒螨灵在江西红壤、河南二合土和东北黑土中的降解半衰期分别为41．0、55．9和72．2d,属于易降解农药,其降解速率依次为江西红壤〉河南二合土〉东北黑土。酸性条件有利于哒螨灵的降解,土壤pH值对哒螨灵降解的影响比土壤有机质含量大。3种土壤对哒螨灵农药的吸附均较好地符合Freundich方程,吸附系数鼠值分别为3．35×10^3,6．17×10^3和8．48×10^3,具有极强的吸附性,且土壤有机质含量越高,对哒螨灵的吸附性越强。土壤对哒螨灵的吸附自由能变化均小于40kJ·mol^-1,属于物理吸附。哒螨灵在土壤中不易移动,3种土壤薄层移动试验的Rf值均仅为0．05,正常条件下不会造成对地下水的污染。     

Distribution of Chemical Forms for Co, Cr, Ni and V in Typical Soils of China

Co,Ni,Cr and V in 25 typical soils of China were fractionated into exchangeable,carbonate bound (calcareous soils),Mn oxide bound,organically bound,amorphous Fe oxide bound,crystalline Fe oxide bound and residual forms using a seven-step sequential extraction procedure,so as to study the distribution of chemical forms of these metals as well as the effects of soil proiperties on the distribution.The results showed that most of soil Co,Ni,Cr and V were present in residual forms,and the distribution ratio averaged 48.2% for Co,53.0% for Ni,81.5% for Cr and 68.7% for V.The speciation of heavy metals was greatly influenced by soil physico-chemical properties and the chemistry of elements.The results also indicated that the recovery of metal elements by the sequential extraction procedure was satisfactory,with the relative difference between the sum of seven forms and the total content in soils averaging 9.5% for Co,12.8% for Ni,6.6% for Cr and 7.2% for V.     

贵州遵义地区硒在耕地土壤及农作物中的分布规律

利用贵州省耕地质量地球化学调查系统采集大量样品的契机,开展硒(Se)在耕地土壤及农作物有用器官中的分布规律研究.统计分析研究表明,遵义地区表层土壤绝大部分处于足Se和富Se水平,仅有极少部分属缺Se和高Se土壤;单就Se元素而言,整体属优质土壤.相关分析结果表明,土壤中Se含量与土壤有机质含量、海拔高度显著相关,受成土...     

重庆市全新统冲积物发育土壤的系统分类研究

为明确重庆市第四系全新统(Qh)冲积物发育土壤在中国土壤系统分类中的归属,本文以该成土母质发育的土壤为研究对象,挖掘9个典型土壤剖面,通过野外观测、分层取样及理化性质分析等,依据现行中国土壤系统分类检索,对其进行分类和命名,并与发生分类进行参比。结果表明:9个供试土壤剖面分别归属于雏形土和新成土2个土纲,5个亚类,其中5个为石灰淡色潮湿雏形土,1个为铁质简育常湿雏形土,1个为斑纹简育湿润雏形土,1个为潜育潮湿冲积新成土,1个为石灰潮湿冲积新成土;隶属于发生学分类潮土土类的6个供试剖面分别归为系统分类中淡色潮湿雏形土、简育常湿雏形土和简育湿润雏形土3个土类,而隶属于发生学分类新积土土类的3个供试剖面则分别归为系统分类中淡色潮湿雏形土和潮湿冲积新成土2个土类。结合成土环境分析可知,地形、气候和母质是影响重庆市第四系全新统冲积物发育土壤系统分类的重要因素。     

Fractionation of Zinc in Paddy Soils of China

The rice fields in China amount to 25.4 million hectares of which low yield paddy soils areabout 26％(Xu,1981;Xiao,1981).One of the most important causes of low yield is the defi-ciency in nutrients including zinc.Zinc deficiency usually occurs in calcareous paddy soils withpH>6.5(Zhu and Liu,1981).And the availability of zinc in calcareous paddy soils is lowerthan that in neutral and acid paddy soils.     

Effect of Biuret Content in Urea on the Growth and Nitrogen uptake of some Grain Crops in Egyptian Soils

Seven pot experiments were conducted to study the direct and the accumulative effect of urea containing (0.4, 1.0, 1.5, 2.0, 3.0 and 4.0 %) biuret on the growth of rice, wheat, and maize plants and their N content and N uptake in two fine textured alluvial soils and one sandy clay loam (highly calcareous) soil. It was found that both rice and wheat grain yields were not significantly reduced in all soils where urea containing high percentage of biuret was used namely 3 % and 4 %. Ammonium sulphate fertilizer was superior to urea in plant production only in the sandy clay loam. Moreover, the N recovery was higher in the alluvial soils in comparison to the sandy clay loam. The accumulative addition of biuret to the soils did not further reduce either the growth rate or the N uptake of the plants.     

壬基酚在土壤中的降解和吸附特性

采用室内模拟试验,研究了壬基酚（NP）在3种土壤中的降解和吸附特性。结果表明,NP在土壤中的降解分为快速和慢速降解阶段,半衰期分别为6.74～9.72d和70.02～78.77d。降解前期3种土壤中的降解速率相差较大,依次为黑龙江黑土〉北京潮土〉广西红壤,与土壤有机质含量相一致,随培养时间推移,降解速率差异减小。NP在土壤中具有不同结合状态及异构体降解性不同可能是出现慢速降解阶段的主要原因。土壤对NP的吸附较为符合Linear等温吸附方程（r≥0.9686）,黑龙江黑土、北京潮土和广西红壤中吸附常数Kd值分别为65.52、31.66和32.71,黑龙江黑土对NP的吸附最强,广西红壤和北京潮土的吸附能力较为接近。各土壤理化性质参数中,以土壤有机质含量对NP吸附的影响最大（r=0.9950）,阳离子交换量对吸附也有一定影响,粘粒含量和pH对吸附的影响较小。NP在3种土壤中的有机碳吸附常数KOC在3696.22～4334.51之间,移动性很弱,吸附自由能变化均小于40kJ·mol-1,NP在土壤中的吸附以物理吸附为主。     

土壤中硒含量、形态及有效性分析

近年来,硒(Se)对于植物以及人体的有效性逐渐得到重视,越来越多的富硒土壤被发现和利用,但目前人们对于土壤中硒的含量、形态、转化及其有效性还没有形成系统、全面和准确的认识。本文通过对国内外硒研究文献的整理和分析,认为当前对土壤中硒总量有较全面的数据,但对于硒的植物有效性与其他影响因素之间的关系认识不一,主要原因在于研究前提(土壤类型、气候等)的差异以及不同因素之间的掩盖。今后应在相对控制某一变量的前提下,采用定量模型技术,分析土壤硒有效性的真实影响因素和定量规律。在区域大气-土壤-水-植物系统的硒平衡方面,针对大气沉降、硒甲基化(挥发)、硒的淋失等途径的定量规律和影响因素,应开展大尺度范围的监测和分析。利用硒同位素技术(自然丰度和加富标记),更加准确地追踪硒在土壤、植物等子系统的转化规律,从而为提高硒的利用效率提供科学依据。     

Selenium Behavior in Open Bulk Precipitation, Soil Solution and Groundwater in Alluvial Fan Area in Tsukui, Central Japan

A monitoring study was carried out in an alluvial fan area in Tsukui, Central Japan during the study period of 1999–2003, in order to explain selenium (Se) behaviors in ecosystem combined with air, soil and groundwater. Monthly Se concentrations in open bulk precipitation (rainfall+aerosol, gaseous deposition and etc.), soil solution (collected by porous ceramic-cup) and groundwater ranged from 0.1 to 1.4 μg L^?1 (volume-weighted average: 0.34 μg L^?1), 0.21 to 1.0 μg L^?1 (0.48 μg L^?1) and 1.6 to 2.4 μg L^?1 (2.2 μg L^?1), respectively. Se concentration in open bulk precipitation was negatively correlated with the rainfall amount. Se concentration in soil solution significantly increased with DOC concentration in soil solution. Besides, despite atmospheric Se input and rainfall to the grassland study area, Se concentration in soil solution and groundwater received no significant effect from the rainfall amount, pH, Se, DOC, SO₄ ^2?, NO₃ ^? and EC in rainfall. Even though Se concentrations in groundwater were significantly correlated with soil solution volume, Se, DOC and NO₃ ^? and groundwater level, the result of multiple regression analyses (MRA) indicated that the groundwater Se was negatively influenced by groundwater level, which depended on groundwater recharge. Se was transported into the groundwater through the groundwater recharge that largely increased in this alluvial fan study area after heavy rain.     

Distribution of Aluminum Fractionation in the Acidic Rhizosphere Soils of Masson Pine (Pinus massoniana Lamb)

The modified Tessier’s sequential extraction procedure and rhizobox cultivation were employed to investigate the distribution of aluminum (Al) fractions in the acidic rhizosphere soil of Masson pine (Pinus massoniana lamb) seedlings. The results showed that the Al in soils was fractionated into five operationally defined fractions. Three sets of soil samples used in the rhizoboxes were collected from the three forest sites in the southeast of China: Sichuan, Zhejian, and Jiangsu. At the end of 100-day cultivation, the rhizosphere Al fractions for the original or bulk soils were in the order of residual > iron-manganese (Fe-Mn) oxides > organic > carbonate > exchangeable. However, in rhizosphere soil, the Al fraction follows the order of residual > organic > Fe-Mn oxides > carbonate > exchangeable. On average, the rhizosphere experienced significant increase in organically bound Al and slight decrease in exchangeable Al contents, but had decreases in contents for the other three Al fractions compared to the nonrhizosphere. The correlation analysis indicated that the Al contents accumulated in roots were significantly and positively correlated with exchangeable Al contents in the rhizosphere, and also characterized by the major portion of organically bound Al, which exhibited a bioavailable transformation of Al fractions. Results indicated that decreases in both redox potential and soil pH, as well as increase in dissolved organic carbon (DOC), were observed in the rhizosphere. Exchangeable Al and organic Al fractions were dependent mainly on soil pH (hydrogen ion concentration) and DOC, accordingly. Decreasing rhizosphere pH from 5.93 to 3.42 accelerated the secretion of organic carbon. These data are helpful for understanding the mobility and bioavailability of Al fractions in the acidic rhizosphere soils of Masson pine.     

污染水稻土中重金属的形态分布及其影响因素

通过BCR3步提取法研究了江西省贵溪铜冶炼厂污染区水稻土中重金属的形态分布。研究表明,废渣场渗滤液污染区域(渣场区)的污染较污水灌溉污染区(污灌区)严重,渣场区土壤中Cu、Pb、Cd的含量高于污灌区,而污灌区土壤Ni含量较高。在表层(0～20cm)水稻土中,Cu以可氧化态为主,Pb以可还原态和可氧化态为主,Cd以酸溶态为主,Ni以残渣态为主,不同重金属元素的有效态所占总量百分比大小顺序是Cd>Cu>Pb>Ni。土壤重金属不同形态之间也呈现一定的相关性,说明Cu与Pb、Cd、Ni之间具有同源性。土壤pH主要影响了污灌区中Cu的形态分布,以及渣场区土壤酸溶态Ni的分布。土壤有机质含量对各重金属形态分布的影响不明显。     

Adsorption,Desorption And Mobility of Fomesafen in Chinese Soils

Fomesafen, 5-[2-chloro-4-(trifluoromethyl)phenoxy]-N-(methylsulfonyl)-2-nitrobenzamide, is used widely for weed control in soybeans since its introduction to China. Little information is available on its adsorption, desorption and movement in Chinese soils. The adsorption, desorption and mobility of fomesafen in six Chinese soils was studied. Adsorption isotherms agreed with the Freundlich equation very well. The results of regressionanalysis indicated that soil pH was more important than organic matter for fomesafen adsorption. Fomesafen was more readily desorbed from soils with 0.01 M CaSO₄ solution. Soil TLC and column leaching studies showed that fomesafen and its metabolites was less mobile in Chinese soils. About 89.82% of applied fomesafen and its metabolites still remained in upper 5 cm layer 60 days after treatment under field conditions.