土壤矿物对汞的吸持特性研究

吸附热力学与动力学试验研究结果表明 ,5种土壤矿物对Hg的吸附容量与吸附强度均表现为MnO2 >Fe2 O3 >膨润土 >高岭土 >CaCO3 。MnO2 对Hg吸附容量大且固持能力强 ,CaCO3 则与之相反。各土壤矿物结合汞的形态分布特征表明各土壤矿物结合汞在不同环境的稳定性及相应数量比例。挥发试验结果表明各土壤矿物结合汞的环境活性 (挥发活性 )大小受土壤矿物对Hg吸附容量与吸附强度制约 ,并与矿物结合汞的形态分布特征相关 ,水溶交换态和酸溶态比例越高则土壤矿物结合汞挥发活性越强 ,碱溶态和残渣态比例越高则土壤矿物结合汞挥发活性相应越弱     

外源铜和镍在土壤中的化学形态及其老化研究

采用连续提取法测定了外源铜和镍进入田间土壤后的化学形态分布,比较研究了这2种重金属在3种不同类型土壤(红壤,水稻土和潮土)中随老化时间的形态转化和分布.结果表明,外源铜以残留态(40%～60%)和EDTA可提取态(40%)为主;随老化时间,EDTA可提取态、易还原锰结合态及铁铝氧化态向残留态转化;外源镍在酸性红壤中以可交换态(40%)和残留态(30%～50%)为主,在中性水稻土中以EDTA可提取态(30%)和残留态(30%～50%)为主,在碱性潮土中以铁铝氧化态(20%)和残留态(40%)为主.随老化时间,水溶态、可交换态、EDTA可提取态等向残留态转化.土壤pH较低时水溶态和可交换态含量较高,但是同时随老化时间的降低量也明显;pH较高时有利于易还原锰结合态和有机质结合态的转化.     

吉林西部土壤砷的形态分布及其与土壤性质的关系研究

按照生态地球化学土壤样品元素形态分析方法,将土壤无机砷分成水溶态、离子交换态、碳酸盐态、腐植酸结合态、铁锰氧化物结合态、强有机结合态和残渣态。通过对吉林西部36个表层土壤样品的测试,分析了土壤不同形态砷的分布和不同形态砷与土壤性质的关系。研究表明,洮南市不同形态砷的分布为：残渣态（65．30％）〉腐植酸结合态（17．39％）〉铁锰氧化物结合态（10．70％）〉碳酸盐态（2．23％）〉水溶态（2．17％）〉强有机结合态（1．17％）〉离子交换态（1．04％）。通榆县不同形态砷的分布为：残渣态（56．66％）〉腐植酸结合态（23．82％）〉铁锰氧化物结合态（11．08％）〉碳酸盐态（2．81％）〉水溶态（2．18％）〉离子交换态（1．98％）〉强有机结合态（1．46％）。残渣态砷是吉林西部土壤砷的主要形态。土壤水溶态砷和铁锰氧化物结合态砷与土壤pH值皆呈极显著正相关;残渣态砷与土壤有机质皆呈极显著负相关,而与土壤阳离子交换量呈极显著正相关。离子交换态砷、碳酸盐态砷、铁锰氧化物结合态砷和强有机结合态砷与土壤矿质元素的关系不大,而水溶态砷、腐植酸结合态砷和残渣态砷与土壤矿质元素的关系密切。     

腐殖酸对灰棕紫泥中汞赋存形态的影响

通过室内培养探讨不同富里酸/胡敏酸(FA/HA)、腐殖酸含量、汞污染浓度对灰棕紫泥中汞赋存形态的影响。结果表明,施用腐殖酸降低汞的活性,腐殖酸各处理均能促进土壤中水溶态、交换态和酸溶态汞向碱溶态、有机结合态和残渣态汞转化。FA/HA≤0.7时,腐殖酸能够促进土壤中的活性态汞向惰性态汞转化,但当FA/HA≥1时,腐殖酸对土壤汞有一定的活化作用;含碳2%的腐殖酸对土壤汞的固定效果好于其他碳含量(0.5%,1%,1.5%碳)腐殖酸;当土壤中汞污染浓度达到3mg/kg时,腐殖酸对汞的固定效果要降低。     

粤东凤凰山茶区土壤铜、铬化学形态分布及茶叶有效性研究

采用连续化学提取法对粤东凤凰山茶区12个大型茶园共60份土壤样品中Cu和Cr的5种化学形态分布和茶叶有效性进行研究。结果发现,土壤中Cu的5种化学形态的分布规律为残渣态〉有机束缚态〉铁锰氧化态〉碳酸盐态〉交换态,而Cr的化学形态分布为残渣态〉有机束缚态〉交换态〉碳酸盐态〉铁锰氧化态。可交换态Cu和有机束缚态Cu含量与土壤有机质呈显著正相关,而土壤pH值与土壤可交换态Cu呈极显著负相关,与碳酸盐态Cu呈极显著正相关,与有机束缚态Cu和铁锰氧化态Cu呈显著正相关。可交换态Cr含量与土壤有机质呈显著正相关,而土壤pH值与土壤可交换态Cr呈极显著负相关,与碳酸盐态Cr呈极显著正相关。凤凰山茶叶Cu含量的范围在41.20～118.93mg·kg^-1之间,平均为52.92mg·kg^-1。茶叶中Cu含量与土壤可交换态Cu、有机束缚态Cu、有机质都有显著的正相关性,而与土壤pH值有显著的负相关性。茶叶Cr含量的范围在2.73～6.29mg·kg^-1之间,平均为4.13mg·kg^-1。茶叶Cr含量与土壤有机质和pH值分布呈显著正相关和显著负相关。     

广东韶关主要矿区周边农田土壤铅、镉的形态分布及生物有效性研究

采用改进BCR法和DTPA提取法研究了韶关主要矿区周边农田土壤Pb、Cd的形态分布和生物有效性。结果表明,参照土壤环境质量标准二级标准,韶关主要矿区周边农田土壤Pb、Cd的超标率分别为14.1%和92.3%;参照食品中污染物限量标准,调查的5种蔬菜样品Pb、Cd的超标率分别为57.7%和48.7%。土壤Pb以可还原态为主,占到4种形态和的76.13%,Pb各形态的分布顺序为：可还原态〉残渣态〉可氧化态〉酸提取态;土壤Cd以酸提取态和可还原态为主,占到4种形态和近89%,Cd各形态的分布顺序为：酸提取态〉可还原态〉可氧化态〉残渣态。用DTPA提取得到的土壤Pb、Cd有效态均值分别为24.91、1.29 mg·kg-1。相关性分析表明,除了胡萝卜Cd,5种蔬菜Pb、Cd含量与土壤酸提取态、可还原态、可氧化态及土壤有效态含量显著相关,与土壤pH和有机质相关性不大。逐步回归分析表明,只有土壤残渣态含量对蔬菜Pb、Cd含量影响不显著。     

外源铬在土壤中的形态转化

本试验用逐级提取方法，研究了外源铬进入土壤后的形态转化，结果表明：添加到土壤中的Ｃｒ（Ⅵ）很快还原为Ｃｒ（Ⅲ）而失去其活动性，水溶态和变换态铬含量在培育６周后已恢复到对照水平，添加的Ｃｒ（Ⅲ）很快被土壤吸附和沉淀而固定，难以被Ｈ２Ｏ和ＮＨ４Ａｃ提取。添加的有机结合态铬能显土壤中水溶态和交换态铬含量，并能在较长时间内稳定存在于土壤中，添加污泥形式的铬进入土壤主要以残渣态、沉淀态和有机紧结合态铬为主     

干湿交替过程中石灰性土壤无机磷的转化及有效性

盆栽试验和培养试验结果表明：淹水能显著提高石灰性土壤磷含量，其作用顺序为，两合土〉淤土；淹水促使土壤无机磷组分中Ｃａ２－Ｐ、Ｃａ８－Ｐ含量增加，说明石灰性土壤淹水后土壤磷有效性的提高主要是Ｃａ－Ｐ体系的活性提高所致。回旱后，土壤速效磷值明显降低，土壤无机磷组分中，Ｃａ２－Ｐ、Ａｌ－Ｐ、Ｆｅ－Ｐ组分均呈降低趋势，土壤无机磷向难溶态转化。淹水降低了外加磷肥的肥效。     

污灌土壤中Pb,Cd形态的研究

运用顺序提取法研究了一些污灌区土壤中Ｐｂ，Ｃｄ的化学形态分布及影响因素。石灰性污灌土壤０－２０ｃｍ土层中，Ｐｂ，Ｃｄ主要以碳酸盐结合态和硫化物残渣态存在，其次是有机结合态，交换态和吸附态较少。０－２０ｃｍ土层中，Ｐｂ的吸附态＞交换态，而Ｃｄ则相反。影响Ｐｂ，Ｃｄ形态分布的主要因素有ＰＨ，有机质含量，腐殖酸组成和碳酸钙会含量等。西安污灌区土壤中的Ｃｄ明显增加，且主要为有机结合态，碳酸盐结合态则相对减     

贵州省万山汞矿区周围土壤中不同形态汞的空间分布特征

利用连续提取法对贵州省万山汞矿区周边土壤的形态与分布特征进行了测试分析。结果表明,研究区土壤中汞含量在1.34～291.71mg·kg-1之间,明显高于我国土壤汞背景值。表层土壤中汞含量在东部区域普遍较高,西部区域相对较低,并呈现随距污染源距离的增加逐渐降低的趋势。剖面土壤中的汞则表现出明显的表层富集规律。研究区土壤中汞的形态主要以残渣态、难氧化降解有机质及某些硫化物结合态和易氧化降解有机质结合态汞为主,且不同形态的汞含量与总汞含量具有较大的相关性。     

Preventing Hg Transference from Soil to Terrestrial Food Chain

Hg in acid soil could be activited by liming and become available to plant,if excessive or insufficient amount of line was applied.The changes of Hg activity in acid soil with different rates of CaCO3 amendment were studied by a pot experiment.To predict the adequate amount of lime application,a simple method using the pH(EDTA) as an indicator was suggested.The suitable range of lime application was the amount of lime addition when the pH of soil-EDTA system was raised to 4.0-4.3.     

Soil pH influence on cadmium uptake by tobacco in high cadmium exposure

Cadmium (Cd) is a non‐essential toxic element, which is highly accumulated by tobacco leaves and is transferred to tobacco smoke thus contributing substantially to the permitted level of Cd intake by humans. Therefore, measures to reduce Cd accumulation by tobacco are of significant importance. The purpose of the present study was to investigate the influence of soil liming on Cd uptake by tobacco plants in high Cd exposure. A pot experiment was conducted with Nicotiana tabacum L. Samsun 53 on an acid Typic Haploxeralf amended with refuse sugarbeet lime to obtain a pH range from 5.3 to 7.0 and contaminated with 20 mg kg^‐1 Cd applied as CdCl₂. Tobacco was grown in pots for three months under natural conditions, harvested in four cuts and Cd uptake by leaves was estimated. In soil samples selected, pH, Cd extracted by DTPA method, and Cd fractions such as exchangeable, organically bound, carbonate and residual were determined. The results showed that Cd uptake influenced negatively tobacco yield. Soil liming decreased Cd uptake by tobacco plants. The DTPA method was not a good indicator for Cd availability in tobacco. A very strong relationship was recorded between exchangeable Cd and total Cd uptake showing that this Cd fraction is available to tobacco plants. Soil pH was correlated strongly in a negative way with this Cd fraction suggesting that this soil factor is very important in controlling Cd accumulation by tobacco.     

MODELLING LEACHING OF INORGANIC Hg(II) IN A SCANDINAVIAN IRON-HUMUS PODZOL - VALIDATION AND LONG-TERM LEACHING UNDER VARIOUS DEPOSITION RATES

Increasing mercury contents are reported from freshwater systems and fish in northern Europe and North America. Mercury input from soils is a major source with the leaching being affected by increased atmospheric mercury deposition compared to pre-industrial times and by other environmental conditions such as acid rain. The results of a mathematical model-calculation of vertical inorganic Hg(II) leaching in a Scandinavian iron-humus podzol under different atmospheric input rates of mercury are presented. Leaching under background rain conditions was calculated to be considerably stronger than under acid rain conditions. Increasing fractions of deposited soluble or solute atmospheric mercury were leached from the O _f(h)-horizon with decreasing soil content of soluble mercury under acid rain conditions; this effect was less pronounced under background rain conditions. The steady state concentrations of soluble mercury of the upper soil horizons were calculated and compared with the actual concentrations of total (= soluble + insoluble mercury) and extractable (= estimate of soluble) mercury measured in these horizons. The results indicate that even if the deposition of airborne mercury to soil is strongly reduced, the total mercury content of the soil decreases only slowly. It may take decades or even centuries before a new steady state concentration of total mercury is established in the soil. The decrease of the mercury concentration in the O _f(h)-horizon is probably largely dependent on the turnover of organic matter, binding most of the deposited airborne mercury in an insoluble form. Hence, present day mercury leaching is likely to be dominated by mercury deposited during former times and temporarily retained in an insoluble form in the organic matter.     

Effects of liming and phosphorus on three soils from the wet coast of North Queensland

Abstract

A pot experiment using Urochloa mozambicensis as the test plant showed that the P requirements of three acid soils from the wet coast of North Queensland are in accord with their P sorption characteristics; P requirements of two soils with dark, humic A horizons were very high. Responses to liming (dolomite) were also found on two soils.

Effects of liming on P sorption, P concentration in solution, and plant response to P were small and thus liming does not offer a means of reducing P needs on these soils.

Analyses of the plant dry matter, the soil and soil solution recovered from the cropped soils indicate that aluminium and manganese toxicities were not important for the growth of the test plant on these soils, but magnesium deficiency was a contributing factor to the response to dolomite on one soil.     

生物质炭施用对杉木幼苗土壤磷组分的影响

通过盆栽试验，采用Hedley连续浸提法研究不同生物质炭施用量处理（CK：0 t/hm²；B₁₂：12 t/hm²；B₃₆：36 t/hm²）对杉木幼苗土壤磷组分的影响。结果表明：与CK相比，试验180 d后B₁₂和B₃₆处理土壤全磷与有效磷含量分别增加了8.7%~26.0%和24.0%~101.7%，有效磷在全磷中的比例显著提高；土壤磷组分中，残余态磷在全磷及无机磷组分中的比例均最高，分别为48.5%~51.1%和58.7%~68.3%。B₃₆处理下，土壤各无机磷组分均显著增加，其中易分解态磷和中等易分解态磷在无机磷中的比例显著提高，而稳定态磷和残余态磷的比例显著降低。中等易分解态磷占总有机磷的比例最高，达69.3%~70.2%，生物质炭施用对各有机磷组分在总有机磷中的比例影响均不显著，仅在B₃₆处理下，土壤有机磷中易分解态磷和中等易分解态磷含量显著降低。冗余分析表明，土壤全碳与各无机磷组分呈显著正相关关系，与有机磷组分呈显著负相关关系，是影响土壤磷组分变化的关键因子。     

Effects of artificial acidification and liming on the activity of digestive enzymes in Cognettia sphagnetorum (Vejdovsky´, 1878) (Annelida, Enchytraeidae)

The effects of simulated acid rain and acidification, combined with liming, on amylolytic, laminarinolytic and xylanolytic activity in whole body homogenates of enchytraeids Cognettia sphagnetorum were studied under field conditions. Simulated acid rain (pH 2.5) and simulated acid rain with subsequent liming (CaCO₃) were applied to experimental plots in a mixed forest soil. The pH of the soil was lowered by acid treatment (4.3), while the pH increased after liming (6.3) in comparison with the control (4.5). Acidification of soil caused a decrease in enchytraeid body mass and amylolytic activity. In acidified plots after liming, amylolytic activity and laminarinolytic activity increased, while live body mass decreased. The enzymatic activity of enchytraeids depended on season and also indirectly on individual mean mass. Received: 12 February 1996     

Effect of liming and phosphate application on sudangrass growth and phosphorus availability in two temperate acid soils

Abstract

A pot experiment was carried out in the greenhouse with two loamy sand Dystric Cambisols derived from schist to investigate the effect of liming and phosphorus (P) application on plant growth and P availability and its assessment by four soil test methods: 0.01M calcium chloride (CaCl₂), cation anion exchange membrane (CAEM), Egnér‐Riehm, and Olsen procedures. Soils were first incubated for two weeks with lime at four levels, depending on their content of exchangeable aluminum (Al). Phosphorus was added at two rates (75 and 150 mg P kg^‐1) and the incubation proceeded for an additional two‐week period. Sudangrass (Sorghum sudanenses cv. Tama) was then planted and harvested four weeks later. During incubation and plant growth, soils were maintained at 70% of field moisture capacity. Although pH value and soil extractable P in original soils were similar, the results showed a significant difference on the effect of liming and P application. Acidity was the major limitation for DM yield in the soil with the highest amount of exchangeable Al, while P availability was the main constraint in the other soil. Liming above pH (0.01M CaCl₂) 5.3–5.5 did not increase DM yield in either soil and showed a negative effect on one soil (9.7 to 6.9 and 10.2 to 7.8 g pot^‐1). Phosphorus content and uptake by sudangrass increased with liming, revealing a positive effect of lime on the availability of P to plants. Added P showed a lower efficiency in the soil with highest amounts of Al compounds. Soil tests performed after the execution of the pot experiment showed variable tendencies to predict P availability, according to the nature of the procedures and soils. Soluble‐P in 0.01M CaCl₂ increased with the rise of soil pH. Extractable CAEM‐P and Egnér‐Riehm‐P also increased with liming, but reflected the soil depletion caused by plant uptake. Extractable Olsen‐P presented the most inconclusive results, suggesting the limitation of this method for acid soils which have been limed.     

Effect of corncob compost on plant growth in an acid red soil

Abstract

A comparison of corncob compost with lime on plant growth was studied in acid red soil with pH of 4.07. Lettuce, pea, and corn were selected as test plants for their varying tolerance to acid soil. The pot experiment compared six soil treatments and a check. Soil amendments were 1, 2, and 4 cmol calcium carbonate (CaCO₃) kg^‐1 and 5, 10, and 20 g corncob compost kg^‐1 soil. Results showed higher manganese (Mn) than aluminum (Al) content of the shoot in all check group plants. Reduced shoot Mn content increased shoot dry weight in all test plants, regardless of acid soil tolerance or soil treatment. The higher the test plant resistance to soil acidity, the weaker the detoxification effect of corncob compost was on Al uptake when compared with the check group. Liming was more effective at reducing shoot Mn content than corncob compost with the exception of the more acidity sensitive lettuce. Shoot phosphorus (P) content, however, increased with corncob compost from enhanced organic matter rates. Corncob compost treatments significantly increased shoot dry weight over liming in the acid soil. This study demonstrated an environmentally acceptable use for an agricultural waste.     

Effect of Five Phosphate Rocks on Red Clover (Trifolium pratense L.) Yield in Pot Trial

Abstract

Phosphorus (P) availability in five phosphate rocks with different P solubility was compared with that in single superphosphate and superphosphate+lime in a pot experiment with red clover as test plant on a Lamellic Arenosol with sand soil texture and on a Haplic Luvisol with clay loam soil texture, both strongly acid with low P supply. Phosphorus rates in the pot experiment were 0, 100, 400, and 1600 mg total P₂O₅ kg^?1. On both soils, there was a weak correlation between total added P and red clover P responses. If P solubility of the PRs was also taken into account, the correlation between formic acid–, citric acid–, or neutral ammonium citrate–soluble P amounts added and red clover responses became much stronger. Soil P availability was estimated by water, Olsen, Lakanen‐Erviö, and ammonium lactate tests. Among the P extractants studied, Olsen soil P test gave the best correlation with red clover yields.     

Examination of nanoparticulate phosphate rock as both a liming agent and phosphorus source to enhance the growth of spinach in acid soil

ABSTRACT

To examine the effect of nanoparticulate phosphate rock (NPR) as both a liming agent and phosphorus source in a tropical acid soil. The study examined five rates of NPR (0, 250, 500, 1000, or 2000 kg ha^?1), which supplies 30, 60, 120 or 240 kg P ha^?1, in a randomized complete pot experiment design with 3 replications. The pots of soil were incubated in a climate-controlled greenhouse for 21 days and then spinach was grown for 49 days. Soil parameters (pH, available P and exchangeable acidity), spinach parameters (leaf area, root hair surface area, root length and dry matter yield) and the effectiveness of NPR dissolution were estimated. The soil and plant parameters and the effective NPR dissolution all increased to the same degree at 1000 and 2000 kg NPR ha^?1. Therefore, the use of 1000 kg ha^?1 was most economically justified. Although, NPR has been appeared as an effective liming agent and phosphorus source in tropical acid soil. However, a regular application of NPR and further research for economic comparison between NPR and both of lime and superphosphate, as well as the original PR, will be needed.