Soil Zinc contamination from corrosion of galvanized structures

The present work relates to galvanized structures with several years of time life subjected to atmospheric corrosion, like galvanized high tension steel pylons. The mass and fate of zinc released is evaluated both via empirical and experimental procedures. The corrosion rate determination requested atmospheric condition characterization, especially for SO 2 concentration and experimental activities focused on soil sampling around pylons. The soil zinc content, total and exchangeable, is determinates by different analytical procedures. The zinc diffusion in environment and the zinc extension under the top soil is evaluated using 1-dimensional mathematical model for miscible species in porous soil.     

An atmospheric—terrestrial heavy metal transport model. I. model theory

A general model TOHM was developed to predict the terrestrial fate of zinc, cadmium, chromium, lead and mercury emitted by the operation of a coal-fired electric generating facility. The general model consisted of interfacing submodels describing atmospheric dispersion, precipitation, soil chemistry, and soil erosion. The models were developed from input data from a semi-arid region of the southwest United States, and except for the climatic and topographic constraints, are not site specific. TOHM was found to predict no substantial increase in indigenous levels of zinc, chromium and lead in the impact (deposition) area. However, both mercury and cadmium were predicted to be emitted and eroded to the environmental sink (receiving lake) in concentrations exceeding that naturally present in the system. TOHM is currently unvalidated, though comparison of soil erosion predictions with erosion quantities measured in the impact area gives good agreement.     

An atmospheric—terrestrial heavy metal transport model. II. Process equations

The process equations used by Wagenet et al. (1978) to describe the atmospheric— terrestrial transport of heavy metals are presented in detail. The accounting procedures allowing calculation of sediment eroded, heavy metal distribution, soil chemical reactions and precipitation are explained. The process equations for the atmospheric dispersion model of Wagenet et al. (1978) are not included.     

Human bioaccessibility of Cr, Cu, Ni, Pb and Zn in urban soils from the city of Torino, Italy

Several physiologically based extraction procedures have been proposed to estimate the fraction of the potentially toxic element content that would be bioaccessible in the human gastro-intestinal tract following accidental ingestion of soil. Many of these procedures are complex, they have been applied to a very limited range of soils, and most work has focussed on arsenic and lead. In the present study, a simplified, two-stage extraction, simulating the human stomach and intestine, was developed and applied to urban soil samples from ten public-access areas in the City of Torino, Italy. The human oral bioaccessibility of chromium, copper, nickel, lead and zinc was estimated. Lead and zinc bioaccessibilities were found to be higher in the stomach, but chromium was more bioaccessible in the intestine. Analyte concentrations were higher in roadside soils than in soils from parks. A higher proportion of the soil metal content was found in bioaccessible forms at roadsides than in parks. Comparison of the current findings with results of earlier work involving sequential extraction of the same soils indicated that the sequential procedure gave a relative, but not an absolute, indication of bioaccessibility. Calculations based on the bioaccessible analyte concentrations suggest that ingestion of only 2–3 g of some of the roadside soil samples from Torino could deliver the tolerable daily oral intake of chromium, nickel and lead to a 20-kg child. The developed procedure is useful for preliminary screening of soils and prediction of whether their bioaccessible metal contents are likely to pose a risk to human health.     

Influence of temperature on the heavy metals accumulation of five vegetable species in semiarid area of northwest China

The aim of the present study was to investigate the possible effects of temperature on cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) accumulation in five vegetable species collected at different sites (Shuichuan, Beiwan, Dongwan and Wufe) in northwest China. The meteorological data of air and soil temperatures were recorded daily during the period from sowing to harvest for the five vegetables. The air and soil temperatures affected the capacity of pumpkin, cabbage, brassica napus and Chinese cabbage to accumulate Zn, Cd, Cu and Pb. Principal component analysis showed that temperature, photosynthetic and physiological factors all contributed to the soil–plant transfer properties of DTPA-extractable heavy metals. Temperature played a more important role in Cd, Pb, Cu and Zn accumulation in four vegetables in this semiarid area. However, the enormous surface area of spinach was likely to elevate heavy metal loads owing to atmospheric deposits. For most vegetables studied, there was a striking dissimilarity in the uptake and translocation ability of Cd, Zn and Cu in soil, but similar accumulation to translocation for Pb in soil.     

石灰性土壤环境中缺锌机理的探讨

作者认为石灰性土壤中锌活性较低的原因,是由于碳酸盐导致土壤pH上升,在较高pH条件下氧化铁对锌的强烈固定,造成了大量专性吸附状态的氧化铁结合态锌及部份碳酸盐结合态锌,使交换态的有效锌含量很低,同时还证明:自然的石灰性土壤中,松结有机态锌与碳酸盐结合态是活性锌的直接给源,外源加入的锌仅为松结右机态锌。此外,石灰性土壤中各主要土壤的化学组份对外源锌的固定量高伛顺序为:氧化铁>有机质>粘土矿物>碳酸盐>氧化锰:对土壤中原有锌的固定作用大小依次为:粘土矿物>氧化铁>有机质>氧化锰>碳酸盐。     

海南岛土壤中的锌

土壤中锌的含量异常会阻碍植物生长．海南岛地处热带地区，上壤中锌的含量为1.85～107.89mg／kg，平均31.46mg／kg；0.1mol／L盐酸提取有效锌含量0.50～9.80mg／kg，平均3.86mg／kg．玄武岩上的土壤含锌量为87.35～107.89mg／kg，滨海砂上含锌量大多不足20mg／kg，其它土类的锌含量大多在15～50mg／kg．除了个别土壤锌含量偏低外，绝大多数土壤锌含量是正常的．土壤锌含量的地理分布是：东北部地区明显高，其次是西南部，再次为西北部、中部和东南部地区，岛四周的滨海砂土地区最低．海南岛的土壤锌含量与母质种类的关系最为密切，玄武岩母质上的比花岗岩的高得多．气候条件也是影响锌含量的重要因素之一，湿润地区锌有向下淋溶的趋势．干热地区锌有上移的倾向．质地粘重的土壤含锌量往往较高．土壤有机质对锌含量的影响不明显．     

碳酸盐岩山地土壤施用有机肥的溶蚀作用探讨

选择碳酸盐岩山地常见耕植、未耕植土层,通过概化制作为系列模拟柱试验土层,按当地正常施肥方法,向土层定量施入有机肥并浇灌及控制其它相关条件变化,再定期观测预埋土层不同深度碳酸岩石片的溶蚀量和土层其它指标的变化,作了施用有机肥的土中碳酸岩石溶蚀变化研究。结果揭示,在未耕植红黏土表层施用有机肥,大大减弱了土中碳酸岩石的溶蚀作用,且减弱程度随土深加大而降低。但对其下伏碱性岩粉层而言,施肥又引起了溶蚀量的微小增加变化;另在耕植土表层施用有机肥,对其土中碳酸岩石的溶蚀作用改变不大,且无论施肥与否溶蚀作用随土深加大又略显增大变化。而其下部红黏土中碳酸岩石的溶蚀量要远大于耕植土中的溶蚀量,并受施肥的影响较小。表明,农业施肥对未耕植土土中包被、包裹的碳酸岩石溶蚀影响较大,对下伏碱性岩粉层的层中、层下碳酸岩石的溶蚀影响较小。同时,施肥对耕植土土中、土下碳酸岩石的溶蚀影响不大。人类可采取禁令开垦较薄土层措施,来有效规避耕作施肥对土中碳酸岩石溶蚀作用的抑制,减少反石漠化的不利因素。此将为丰富碳酸盐岩山地成土演化理论和石漠化灾害的防治提供依据。     

干旱区绿洲灌漠土Cu、Zn和Pb的吸附解吸特征

土壤重金属吸附解吸是影响土壤系统中重金属移动性和归宿的主要过程,影响重金属的生物有效性以及重金属在食物链中的传递等.配制一系列不同浓度的重金属,灌漠土对重金属溶液进行吸附实验24 h以达到平衡,再用硝酸铵和乙酸铵进行解吸实验24 h以达到平衡.利用热力学吸附平衡法,对西北干旱区绿洲灌漠土重金属Cu、Ni和Pb的吸附解吸行为进行序批实验研究.实验结果表明:(1)灰漠土在常温下对铜、锌和铅重金属离子的吸附等温线符合Freundlich型吸附模式,灰漠土对重金属铜、锌和铅的吸附能力由强到弱的顺序为:铅,铜,锌.(2)硝酸铵和乙酸铵解吸重金属的量与灰漠土吸附重金属量呈现出线性正相关,乙酸铵解吸重金属的量比硝酸铵解吸重金属的量大,两种解吸剂对铜、锌和铅重金属离子的解吸能力由大到小的顺序都为:铜,锌,铅,说明了一般外源的铜、锌和铅进入土壤以后,铜和锌可能比铅容易向四周转移.(3)硝酸铵和乙酸铵的解吸率呈谷形曲线,开始时硝酸铵和乙酸铵解吸重金属量的百分比随灰漠土吸附重金属量的增加而减小,在吸附量达到某一特定值时,解吸率随吸附量的增加而增加.灰漠土对铜、锌和铅的吸附作用以专性吸附为主,被灰漠土吸附的铜、锌和铅重金属离子较难解吸.     

Factors influencing corrosion of metal pipes in soils

Deterioration of buried metal pipes due to corrosive soil environment is a major issue worlwide. Although failures of buried pipe due to corrosive soil is an old problem, yet such failures are still uncontrollable even with the application of advanced corrosion protection technologies. Therefore, understanding factors causing corrosion of buried pipes is necessary. This article reviews factors causing corrosion of buried pipes in soils. Factors include moisture content, soil resistivity, pH, dissolved oxygen, temperature and microbial activity. Moreover, we discuss the influence of manufacturing method and the comparison of corrosion behaviour of cast iron, ductile and mild steel pipes. We found that corrosion rate of pipes increases with moisture contents up to the critical moisture value. Although pH affects corrosion, there is no relationship between corrosion and pH and the corrosion rates of buried pipes are inversely proportional to soil resistivity. Soils containing more organic matter show high resistivity. Dissolved oxygen in soil develops differential cell which accelerates corrosion of metallic pipe. Different types of bacteria present in soil develop biofilms on metallic pipes, which deteriorates pipes with time.     

Chemistry of atmospheric dust and critical load assessment in Delhi region (India)

This is the first study in the Delhi region that assesses the critical load capacity of soil systems with respect to the atmospheric deposition and air quality, from July to October in 2012. Trend analysis of NO₂ and SO₂ in Delhi, using the Central Pollution Control Board (CPCB) data, showed interesting patterns matching with the trends in vehicular load in the city. This was followed by the calculation of the critical load of atmospheric acidity for sulphur and nitrogen in order to check the vulnerability of the soil systems in Delhi. Here, the steady state mass balance approach was majorly applied and the study conducted in the Agra region was taken as reference. The calculated values of critical loads of sulphur (225–275?eq/ha/yr) and nitrogen (298–303?eq/ha/yr), for the soil system in Delhi, were calculated with respect to three plant species, namely Anjan grass, Hibiscus and Black siris. The present loads of sulphur (PL(S)?=?26.40?eq/ha/yr) and nitrogen (PL(N)?=?36.51?eq/ha/yr) were found to be much lower than their respective critical loads. From the results, it can be concluded that the present loads of atmospheric acidic deposition in Delhi region do not pose any danger of acidification of soil system because it is countered by buffering capacity of soil generated dust. However, considering the pace at which the city is growing, it is likely that in coming decades, the present load will increase and thus the values evaluated in this study are likely to serve as an important reference for future assessment of the pollution scenario in the city.     

Effect of zinc oxide nanoparticles on the trace element contents of soils

In the last few decades, metal oxide nanoparticles have shown impact in various areas, and such an impact causes an increased release in a different environment like soil, water, or air. A limited number of studies on soils showed that the biochemical parameters were affected by the metal oxide nanoparticles. However, the influence of metal oxide nanoparticles on soil elements has not been investigated. For this aim, zinc oxide nanoparticles were applied to two different soils; also, the effect of planting on soil elements was investigated via the cultivation of various plants roots (taproots, fibrous, bulb). Soils were treated with zinc oxide nanoparticles at 0, 1.0 and 20.0?mg during 4 weeks. Then, surface soil samples were collected and digested using an acid digestion procedure. Some biochemically important elements (Ca, Zn, Mg, Fe, Al, Cu, Co, Ni) were determined using a microwave plasma atomic emission spectrometer. The effect of time and dose-dependent zinc oxide nanoparticles on the element contents of different soils was investigated during planting, and the results were statistically evaluated.     

利用农业土壤固定有机碳——缓解全球变暖与提高土壤生产力

大气CO     

Baseline zinc content of soils and plants in Poland

Topsoils from Poland were analysed for total and extractable zinc, and for a range of major elements and selected soil properties. Plant samples from the same locations were also analysed for zinc content. The geometric mean concentrations of zinc in samples were (mg/kg dry weight): soil total-Zn, 45.9; soil extractable-Zn 3.1; grass, 30.0; dandelion-tops, 45.9; dandelion-roots, 23.2; oat-leaves, 20.0; oat-grains, 29.7; lichens, 111.5. Significant relationships were found for zinc in grass and extractable-Zn in soils as well as for zinc in lichens and both total and extractable Zn in soils. Zinc in soils varied for soil kinds and regions.     

土壤锌自然消减的研究进展

从影响土壤锌自然消减的因素方面，阐述了锌自然消减的研究进展。土壤锌自然消减受温度、水分、pH值、有机质、改良剂、化学肥料、栽培植物等因素的影响。温度降低、pH升高和淹水均使土壤中锌的有效性降低。种植超积累植物如遏蓝菜、紫花苕子、印度芥菜等，可以超量吸收土壤中的锌，加速锌的消减。土壤中的某些动物和微生物有吸收利用锌的特性，蚯蚓对锌有良好的富集作用。采取农业措施如施用有机肥、化肥、加入改良剂，栽培植物等，都能降低污染土壤中锌的有效性。文章还提出了该方面今后的研究重点。     

Sensitivity of the SWAT model to the soil and land use data parametrisation: a case study in the Thyle catchment,Belgium

The sensitivity of the distributed hydrological SWAT model to the pre-processing of soil and land use data was tested for modelling rainfall-runoff processes in the Thyle catchment in Belgium. To analyse this sensitivity, 32 different soil and land use parameterisation scheme were generated and evaluated. The soil input data sources were a generalised soil association map at a scale of 1:500,000, a detailed soil map at a scale of 1:25,000 and the soil profile analytical database AARDEWERK. These soil data were combined with a detailed and a generalised land use map. The results suggest that the SWAT model is extremely sensitive to the quality of the soil and land use data and the adopted pre-processing procedures of the geographically distributed data. The resolution and fragmentation of the original map objects are significantly affected by the internal aggregation procedures of the SWAT model. The catchment size threshold value (CSTV) is thereby a key parameter controlling the internal aggregation procedure in the model. It is shown that a parabolic function characterises the relationship between the CSTV and the hydrological modelling performance of the uncalibrated model, suggesting that optimal uncalibrated modelling results are not obtained when the CSTV is minimised. The hydrological response of the SWAT model to the calculated soil properties is significant. Therefore preference should be given to the calculation of the derived hydrologic soil properties prior to averaging of the profile data. Finally some general guidelines are suggested for parameterising soil and land use in the SWAT model application.     

酸雨对长江三角洲地区四种典型土壤中锌解吸的影响

近年来酸雨危害频繁发生,特别是长江三角洲地区,酸雨致使土壤中重金属锌的吸附和解吸发生了一定的变化。选取具有代表性的长江三角洲地区4种典型土壤,通过加入外源重金属锌培育污染土样,在不同pH的酸雨下对已污染土样进行解吸。通过实验探究土壤母质对于重金属锌的吸附及解吸的特点,为国家制定土壤标准提供可靠的数据支持。结果表明：土壤中锌的解吸量随着pH的降低而增加;比较不同母质发育而成的土壤,在pH=4.0、5.6模拟已污染土壤中锌的解吸量顺序为：沟沟堆积母质〉湖相沉积物母质〉河相沉积物母质〉海相沉积物母质。在pH=2.0、3.0时,河相沉积物母质、湖相沉积物母质解吸量迅速增加,超过海相沉积物母质锌的解吸量。     

氮肥对土壤氧化大气甲烷影响的机制

综合评述了氮素对土壤氧化甲烷的抑制机制。包括 :( 1)竞争甲烷单氧化酶的竞争抑制机制 ,( 2 )代谢产物的毒害抑制机制 ,( 3)外源盐引起的微生物生理缺水抑制机制和 ( 4)氮素周转作用引起的抑制机制。提出了氧化菌竞争利用土壤空气有限O2 的竞争抑制机制 ,即氨氧化菌利用更多的土壤有限氧气→产生优势氨氧化菌→形成优势菌群→限制甲烷氧化菌繁殖和功能发挥的氨长期抑制土壤氧化大气甲烷的机制 ,并认为这种抑制作用是不可逆的     

Simultaneous removal of Co,Cu, and Cr from water by electrocoagulation

This study provides an electrocoagulation process for the removal of metals such as cobalt, copper, and chromium from water using magnesium as anode and galvanized iron as cathode. The various parameters like pH, current density, temperature, and inter electrode distance on the removal efficiency of metals were studied. The results showed that maximum removal efficiency was achieved for cobalt, copper, and chromium with magnesium as anode and galvanized iron as cathode at a current density of 0.025?A?dm^?2 at pH 7.0. First- and second-order rate equations were applied to study adsorption kinetics. The adsorption process follows second-order kinetics model with good correlation. The Langmuir and Freundlich adsorption isotherm models were studied using the experimental data. The Langmuir adsorption isotherm favors monolayer coverage of adsorbed molecules for the adsorption of cobalt, copper, and chromium. Temperature studies showed that adsorption was endothermic and spontaneous in nature.     

An Investigation Into the Mechanism by Which Synthetic Zeolites Reduce Labile Metal Concentrations in Soils

The addition of synthetic zeolites and similar materials to metal contaminated soils has been shown to reduce soil phytotoxicity and to improve the quality of plant growth on such amended soils. To gain an understanding of the mechanism by which the phytotoxicity of contaminated soils is reduced when treated with synthetic zeolites, sequential extraction procedures and soil solution techniques have been used to identify changes associated with metal speciation in amended soils. Sequential extraction data and changes in soil solution composition are presented for three different contaminated soils, amended with three synthetic zeolites (P, 4A and Y) at concentrations of 0.5%, 1% and 5% w/w, or lime at 1%. The soils were collected from the site of a metal refinery, an old lead zinc mine spoil tip and from a field which had been treated with sewage sludge. After incubation of the zeolite treated soils for between one and three months, results showed a reduction in the metal content of the ammonium acetate fraction between 42% and 70%, depending on soil, zeolite and rate of addition, compared with the unamended soils. In addition, soil solution experiments indicated that synthetic zeolite amendments were more efficient at reducing metal content than comparable lime treatment. The mechanism by which synthetic zeolites reduce metal bioavailability in contaminated soils is discussed and compared to other amendments.