Fertilizer Applications and Trace Elements in Vegetable Production Soils of California

We collected and analyzed over 600 soil samples from the vegetable production fields in seven regions across California, examining the total As, Cd, Pb, P, and Zn concentrations of the soils. The ranges for baseline concentrations were determined for each region. The total P and Zn contents of the soils in comparison to the baseline ranges served as indicators on P fertilizers and micronutrients inputs through cultivation, the greater the total contents the larger the inputs. When the soil As, Cd, and Pb concentrations of each region were plotted with respect to those of P and Zn, three data distribution patterns emerged: (1) the soil As, Cd and Pb concentrations of the cropland soils remained within the baseline range regardless of the phosphorus or zinc inputs in 5, 2, 4 of the 7 regions, respectively, (2) the soil As, Cd and Pb concentrations of the cropland soils had moved upward and exceeded the baseline ranges but their concentrations did not rise in proportion to the phosphorus or zinc concentrations of soils in 1, 4, and 3 of the 7 regions, respectively. The enrichment was due to diffuse sources other than phosphorus fertilizers or micronutrients. (3) The soil As and Cd concentrations of the cropland soil in the Oxnard/Ventura Area and Fresno showed trends of increasing with respect to inputs of P and or Zn indicating P fertilizer or micronutrients applications over time have caused As and Cd to slowly accumulate in the cropland soils.     

Location of Trace Elements in Unpolluted Soils by a Combined Method

Abstract

A sequential extraction procedure was combined with physical fractionation and mineralogy to determine the distribution of trace elements (TE) among the different phases of a poorly weathered sample. It was first fractionated into five particle‐size fractions. Two of these were selected for sequential extractions on the basis of their contrasting mineralogical compositions. A five‐step sequential extraction scheme was employed. The studied sample is mostly composed of hornblende, quartz, and feldspars. Early weathering has already occurred, resulting in the formation of smectite and oxides. Sequential extractions show that the studied elements are mostly associated with the residual phases. Hornblende was the main TE bearer of the primary minerals, whereas TEs released through weathering precipitated in both smectite and oxides. Oxides were found to scavenge copper (Cu) and cobalt (Co) more efficiently than smectite. Copper and nickel (Ni) were more concentrated in smectite than in hornblende.     

不同城市功能区绿地土壤重金属分布及其生态风险评价

对山东中部某典型城市9个城市功能区64个绿地土壤样品中的Cu,Zn,Pb,Cd 4种重金属元素含量进行了测定,评价了土壤重金属污染特征及其生态风险。结果表明:各功能区绿地表层土壤Cu,Zn,Pb和Cd的平均含量均高于当地自然植被土壤背景值,已表现出富集状态,其中Cd平均含量超标严重;工业区、风景名胜区、商业区和居民区等绿地土壤污染程度居前;单因子污染评价表明,该市绿地土壤中Cu,Zn和Pb已处于潜在污染状态,而Cd已经处于重污染状态;综合污染评价研究表明,处于“中度污染”污染级别的绿地类型有工业绿地、商业区绿地、风景名胜区和居住区绿地,而且苗木生产区和道路绿地也接近“中度污染”级别;潜在生态危害评价表明,该市绿地土壤处于轻微生态风险,但Cd潜在生态危害指数已经处于中等生态风险;土壤中Cu-Zn,Cu-Cd,Pb-Cd显著相关,Cu-Pb,Zn-Cd极显著相关,重金属之间存在一定复合污染现象,表明这些重金属元素的来源可能相同。该市绿地土壤Cd污染的防治应该引起重视。     

Nutrients, Trace Elements and Net N Mineralization in Acidic Kenyan Soils

The nutrients status and properties in Kenyan soils (Kiambu, Mbeere Districts) are reported with the aim to elucidate the factors of productivity decline. According to the FAO (1988) system the studied soils were classified as humic Nitisols, haplic Acrisols or luvic Arenosols. The soils were found acidic, as a result of leaching of exchangeable cations and they are poor in organic carbon. Cation exchange capacity was extremely low in the sandy soils of Mbeere. Available phosphorus and exchangeable K⁺ were low inducing a crucial problem of soil fertility. Among the micronutrients, manganese extracted by DTPA was most abundant element, while micronutrients extracted by 4 M HNO₃ ranked as follows: Fe>Mn>Zn>Cu. Copper (DTPA) was low and manganese was extremely high in Kiambu. Iron content varied greatly, while decreased zinc was observed in Mbeere. Nitrogen mineralization over an incubation period of 30 weeks ranged from 54.64 to 145.50 mg kg⁻¹ and represents 4.53–21.09% of the total soil nitrogen. Soil nitrogen was associated to soil organic carbon and was strongly correlated to total soil N. Water harvesting, liming, and improved management of composting and manure are amongst the measures to restore soil fertility.     

Nutrients,Trace Elements and Net N Mineralization in Acidic Kenyan Soils

The nutrients status and properties in Kenyan soils (Kiambu, Mbeere Districts) are reported with the aim to elucidate the factors of productivity decline. According to the FAO (1988) system the studied soils were classified as humic Nitisols, haplic Acrisols or luvic Arenosols. The soils were found acidic, as a result of leaching of exchangeable cations and they are poor in organic carbon. Cation exchange capacity was extremely low in the sandy soils of Mbeere. Available phosphorus and exchangeable K⁺ were low inducing a crucial problem of soil fertility. Among the micronutrients, manganese extracted by DTPA was most abundant element, while micronutrients extracted by 4 M HNO₃ ranked as follows: Fe>Mn>Zn>Cu. Copper (DTPA) was low and manganese was extremely high in Kiambu. Iron content varied greatly, while decreased zinc was observed in Mbeere. Nitrogen mineralization over an incubation period of 30 weeks ranged from 54.64 to 145.50 mg kg^?1 and represents 4.53–21.09% of the total soil nitrogen. Soil nitrogen was associated to soil organic carbon and was strongly correlated to total soil N. Water harvesting, liming, and improved management of composting and manure are amongst the measures to restore soil fertility.     

Trace Elements in Tephra Soils of Mounts Kupe and Manengouba (Cameroon)

Eurasian Soil Science - Increasing demographic pressure in the area around the Mounts Kupe and Manengouba (Cameroon) is leading to increased agricultural activities with potential heavy metal...     

Identifying the Sources and Contamination Status of Potentially Toxic Trace Elements in Agricultural Soils

Elevated concentrations of potentially toxic trace elements in agricultural soils contribute to soil pollution affecting food quality and safety. We assessed pollution levels in agricultural systems, lowland rice (LL) and highland cash crops (HL), by comparing with non-agricultural soils (NA). Correlation analysis and principal component analysis (PCA) were performed, and geo-accumulation index (I_geo) and pollution loading index (PLI) were calculated. Zinc in LL, and Cd in LL and HL, were significantly higher than in NA. The I_geo values of cooper (Cu), lead (Pb), nickel (Ni), zinc (Zn), and cadmium (Cd) ranged from uncontaminated to moderately contaminated (Class 0 to 2) for LL, HL, and NA. Overall, trace element levels were categorized as unpolluted based on PLI. Soil properties significantly correlated with Cu, Pb, Ni, and Zn concentrations but not with Cd. Based on PCA, sources of origin for Cu, Pb, Ni, and Zn were lithogenic, while the sources for Cd was anthropogenic in the studied agricultural soils.     

Trace Elements in Paddy Soils from the Central Region of the Mekong River,Laos

Extract

Laos (14–22.5°N and 100–107.5°E) is a land-locked country located in the Indo-China Peninsula, adjacent to Vietnam, Cambodia, Thailand, Myanmar, and China. The total area of the country is 236,800 km² and about 70% of the land is occupied by mountains. Paddy fields are distributed in flood plains along the Mekong River and its tributaries and in valley bottom plains dissected by small rivers. The climate is dominated by tropical monsoon.     

不同尺度下低山茶园土壤主要微量元素的空间变异性

利用地统计学、主成分分析方法对不同尺度下四川蒙顶山茶园土壤微量元素空间变异性、影响因素及多元素综合制图进行了研究.结果表明:①两个尺度下土壤微量元素的空间相关性存在差异,同时其空间变异方向具有相似性,Mn和Cu在山脉走向垂直方向变异较大,Fe和zn在水平方向变异较大且具有各向同性发展的趋势.普通Kriging插值结果说明微量元素含量从东北至西南呈明显的带状分布,垂直方向上随海拔升高而变化.②主成分综合制图较好地反映了微量元素分布的总体规律.两种主成分均具有较明确的物理意义,其插值图体现了微量元素特性沿坡面方向的带状变化特点,与半方差函数分析的结果完全吻合.③土壤环境条件对蒙顶山茶园土壤微量元素影响较大,而坡度是影响土壤微量元素空间分布形态的主要地形因素.     

Trace Element Concentrations in Saltmarsh Soils Strongly Affected by Wastes from Metal Sulphide Mining Areas

Soil and water samples were analysed for trace metals and As in two watercourses and 14 sampling plots in a salt marsh polluted by mine wastes in SE Spain. Groundwater levels, soil pH and Eh were measured ‘in situ’ for a 12-month period in each sampling plot, and total calcium carbonate was also determined. Low concentrations of soluble metals (maximum Mn 1.089 mg L^?1 and maximum Zn 0.553 mg L^?1) were found in the watercourses. However, total metal contents were extremely high in the soils of a zone of the salt marsh (maximum 1,933 mg kg^?1 of Mn, 62,280 mg kg^?1 of Zn, 16,845 mg kg^?1 of Pb, 77 mg kg^?1 of Cd, 418 mg kg^?1 of Cu and 725 mg kg^?1 of As), and soluble metals in the pore water reached 38.7 mg L^?1 for Zn, 3.15 mg L^?1 for Pb, 48.0 mg L^?1 for Mn, 0.61 mg L^?1 for Cd and 0.29 mg L^?1 for As. Variable concentrations with depth indicate a possible re-mobilisation of the metals, which could be related to spatial and temporal variations of water table level, pH and Eh and to the presence of calcium carbonate. A tendency for the Eh to decrease in the warmest months and to increase in the coldest ones was found, especially, in plots that received water with a high content of dissolved organic carbon. Hence, the existence of nutrient effluent-enriched water may modify the physical–chemical conditions of the soil–water system and influence metal mobility.     

Distribution of Trace Elements in Soils from the Sudbury Smelting Area (Ontario,Canada)

The sequential extraction procedure proposed by the European Commission Measurement and Testing Programme, combined with Scanning Electron Microscopy and Energy Dispersive X-ray Analysis(SEM/EDS), was applied to identify and quantify the chemical andmineralogical forms of Cu, Ni, Fe, Mn, Zn, Pb, Cr and Cd presentin the topsoil from a mining and smelting area near Sudbury (Ontario, Canada). The possible mobility of the chemical forms was also assessed. The metal fractions: (1) soluble and exchangeable, (2) occluded in manganese oxides and in easily reducible iron oxides, (3) organically bound and in form of sulphides, (4) residual mainly present in the mineral lattice structures were separated. Cu and Ni were the major metallic contaminants, occurring in soils in broad ranges of concentrations: Cu 11–1890 and Ni 23–2150 mg kg^-1. Cu was uniformly distributed among allthe extracted fractions. Ni was found associated mainly withthe residual forms, accounting for 17–92%, with an averageof 64%, of the total Ni present in the soils. Fe, Mn, Zn,Pb, Cr and Cd, while occurring in most analysed samples innormal soil concentrations, were primarily held in theresidual mineral fraction (on average >50%). The solubleand exchangeable forms made a small contribution (≤8.1%)to the total content of metals extracted. At least 14% ofthe total Cd, Mn and Pb was mobilised from the reducibleforms. The oxidizable fraction assumed mean values higher than10% only for Pb and Zn. Statistical treatment of the experimental data showed significant correlations between totalmetal content of the soils, some soil properties such as pH value, clay and organic matter content, and metal concentrationsin the various fractions. SEM/EDS analysis showed Fe in form ofoxides and sulphides in soils and Cu, Ni, Mn, Zn and Cr in association with iron oxides. Numerous black carbonaceous particles and precipitates of aluminium fluoride salts, observedin the solid residue left after `total’ digestion, were found tocontain Fe, Ni and Cr.     

Rare Earth Elements in Soils

Abstract

Rare earth elements (REEs) comprise a group of 17 elements with very similar chemical and physical properties, which include scandium (Sc, Z=21), yttrium (Y, Z=39), and the lanthanides with successive atomic numbers (Z from 57 to 71). Lanthanides are the elements lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). REEs are required in modern industry, and their use in agriculture yielded positive effects in terms of crop yield and body weight of poultry. However, the question of whether the use of REEs in agriculture yields an enrichment of these elements in the environment remains open. It was the aim of this review to summarize the data about REEs in soils with view to their content, fractions, availability, chemical behavior, and translocation in soils and to elucidate further research needs.     

Statistical Approach to Discriminate Background and Anthropogenic Input of Trace Elements in Soils of Catalonia,Spain

A study was conducted in Catalonia (NE Spain) to determine the baseline levels and the polluted contents of Ba, Cd, Cr, Cu, Ni, Pb, V and Zn (aqua regia-extractable) in soils of an agroindustrial area near Barcelona. The samples analyzed proceeded from two soil surveys. 268 samples belonged to 67 representative, and slightly disturbed, soil profiles sampled during a previous soil survey, and 95 superficial samples were taken near a composting plant (heavily disturbed and presumably polluted). Probability plots were used to establish the reference (or background) levels and a literature comparison was made to check the validity of the background ranges established. The raw data sets and the uncontaminated resulting populations were studied by means of frequency histograms and of statistical tests in order to verify the general assumption, which states that trace element distributions in soils follow the log-normal law. The results showed that the studied elements were distributed in these soils following the log-normal law and that the established reference values were in agreement with those reported in the literature.     

Seasonal Trend of Potentially Toxic Trace Elements in Soils Supporting Medicinal Plants in the Eastern Region of Ghana

Investigation was conducted into the occurrence and extent of potentially toxic heavy metals and/or trace elements in soils from three study areas in the Eastern Region of Ghana namely Abonse, Pepease and Mamfe. A protocol for soil sampling, preparation and analysis was developed to yield sufficient information on elemental concentrations in the soils. The soil samples were analysed for As, Co, Cr, Cu, Sb, Th, U, V and Zn, using Instrumental Neutron Activation Analysis (INAA) coupled with conventional counting system. Concentrations of Co, Cr, Th and Zn positively correlate with As, and regressions performed on Co-Zn, Co-Cr, Co-Th, Cr-Th and Zn-Cr values also show strong correlations. The regressions suggest that these elements are geochemically associated and might be enriched simultaneously. Though there are relatively high concentrations of Cu (maximum; 46.3 mg/kg), Co (maximum; 9.17 mg/kg), Th (maximum; 15.1 mg/kg) and U (maximum; 2.38 mg/kg) in some of the soils compared with their levels in world average soils, the average concentrations of the trace elements in general are below or within levels in world average soils/uncontaminated soils. Also, the enrichment index computed in the soils indicates that all the study areas are not enriched with toxic elements, particularly As, Cu, Sb and Zn, and the enrichment index values decrease in the order of Pepease > Mamfe > Abonse. When the average composition of the soils was normalized to the average composition of the underlying rocks, the soils were depleted in the trace elements determined, indicative of background concentration values. Lack of correlations between soil characteristics such as texture, organic carbon, organic matter, total nitrogen and available phosphorous, and most of the trace elements suggests that the influence of these parameters on the distribution of the trace elements is not important in the surface soils.     

Effects of Changed Soil Conditions on the Mobility of Trace Metals in Moderately Contaminated Urban Soils

Changes in the soil chemical environment can be expected to increase the leaching of trace metals bound in soils. In this study the mobility of trace metals was monitored in a column experiment for two contaminated urban soils. Four different treatments were used (i.e. rain, acid rain, salt and bark). Leachates were analysed for pH, dissolved organic carbon (DOC) and for seven trace metals (cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn)). The salt treatment produced the lowest pH values (between 5 and 6) in the effluent whereas the DOC concentration was largest in the bark treatment (40–140 mg L^?1) and smallest in the salt and acid treatments (7–40 mg L^?1). Cadmium, Ni and Zn were mainly mobilised in the salt treatment, whereas the bark treatments produced the highest concentrations of Cu and Pb. The concentrations of Cu, Cr, and Hg were strongly correlated with DOC (r ²?=?0.90, 0.91 and 0.96, respectively). A multi-surface geochemical model (SHM-DLM) produced values for metal dissolution that were usually of the correct magnitude. For Pb, however, the model was not successful indicating that the retention of this metal was stronger than assumed in the model. For all metals, the SHM-DLM model predicted that soil organic matter was the most important sorbent, although for Pb and Cr(III) ferrihydrite was also important and accounted for between 15 and 50% of the binding. The results confirm the central role of DOC for the mobilization of Cu, Cr, Hg and Pb in contaminated soils.     

Assessment of the Contamination of Cultivated Soils by Eighteen Trace Elements Around Smelters in the North of France

Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn,Tl, Th, U and Zn contamination of cultivated surfacehorizons has been assessed around two lead and zincsmelters in the North of France. The verticaldistribution of Ag, As, Bi, Cu, Hg, Se, Sb and Tl inthe soils has also been examined. The soils around thelead and zinc smelter at Noyelles-Godault arecontaminated by Ag, As, Bi, Cd, Cu, Hg, In, Ni, Pb, Sb,Se, Sn, Tl and Zn. The original concentration in themost contaminated soils may be multiplied by a factorof around 2 to 100, according to the element. Cadmium,Pb and Zn are the most abundant contaminants. The Pband Zn concentrations are correlated to those of theother contaminants, with the exception of Se. Aroundthe Auby zinc smelter, there is a contamination by thesame elements, but in different proportions, inaddition to Cr contamination. Contamination by Se canreach a depth of around 1 m, whereas contamination byAg, As, Bi, Cu, Hg, Sb and Tl is confined to the top 30cm. Although the contaminant content in most soilsdepends on the distance from the plant, Secontamination would appear to vary to a greater extentaccording to the physico-chemical soil conditions.     

Effects of ISPOLIN Fertilizer on Uptake of Macro- and Trace Elements by Wheat Grown in Two Different Soils

Variations in concentrations of 24 elements in soils with loam and sandy loam texture and in Triticum aestivum wheat seedlings grown in the soils under greenhouse conditions were studied. Initial soils differed significantly in concentrations of 20 elements. Elemental composition of wheat seedlings depended on the soil where the plants were grown. An application of ISPOLIN (fertilizer enriched with potassium) resulted in variations in soil pH, plant biomass, and concentrations of several elements both in soils and in plants. An excess of bioavailable potassium (K) in soil led to significant increase of K and deficiency of calcium (Ca) and magnesium (Mg) in all parts of T. aestivum. Concentrations of many other elements in the plants also changed. The effects of soil fertilization on plant biomass, leaf chlorophyll, and plant element concentrations were soil-dependent. Depending on the ratio of K/Mg in the soils, there was either an increase of plant yield and chlorophyll content or no effect at all.     

重庆市不同功能区城市绿地土壤重金属分布特征与评价

调查并分析了重庆市不同功能区城市绿地土壤重金属含量分布特征,采用综合污染指数法对其污染状况进行了评价。结果表明,不同功能区城市土壤Cu、Zn、Pb和Cr含量整体较低,其中Cr平均含量低于当地土壤环境背景值,调查区域土壤环境质量基本达到国家土壤环境质量二级标准。不同功能区土壤Cu的含量由高到低为交通区>商业区>居住区>休闲区,土壤Zn的含量为商业区>交通区>居住区>休闲区,土壤Pb的含量为商业区>交通区>居住区>休闲区,土壤Cr的含量为商业区>交通区>居住区>休闲区。居住区和休闲区重金属污染程度已达到警戒线,但土壤尚清洁;而商业区和交通区存在不同程度的重金属轻度污染。综合污染指数土壤重金属污染程度由大到小为商业区>交通区>居住区>休闲区。     

Evaluation of Poultry Litter Amendment to Agricultural Soils: Leaching Losses and Partitioning of Trace Elements in Collard Greens

Water, Air, &; Soil Pollution - Leaching of trace metals and greenhouse plant growth (Collard greens; Brassica oleracea var. acephala) response studies were conducted in two types of soils with...     

Incinerated Sewage Sludge Products as Amendments for Agricultural Soils: Leaching and Plant Uptake of Trace Elements

Preliminary leaching column and greenhouse plant uptake studies were conducted in two soils with contrasting characteristics amended with varying rates (0 to 148.3 Mg ha^?1) of incinerated sewage sludge (ISS) and weathered sewage sludge (WISS) to estimate the leaching losses of trace elements from the soils amended with incinerated sewage sludge by products and to evaluate the uptake and accumulation of these elements in various parts of Sorghum vulgaris var. sudanense Hitche. (“Sorgrass''), a Sorghum-Sudan grass hybrid. Results of this study indicated that leaching of Cr, Cd, Zn, Cu, Ni, Fe and Mn from soils amended with ISS and WISS increased with increasing rates of amendment. Results of the leaching column study further revealed greater leaching losses from coarse-textured soil compared to medium-textured soil and also from ISS amended soils than with WISS amended soils. Results further suggested that the type of element and the interaction between the element and soil properties affected the leachability of various trace elements. The uptake study indicated uptake and accumulation of trace elements by plant parts increased with increasing rates of amendments. Greater plant uptake and accumulation of trace elements were observed in plant parts grown in soils amended with ISS compared to that of WISS. Results also indicated a greater accumulation of trace elements in below ground part of the plants (roots) compared to that was observed in above ground parts (shoots). Limited data obtained from this one season preliminary studies demonstrated that incinerated sewage sludge products from wastewater treatment plants could be used as soil amendments at low application (no more than 24.7 Mg ha^?1) for optimum plant growth, and dry matter yield without resulting in substantial accumulation of metals in plant parts at concentrations above the recommended critical limits and without causing significant leaching losses of various trace elements. It is imperative that long-term field studies are necessary to evaluate the long-term impact of using these new products in leaching and accumulation of various trace elements in plants and soils.