Potential Groundwater Pollution Risks by Heavy Metals from Agricultural Soil in Songon Area(Abidjan,Cote d’Ivoire)

The soil samples were collected taking into account the land use in Songon area. The hydraulic conductivity (K) of soils was characterized in-situ when specific yield (Sy), pHw and concentrations of Cooper, Iron, Zinc, Cadmium, Chromium and Lead were measured in the laboratory. Pollution load indices (PLI) were calculated to evaluate the soil contamination levels. The soils were neutral and alkaline (6.7≤ pH ≤ 9.20), permeable (1.9 í 10-5?m·s-1?≤ K ≤ 8.2 í 10-4?m·s-1), with a high specific yield (13.33% ≤ Sy ≤ 33.33%) which can favor the pollutants transfer. The heavy metals (Fe, Cu, Zn, Cd, Cr and Pb) have very high concentrations in soils. The integrated pollution indices (PLI) indicate that almost 70% of Songon soils are moderately contaminated by the investigated heavy metals, with windows presenting high indices of pollution related to the intensive use of fertilizers and pesticides. The establishment of new boreholes in the Songon area should consider these heavy metals, so as to avoid the risk of groundwater pollution due to the physical properties of soils.

Assessment on heavy metals pollution of agricultural soil in Guanzhong District

The monitored soil samples were collected from Heihui irrigated area, Jiaokou irrigated area, Qianhe river valley and Jinghe river valley （hereafter Heihui, Jiaokou, Qianhe and Jinghe for short respectively） of Guanzhong District. According to the Environment Quality Standard for Soil （GB 15618-1995II）, we evaluated the pollution status of heavy metals （Cd, As, Cr and Pb） that could seriously endanger soil environment and human health by using single-factor index and synthetic pollution index methods. The results indicate that the synthetic pollution indices P of soil heavy metals are less than 0.7 in Heihui, Jiaokou, Qianhe and Jinghe of Guanzhong, the single-factor indices Pi of soil heavy metals of most soil samples are less than 0.7, so the soil environmental quality is in a good condition in Guanzhong on the whole; the enrichment degree of soil heavy metals is in the order of Heihui, Jinghe, Qianhe and Jiaokou; the contaminated degree of soil heavy metals has the feature of Cd 〉 As 〉 Cr 〉 Pb; heavy metals contents in the cultivated horizon soil are generally higher than those in its underlayer soil, heavy metals contents of soil have the characteristic of enriching towards the cultivated horizon; Cd exceeds standard in the soil samples HS07a, b and HS08a, b at the Yangtao orchard in Heihui and in the soil sample QHS01a at the suburban vegetable plot in Qianhe, which was mainly caused by the long-term irrational use of chemical fertilizer and pesticide.

Effects of Wastewater Discharge on Heavy Metals Pollution in Fadama Soils in Kano City, Nigeria

Objective To present the results of a research project on 6 heavy metals （Cd, Cu, Zn, Pb, Hg, and Cr） at 30 Fadama fields scattered around Kano. Methods Following a reconnaissance conducted, 30 representative Fadama lands being irrigated with wastewater were selected from zones of the city under residential, industrial, commercial, and mixed but largely residential landuses. Five additional Fadama lands not being irrigated with wastewater were selected to serve as control. Using grid sampling procedure, soil samples were selected from 0-15 cm and 20-30 cm depths and analyzed for the above listed heavy metals using atomic absorption spectrophotometry. T-test was used to compare the mean values of the metals for the Fadama lands under different landuse zones with those of the control. Results Analyses of the soil data collected showed that the metals were concentrated in higher amounts in the lower （20-30 cm） than the upper （0-15 cm） depths, which was an indication of downward movement of the metals in profile of the soils. In the two soil depths, Zn was generally the most abundant, followed by Cr, then Pb, Cu, and Cd while Hg was the least. The Fadama soils in areas of mixed landuses with industrial as the dominant ones maintained the highest concentrations of the various metals. Conclusions These results indicate clearly that the Fadama soils are significantly polluted by industrial and household wastewater and that there is a particular threat from Cr and Pb pollution. There is also evidence that the metals are accumulating at lower layers of the soil profile, suggesting that not only plants and soil, but even water bodies could be under the threat of heavy metal pollution in the area.

Investigation and Analysis of Soil Pollution of Heavy Metals(Hg,As) in Duanzhou District,Zhaoqing City

The soil heavy metals(Hg and As)in Duanzhou District of Zhaoqing City were determined by AFS200 T atomic fluorescence spectropho-tometer,and the soil environment in Duanzhou District was evaluated by several evaluation methods of soil heavy metal pollution,such as single factor index method,pollution load index method and Nemerow comprehensive pollution index method.Finally,according to the data and conclu-sions,the soil pollution situation in Duanzhou District of Zhaoqing was analyzed.The results will let more people pay attention to the changes of the environment and realize the harm of the environment,and the government can formulate a new plan conducive to the coordinated development of the environment and economy.

Control Approaches to Soil Pollution from Heavy Metals

With the continuous development of human society and economy and the continuous progress of industrial technology,more and more pollutants are discharged into the natural environment,and soil environment is also affected at the same time. Among pollutants leading to soil pollution,heavy metals have resulted in most serious soil pollution. Here,many control and restoration approaches to soil pollution from heavy metals are proposed,and characteristics and applicable conditions of various methods are compared,so as to provide theoretical references for the control and restoration of soil pollution from heavy metals in future.

Ecological Risk Assessment of Combined Pollution of Heavy Metals and Pesticides in Urban Soils

Urban soil is the main component of urban ecological systems and the key risk receptor from urbanization. Heavy metal and green pesticide pollutions in urban soils have been widely reported with the expanding of urbanization. Since urban soil pollution comes from various resources, application of integrated thinking and methods is needed in ecological risk assessment of urban soil pollution. This paper synthetically reviewed the combined pollution of heavy metals and pesticide, and ecological risk assessment, and then proposed some research trends and areas in the future that are required to carry out intensively according to the present situation of environmental pollution and international research fronts.

Calculating Pollution Indices by Heavy Metals in Ecological Geochemistry Assessment and a Case Study in Parks of Beijing

Pollution index is a powerful tool for ecological geochemistry assessment. The commonly used pollution indices by heavy metals in soils and sediments were classified as two types of single index and integrated index in an algorithm point of view. Four single indices of contamination factor （or concentration factor）, ecological risk factor, enrichment factor, and index of geo-accumulation were illustrated, and the reference values for calculating single indices were distinguished into background levels and threshold pollution values. Eight integrated indices were divided into two groups. One group is suitable for the normal distribution single indices including the sum, average, weighted average, vector modulus, and Nemerow pollution indices, and the other for log-normal distribution including the product, root of product, and weighted power product pollution indices. Using background levels as reference values, five contamination classes were divided, and the terminologies are suggested for the single and integrated indices to unify the assessment results. Software of EGAPI was developed in a single document interface to calculate the four single and eight integrated indices by heavy metals to assess the quality of soil and sediment ecological geochemistry. Pollution indices by heavy metals of Cu, Pb, and Zn in soils in parks of Beijing were calculated using EGAPI software, and these five contamination classes and terminologies suggested in this study were evaluated and used. Results of integrated indices of Cu, Pb, and Zn in soils indicated that the soil qualities are unpolluted as a whole and varied from low polluted to unpolluted status from the center to the outskirts of Beijing City.

Analysis and Assessment on the Heavy Metals in a Severely Degraded Subtropical Red Soil Region

5 different forests of Pinus massoniana, Schima superba, Liquidambar formosana, P. massoniana × S. superba, P. massoniana × L. formosana as the research object were set up to study the Cr, Cu and Zn content of degraded red soil region in subtropics. The soil heavy metal pollution degree was evaluated by national environmental quality standard (II class). The results showed that three soil metals of P. massoniana × S. superba were the highest, and the soil metals enrichment ability was strong. The order of single factor pollution index of metal elements was Cu (1.38) > Cr (0.81) > Zn (0.42), and moderately pollution, pollution warning and no pollution, respectively. There was no significant correlation between three soil heavy metals and soil total carbon (TC), total nitrogen (TN) and total phosphorus (TP). These results suggested that the accumulation of heavy metal elements was not derived from the parent material of soil. There was a significant positive correlation between the three metal elements which indicated that the sources of the three elements were similar. The structural equation model showed that the direct and indirect effects among the influencing factors ultimately affected the activity of heavy metals by cascade effects.

Risk assessment of heavy metals in soils and vegetables around nonferrous metals mining and smelting sites,Baiyin,China

A field survey was conducted to investigate the metal and arsenic contamination in soils and vegetables on four villages （Shuichuan （SCH）, Beiwan （BWA）, Dongwan （DWA） and Wufe （WFE）） located along, Baiyin, China, and to evaluate the possible health risks to local population through foodchain. Results show that the most significantly contaminated soils occurred upstream at SCH where Cd, Cu and As concentrations exceeded maximum allowable concentrations for Chinese agricultural soil. Further downstream the degree of contamination semi-systematically decreased in concentrations of metal. Generally, the leafy vegetables were more heavily contaminated than non-leafy vegetables. Chinese cabbage is the most severely contaminated, the concentrations of Cd exceeded the maximum permit levels （0.05 mg/kg） by 4.5 times. Bio-accumulate factor also shows that an entry of Cd to food chain plants is the greatest potential. Furthermore, the estimated daily intake amounts of the considered toxic elements （Cd, Pb and Cu） from the vegetables grown at SCH and BWA and DWA have exceeded the recommended dietary allowance levels. Thus, the vegetables grown in three villages above, which affected by Baiyin mining and smelting have a health hazard for human consumption.

Heavy metal pollution of soils and vegetables in the midstream and downstream of the Xiangjiang River, Hunan Province

A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.

Comparison of Heavy Metal Accumulation in Four Vegetables Grown in the Soils Contaminated with Multiple Heavy Metals

In order to compare the differences in the accumulation of plumbum(Pb),cadmium(Cd),chromium(Cr),cuprum(Cu),nickel(Ni)and zinc(Zn)from the multi-contaminated,alkalescent soil in the plants of four-season big-leaf coriander,butter lettuce,four-season fast-growing pakchoi and four-season parsley to choose low accumulation vegetables,a pot experiment was conducted by using heavy metal salts to simulate high-,moderate-and low-level heavy metals multi-contaminated soils.The results showed that the multi-contaminated soil by high levels of Pb,Cd,Cr,Cu and Zn produced inhibition on biomass of four-season fast-growing pakchoi,failing to collect samples,but had no obvious inhibition on the growth of the three other vegetables.Among the four kinds of vegetables examined,the accumulation ability of four-season parsley to the five heavy metals of Pb,Cd,Cr,Cu and Zn was the strongest,while the accumulation ability of four-season fast-growing pakchoi to Ni was the strongest.In the high-level contaminated soil,the underground part of these four vegetables grown was more likely to accumulate heavy metals than their aboveground part.Both of vegetable varieties and heavy metal types can affect the accumulation of heavy metals in vegetables.Our research also found that four-season big-leaf coriander was high yielding and low accumulation of heavy metals.

Heavy Metals in Soils Associated with Fertilizers in Trinidad

Heavy metals in agricultural soil pose human health risks through food consumption. In a novel study for Trinidad, concentration and pollution index levels of heavy metals were assessed from 18 agricultural farms using the X-Ray fluorescence technique, then to evaluate the Geo-accumulation and Nemerow’s Integrated Pollution indexes. Toxic elements Pb and As were present but soil quality due to anthropogenic input was found as unpolluted. Overall heavy metal pollution was classified at a precautionary level for 33% of farms, slightly polluted for 61% and moderately polluted for 6% of the farms assessed, thus, regular monitoring and mitigation measures are important for food safety and human health in Trinidad.

Heavy Metals, Phosphorus and Some Other Elements in Urban Soils of Hangzhou City, China

Health implications of inhaling and/or ingesting dust particles with high concentrations of heavy metals from urban soils are a subject of intense concern. Understanding the geochemistry of these metals is key to their effective management. Total concentrations of heavy metals,phosphorus (P) and 8 other elements from topsoil samples collected at 82 locations in Hangzhou City were measured to:a) assess their distribution in urban environments; and b) understand their differentiation as related to land use. Metal mobility was also studied using a three-step sequential chemical fractionation procedure. About 8.5%,1.2%,3.6%,11.0% and 30.3% of the soil samples had Cd,Cr,Cu,Pb,and Zn concentrations,respectively,above their allowable limits for public and private green areas and residential use. However,in commercial and industrial areas,most samples had metal concentrations below their allowable limits. Statistical analyses revealed that the 16 measured elements in urban soils could be divided into four groups based on natural or anthropic sources using a hierarchical cluster analysis. Additionally,Cu,Pb,and P showed similar spatial distributions with significant pollution in commercial zones,suggesting vehicle traffic or commercial activities as dominant pollutant sources. Also,Cd,Co,Cr,Ni,Zn,Mn and Fe had the highest concentrations in industrial locations,signifying that industrial activities were the main sources of these seven metals. Moreover,the data highlighted land-use as a major influence on heavy metal concentrations and forms found in topsoils with large proportions of soil Cd,Co,Cr,and Ni found in residual fractions and soil Cu,Pb and Zn mainly as extractable fractions.

Soil Heavy Metal Pollution Around the Dabaoshan Mine,Guangdong Province,China

Soil contamination in the vicinity of the Dabaoshan Mine, Guangdong Province, China, was studied through determi- nation of total concentrations and chemical speciation of the toxic metals, Cu, Zn, Cd, and Pb, using inductively coupled plasma mass spectrometry. The results showed that over the past decades, the environmental pollution was caused by a combination of Cu, Zn, Cd, and Pb, with tailings and acid mine drainage being the main pollution sources affecting soils. Significantly higher levels （P ≤ 0.05） of Cu, Zn, Cd, and Pb were found in the tailings as compared with paddy, garden, and control soils, with averages of 1486, 2516, 6.42, and 429 mg kg^-1, respectively. These metals were continuously dispersed downstream from the tallings and waste waters, and therefore their concentrations in the paddy soils were as high as 567, 1 140, 2.48, and 191 mg kg^-1, respectively, being significantly higher （P ≤ 0.05） as compared with those in the garden soils. The results of sequential extraction of the above metals from all the soil types showed that the residual fraction was the dominant form. However, the amounts of metals that were bound to Fe-Mn oxides and organic matter were relatively higher than those bound to carbonates or those that existed in exchangeable forms. As metals could be transformed from an inert state to an active state, the potential environmental risk due to these metals would increase with time.

Effects of heavy metal pollution of highway origin on soil nematode guilds in North Shenyang, China

Soil samples were collected with distance at 5, 20, 40, 80, 160, and 320 m from the Shen-Ha （Shenyang-Harbin） Highway, Northeast China, to investigate the effect of heavy metals of highway origin on soil nematode guilds. The contents of soil Pb, Cu, Zn, and the nematode community structure were analyzed. The results showed that the contents of total and available Pb, Ca, Zn varied significantly with the different distances from the highway. Pb was the main pollutant in the soils in the vicinity of Shen-Ha Highway. The zone from 20 to 40 m away from the highway was the most polluted area. The highest abundance of soil nematodes was found at 5 m while the lowest at 20 m away from the highway. Thirty six genera of nematodes belonging to 23 families were identified. Nematode guilds having different responses to soil heavy metals were classified into four types. Soil nematode guilds may act as a prominent indicator to heavy metal pollution of highway origin.

Studies on Heavy Metal Pollution in Soil-Plant System:A Review

Heavy metal pollution in soil-plant system is of major environmental concern on a world scale and in China in particular with the rapid development of industry. The heavy metal pollution status in soil-plant system in China, the research progress on the bioavailability of heavy metals (affecting factors, extraction methods, free-ion activity model, adsorption model, multivariate regression model, Q-I relationship, and compound pollution), and soil remediation are reviewed in the paper. Future research and monitoring is also discussed.

Heavy Metal Pollution in Soils on Railroad Side of Zhengzhou-Putian Section of Longxi-Haizhou Railroad, China

The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10-30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0-10 m), medium pollution zone (10-50 m), slight pollution zone (50-100 m), and warning zone (100-500 m), respectively.

Current Situation of Heavy Metal Pollution in Soil and Dustfall in Some Cities of China

Because of human activities, urban dustfall and soil in China have been polluted by heavy metals in different degrees. However, the type and pollution degree of heavy metal hazard are different among cities. Based on data about the heavy metal pollution of urban soil and dustfall as well as related information inves- tigated, the present situation of heavy metal pollution in soil and dustfall in 23 regions of China were summarized, and some suggestions were put forward accord- ing to the existing problems of research on heavy metal pollution, aiming to provide reference for government decision-making and related research in future.

Heavy Metals Contamination in Greenhouse Soils and Vegetables in Guanzhong, China

This study used a flame atomic absorption spectrometer (FAAS) and atomic fluorescence spec-trophotometer (AFS) to detect the concentrations of chromium (Cr), cadmium (Cd), lead (Pb), hy-drargyrum (Hg) and arsenic (As) in soils and three genotypes of vegetables in greenhouse, as well as analyzed the physical and chemical properties of soils, including soil pH, soil organic matter (OM), basic nutrients, electrical conductivity (EC) and cation exchange capacity (CEC) in Guan- zhong areas, Shaanxi province, China. The results showed that comparing to subsoil, the sampled topsoil is enriched in Cr, Cd, Pb, As and Hg. Cd (0.83 - 3.17 mg·kg-1) and Hg (0.40 - 1.44 mg·kg-1) are exceeding the limited value stated in “the 2006 Greenhouse Vegetable Producing Environmental Quality Evaluation Standards” of 0.40 mg·kg-1 and 0.35 mg·kg-1 respectively. However, Nanzhuang greenhouse soil is within the limits. The heavy metal pollution index (HPI) of soil in Sanyuan (8.10) is the highest and in Dongzhang (4.23) is the lowest. The contents of Pb (0.201 - 0.376 mg·kg-1) were exceeding the limited value (0.20 mg·kg-1) in vegetables species, and Cd (0.0363 - 0.0572 mg·kg-1) in some place were also exceeding the limited value (0.05 mg·kg-1). Greenhouse soils were becoming acidified year after year;the ratios of N, P and K in soil were seriously imbalanced. According to the impacting factors, OM, pH, available P, EC and CEC have obviously effected the accumulation of Cr and Hg. However, there was not enough evidence for the effects of available nitrogen and available potassium.