Multielement concentrations in vegetable species grown in two typical agricultural areas of Greece

Evaluating the health risks of heavy metals from vegetables grown on soil irrigated with untreated and treated wastewater in Arba Minch, Ethiopia

Available freshwater scarcity significantly affects sustainable food production for the rapidly growing population. This problem has forced people in most parts of the world to use wastewater as a viable solution. However, wastewater reuse has some deleterious effects on human and environmental health. This study was designed to investigate the health risks (HRs) of heavy metals (HMs) from vegetables irrigated with untreated and treated wastewater. The composite wastewater was collected at various sites in Arba Minch town and subjected to aerobic-anoxic treatment. Treated and untreated wastewater (UTW) was used to irrigate vegetables (lettuce, cabbage and tomato), and HM results were compared with the control (tap water) and standards. Water, soil and vegetables were investigated for various physical and chemical properties. Human health effects due to vegetable consumption were analyzed using HR- index (HRI), target hazard quotient (THQ) and hazard index (HI). The results revealed that most of the water quality indexes were significantly enhanced after aerobic-anoxic treatment, suggesting that wastewater collected from different sites was suitable for biodegradation. Soil physicochemical analyses also showed that pH, cation exchange capacity, organic carbon and organic matter were higher for UTW irrigated soil. Heavy metal concentrations were relatively greater in soils than water used for irrigation purposes and vegetables. The HM concentration in vegetables was higher for UTW than for treated and tap water irrigated vegetables. In vegetables, the order of HM content was Fe > Mn > Zn > Pb > Cu > Cd. Tomato followed by cabbage and lettuce accumulated significant amount of HMs (Fe > Mn > Zn > Pb > Cu > Cd) in their different organs (fruit/leaf>root>stem). The individual and combined health indexes (HRI, THQ and HI) showed that Pb and Cd have values greater than unity for wastewater irrigated vegetables, which could result in non-carcinogenic disease for short/lifetime exposure in adults and children. Overall, consumption of vegetables can be safer when grown with treated effluent than with UTW.

Health risks of heavy metal exposure and microbial contamination through consumption of vegetables irrigated with treated wastewater at Dubai, UAE

The shortage of fresh water is a major problem throughout the world, but the situation is worst in the arid and semiarid regions. Therefore, reuse of nonconventional water resources such as treated wastewater (TWW) is a common practice to irrigate field crops, vegetables, and forestry sectors. The present study was conducted to evaluate the significant impact of different heavy metals such as copper (Cu), iron (Fe), chromium (Cr), and zinc (Zn) on the soil and leafy, root, and fruit vegetables following irrigation with TWW through subsurface drip irrigation. Our results indicate that iron (Fe) was highest in lettuce followed by spinach, and Zn and Cr were second and third most abundant element in the different vegetables. Eggplant and radish showed the lowest concentrations of various heavy metals. A significant difference was observed in transfer factor (TF) among vegetables, and highest TF_soil-veg was observed for Fe in lettuce and the lowest for Cr in eggplant. Estimated daily intake (EDI) was the lowest in adults and highest in children. Target hazard quotient (THQ) of Cu, Zn, and Fe being < 1.0 appears relatively safe in all the tested vegetables. Risk index (RI) values showed that heavy metals were lower than 1.0 and hence lower risk for human. The combined HI values for Cu, Zn, Cd, Cr, and Pb were substaintionaly higher 12.8 and 9.21 after consumption of lettuce and carrot. So, consumption of these vegetables should be avoided after irrigation with TWW. Spinach exhibited maximum total coliform loading, while ecological risk was negligible due to sandy nature of soil type. Health risks to human could be reduced through proper selection of suitable vegetables, time of maturity, and consumed organs (leaf, fruit, or root part). Appropriate should be followed to decontaminate the microbial load in order to avoid any risks to human health (both adults and children).

Trace Element Uptake by Herbaceous Plants from the Soils at a Multiple Trace Element-Contaminated Site

The uptake of trace elements by wild herbaceous plants in a multiple trace element-contaminated site was investigated. The bioaccumulation factor (BF) of trace elements was markedly variable among the different plant species. On average, the BF for various trace elements was in the following decreasing order: Zn > Cu > Mn > Ni > As > Pb > Cr. The translocation factor among the investigated plant species was also considerably variable and showed the following decreasing order: Mn > Zn > Ni > Cu > Cr > As > Pb. Several hyperaccumulating plants were identified: Artemisia vulgaris for As, Mn and Zn, Phalaris arundinacea for Mn and Ni, Heracleum sphondylium for Cr and Zn, and Bistorta officinalis for Mn and Zn. The marked accumulation of trace elements in the plant tissue suggests that the site may not be suitable for urban agricultural production. The plant tissue-borne trace elements could affect microbial activities and consequently interfere with the ecosystem functioning in the affected areas.

Heavy metals (Pb, Cd, Cu, Zn, Ni, Co) in leafy vegetables collected from production sites: their potential health risk to the general population in Shiraz, Iran

Heavy metal contamination of vegetables is a great public health concern. One hundred samples of spinach, dill, cilantro, and cress from the production sites of Shiraz, Iran, and its outskirts were, therefore, examined for lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), nickel (Ni), and cobalt (Co) content. The potential health risks of these metals to local residents via the consumption of leafy vegetables were also estimated. The mean concentrations of Pb, Cd, Cu, Zn, Ni, and Co were 3.21, 0.28, 4.55, 40.44, 3.11, and 1.86 mg/kg dry weight, respectively. The Pb level exceeded the permissible limit of 0.3 mg/kg in 44.7% of vegetable samples. The other elements were, however, within FAO/WHO standards. The estimated daily intake (EDI) of Pb, Cd, Cu, Zn, Ni, and Co from leafy vegetables was 0.10, 0.01, 0.14, 1.26, 0.10, and 0.06 μg/kg body weight/day, respectively. At the mean and 97.5 percentile levels, all health risk index (HRI) values were less than the safe limit (< 1). Thus, within the area this study was focused on, leafy vegetables did not make a major contribution to the dietary intake of the elements which could be mainly attributed to the low vegetable consumption by the study population (20 g/day). Nevertheless, the lead content of the vegetables should be viewed with some concern. Regular monitoring of heavy metal contamination of foodstuff is recommended to control the sources of contaminants in the food chain.

Biodegradation of Pollutants in Waste Water from Pharmaceutical, Textile and Local Dye Effluent in Lagos, Nigeria

BACKGROUND

Discharged effluents from industry have been responsible for the deterioration of the aquatic environment in many parts of the world, especially in developing countries. Increasing industrialization and urbanization have resulted in the discharge of large amounts of waste into the environment, resulting in high pollution loads. Utilization of microbes such as fungi and bacteria have been used for pollution degradation.

OBJECTIVES

The aim of this research was to utilize microbial agents such as fungi and bacteria to reduce pollutant loads such as heavy metals in effluent samples.

METHODS

Three types of effluent (pharmaceutical, textile effluent, and dye) were obtained from Surulere in Lagos Metropolitan Area, Nigeria. Heavy metals analysis was carried out using a flame atomic adsorption spectrophotometer according to standard methods. Samples were cultured for microbes and identified. Bacteria samples were inoculated on nutrient agar and incubated at 37°C for 24 hours. Fungi counts were carried out using potato dextrose agar and incubated at 28°C for 3-5 days. The isolated organisms were identified based on their morphological and biochemical characteristics. Then 100 mL of the effluents was dispensed into 250 mL flasks, and the pH of the medium was adjusted to 7.2 by the addition of either sodium hydroxide or hydrogen chloride and autoclaved at 121°C for 15 minutes. The autoclaved flask was inoculated with 1 mL of bacteria and fungi for 21 days and pH was recorded properly every 48 hours.

RESULTS

The results of the physicochemical parameters indicated that conductivity, total suspended solids, total dissolved solids, turbidity, chemical oxygen demand and biochemical oxygen demand for all the three industrial effluents were higher than the World Health Organization (WHO) permissible limits. Heavy metal analysis results show that the effluents had high values for cadmium, above the WHO limit of 0.003 mg/L. Concentrations of zinc ranged from 0.136-1.690 mg/L, and nickel ranged between 0.004-0.037mg/L for the three effluents, within the WHO limit. The identified bacteria were Bacillus subtilis, Klebsiella pneumonia, Salmonella typhi and Bacillus cereus and isolated fungi were Aspergillus flavus and Penicillium chrysogenum. All the physicochemical parameters and heavy metal concentrations were reduced after the biodegradation study in the effluents.

CONCLUSIONS

The responses observed in the various microbes indicated that the use of microbes for the reduction of environmental pollutants has an advantage over the use of other methods because it is environmentally friendly, low cost, and no new chemicals are introduced into the environment. This method should be encouraged for pollution reduction to bring about ecosystem sustainability advocated for Ghana.

Concentration of heavy metals and trace elements in soils, waters and vegetables and assessment of health risk in the vicinity of a lignite-fired power plant

The pollution of agricultural soils, waters and products in the regions of lignite mines and fired power plants is of great importance. The concentration of As, Βa, Co, Cr, Sr, Sc, Th, U, Zn in soils and waters in the vicinity of a lignite-fired power plant in Northern Greece was determined using Instrumental Neutron Activation Analysis. The determination frequency was every three months during a period of one year in order to evaluate the seasonal impact of the pollution to the environment. Measurements were performed in three locations around the lignite mine as well as in one reference location at a certain distance from the mine. The results, which exhibited a slight seasonal variation, were compared, where possible, with literature values from other countries. The obtained data in most of the cases did not exceed the normal levels and indicated that the investigated area was only slightly contaminated. The concentration of heavy and trace metals was also measured in three common garden crops (tomato, cucumber and parsley) grown in this area. The calculated transfer factors (TF) from soil to vegetables and health risk quotients (HQ) do not denote a health risk.

Levels and potential health risk of heavy metals in marketed vegetables in Zhejiang, China

The present study analyzed 5785 vegetables for concentrations of As, Cd, Cr, Pb, Ni and Hg, and estimated the health risk to local consumers by deterministic (point estimates) approaches. Levels of elements varied in different vegetables. Average levels of As, Cd, Cr, Ni, Hg and Pb were 0.013, 0.017, 0.057, 0.002, 0.094 and 0.034 mg/kg (fresh weight), respectively. The samples with 0.25% for Cd and 1.56% for Pb were exceeding the maximum allowable concentrations (MACs) set by the Chinese Health Ministry. No obvious regular geographical distribution for these metals in vegetables was found in areas of Zhejiang, China. The mean and 97.5 percentile levels of heavy metal and metalloid were used to present the mean and high exposure assessment. The health indices (HIs) were less than the threshold of 1 both in mean and high exposure assessment. It indicates that for the general people there is very low health risk to As, Cd, Cr, Pb, Ni and Hg by vegetable intake.

Vertical distribution of heavy metals in soil profile in a seasonally waterlogging agriculture field in Eastern Ganges Basin

The accumulation of heavy metals in soil and water is a serious concern due to their persistence and toxicity. This study investigated the vertical distribution of heavy metals, possible sources and their relation with soil texture in a soil profile from seasonally waterlogged agriculture fields of Eastern Ganges basin. Fifteen samples were collected at ~0.90-m interval during drilling of 13.11 mbgl and analysed for physical parameters (moisture content and grain size parameters: sand, silt, clay ratio) and heavy metals (Fe, Mn, Cr, Cu, Pb, Zn, Co, Ni and Cd). The average metal content was in the decreasing order of Fe > Mn > Cr > Zn > Ni > Cu > Co > Pb > Cd. Vertical distribution of Fe, Mn, Zn and Ni shows more or less similar trends, and clay zone records high concentration of heavy metals. The enrichment of heavy metals in clay zone with alkaline pH strongly implies that the heavy metal distributions in the study site are effectively regulated by soil texture and reductive dissolution of Fe and Mn oxy-hydroxides. Correlation coefficient analysis indicates that most of the metals correlate with Fe, Mn and soil texture (clay and silt). Soil quality assessment was carried out using geoaccumulation index (I(geo)), enrichment factor (EF) and contamination factor (CF). The enrichment factor values were ranged between 0.66 (Mn) and 2.34 (Co) for the studied metals, and the contamination factor values varied between 0.79 (Mn) and 2.55 (Co). Results suggest that the elements such as Cu and Co are categorized as moderate to moderately severe contamination, which are further confirmed by I(geo) values (0.69 for Cu and 0.78 for Co). The concentration of Ni exceeded the effects-range median values, and the biological adverse effect of this metal is 87%. The average concentration of heavy metals was compared with published data such as concentration of heavy metals in Ganga River sediments, Ganga Delta sediments and upper continental crust (UCC), which apparently revealed that heavy metals such as Fe, Mn, Cr, Pb, Zn and Cd are influenced by the dynamic nature of flood plain deposits. Agricultural practice and domestic sewage are also influenced on the heavy metal content in the study area.

An eco-sustainable green approach for heavy metals management: two case studies of developing industrial region

Multifaceted issues or paradigm of sustainable development should be appropriately addressed in the discipline of environmental management. Pollution of the biosphere with toxic metals has accelerated dramatically since the beginning of the Industrial Revolution. In present review, comparative assessment of traditional chemical technologies and phytoremediation has been reviewed particularly in the context of cost-effectiveness. The potential of phytoremediation and green chemicals in heavy metals management has been described critically. Further, the review explores our work on phytoremediation as green technology during the last 6 years and hand in hand addresses the various ecological issues, benefits and constraints pertaining to heavy metal pollution of aquatic ecosystems and its phytoremediation as first case study. Second case study demonstrates the possible health implications associated with use of metal contaminated wastewater for irrigation in peri-urban areas of developing world. Our researches revealed wetland plants/macrophytes as ideal bio-system for heavy metals removal in terms of both ecology and economy, when compared with chemical treatments. However, there are several constraints or limitations in the use of aquatic plants for phytoremediation in microcosm as well as mesocosm conditions. On the basis of our past researches, an eco-sustainable model has been proposed in order to resolve the certain constraints imposed in two case studies. In relation to future prospect, phytoremediation technology for enhanced heavy metal accumulation is still in embryonic stage and needs more attention in gene manipulation area. Moreover, harvesting and recycling tools needs more extensive research. A multidisciplinary research effort that integrates the work of natural sciences, environmental engineers and policy makers is essential for greater success of green technologies as a potent tool of heavy metals management.

Concentration and potential health risk of heavy metals in market vegetables in Chongqing, China

Concentration and daily intake (DI) of heavy metals (Pb, Zn, Mn, Cu, Cd and Cr) in market vegetables in Chongqing of China are investigated and their potential health risk for local consumers is simultaneously evaluated by calculating the target hazard quotient (THQ). The results showed that the measured Pb and Cd concentrations exceeded the safety limits given by FAO/WHO and Chinese regulations, indicating serious contamination of market vegetables by these metals. As respective DI values for Pb, Mn and Cd were also above the international guideline bases, health risk to the consumers is obvious. The individual THQ for Pb and Cd in pakchoi and Cd in mustard, and the combined THQ for all metals in each vegetable species excluding cos lettuce were above the threshold 1.0, implying the obviously adverse effect on health. Therefore, attention should be paid particularly to the potential hazardous exposure to vegetable heavy metals, especially for Pb and Cd, over a lifetime for people in Chongqing.

Transfer characteristics of cobalt from soil to crops in the suburban areas of Fujian Province, southeast China

The bioavailability of cobalt and its transfer from soil to vegetables and rice were investigated. Among 312 soils collected from vegetable and paddy fields in the suburban areas of some major cities of Fujian Province, southeast China, total soil Co ranged from 3.5 to 21.7 mg kg(-1), indicating a slight accumulation compared with the background value of the province. DTPA extracted 0.1-8.5% of soil total Co. Total and DTPA-extractable Co correlated with soil pH, CEC, free Fe, total Mn, clay and silt content more significantly in paddy soils than in the soils from vegetable fields. The average Co concentrations in the edible parts of vegetables and rice were 15.4 microg kg(-1) and 15.5 microg kg(-1), respectively. The transfer factor (the ratio of plant Co to soil DTPA-extractable Co, TF(DTPA)) ranged from 0.003 to 0.126 with a median of 0.049. The TF(DTPA) decreased in the order of leafy vegetables > fruit vegetables > root vegetables > rice. The TF(DTPA) of all crops decreased with increasing DTPA-extractable Co. Increase in pH, CEC, organic matter, clay, silt, free iron and total Mn limited the soil-to-plant transfer of Co to varying degrees. The transfer of Co from the soils to the edible parts of the crops was lower than that of Zn, Cu and Cd, but higher than that of Pb in the same areas. The concentrations of Co in rice and vegetables in the study areas were considered to be safe for the local residents because of the slight anthropogenic input and the low transfer potential to the edible parts of Co from the soils.

Concentration of Cd, Cu, Pb, Zn, Al, and Fe in soils of Manresa, NE Spain

The aims of this study were to determine the contents of cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), aluminium (Al), and iron (Fe) (aqua regia-extractable) in 27 soil plots (54 samples) from Manresa, NE Spain, and to establish relationships between heavy metals and some soil properties. The main soil types were surveyed and the median concentrations (mg kg(-1)) obtained were Cd 0.28, Cu 20.3, Pb 18.6, Zn 67.4, Al 22,572, and Fe 21,551. Element concentrations for these soils were lower than the published values for the Valencia region (Spain) and Torrelles and Sant Climent municipal districts (Catalonia, Spain). In terms of soil properties, the results of this study suggest that, in Manresa soils, both trace element adsorption and retention are influenced by several properties such as clay minerals, carbonates, organic matter, and pH. All element contents were positively correlated with clay content. Pb and Zn were negatively correlated with pH and CaCO(3).

Influence of some soil parameters on heavy metals accumulation by vegetables grown in agricultural soils of different soil orders

The main purpose of this research was to determine the levels of heavy metals in tomato, potato and lettuce, grown in agricultural soils of different soil orders (Alfisols, Endisols and Vertisols), located at Central Greece. Soil samples were analysed for available forms (after extraction with DTPA) and for total concentrations (after digestion with Aqua Regia) of metals. Zn, Cu, Cr and Ni were the common metals detected in the vegetables studied. Pb and Cd concentrations were low and in some cases not detectable. Significant correlations among metals concentrations and soil physicochemical parameters were obtained and discussed. The pH value and the percentage of clay content were found to determine the solubility of metals in the soil and their availability for uptake by plants.

Influence of clinoptilolite rock on chemical speciation of selected heavy metals in sewage sludge

The chemical speciation of Cd, Cu, Pb, Cr and Ni in Torun municipal sewage sludge is investigated with addition of a natural sorbent (clinoptilolite rock). The total contents of the heavy metals in the sludge are substantially lower than the corresponding limits established by European or Polish legislation excepting nickel only. But the metals concentrations excepting lead exceed significantly the natural background (average contents in soils and in the Earth's crust) in dozens. Application of the sequential chemical extraction indicated that the metals in the sewage sludge are bound mainly (over 50%) in the residual fraction. The metals form the following order by parts of the mobile form: Ni> Cd>> Cr> Cu>> Pb. Addition of the clinoptilolite to the sludge leads to the metals contents fall in all four fractions of the sequential procedure. Concentrations of mobile forms of cadmium, chromium, copper and nickel decrease by 87, 64, 35 and 24%, respectively, as a result of addition of 9.09% of the clinoptilolite. The total decreases of the metals amount after 9.09% clinoptilolite addition to the sludge are around 11, 15, 25, 41 and 51% for copper, nickel, chromium, cadmium and lead, respectively.

Determination and evaluation of cadmium, copper, nickel, and zinc in agricultural soils of western Macedonia, Greece

The objective of this study was to determine the levels of major phytotoxic metals--including cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn)--in agricultural soils of Western Macedonia, Greece. We also wanted to determine the possible relationships among elements and between soil properties and elemental concentrations. Surface soil samples, n = 570, were collected and analyzed. The results of the elemental analysis showed that the mean metal concentrations were consistent with reported typical concentrations found in Greek agricultural soils in the cases of Zn and Cu. Cd exhibited lower and Ni higher mean concentrations than the typical levels reported in the literature. Metal concentrations in the majority of the examined samples (>69%) were found to be higher than the respective critical plant-deficiency levels. However, only 0.4% and 0.2% of the analyzed soil samples, respectively, exhibited Cd and Ni concentrations higher than the levels that cause plant toxicity, as referenced by other investigators. These results suggest that the soils studied can be considered as unpolluted with respect to the examined food-chain metal contaminants. However, the levels of the metal concentrations in some of the soil samples, and the low correlation of the metals with soil properties, suggest an anthropogenic rather that lithogenic origin.

Assessing heavy metal sources in agricultural soils of an European Mediterranean area by multivariate analysis

According to the European Thematic Strategy for Soil Protection, the characterization of the content and source of heavy metals in soils are necessary to establish quality standards on a regional level that allow the detection of sampling sites affected by pollution. In relation to this, the surface horizons of 54 agricultural soils under vegetable crops in the Alicante province (Spain), a representative area of the European Mediterranean region, were sampled to determine the content of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Analytical determinations were performed by atomic absorption spectroscopy after microwave sample digestion in acid solution. Results indicated that heavy metal levels were similar to those reported by authors working on agricultural soils from other parts of the Mediterranean region, with the exception of Cu and Pb in some samples. Multivariate analysis (principal component analysis and cluster analysis) was performed to identify a common source for heavy metals. Moreover, soil properties were determined in order to characterize agricultural soils and to analyze relationships between heavy metal contents and soil properties. The content of Co, Cr, Fe, Mn, Ni and Zn were associated with parent rocks and corresponded to the first principal component called the lithogenic component. A significant correlation was found between lithogenic metals and some soil properties such as soil organic matter, clay content, and carbonates, indicating an important interaction among them. On the other hand, elements such as Cd, Cu and Pb were related to anthropic activities and comprised the second (Cu and Pb) and third principal components (Cd), designated the anthropogenic components. Generally, Cd, Cu and Pb showed a lower correlation with soil properties due to the fact that they remain in available forms in these agricultural soils. Taking into account these results and other achieved in other parts of the European Mediterranean region, it can be concluded that soil quality standards are highly needed to declare soils affected by human induced pollution. This is particularly relevant for anthropogenic metals (Cd, Cu and Pb, and in some areas also Zn). Further research in other agricultural areas of the region would improve the basis for proposing such soil quality standards.

Risk assessment for safety of soils and vegetables around a lead/zinc mine

Concentrations of heavy metals (Pb, Zn, Cd, Cu) were determined in soils and vegetables (chrysanthemum, spinach and four cultivars of Chinese cabbage from the area adjacent to a Pb/Zn mine in Shaoxing, Zhejiang province, China, and compared with the Chinese National Standards for Soil Environmental Quality. The accumulation of heavy metals in cabbage cv. Siyuegreen was investigated at different distances from the center of the mine. The vegetable plantation soils were polluted with Pb, Cd, Cu and Zn, especially by Pb and Cd. The levels of Pb and Cd were 20 and 30 times higher than the permitted standards, indicating that this Pb/Zn mining area is unsuitable for agricultural use. Chinese cabbage, chrysanthemum and spinach had different enrichment coefficients. The enrichment coefficient of Cd from soil to roots of chrysanthemum was >80% and from roots to leaves of cabbage cv. Shanghaigreen was >120%. These vegetables were polluted by heavy metals and could not be regarded as safe for human consumption. Environmental accumulation of heavy metals in the vegetable plantation soils was proportional to heavy metal accumulation in vegetables and both were inversely proportional to the distance from the lead/zinc mine.

Risk assessment of heavy metals in soils and vegetables around non-ferrous 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.

Metal contamination of soils and crops affected by the Chenzhou lead/zinc mine spill (Hunan, China)

In 1985, the collapse of the tailing dam in Chenzhou lead/zinc mine (Hunan, southern China) led to the spread of mining waste spills on the farmland along the Dong River. After the accident, an urgent soil cleaning up was carried out in some places. Seventeen years later, cereal (rice, maize, and sorghum), pulses (soybean, Adzuki bean, mung bean and peanut), vegetables (ipomoea, capsicum, taro and string bean) and the rooted soils were sampled at four sites: (1) the mining area (SZY), (2) the area still covered with the mining tailing spills (GYB), (3) the cleaned area from mining tailing spills (JTC), and (4) a background site (REF). Metal concentrations in the crops and soils were analyzed to evaluate the long-term effects of the spilled waste on the soil and the potential human exposure through food chains. The results showed that the physical-chemical properties of the soils obviously changed due to the different farming styles used by each individual farmer. Leaching effects and plant extraction of metals from some soils were quite weak. Certain soils were still heavily polluted with As, Cd, Zn, Pb and Cu. The contamination levels were in the order of GYB>SZY>JTC showing that the clean-up treatment was effective. The maximum allowable concentration (MAC) levels for Chinese agricultural soils were still highly exceeded, particularly for As and Cd (followed by Zn, Pb and Cu), with mean concentrations of 709 and 7.6 mg kg(-1), respectively. These concentrations exceed the MAC levels by 24 times for As and 13 times for Cd at GYB. Generally, the edible leaves or stems of crops were more heavily contaminated than seeds or fruits. Ipomoea was the most severely contaminated crop. The concentrations of Cd and Pb were 3.30 and 76.9 mg kg(-1) in ipomoea leaves at GYB, which exceeded the maximum permit levels (0.5 mg kg(-1) for Cd and 9 mg kg(-1) for Pb) by 6.6 and 8.5 times, respectively. Taro (+skin) could accumulate high concentrations of Zn and Cd in the edible stem, and rice and capsicum had high Cd concentration in the edible parts. However, the toxic element concentrations in maize, sorghum, Adzuki bean, soybean and mung bean remained lower than the threshold levels. The bio-accumulation factors (BAFs) of crops were in the order: Cd>Zn>Cu>Pb>As. BAF was typically lower in the edible seeds or fruits than in stems and leaves. The accumulation effect strongly depends on the crop's physiological properties, the mobility, of the metals, and the availability of metals in soils but not entirely on the total element concentrations in the soils. Even so, the estimated daily intake amount of Cu, Zn, Cd, and Pb from the crops grown in the affected three sites and arsenic at SZY and GYB exceeded the RDA (Recommended dietary allowance) levels. Subsequently, the crops grown in Chenzhou Pb/Zn mine waste affected area might have a hazardous effect on the consumer's health. This area still needs effective measures to cure the As, Cd, Pb, Zn and Cu contamination.

Sulfur, chromium, and selenium accumulated in Chinese cabbage under direct covers

Currently, pollution of our agricultural soils and waters is increasing and is often associated with many human health ailments. Soils contaminated with low levels of heavy metals and other trace elements are frequently used for growing vegetable crops and in such a situation, these toxic contaminants often accumulate in the edible portions of these agricultural plants and thereby enter the human food chain. In 3 consecutive years of field experiments (1994-1996), two different crop-covering treatments--T (50 microm perforated polyethylene), and T2 (17 gm(-2) non-woven polypropylene)--were used to modify the environmental conditions for the growth of Chinese cabbage 'Nagaoka 50' [Brassica rapa L. (Pekinensis group)]. Open-air plots (T(0)) were used as controls. Analytical determinations of chromium (Cr), selenium (Se), two forms of sulfur (total-S and sulfate-S), and amino acids (Isoleucine, leucine, lysine, methionine, serine, threonine, and valine) were performed utilizing plant shoots for analysis. The T1 and T2 treated plants contained concentrations of lysine, methionine, serine, and threonine higher than in T(0). Under T1, the extent of Cr and Se removal in the field was more favorable. Direct covers could be used in contaminated agricultural zones for a variety of plant species, not just for use with those plants previously reported to be efficient at bio-accumulating toxic elements because the thermal effect created by the covers favors phytoextraction processes. However, it is clear that the accumulation of these toxic substances in the plants (Cr) would deem the plant material unsuitable for human consumption and use as animal fodder.

Assessment of essential and toxic elements in some kinds of vegetables

Vegetables provide the human body with the essential bioavailable trace elements, and a constant supply of these various elements is necessary and highly recommended for daily life. Minor elements such as Ca, Fe, K, Mg, and Na as well as trace elements such as Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined using an atomic absorption spectrophotometer in 12 different species of vegetables from Saudi Arabia (the Al-Taif district). These vegetables were cucumber, vegetable marrow, tomato, potato, green pepper, eggplant, carrots, parsley, lettuce, spinach, salq, onion, leek, watercress, and cabbage. The results reveal that the different element concentrations of each vegetable depend upon the selective uptake of the elements by the plant. Salq and watercress exhibited higher element concentrations than the other vegetables. Cluster analysis, principle component analysis, and transfer factor analysis of elements from soil to plant were applied to the elements database and produced good interpretations of the data. The element concentrations of these vegetables were within safety baseline levels for human consumption.

Phylogenetic variation in heavy metal accumulation in angiosperms

•  The influence of phylogeny on shoot heavy metal content in plants was investigated and the hypothesis tested that traits impacting on the accumulation of cadmium, chromium, copper, nickel, lead and zinc in plant shoots are associated. •  Data suitable for comparative analyses were generated from a literature survey, using a residual maximum likelihood (REML) procedure. Both pair-wise regressions and principal components analyses (PCA) were performed on independent contrasts of shoot metal content. •  Significant variation in shoot metal content occurred at the classification level of order and above, suggesting an ancient evolution of traits. Traits impacting on the accumulation of metals in plant shoots were associated. •  This information can be used to improve predictions of soil-to-plant metal transfer, to formulate hypotheses on the origins of metal-accumulating phenotypes and to inform the exploitation of plant genetic resources for nutritional improvement and phytoremediation.

Evaluation of heavy metal availability in polluted soils by two sequential extraction procedures using factor analysis

Superficial soil and grass samples from 13 locations affected by several anthropogenic sources (mining, metal factory, traffic emissions) were collected in Gipuzkoa, northern Spain. The more labile metal fractions, the mobile (extracted by 0.01 mol l(-1) CaCl(2)) and the mobilisable (extracted by 0.005 mol l(-1) DTPA), were evaluated using a short sequential procedure with two steps. From the results a short-medium term potential lability of Cd, Cu, Zn and Pb can be concluded. The labile levels were compared with the results obtained using the Tessier sequential procedure. Factor analysis was used to check the associations between the total metal contents in soil and grass, as well as between the levels of the different sequential fractions and the total content in grass. Cd, Cu and Zn labile levels were related to total metal grass contents indicating its suitability for the availability studies in polluted soil-plant system.

Dietary intake of trace elements and polycyclic aromatic hydrocarbons via vegetables grown in an industrial Greek area

In order to assess the importance of vegetables cultivated in industrialized regions in Greece as a dietary factor, the daily intake of trace elements and PAHs via vegetables were estimated. Intake estimations were based on vegetable availability data and analyses of vegetable contaminants. The mean daily intake of potentially toxic elements ranged between 1.7% (for As) and 23.6% (for Pb) the provisional tolerable daily intakes for adults. Vegetables were found to contribute significantly to the recommended daily intake of essential elements, such as Cr and Mn. The intakes of Cr, Pb, Zn, Co and Hg were highest in spring, whereas the intakes of As and Se were highest in winter. The daily intake of PAHs via vegetables was in general low. The potential doses of carcinogenic PAHs was at the lower range of estimates worldwide.