Maximum Concentrations Of Pb Research Articles

Lead in soil and agricultural products in the Huainan Coal Mining Area, Anhui, China: levels, distribution, and health implications.

Heavy metal accumulation in agricultural soil is of great concern, as heavy metals can be finally transferred to the human body through the food chain. A field survey was conducted to investigate the lead (Pb) levels and distribution in soil, agricultural products (wheat, paddy, and soybean), and fish, in the Huainan Coal Mining Area (HCMA), Anhui Province, China, to provide reference information to local inhabitants. The daily intake and target hazard quotients of Pb through food consumption were assessed. Results showed that the mean Pb concentration in soil was higher than the Huainan soil background Pb value but lower than the maximum allowance Pb concentration for agricultural soil (GB 15618-2008). The elevated Pb in soil, especially in rainy months (June to August in Huainan), might be related to Pb leaching from ambient coal gangue piles. Excessive Pb concentration was found in the grains of food crops, which would pose a potential health risk to local inhabitants. Therein, wheat showed higher Pb bioaccumulation ability than other crops. With regard to the Pb levels in muscles, fishes were considered to be safe for consumption. The calculations on daily intake and tolerable hazard quotient of Pb suggest that the potential health hazard posed by Pb is currently insignificant for the inhabitants in the HCMA.

Geochemical normalization and assessment of heavy metals (Cu, Pb, Zn, and Ni) in sediments from the Huaihe River, Anhui, China

Fifty-four surface sediment samples were collected in July 2013, from the Huaihe River (Anhui Province) in eastern China, which flows through Shouxian, Fengtai and Huaiyuan counties and Huainan city. The total Cu, Pb, Zn, Ni, Al and Fe concentrations were determined using an inductively coupled plasma-optical emission spectrometer (ICP-OES). Heavy metal geochemical normalization with Al was utilized to minimize the natural metal variability in the sediments before the metal enrichment was evaluated. Moreover, the predicted and maximum Cu, Pb, Zn and Ni natural concentrations were obtained using a linear regression model. A modified geo-accumulation index, where the regional background value was substituted with the predicted natural metal concentrations, was used to assess heavy metal contamination. Zn exhibited the most substantial contamination, followed by Pb, Cu, and Ni. Furthermore, the high Pb concentrations are likely attributed to exhaust discharged by automobile or ships, and coal combustion flue gas deposition, the latter of which may also be the source of Zn. Copper and Ni originate mainly from natural sources, with only a small anthropogenic contribution.

Contaminants in surface water and sediments near the Tynagh silver mine site, County Galway, Ireland

A former silver mine in Tynagh, Co. Galway, Ireland is one of the most contaminated mine sites in Europe with maximum concentrations of Zn, As, Pb, Mn, Ni, Cu, and Cd far exceeding guideline values for water and sediment. The aims of this research were to 1) further assess the contamination, particularly metals, in surface water and sediment around the site, and 2) determine if the contamination has increased 10years after the Environmental Protection Agency Ireland (EPAI) identified off-site contamination. Site pH is alkaline to neutral because CaCO3-rich sediment and rock material buffer the exposed acid generating sulphide-rich ore. When this study was compared to the previous EPAI study conducted 10years earlier, it appeared that further weathering of exposed surface sediment had increased concentrations of As and other potentially toxic elements. Water samples from the tailings ponds and adjacent Barnacullia Stream had concentrations of Al, Cd, Mn, Zn and Pb above guideline values. Lead and Zn concentrations from the tailings pond sediment were 16 and 5 times higher, respectively, than concentrations reported 10years earlier. Pb and Zn levels in most sediment samples exceeded the Expert Group (EGS) guidelines of 1000 and 5000mg/kg, respectively. Arsenic concentrations were as high as 6238mg/kg in the tailings ponds sediment, which is 62 and 862 times greater than the EGS and Canadian Soil Quality Guidelines (CSQG), respectively. Cadmium, Cu, Fe, Mn, Pb and Zn concentrations in water and sediment were above guideline values downstream of the site. Additionally, Fe, Mn and organic matter (OM) were strongly correlated and correlated to Zn, Pb, As, Cd, Cu and Ni in stream sediment. Therefore, the nearby Barnacullia Stream is also a significant pathway for contaminant transport to downstream areas. Further rehabilitation of the site may decrease the contamination around the area.

Children's health risk assessment based on the content of toxic metals Pb, Cd, Cu and Zn in urban soil samples of Podgorica, Montenegro.

Due to their low tolerance to pollutants and hand-to-mouth pathways the health risk is very high in children's population. The aim of this study was to evaluate risk to children's health based on the content of heavy metals in urban soil samples from Podgorica, Montenegro. This study included the investigation of several toxic metals such as Pb, Cd, Cu and Zn in soil samples from public parks and playgrounds. Sampling was conducted in a period October-November, 2012. Based on cluster analysis, soil samples were divided into two groups related to similarity of metal content at examinated locations: the group I--near by recreational or residential areas of the city, and the group II--near traffic roads. Concentration of toxic metals, in urban soil samples were determined by a graphite furnace atomic absorption spectrometry (Pb and Cd) and by inductively coupled plasma optical emission spectrometry technique after microwave digestion. Due to exposure to urban soil, non-cancerogenic index hazardous index (HI) for children was estimated using 95th percentile values of total metal concentration. The value of the total (ingestion, dermal and inhalation) HI is calculated for maximum, minimum and the average concentration of metals for children. Mean concentrations of Pb, Cd, Cu and Zn in the surface layer of the studied urban soils were 85.91 mg/kg, 2.8 mg/kg and 52.9 mg/kg and 112.5 mg/kg, respectively. Samples from group II showed higher metal content compared to group I. Urbanization and traffic are the main sources of pollution of the urban soils of Podgorica. Most of the samples (93.5%) had a high Pb content, 12.9% of the samples had a higher content of Cd, while Cu and Zn were within the limits prescribed by national legislation. At one location the level of security for lead is HI = 0.8 and very closed to maximum acceptable value of 1. It is probably the result of intensive traffic near by. All metals investigated showed relatively higher concentrations at sites that were close to industrial places and high ways. The mean concentrations of Pb and Zn and maximum concentrations of Pb, Cd, and Zn were higher than presented values in the National Regulation.

Food Safety Study of Duck Eggs Produced Along Laguna Lake Areas, Philippines

This study aimed to determine the farm practices related to duck egg production as well as assess the safety of duck eggs for human consumption. Specifically, it aimed to 1) describe farm practices related to duck egg production in the Province of Laguna.; 2) determine the volume of egg production and its geographic flow; and 3) assess the safety of the duck eggs for human consumption in terms of its lead (Pb) content by comparing it with the maximum tolerable daily intake of Pb set by the World Health Organization (WHO). Results showed that the number of ducks raised ranged from 800 to 45,000 heads. Each farm had their own way of feeding ducks except for the use of snails as feeds that is common to all. In addition to snails, a mixture of commercial feeds, desiccated coconut (sapal) and fine rice particles (binlid) were given as feeds. A special “all natural diet” with probiotics was used as feeds in the sample farm in Victoria as feeds. The lead concentrations of raw duck eggs from the three farms were 0.20 mg/kg Fresh Weight (FW), 0.22 mg/kg FW and 0.20 mg/kg FW for samples A (Los Banos), B (Bay) and C (Victoria), respectively with a mean Pb content of 0.21 mg/kg FW. Also, the mean Pb content of duck eggs analyzed is far higher than the mean Pb content of eggs in developed countries (0.02 mg/kg) as well as with the Pb content of water spinach that were grown near the domestic areas alongside Laguna de Bay (0.02 mg/kg FW). Furthermore, it is found to be within the recommended maximum concentration of Pb in solid food, that is, 6 mg/kg. Using the maximum tolerable daily intake of Pb for adult set by the WHO (2001) which is 0.21 mg/kgBW as reference, developing Pb toxicity from the intake of duck eggs over a short period of time is therefore impossible. Nonetheless, heavy metals like Pb can accumulate in the body when consumed over a long period of time and pose health hazards. As a conclusion, the presence of Pb in duck egg may cause health hazards when taken in excess amounts over a long period of time. Further studies on safety of duck egg for human consumption as well as health risk assessment are recommended as basis for development of policies related to human health and environment.

Lead, mercury and arsenic content in spices: Black, white and green pepper, black cumin and ginger

In order to evaluate the safety of selected commercial spices brands, concentration of lead, mercury and arsenic, as well as moisture and mineral contents were analyzed in samples of dried black and white pepper powders, black, white and green peppercorns, black cumin seeds and ginger powder. Lead (Pb), mercury (Hg) and arsenic (As) concentrations in spice samples purchased from local markets in Belgrade were determined, after a microwave digestion of the samples, by atomic absorption spectrometry (AAS), using the graphite furnace AAS technique (Pb), cold vapor AAS technique (Hg) and hydride generation AAS technique (As). Trace levels of Pb, Hg and As in the selected dried spices samples were in the range 0.10 ppm - 0.79 ppm, 0.01 ppm - 0.10 ppm and 0.01 ppm - 0.51 ppm, respectively. The maximum Pb concentration was determined in the sample of ginger and it was 0.79 ppm, the maximum concentration of Hg was 0.10 ppm, determined in green peppercorns samples, while the maximum concentration of As in powdered black pepper sample was 0.51 ppm. The moisture and mineral contents in the different analyzed spices were in the range 1.70-13.10% and 3.40-6.50%, respectively. According to the obtained results, the concentrations of the analyzed toxic elements, as well as the moisture and mineral content in selected spices, were below the maximum permissible limits declared by the national legislations deemed safe for human consumption.

Seasonal variations in the body composition and bioaccumulation of heavy metals in Nile tilapia collected from drainage canals in Al-Ahsa, Saudi Arabia

The body composition of Nile tilapia (Oreochromis niloticus) collected from drainage canals in Al-Ahsa, Saudi Arabia and the concentration of four heavy metals; zinc (Zn), cadmium (Cd), cobalt (Co) and lead (Pb) in both fish muscles and the water collected from this environment were assessed across the four seasons. The body composition was found to change with the seasons, with the best body composition being recorded in autumn and winter, where higher levels of protein (17.24, 17.65%), and fat (0.58, 0.71%) and lower water content (80.15, 79.86%) respectively were noted. The concentration of heavy metals in both fish muscles and the water body also varied significantly with the seasons. In the fish muscles, the highest content of Zn (0.409mg/kg dry weight) and Cd (4.140mg/kg dry weight) was recorded in winter, however, the highest concentration of Co (0.318mg/kg dry weight) and Pb (1.96mg/kg dry weight) was observed in spring and summer respectively. On the other hand, the water samples collected in autumn showed the maximum concentration of Cd (1.385mg/L), Co (0.762mg/L) and Pb (0.18mg/L) however, the maximum concentration of Zn (0.0041mg/L) was recorded in winter. With the exception of Cd, the accumulation of the studied heavy metals in fish muscles was within the safe limits for seafood recommended by various organizations.

Health hazard prospecting by modeling wind transfer of metal-bearing dust from mining waste dumps: application to Jebel Ressas Pb–Zn–Cd abandoned mining site (Tunisia)

This work presents a modeling approach to simulate spatial distribution of metal contamination in aerosols with evaluation of health hazard. This approach offers the advantage to be non-intrusive, less expensive than sampling and laboratory analyses. It was applied to assess the impact of metal-bearing dust from mining wastes on air quality for a nearby community and agricultural lands in Jebel Ressas (Tunisia) locality. Dust emission rates were calculated using existing parameterization adapted to the contamination source composed of mining wastes. Metal concentrations were predicted using a Gaussian model (fugitive dust model) with, as input: emission rates, dump physical parameters and meteorological data measured in situ for 30days in summertime. Metal concentration maps were built from calculated PM10 particle concentrations. They evidence the areas where Pb and Cd concentrations exceeded WHO guidelines (0.5 and 0.005µg/m(3), respectively). Maximum concentrations of Pb and Cd in PM10 are, respectively, of 5.74 and 0.0768µg/m(3) for measured wind speed values up to 22m/s. Preferential areas of contamination were determined in agricultural lands to the NW from the source dump where Pb and Cd exceeded guidelines up to a distance of 1,200m. The secondary spreading directions were SW and E, toward the village. Health hazard prospecting shown that a major part of the village was exposed to contaminated dust and that daily hazard quotient (HQ) values reached locally 118 and 158, respectively, for Pb and Cd during the study period. However, HQ variations in the village are high, both temporally and geographically.

English

The aim was to measure the concentrations of heavy metals in groundwater obtained from 30 randomly selected domestic wells and 10 stream locations all in Ibadan, Nigeria, compare the results with the World Health Organization guidelines, draw conclusions and make recommendations. Water samples were obtained and analysed for Pb, As, Cd, Zn, Cu, Cr, Fe and Mn. Overall, the minimum concentrations of Pb, As, Cd, Cr and Fe in the well water samples were below detection limit (BDL). The maximum values were 0.02, 0.45, 0.01, 0.445, 0.135, 0.09, 0.245 and 0.155 mg/l respectively. In the surface water samples, the minimum concentrations of Pb, As, Cd and Cr were below detection level, while the maximum concentrations of Pb, As, Cd, Zn, Cu, Cr, Fe and Mn were respectively 0.075, 0.05, 0.001, 0.445, 0.120, 0.065, 0.45 and 0.16 mg/l. No evidence of contamination of these water supply sources with heavy metals was found going by the fact that the values obtained were lower than the guideline values established by the World Health Organization. A possible exception is As which in some samples had higher concentrations than the WHO guideline. The recommendations of the study include continuous and close monitoring of these private drinking water supplies. There must also be strict compliance to regulatory limits in sludge and wastes to be released into the environment, and enforcement of other environmental protection regulations. Findings from this study will be of immense help to the general public as well as researchers and environmental regulators working in this area of interest in developing countries.       Key words:  Heavy metals, drinking water, Ibadan

Heavy Metals in Oysters, Shrimps and Crabs from Lagoon Systems in the Southern Gulf of México

Lagoon systems in the southern Gulf of Mexico are highly productive. These aquatic systems have been severely negatively impacted by anthropogenic and industrial activities. The objective of this research was to estimate the concentration of heavy metals Pb, Cu, Cd and Zn in oysters, shrimp and crabs from the Carmen-Pajonal-Machona and Mecoacán lagoon systems in Tabasco, México. Samples were collected from fishing zones within these lagoon systems and included oysters Crassostrea virginica, and crustaceans such as Litopenaeus setiferus (shrimp) and Callinectes sapidus (crab). Concentrations of Pb, Cu, Cd and Zn were determined by atomic absorption using flame spectrophotometry. The heavy metal concentration pattern in oysters, shrimp and crab in the Carmen-Pajonal-Machona system was Cu > Pb > Cd. The maximum average concentration of Cu was 259.12 ± 12.312 in oyster; 0.516 ± 0.154 in shrimp, and in crab 0.907 ± 0.273 µg g-1. Pb had a maximum concentration of 1.37 ± 0.77 in oyster, in shrimp was 0.059 ± 0.044, and for crab was 0.0055 µg g-1 (p>0.05), while in the Mecoacán lagoon system the pattern showed Pb > Cd > Zn. The maximum average concentration of Pb was 321.15 ± 28.828 µg g-1, the minimum was 84.70 ± 8.612 µg g-1. The highest concentration of Cd was 63.74 ± 8.446 µg g-1, and the minimum 13.00 ± 0.64 µg g-1. For Zn the maximum average concentration obtained was 24.42 ± 2.665 µg g-1.

Effectiveness of Phytoremediation Technologies to Clean Up of Metalloids Using Three Plant Species in Iran

Phytoremediation is a potential, innovative, and cost-effective technology for non-destructive remediation of heavy-metal contaminated soils. A field trial was conducted to evaluate the phytoremediation efficiencies of three plants and the effects of ethylenediaminetetraacetic acid (EDTA) or ammonium addition [(NH4)2SO4 and NH4NO3] for assisting removal of heavy metals (Pb, Hg, and Cd) from contaminated soil. The tested plants include Amaranthus retroflexus, Sorghum bicolor, and Lolium perrene. Results showed that maximum concentration of Pb, Hg, and Cd were detected in shoots of A. retroflexus, S. bicolor, and L. perrene at high concentrations in pH=6.2. The application of EDTA as a chelating agent to soil was the most efficient to enhance the phytoavailability of Pb, Hg and Cd. The concentrations of Pb, Hg, and Cd in the shoots of A. retroflexus treated with EDTA were 57 mg/kg, 14.1 mg/kg, and 30 mg/kg, respectively. Results indicated that among the three plants, A. retroflexus had great potential in phytoremediation of contaminated soils.

Assessing of Heavy Metal Concentrations in the Tissues of Rutilus rutilus caspicus and Neogobius gorlap from Miankaleh International Wetland

The concentrations of four heavy metals (Pb, Cd, Ni and Cr) were measured in tissues of pelagic (Rutilus caspicus) and benthic (Neogobius gorlap) fishes from the Miankaleh international wetland. The maximum concentrations of Pb, Cd, Ni, and Cr (2.06, 1.20, 1.14 and 0.70 μg g(-1), respectively) were measured in the liver of N. gorlap, while the lowest concentrations were measured in muscle tissue collected from R. caspicus (Pb 0.67; Cd 0.25; Ni 0.21 and Cr 0.08 μg g(-1)). The mean concentrations of metals in liver of R. caspicus and N. gorlap followed a trend where Pb > Cd > Ni > Cr, whereas in R. caspicus and N. gorlap gills and N. gorlap muscle the following trend was observed Pb > Ni > Cd > Cr. The data of presented study show that the liver and gill tissues have higher metal concentrations than muscle and also the metal concentrations in tissues of N. gorlap (benthic) were higher in comparison with R. caspicus (pelagic).

Source assessment of deposited particles in a Slovenian show cave (Postojnska jama): evidence of long-lasting anthropogenic impact

Postojnska jama (Postojna Cave) is one of the most famous karst caves in the world and has been a well-known tourist attraction for nearly 200 years. It is particularly famous for its unique double-track railway. Eight heavy metals – aluminium (Al), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), strontium (Sr), and zinc (Zn) – were determined in dust deposits by ICP-MS in order to assess sources of deposited particles on the cave walls. The samples were collected along the main passage in the cave, at different horizontal and vertical levels, in order to test horizontal homogeneity and study vertical distribution of the particles. It seems that the railway is an important anthropogenic source of particles, reflected in increased concentrations of Cu, Pb, and Zn, as well as of Fe and Mn in dust deposits at individual sampling sites. The maximum concentrations of Cu (217 µg g -1 ), Pb (4,940 µg g -1 ), and Zn (1,060 µg g -1 ) considerably exceeded their natural abundance and were explained by anthropogenic impact. The three heavy metals are markers for vehicles, engine oil and brake wear. On the other hand, mixed sources could prevail for Fe and Mn. The maximum concentrations of Fe (85,900 µg g -1 ) and Mn (682 µg g -1 ) in dust deposits were similar to the concentrations determined in fragments of the railway tracks (97,100 µg g -1 for Fe and 821 µg g -1 for Mn) and were explained by track wear and/or corrosion. In most other parts of the cave, Fe and Mn concentrations were, however, below the concentration of their natural abundance. Al, Sr, and Cr seem to be predominantly of natural origin. They generally exhibited concentrations lower than their natural abundance.

Absorptive Extraction of Pb by Cattail Plant

A kind of cattail (Typhaorientalis Presl) were collected from a tailings of Pb mine and cultivated in a hydroponic solution containing different concentrations of Pb (NO3)2 in order to identify whether T.orientalis is potential for phytoremediation of Pb. The results showed that cattail collected from the Pb mine had a strong accumulation of Pb: the average Pb concentrations in the leaves and roots are 619 mg kg-1 and 1233 mg kg-1, respectively; the translocation factors were high ranging from 0.48 to 0.52; the growth of this cattail was not affected by Pb up to 300 mg L-1. The Pb concentrations in the leaves and roots increased with the increase of Pb level in the nutrient solution and the maximum Pb concentrations in the leaves and roots were 16190 mg kg-1 and 64405 mg kg-1, respectively. This study suggests that T.orientalis could accumulation Pb with great efficiency and is potential for phytoremediation.

Heavy metal and sulfur concentrations and mycorrhizal colonizing status of plants from abandoned lead/zinc mine land in Gejiu, Southwest China

A field survey of heavy metals and sulfur concentrations and mycorrhizal status of plants grown in abandoned lead/zinc mine land was conducted in Gejiu City, Yunnan Province, Southwest China. Low or no root arbuscular mycorrhizal fungi (AMF) infection was detected in most of the plants for 21 species of 13 families collected from the abandoned Pb/Zn mine land. The maximum concentrations of Pb, Zn, Cd and As was up to 11255.3 ± 1887.2, 5884.2 ± 531.9, 70.5 ± 0.8 and 498.9±38.1 mg/kg in soils, respectively. The maximum concentration of Pb, Zn, Cd and As in plants shoot was 2323.4 ± 125.0, 1273.7 ± 140.0, 238.5 ± 19.5 and 326.7 ± 53.2 mg/kg, and which in plants root was 3480.0 ± 642.9, 1421.6 ± 251.3, 291.8 ± 11.2 and 390.6 ± 30.1 mg/kg, respectively. The average S concentrations were 0.29 and 0.19% DW in plants shoots and roots, respectively. Significant correlation between S and Pb, Zn, As concentrations in plants shoots, and between S and Pb, Zn, Cd, As concentrations in plants roots was observed. Key words: Lead/zinc mine, heavy metal, sulfur, arbuscular mycorrhizal fungi, relation, Gejiu.

Health risk assessment and multivariate apportionment of trace metals in wild leafy vegetables from Lesser Himalayas, Pakistan

Fresh wild leafy vegetables and related soil samples were collected from Lesser Himalayas, Pakistan to evaluate the trace metal levels and related health risk to the consumers. The samples were prepared by acid digestion, followed by quantification of selected trace metals (Fe, Zn, Cu, Mn, Cr, Cd and Pb) on atomic absorption spectrophotometer. Generally, in the vegetables highest concentrations were detected for Fe, followed by Zn, Mn and Pb. Among the vegetables, highest concentrations of Zn, Cu and Cr were found in Solanum nigrum, while Stellaria media showed the elevated levels of Fe and Cd. Nevertheless, maximum concentrations of Mn and Pb were found in Convolvulus arvensis and Amaranthus viridis, respectively. In the case of soil, highest levels were observed for Fe, followed by Mn, Zn, Pb, Cr and Cu. Translocation of trace metals from soil to the vegetables exhibited highest values for Cd, followed by Zn. Multivariate principal component analysis showed significant anthropogenic contributions of the Pb, Cr, Zn, Cd and Fe in the vegetables. Health risk assessment was evaluated in terms of health risk index, target hazard quotient and hazard index which showed that the intake of some trace metals through vegetables was higher than the recommended values, consequently consumption of the vegetables may be associated with non-carcinogenic health risks. Nonetheless, elevated levels of Cr and Pb were also found to be associated with lifetime carcinogenic risk to the consumers.

Concentration of some metals in the muscles of fish from selected lakes of Warmia and Mazury region (Poland)

In view of very scarce and limited information concerning the content of heavy metals in tissues of fish from the lakes in north-eastern Poland, the aim of the study was to determine the content of some heavy metals in the muscle tissue of two fish species: bream (Abramis brama) (n = 60) and pikeperch (Sander lucioperca) (n = 60) caught in selected lakes of Warmia and Mazury region (Poland) in 2010 as well as to asses human health safety. The concentration of lead (Pb), mercury (Hg), copper (Cu), iron (Fe) and zinc (Zn) in the muscle tissue of bream and pikeperch was determined by atomic absorption spectrometry. The mean concentration of toxic metals (Pb and Hg) in muscles of bream was 0.07 mg/kg and 0.03 mg/kg, respectively, and 0.10 mg/kg and 0.13 mg/kg in muscles of pikeperch, respectively. The mean concentration of Cu, Fe and Zn found in the muscles of bream was 0.33 mg/kg, 7.27 mg/kg and 6.12 mg/kg in muscles of pikeperch it was 0.21 mg/kg, 5.56 mg/kg and 6.02 mg/kg, respectively. It was found that the content of the analysed metals in fish muscles was low and did not exceed the values of limits admissible in the European Union. At the assumed mean and maximum concentration of Pb and Hg, the values of PTWI (provisional tolerable weekly intake) were not exceeded (i.e. 0.56% PTWI for Pb and 3.01% PTWI for Hg), therefore the consumption of fish originating from selected lakes of Warmia and Mazury does not constitute a threat to consumer health.

Improving the 210Pb-chronology of Pb deposition in peat cores from Chao de Lamoso (NW Spain)

The natural radionuclide 210Pb is commonly used to establish accurate and precise chronologies for the recent (past 100–150years) layers of peat deposits. The most widely used 210Pb-dating model, Constant Rate of Supply (CRS), was applied using data from three peat cores from Chao de Lamoso, an ombrotrophic mire in Galicia (NW Spain). On the basis of the CRS-chronologies, maximum Pb concentrations and enrichment factors (EFs) occurred in the 1960s and late 1970s, consistent with the historical use of Pb. However, maximum Pb fluxes were dated in the 1940s and the late 1960s, 10 to 20 years earlier. Principal component analysis (PCA) showed that, although the 210Pb distribution was mainly (74%) controlled by radioactive decay, about 20% of the 210Pb flux variability was associated with atmospheric metal pollution, suggesting an extra 210Pb supply source and thus invalidating the main assumption of the CRS model. When the CRS-ages were recalculated after correcting for the extra input from the 210Pb inventory of the uppermost peat layers of each core, Pb flux variations were consistent with the historical atmospheric Pb deposition. Our results not only show the robustness of the CRS model to establish accurate chronologies of recent peat deposits but also provide evidence that there are confounding factors that might influence the calculation of reliable peat accumulation rates (and thus also element accumulation rates/fluxes). This study emphasizes the need to verify the hypotheses of 210Pb-dating models and the usefulness of a full geochemical interpretation of peat bog records.

Children’s Health Risk Assessment of Lead Exposure

Increasing studies in China are assessing the soil Lead (Pb) levels due to its adverse health effects. However, few of them directly focus on the Pb related health risk, especially on those susceptible children living in the urban industrial park. This study evaluated the health risks of Pb-exposed children in an industrial park of XX City using the IEUBK model. Results show that the excessive Pb concentrations existed in few sampling points and the maximum Pb concentration is 1.35 times more than the second level of Soil Environmental Quality Standard of China (SEQSC). Meanwhile, the difference of the Pb-exposed health risks for children under two scenarios (with or without Pb polluted vegetables intake) is 14.61%. It can be concluded that the health risk of Pb-exposed children in study area is unacceptable and the risk might be predominantly attributed to ingestion of vegetables.

Leaching behavior of heavy metals and transformation of their speciation in polluted soil receiving simulated acid rain.

Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.