Biomonitoring of Cd, Cr, Hg and Pb in the Baluarte River basin associated to a mining area (NW Mexico)

With the purpose of knowing seasonal variations of Cd, Cr, Hg and Pb in a river basin with past and present mining activities, elemental concentrations were measured in six fish species and four crustacean species in Baluarte River, from some of the mining sites to the mouth of the river in the Pacific Ocean between May 2005 and March 2006. In fish, highest levels of Cd (0.06 μg g^− 1 dry weight) and Cr (0.01 μg g^− 1) were detected during the dry season in Gobiesox fluviatilis and Agonostomus monticola, respectively; the highest levels of Hg (0.56 μg g^− 1) were detected during the dry season in Guavina guavina and Mugil curema. In relation to Pb, the highest level (1.65 μg g^− 1) was detected in A. monticola during the dry season. In crustaceans, highest levels of Cd (0.05 μg g^− 1) occurred in Macrobrachium occidentale during both seasons; highest concentration of Cr (0.09 μg g^− 1) was also detected in M. occidentale during the dry season. With respect to Hg, highest level (0.20 μg g^− 1) was detected during the rainy season in Macrobrachium americanum; for Pb, the highest concentration (2.4 μg g^− 1) corresponded to Macrobrachium digueti collected in the dry season. Considering average concentrations of trace metals in surficial sediments from all sites, Cd (p < 0.025), Cr (p < 0.10) and Hg (p < 0.15) were significantly higher during the rainy season. Biota sediment accumulation factors above unity were detected mostly in the case of Hg in fish during both seasons. On the basis of the metal levels in fish and crustacean and the provisional tolerable weekly intake of studied elements, people can eat up to 13.99, 0.79 and 2.34 kg of fish in relation to Cd, Hg and Pb, respectively; regarding crustaceans, maximum amounts were 11.33, 2.49 and 2.68 kg of prawns relative to levels of Cd, Hg and Pb, respectively.     

Temporal variations in arsenic uptake by rice plants in Bangladesh: The role of iron plaque in paddy fields irrigated with groundwater

The transfer of arsenic to rice grains is a human health issue of growing relevance in regions of southern Asia where shallow groundwater used for irrigation of paddy fields is elevated in As. In the present study, As and Fe concentrations in soil water and in the roots of rice plants, primarily the Fe plaque surrounding the roots, were monitored during the 4-month growing season at two sites irrigated with groundwater containing ∼ 130 μg l^− 1 As and two control sites irrigated with water containing < 15 μg l^− 1 As. At both sites irrigated with contaminated water, As concentrations in soil water increased from < 10 μg l^− 1 to > 1000 μg l^− 1 during the first five weeks of the growth season and then gradually declined to < 10 μg l^− 1 during the last five weeks. At the two control sites, concentrations of As in soil water never exceeded 40 µg l^− 1. At both contaminated sites, the As content of roots and Fe plaque rose to 1000-1500 mg kg^− 1 towards the middle of the growth season. It then declined to ∼ 300 mg kg^− 1 towards the end, a level still well above As concentration of ∼ 100 mg kg^− 1 in roots and plaque measured throughout the growing season at the two control sites. These time series, combined with simple mass balance considerations, demonstrate that the formation of Fe plaque on the roots of rice plants by micro-aeration significantly limits the uptake of As by rice plants grown in paddy fields. Large variations in the As and Fe content of plant stems at two of the sites irrigated with contaminated water and one of the control sites were also recorded. The origin of these variations, particularly during the last month of the growth season, needs to be better understood because they are likely to influence the uptake of As in rice grains.     

Manganese and lead in children's blood and airborne particulate matter in Durban, South Africa

Despite the toxicity and widespread use of manganese (Mn) and lead (Pb) as additives to motor fuels and for other purposes, information regarding human exposure in Africa is very limited. This study investigates the environmental exposures of Mn and Pb in Durban, South Africa, a region that has utilized both metals in gasoline. Airborne metals were sampled as PM_2.5 and PM₁₀ at three sites, and blood samples were obtained from a population-based sample of 408 school children attending seven schools. In PM_2.5, Mn and Pb concentrations averaged 17 ± 27 ng m^− 3 and 77 ± 91 ng m^− 3, respectively; Mn concentrations in PM₁₀ were higher (49 ± 44 ng m^− 3). In blood, Mn concentrations averaged 10.1 ± 3.4 μg L^− 1 and 8% of children exceeded 15 μg L^− 1, the normal range. Mn concentrations fit a lognormal distribution. Heavier and Indian children had elevated levels. Pb in blood averaged 5.3 ± 2.1 μg dL^− 1, and 3.4% of children exceeded 10 μg dL^− 1, the guideline level. Pb levels were best fit by a mixed (extreme value) distribution, and boys and children living in industrialized areas of Durban had elevated levels. Although airborne Mn and Pb concentrations were correlated, blood levels were not. A trend analysis shows dramatic decreases of Pb levels in air and children's blood in South Africa, although a sizable fraction of children still exceeds guideline levels. The study's findings suggest that while vehicle exhaust may contribute to exposures of both metals, other sources currently dominate Pb exposures.     

Kinetics and mechanism for degradation of dichlorvos by permanganate in drinking water treatment

The degradation kinetics and mechanism of dichlorvos by permanganate during drinking water treatment were investigated. The reaction of dichlorvos with permanganate was of second-order overall with negligible pH dependence and an activation energy of 29.5 kJ·mol⁻¹. At pH 7.0 and 25 °C, the rate constant was 25.2 ± 0.4 M⁻¹ s⁻¹. Dichlorvos was first degraded to trimethyl phosphate (TMP) and dimethyl phosphate (DMP) simultaneously which approximately accounted for <5% and ≥95% with respect to phosphorus mass, respectively. Further oxidation of DMP generated a final byproduct, monomethyl phosphate (MMP). MMP was for the first time identified as a major byproduct in chemical oxidation of dichlorvos. The kinetic model based on degradation mechanism and determined reaction rate constants allowed us to predict the evolution of dichlorvos and its byproduct concentrations during permanganate pre-oxidation process at water treatment plants. These results suggest that even though the dichlorvos concentration in surface water complies with the surface water quality standards of China (50 μg L⁻¹), its concentration after conventional water treatment will most probably exceed the drinking water quality standards (1 μg L⁻¹). Moreover, luminescent bacteria test shows that the acute toxicity of dichlorvos solution evidently increased after permanganate oxidation.     

Yield of trihalomethanes and haloacetic acids upon chlorinating algal cells, and its prediction via algal cellular biochemical composition

The major objective of the present study was to investigate the contribution of major biomolecules, including protein, carbohydrates and lipids, in predicting DBPs formation upon chlorination of algal cells. Three model compounds, including bovine serum albumin (BSA), starch and fish oil, as surrogates of algal-derived proteins, carbohydrates and lipids, and cells of three algae species, representing blue-green algae, green algae, and diatoms, were chlorinated in the laboratory. The results showed that BSA (27 μg mg⁻¹ C) and fish oil (50 μg mg⁻¹ C) produced more than nine times higher levels of chloroform than starch (3 μg mg⁻¹ C). For the formation of HAAs, BSA was shown to have higher reactivity (49 μg mg⁻¹ C) than fish oil and starch (5 μg mg⁻¹ C). For the algal cells, Nitzschia sp. (diatom) showed higher chloroform yields (48 μg mg⁻¹ C) but lower HAA yields (43 μg mg⁻¹ C) than Chlamydomonas sp. (green algae) (chloroform: 34 μg mg⁻¹ C; HAA: 62 μg mg⁻¹ C) and Oscillatoria sp. (blue-green algae) (chloroform: 26 μg mg⁻¹ C; HAA: 72 μg mg⁻¹ C). The calculated chloroform formation of cells from the three algal groups, based on their biochemical compositions, was generally consistent with the experimental data, while the predicted values for HAAs were significantly lower than the observed ones. As compared to humic substances, such as humic and fulvic acids, the algal cells appeared to be important precursors of dichloroacetic acid.     

Environmental occurrence and degradation of the herbicide n-chloridazon

A sampling campaign was carried out for n-chloridazon (n-CLZ) and its degradation product desphenyl-chloridazon (DPC) in the Hesse region (Germany) during the year 2007: a total of 548 environmental samples including groundwater, surface water and wastewater treatment plant (WWTP) effluent were analysed. Furthermore, aerobic degradation of n-CLZ has been studied utilising a fixed bed bioreactor (FBBR).In surface water, n-CLZ was detected at low concentrations (average 0.01 ± 0.06 μg L⁻¹; maximum 0.89 μg L⁻¹) with a seasonal peak, whereas DPC was present throughout the year at much higher concentrations (average 0.72 ± 0.81 μg L⁻¹; maximum 7.4 μg L⁻¹). Higher n-CLZ concentrations were observed in the North compared with South Hesse, which is ascribed to a higher density of agricultural areas. Furthermore, methylated DPC (Me-DPC), another degradation product, was detected in surface water.In the degradation test, n-CLZ was completely converted to DPC at all concentrations tested (Me-DPC was not formed under the test conditions). DPC was resistant to further degradation during the whole experimental period of 98 days. The results obtained suggest persistence and high dispersion of DPC in the aquatic environment.     

Measurement and source identification of polycyclic aromatic hydrocarbons (PAHs) in the aerosol in Xi'an, China, by using automated column chromatography and applying positive matrix factorization (PMF)

In this study, we measured polycyclic aromatic hydrocarbons (PAHs) in aerosols in Xi'an, China from 2005 to 2007, by using a modified Soxhlet extraction followed by a clean-up procedure using automated column chromatography followed by HPLC/fluorescence detection. The sources of PAHs were apportioned by using the positive matrix factorization (PMF) method. The PM₁₀ concentration in winter (161.1 ± 66.4 μg m^− 3, n = 242) was 1.5 times higher than that in summer (110.9 ± 34.7 μg m^− 3, n = 248). ΣPAH concentrations, which are the sum of the concentrations of all detected PAHs, in winter (344.2 ± 149.7 ng m^− 3, n = 45) was 2.5 times higher than that in summer (136.7 ± 56.7 ng m^− 3, n = 24) in this study. These strong seasonal variations in atmospheric PAH concentration are possibly due to coal combustion for residential heating. According to the source apportionment with PMF method in this study, the major sources of PAHs in Xi'an are categorized as (1) mobile sources such as vehicle exhaust that constantly contribute to PAH pollution, and (2) stationary sources such as coal combustion that have a large contribution to PAH pollution in winter.     

Multiple site study of recent atmospheric metal (Pb, Zn and Cu) deposition in the NW Iberian Peninsula using peat cores

In order to estimate atmospheric metal deposition in Southern Europe since the beginning of the Industrial Period (~ 1850 AD), concentration profiles of Pb, Zn and Cu were determined in four ²¹⁰Pb-dated peat cores from ombrotrophic bogs in Serra do Xistral (Galicia, NW Iberian Peninsula). Maximum metal concentrations varied by a factor of 1.8 for Pb and Zn (70 to 128 μg g⁻¹ and 128 to 231 μg g⁻¹, respectively) and 3.5 for Cu (11 to 37 μg g⁻¹). The cumulative metal inventories of each core varied by a factor of 3 for all analysed metals (132 to 329 μg cm⁻² for Pb, 198 to 625 μg cm⁻² for Zn and 22 to 69 μg cm⁻² for Cu), suggesting differences in net accumulation rates among peatlands. Although results suggest that mean deposition rates vary within the studied area, the enhanced ²¹⁰Pb accumulation and the interpretation of the inventory ratios (²¹⁰Pb/Pb, Zn/Pb and Cu/Pb) in two bogs indicated that either a record perturbation or post-depositional redistribution effects must be considered. After correction, Pb, Zn and Cu profiles showed increasing concentrations and atmospheric fluxes since the mid-XX^th century to maximum values in the second half of the XX^th century. For Pb, maximum fluxes were observed in 1955-1962 and ranged from 16 to 22 mg m⁻² yr⁻¹ (mean of 18 ± 1 mg m⁻² yr⁻¹), two orders of magnitude higher than in the pre-industrial period. Peaks in Pb fluxes in Serra do Xistral before the period of maximum consumption of leaded petrol in Europe (1970s-1980s) suggest the dominance of local pollutant sources in the area (i.e. coal mining and burning). More recent peaks were observed for Zn and Cu, with fluxes ranging from 32 to 52 mg m⁻² yr⁻¹ in 1989-1996, and from 4 to 9 mg m⁻² yr⁻¹ in 1994-2001, respectively. Our results underline the importance of multi-core studies to assess both the integrity and reliability of peat records, and the degree of homogeneity in bog accumulation. We show the usefulness of using the excess ²¹⁰Pb inventory to distinguish between differential metal deposition, accumulation or anomalous peat records.     

Particle deposition fluxes of BDE-209, PAHs, DDTs and chlordane in the Pearl River Delta, South China

Year-round bulk air deposition samples were collected at 15 sites in the Pearl River Delta (PRD) on a bimonthly basis from Dec 2003 to Nov 2004, and the particle-phase deposition of BDE-209, PAHs, DDTs and chlordane was measured. The annual deposition fluxes of BDE-209, total PAHs (15 compounds), total DDT (sum of p,p′-DDE, p,p′-DDD, p,p′-DDT, and o,p′-DDT ), and chlordane (sum of trans-chlordane and cis-chlordane) varied from 32.6 to 1970 μg m^− 2 yr^− 1, 22 to 290 μg m^− 2 yr^− 1, 0.8 to 11 μg m^− 2 yr^− 1, and 0.25 to 1.9 μg m^− 2 yr^− 1, respectively. Spatial variations were higher in the centre of the PRD and lower at the coastal sites for all compounds. The seasonal variations of deposition were found to be compound-dependent, influenced by a number of factors, such as the timing of source input, temperature, and precipitation etc. In particular, source input time affected the deposition fluxes of BDE-209 and high-weight PAHs, while temperature-dependent gas-particle partitioning was a key factor for DDT and light-weight PAH deposition. During the whole sampling period, the atmospheric deposition of BDE-209, ΣPAHs, ΣDDTs, and chlordane onto Hong Kong reached about 93, 86, 2.1 and 2.1 kg yr^− 1, respectively, and onto the PRD reached about 13,400, 2950, 82, and 63 kg yr^− 1. By comparing the calculated total air deposition with the burden in the soils, the half residual time of BDE-209 in soils was estimated to be 3 years.     

The tropical African mercury anomaly: lower than expected mercury concentrations in fish and human hair

Mercury is a neurotoxin and global pollutant, and wetlands and newly flooded areas are known to be sites of enhanced production of monomethylmercury, the form of mercury that is readily biomagnified in aquatic food chains to potentially toxic levels. The Okavango Delta in Botswana, Southern Africa, is the largest inland delta in the world and a wetland ecosystem that experiences dramatic annual flooding of large tracts of seasonal floodplains. The Delta was, therefore, expected to be home to high mercury levels in fish and to be an area where local subsistence fishing communities would be at substantial risk of mercury toxicity from fish consumption. Total mercury concentrations measured in 27 species of fish from the Okavango Delta averaged (mean ± s.d., wet weight) 19 ± 19 ng g⁻¹ in non-piscivorous fish, and 59 ± 53 ng g⁻¹ in piscivorous fish. These mercury concentrations are similar to those reported for fish from lakes in other areas of tropical Africa, demonstrating that not all wetlands are sites of elevated mercury concentrations in biota. Even more intriguing is that concentrations of mercury in fish from across tropical Africa are systematically and substantially lower than those typically reported for fish from freshwater ecosystems elsewhere globally. The reasons for this apparent “African mercury anomaly” are unclear, but this finding poses a unique opportunity to improve our understanding of mercury's biogeochemical cycling in the environment. Mercury concentrations measured in human hair collected in subsistence fishing communities in the Okavango Delta were similarly low (0.21 ± 0.22 μg g⁻¹ dry weight) despite high levels of fish consumption, and reflect the low mercury concentrations in the fish here.     

Occurrence of arsenic in core sediments and groundwater in the Chapai-Nawabganj District, northwestern Bangladesh

Groundwater and core sediments of two boreholes (to a depth of 50 m) from the Chapai-Nawabganj area in northwestern Bangladesh were collected for arsenic concentration and geochemical analysis. Groundwater arsenic concentrations in the uppermost aquifer (10-40 m of depth) range from 2.8 μg L⁻¹ to 462.3 μg L⁻¹. Groundwater geochemical conditions change from oxidized to successively more reduced, higher As concentration with depth. Higher sediment arsenic levels (55 mg kg⁻¹) were found within the upper 40 m of the drilled core samples. X-ray absorption near-edge structure spectroscopy was employed to elucidate the arsenic speciation of sediments collected from two boreholes. Environmental scanning electron microscopy and transmission X-ray microscopy were used to investigate the characteristics of FeOOH in sediments which adsorb arsenic. In addition, a pH-Eh diagram was drawn using the Geochemist's Workbench (GWB) software to elucidate the arsenic speciation in groundwater. The dominant groundwater type is Ca-HCO₃ with high concentrations of As, Fe and Mn but low levels of NO₃⁻ and SO₄²⁻. Sequential extraction analysis reveals that Mn and Fe hydroxides and organic matter are the major leachable solids carrying As. High levels of arsenic concentration in aquifers are associated with fine-grained sediments. Fluorescent intensities of humic substances indicate that both groundwater and sediments in this arsenic hotspot area contain less organic matter compared to other parts of Bengal basin. Statistical analysis clearly shows that As is closely associated with Fe and Mn in sediments while As is better correlated with Mn in groundwater. These correlations along with results of sequential leaching experiments suggest that reductive dissolution of MnOOH and FeOOH mediated by anaerobic bacteria represents an important mechanism for releasing arsenic into the groundwater.     

Water, vegetation and sediment gradients in submerged aquatic vegetation mesocosms used for low-level phosphorus removal

Gradients in phosphorus (P) removal and storage were investigated over 6 years using mesocosms (each consisting of three tanks in series) containing submerged aquatic vegetation (SAV) grown on muck and limerock (LR) substrates. Mean inflow total P concentrations (TP) of 32 μg L⁻¹ were reduced to 15 and 17 μg L⁻¹ in the muck and LR mesocosms, respectively. Mesocosm P loading rates (mean = 1.75 g m⁻² year⁻¹) varied widely during the study and were not correlated with outflow TP, which instead varied seasonally with lowest monthly mean values in December and January.The mesocosms initially were stocked with Najas guadalupensis, Ceratophyllum demersum, and Chara zeylanica, but became dominated by C. zeylanica. At the end of the study, highest vegetative biomass (1.1 and 1.4 kg m⁻² for muck and LR substrates) and tissue P content (1775 and 1160 mg kg⁻¹) occurred in the first tank in series, and lowest biomass (1.0 and 0.2 kg m⁻²) and tissue P (147 and 120 mg kg⁻¹) in the third tank. Sediment accretion rates (2.5, 1.9 and 0.9 cm yr⁻¹ on muck substrates), accrued sediment TP (378, 309 and 272 mg kg⁻¹), and porewater soluble reactive P (SRP) concentrations (40, 6 and 4 μg L⁻¹) in the first, second and third tanks, respectively, exhibited a similar decreasing spatial trend. Plant tissue calcium (Ca) near mesocosm inflow (19-30% dry weight) and outflow (23-26%) were not significantly different, and sediment Ca was also similar (range of 24 to 28%) among sequential tanks.Well-defined vegetation and sediment enrichment gradients developed in SAV wetlands operated under low TP conditions. While the mesocosm data did not reflect deterioration in treatment performance over 6 years, accumulation of P-enriched sediments near the inflow could eventually compromise hydraulic storage and P removal effectiveness of these shallow systems.     

Ambient ammonia in terrestrial ecosystems: a comparative study in the Tennessee Valley, USA

Atmospheric ammonia has been shown to degrade regional air quality and affect environmental health. In-situ measurements of ammonia are needed to determine how ambient concentrations vary in different ecosystems and the extent to which emission sources contribute to those levels. The objective of this study was to measure and compare ammonia concentrations in two Tennessee Valley (USA) ecosystems: a forested rural area and a metropolitan site adjacent to a main transportation route. Integrated samples of atmospheric ammonia were collected with annular denuder systems for ~ 4 weeks during the summer of 2009 in both ecosystems. Ancillary measurements of meteorological variables, such as wind direction and precipitation, were also conducted to determine any relationships with ammonia concentration. Measurements in the two ecosystems revealed ammonia concentrations that were mostly representative of background levels. Arithmetic means were 1.57 ± 0.68 μg m^− 3 at the metropolitan site and 1.60 ± 0.77 μg m^− 3 in the forest. The geometric mean concentrations for both sites were ~ 1.46 μg m^− 3. Wind direction, and to a lesser extent air temperature and precipitation, did influence measured concentrations. At the metropolitan site, ammonia concentrations were slightly higher in winds emanating from the direction of the interstate highway. Meteorological variables, such as wind direction, and physical factors, such as topography, can affect measurement of ambient ammonia concentrations, especially in ecosystems distant from strong emission sources. The 12-h integrated sampling method used in this study was unable to measure frequent changes in ambient ammonia concentrations and illustrates the need for measurements with higher temporal resolution, at least ~ 1-2 h, in a variety of diverse ecosystems to determine the behavior of atmospheric ammonia and its environmental effects.     

Comparison of the microbiological and chemical characterization of harvested rainwater and reservoir water as alternative water resources

Rainwater harvesting (RWH) offers considerable potential as an alternative water supply. In this study, all of the harvested rainwater samples met the requirements for grey water but not for drinking water. In terms of microbiological parameters, total coliform (TC) and Escherichia coli (EC) were measured in 91.6% and 72%, respectively, of harvested rainwater samples at levels exceeding the guidelines for drinking water, consistent with rainfall events. In the case of the reservoir water samples, TC and EC were detected in 94.4% and 85.2%, respectively, of the samples at levels exceeding the guidelines for drinking water. Both indicators gradually increased in summer and fall. The highest median values of both TC and EC were detected during the fall. Chemical parameters such as common anions and major cations as well as metal ions in harvested rainwater were within the acceptable ranges for drinking water. By contrast, Al shows a notable increase to over 200 μg L^− 1 in the spring due to the intense periodic dust storms that can pass over the Gobi Desert in northern China. In terms of statistical analysis, the harvested rainwater quality showed that TC and EC exhibit high positive correlations with NO₃⁻ (ρ_TC = 0.786 and ρ_EC = 0.42) and PO₄⁻ (ρ_TC = 0.646 and ρ_EC = 0.653), which originally derive from catchment contamination, but strong negative correlations with Cl⁻ (ρ_TC = − 0.688 and ρ_EC = − 0.484) and Na⁺ (ρ_TC = − 0.469 and ρ_EC = − 0.418), which originate from seawater.     

Health risk associated with dietary co-exposure to high levels of antimony and arsenic in the world's largest antimony mine area

Like arsenic (As), antimony (Sb) is known to be a genotoxic element in vitro and in vivo. Sb is now recognized as a global contaminant and has aroused the global concerns recently. However, knowledge is scarce concerning the transfer of Sb from the environment to humans and the related hazards to human health. In this pilot study, the health risk and main pathway of long-term human exposure to Sb and As for residents around Chinese Xikuangshan (XKS) Sb mine, the world's largest Sb mine, were evaluated by dietary exposure and hair accumulations survey. The concentrations and species of Sb and As in food samples (n = 209) from three main categories and six subcategories, and in hair samples (n = 89) were determined. Residents in the vicinity of XKS had an estimated dietary intake of Sb (554 μg/day) which was 1.5 times higher than the tolerable daily intake (TDI) (Sb, 360 μg/day), whereas their dietary intake of inorganic As (107 μg/day) was slightly lower than the provisional tolerable weekly intake (PTWI) of 15 μg/kg BW/week (equal to 129 μg As/day). Hair Sb and As concentrations (Sb, 15.7 mg/kg, DW; As, 3.99 mg/kg, DW) in XKS residents are both above the normal/toxic level. Rice, vegetables (especially leafy vegetable), drinking water, and meat/poultry were the dominant dietary intake sources of Sb for the residents. In contrast, rice was the uniquely dominant dietary intake source of As. Antimonate (Sb(V)) was the dominant Sb species in vegetables, drinking water and residents' hairs. This study highlighted the difference of exposure characteristics between Sb and As. The preliminary results suggested that dietary exposures to Sb, rather than As, was the dominant health risk to local residents. Nevertheless, the adverse effects of As levels on the health of residents still can not be ignored since the elevated As concentrations in human hair have reached the critical level for health risks. In addition, this pilot study did not consider the possible Sb and As combined effects.     

Speciation and distribution of vanadium in drinking water iron pipe corrosion by-products

Vanadium (V) when ingested from drinking water in high concentrations (> 15 μg L^− 1) is a potential health risk and is on track to becoming a regulated contaminant. High concentrations of V have been documented in lead corrosion by-products as Pb₅(V⁵⁺O₄)₃Cl (vanadinite) which, in natural deposits is associated with iron oxides/oxyhydroxides, phases common in iron pipe corrosion by-products. The extent of potential reservoirs of V in iron corrosion by-products, its speciation, and mechanism of inclusion however are unknown. The aim of this study is to assess these parameters in iron corrosion by-products, implementing synchrotron-based μ-XRF mapping and μ-XANES along with traditional physiochemical characterization. The morphologies, mineralogies, and chemistry of the samples studied are superficially similar to typical iron corrosion by-products. However, we found V present as discrete grains of Pb₅(V⁵⁺O₄)₃Cl likely embedded in the surface regions of the iron corrosion by-products. Concentrations of V observed in bulk XRF analysis ranged from 35 to 899 mg kg^− 1. We calculate that even in pipes with iron corrosion by-products with low V concentration, 100 mg kg^− 1, as little as 0.0027% of a 0.1-cm thick X 100-cm long section of that corrosion by-product needs to be disturbed to increase V concentrations in the drinking water at the tap to levels well above the 15 μg L^− 1 notification level set by the State of California and could adversely impact human health. In addition, it is likely that large reservoirs of V are associated with iron corrosion by-products in unlined cast iron mains and service branches in numerous drinking water distribution systems.     

The distribution of depleted uranium contamination in Colonie, NY, USA

Uranium oxide particles were dispersed into the environment from a factory in Colonie (NY, USA) by prevailing winds during the 1960s and '70s. Uranium concentrations and isotope ratios from bulk soil samples have been accurately measured using inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) without the need for analyte separation chemistry. The natural range of uranium concentrations in the Colonie soils has been estimated as 0.7-2.1 μg g^− 1, with a weighted geometric mean of 1.05 μg g^− 1; the contaminated soil samples comprise uranium up to 500 ± 40 μg g^− 1. A plot of ²³⁶U/²³⁸U against ²³⁵U/²³⁸U isotope ratios describes a mixing line between natural uranium and depleted uranium (DU) in bulk soil samples; scatter from this line can be accounted for by heterogeneity in the DU particulate. The end-member of DU compositions aggregated in these bulk samples comprises (2.05 ± 0.06) × 10^− 3235U/²³⁸U, (3.2 ± 0.1) × 10^− 5236U/²³⁸U, and (7.1 ± 0.3) × 10^− 6234U/²³⁸U. The analytical method is sensitive to as little as 50 ng g^− 1 DU mixed with the natural uranium occurring in these soils. The contamination footprint has been mapped northward from site, and at least one third of the uranium in a soil sample from the surface 5 cm, collected 5.1 km NNW of the site, is DU. The distribution of contamination within the surface soil horizon follows a trend of exponential decrease with depth, which can be approximated by a simple diffusion model. Bioturbation by earthworms can account for dispersal of contaminant from the soil surface, in the form of primary uranium oxide particulates, and uranyl species that are adsorbed to organic matter. Considering this distribution, the total mass of uranium contamination emitted from the factory is estimated to be c. 4.8 tonnes.     

Invertebrate mercury bioaccumulation in permanent, seasonal, and flooded rice wetlands within California's Central Valley

We examined methylmercury (MeHg) bioavailability in four of the most predominant wetland habitats in California's Central Valley agricultural region during the spring and summer: white rice, wild rice, permanent wetlands, and shallowly-flooded fallow fields. We sampled MeHg and total mercury (THg) concentrations in two aquatic macroinvertebrate taxa at the inlets, centers, and outlets of four replicated wetland habitats (8 wetlands total) during two time periods bounding the rice growing season and corresponding to flood-up and pre-harvest (96 total samples). In general, THg concentrations (mean ± standard error) in Notonectidae (Notonecta, back swimmers; 1.18 ± 0.08 µg g^− 1 dry weight [dw]) were higher than in Corixidae (Corisella, water boatmen; 0.89 ± 0.06 µg g^− 1 dw, MeHg: 0.74 ± 0.05 µg g^− 1 dw). MeHg concentrations were correlated with THg concentrations in Corixidae (R² = 0.80) and 88% of THg was in the MeHg form. Wetland habitat type had an important influence on THg concentrations in aquatic invertebrates, but this effect depended on the sampling time period and taxa. In particular, THg concentrations in Notonectidae, but not Corixidae, were higher in permanent wetlands than in white rice, wild rice, or shallowly-flooded fallow fields. THg concentrations in Notonectidae were higher at the end of the rice growing season than near the time of flood-up, whereas THg concentrations in Corixidae did not differ between time periods. The effect of wetland habitat type was more prevalent near the end of the rice growing season, when Notonectidae THg concentrations were highest in permanent wetlands. Additionally, invertebrate THg concentrations were higher at water outlets than at inlets of wetlands. Our results indicate that although invertebrate THg concentrations increased from the time of flood-up to draw-down of wetlands, temporarily flooded habitats such as white rice, wild rice, and shallowly-flooded fallow fields did not have higher THg or MeHg concentrations in invertebrates than permanent wetlands.     

Determination of arsenic leaching from glazed and non-glazed Turkish traditional earthenware

Glazed and non-glazed earthenware is traditionally and widely used in Turkey and most of the Mediterranean and the Middle East countries for cooking and conservation of foodstuff. Acid-leaching tests have been carried out to determine whether the use of glazed and non-glazed earthenware may constitute a human health hazard risk to the consumers. Earthenware was leached with 4% acetic acid and 1% citric acid solutions, and arsenic in the leachates was measured using hydride generation atomic absorption spectrometry. Arsenic concentrations in the leach solution of non-glazed potteries varied from 30.9 to 800 μg L^− 1, while the glazed potteries varied generally from below the limit of detection (0.5 μg L^− 1) to 30.6 μg L^− 1, but in one poorly glazed series it reached to 110 μg L^− 1. Therefore, the risk of arsenic poisoning by poorly glazed and non-glazed potteries is high enough to be of concern. It appears that this is the first study reporting arsenic release from earthenware into food.     

Seasonal and diurnal variations of carbonyl compounds in the urban atmosphere of Guangzhou, China

Seasonal and diurnal variations of carbonyl compounds were investigated at two sampling sites (Liwan and Wushan) in the ambient air of Guangzhou, China. Air samples were collected during 2005 from January to November, and carbonyl compounds were analyzed with HPLC. The results show that carbonyls exhibit distinct seasonal variation. The total concentrations of 21 carbonyls detected ranged from 2.64 to 103.6 μg m⁻³ at Liwan and from 5.46 to 89.9 μg m⁻³ at Wushan, respectively. The average total concentrations of carbonyls at both Liwan and Wushan decreased in order of summer>spring>autumn>winter. Formaldehyde, acetaldehyde, and acetone were the most abundant carbonyl compounds, which accounted for more than 60% of the total concentrations of carbonyls. The mean concentration ratios of summer/winter were all > 1.0 for the total concentrations and the individual carbonyl compound. The diurnal variation of carbonyls was not distinct in this study. The average concentration ratios of formaldehyde/acetaldehyde (C₁/C₂) varied from 0.71 to 1.32 and 0.65 to 1.14 at Liwan and Wushan, respectively, and the average concentration ratios of acetaldehyde/propionaldehyde (C₂/C₃) varied from 5.42 to 7.70 and 5.02 to 13.9 in Liwan and Wushan, respectively. Regarding photochemical reactivity of carbonyls and the ozone production, acetaldehyde, butyraldehyde, formaldehyde, and valeraldehyde account for 75-90% to the total propene-equivalent concentrations, while formaldehyde, acetaldehyde, valeraldehyde, butyraldehyde, and propionaldehyde contribute 89-96% to the total ozone formation potentials (ranging from 105 to 274 μg m^-3). The ozone formation potentials in summer were higher by 1-2 times than those in the other seasons.