Metal Concentrations In Groundwater Research Articles

Polybrominated diphenyl ethers, perfluorinated alkylated substances, and metals in tile drainage and groundwater following applications of municipal biosolids to agricultural fields

Polybrominated diphenyl ethers (PBDEs), perfluorinated alkylated substances (PFAS), and metals were monitored in tile drainage and groundwater following liquid (LMB) and dewatered municipal biosolid (DMB) applications to silty-clay loam agricultural field plots. LMB was applied (93,500 L ha − 1 ) in late fall 2005 via surface spreading on un-tilled soil (SS LMB), and a one-pass aerator-based pre-tillage prior to surface spreading (AerWay SSD) (A). The DMB was applied (8 Mg dw ha − 1 ) in early summer 2006 on the same plots by injecting DMB beneath the soil surface (DI), and surface spreading on un-tilled soil (SS DMB). Key PBDE congeners (BDE-47, -99, -100, -153, -154, -183, -209) comprising 97% of total PBDE in LMB, had maximum tile effluent concentrations ranging from 6 to 320 ng L − 1 during application-induced tile flow. SS LMB application-induced tile mass loads for these PBDE congeners were significantly higher than those for control (C) plots (no LMB) ( p < 0.05), but not A plots ( p > 0.05). PBDE mass loss via tile (0–2 h post-application) as a percent of mass applied was ~ 0.04–0.1% and ~ 0.8–1.7% for A and SS LMB, respectively. Total PBDE loading to soil via LMB and DMB application was 0.0018 and 0.02 kg total PBDE ha − 1 yr − 1 , respectively. Total PBDE concentration in soil (0–0.2 m) after both applications was 115 ng g − 1 dw, (sampled 599 days and 340 days post LMB and DMB applications respectively). Of all the PFAS compounds, only PFOS (max concentration = 17 ng L − 1 ) and PFOA (12 ng L − 1 ) were found above detectable limits in tile drainage from the application plots. Mass loads of metals in tile for the LMB application-induced tile hydrograph event, and post-application concentrations of metals in groundwater, showed significant ( p < 0.05) land application treatment effects (SS LMB > A > C for tile and SS LMB and A > C for groundwater for most results). Following DMB application, no significant differences in metal mass loads in tile were found between SS DMB and DI treatments (PBDE/PFAS were not measured). But for many metals (Cu, Se, Cd, Mo, Hg and Pb) both SS DMB and DI loads were significantly higher than those from C, but only during < 100 days post DMB application. Clearly, pre-tilling the soil (e.g., A) prior to surface application of LMB will reduce application-based PBDE and metal contamination to tile drainage and shallow groundwater. Directly injecting DMB in soil does not significantly increase metal loading to tile drains relative to SS DMB, thus, DI should be considered a DMB land application option.

Human Exposure to Metals in Groundwater Affected by Acid Sulfate Soil Disturbance

The disturbance and oxidation of sulfidic soils can cause an increase in acidity resulting in the mobilization of high concentrations of metals in groundwater or connected surface water. This is an increasing problem in urban areas of Australia and internationally. We hypothesized that the risks of exposure to contaminated water would be increased by this phenomenon. We undertook a preliminary investigation of human exposure to metals recruiting 27 residents in an acid sulfate soil-affected area, 21 residents using a bore (groundwater) for home-grown produce irrigation, and 6 residents who did not. Participants completed a questionnaire and provided a sample of urine (first morning void), toenails (from all 10 toes), hair, and borewater. Only hair metal concentrations were higher in those using bore water and ranged from below detection (<DL) to 38 mg/kg Al; <DL = 0.07 mg/kg As, 0.02-0.57 mg/kg Cd, 0.19-4.3 mg/kg Pb, 11-160 mg/kg Cu, and 99-280 mg/kg Zn. The data indicate exposure to metals in bore-water users might be occurring and further investigation is warranted even though the concentrations recorded in this study are considered low.

DGT use in contaminated site characterization. The importance of heavy metal site specific behaviour

The objective of this study is to provide an insight into the techniques for measuring the lability of heavy metals in solid-phase pool of soils in order to assess the environmental risk arising from pollution. The technique of diffusive gradients in thin films (DGT) and a sequential extraction procedure were used to quantify the labile pools of Cu, Fe, Mn and Ni. These results were compared to metal concentrations in groundwater, measured directly using the in situ piezometers, and to the total concentration of metal in the soils. High concentrations of metal in the directly analysed soil solution compared to DGT measurement were attributed to the presence of colloidal metal. The use of DGT allowed only to calculate leaching parameters of the free ions and labile fractions of the metals. For this reason DGT technique needs preliminary investigation on metal speciation in soil solution before its application as a good tool in the characterization procedure of contaminated sites.

Characterizing Spatial and Environmental Determinants of Prostate Cancer Using a Geographic Information System

ISEE-652 Objective: Prostate cancer (PrCA) incidence in South Carolina (SC) exceeds the national average, particularly among African Americans (AAs). A Geographic Information System (GIS) was used to evaluate spatial and environmental determinants of PrCA in SC, a cancer for which there are few established risk factors. Materials and Methods: Age-adjusted PrCA incidence, standardized incidence ratios (SIRs), and 95% confidence intervals were calculated for census tracts using SC Central Cancer Registry data (1996–2002). Demographic data (groundwater consumption, age, race, median income, land use) were obtained from census data. Metal concentrations in groundwater and soil were obtained from existing federal and state databases to test hypotheses that zinc and selenium are protective, and that cadmium and uranium increase PrCA incidence. Census tract-specific exposure estimates included: geometric mean groundwater and soil metal concentrations, proportion of samples exceeding background, and census tract-centroid concentration obtained via spatial modeling (kriging). A GIS was used to map incidence rates, SIRs, and exposures. Statistical procedures (linear and Poisson regression) were applied with and without censoring of tracts with <50% groundwater consumption per capita (N = 173 and 854, respectively). An adjacency matrix was generated and spatial statistical models were performed using WinBUGS software, with adjustment for correlated and uncorrelated heterogeneity. Results: There were 18,091 PrCA cases; 30% AA and 69% European American. Among uncensored tracts with elevated groundwater zinc, 7 had PrCA rates below expected incidence, and this inverse relationship also was observed using linear regression (P = 0.02). There were 96 census tracts with both elevated soil selenium concentrations and reduced SIRs. Three tracts had both elevated soil cadmium and higher SIRs. Conclusions: A decreasing trend in PrCA rates was observed among SC census tracts with elevated zinc in soil or groundwater. Relationships between environmental factors and cancer incidence can be efficiently explored using GIS, spatial statistics, and existing population databases.

Comparison of Dissolved and Acid-Extractable Metal Concentrations of Ground Water, Eastern Arkansas, USA

The objective of this project was to compare and acid-extractable metal concentrations in ground water in the alluvial and Sparta aquifers in eastern Arkansas, USA. Typically, water samples for metal analyses are filtered through a 0.45 μm pore-size membrane immediately after sample collection, yielding dissolved concentrations. In some situations, acid-extractable metal concentrations (unfiltered samples but acidified) may better represent potential metal availability, e.g., from cation exchange or from dissolution of Fe hydroxyoxides. For this project 41 wells were sampled in the Mississippi River Valley Alluvial and Sparta aquifers. The paired student-T test was used to determine differences in the and acid-extractable concentrations for Fe, Mn, Cu, Pb, Zn, Ca, Mg, Na and K. The test indicated that there are significant differences between and acid-extractable concentrations for Fe, Mn, Pb and Ca at the 95% confidence level. The test indicated no differences for Mg, K, Na, Cu, and Zn (confidence level < 95%). In most cases the difference ratios for and acid-extractable concentrations were less than 25% but in about one third of samples the difference ratios were greater than 90%. Highly turbid samples had the highest difference ratios. The results indicate that acid-extractable concentrations can be important in determining metal availability for Mn, Pb, Ca and, especially for Fe. Fe concentrations show spatial variation that is related to variations in lithology, ground water flow and/or geochemical processes.

Metal mobility in alum shale from Öland, Sweden

A study was initiated to analyse metal flows from alum shale to the environment in an area in Öland, Sweden. The study was performed by elemental analysis and leaching experiments of alum shale together with analysis of groundwater and surface water samples. The metal concentrations in non-weathered alum shale were much higher than in weathered or burnt shale, especially for cadmium (Cd), nickel (Ni) and zinc (Zn), indicating a loss of metals during weathering or burning of the shale. The release of metals through weathering was clearly demonstrated by the leaching tests. A 36-week leaching period of non-weathered shale resulted in a drastic drop in pH and a significant increase in metal concentrations in the leachate. The metal concentrations in groundwater were inversely related to the pH. For surface waters, the concentrations of Cd, copper (Cu), Ni and Zn were generally increased compared to background values. In conclusion, metals are released through weathering or burning of alum shale, as well as from heaps of weathered or burnt shale. The release of metals is strongly related to low pH, especially for Cd, Ni and Zn.

Heavy metal content and speciation in groundwater of the Guadiamar river basin

This work presents the conclusions of a speciation study concerning Zn, Cd, Pb and Cu in groundwater from ten wells in the alluvial aquifers of the Guadiamar river, affected by Aznalcollar mine tailing spill (April 1998). The sampling campaign took place in January 2000, almost two years after the mining accident. Four metal fractions were determined: labile metal forms, H + exchangeable metal forms, strongly inert forms (associated with organic and inorganic matter in solution), and forms associated with suspended matter. Total metal concentration in groundwater followed the trend Cd<Pb<Cu<Zn. The speciation study showed that Zn and Cd were present to a great extent in available forms (labile and H + exchangeable), while Pb and Cu were found mostly in the less available forms (strongly inert). These results can illustrate the potential value of the speciation tool for the follow-up of spill-induced pollution in the area.

Trace metal concentrations in shallow ground water.

Trace metal clean sampling and analysis techniques were used to examine the temporal patterns of Hg, Cu, and Zn concentrations in shallow ground water, and the relationships between metal concentrations in ground water and in a hydrologically connected river. Hg, Cu, and Zn concentrations in ground water ranged from 0.07 to 4.6 ng L-1, 0.07 to 3.10 micrograms L-1, and 0.17 to 2.18 micrograms L-1, respectively. There was no apparent seasonal pattern in any of the metal concentrations. Filtrable Hg, Cu, and Zn concentrations in the North Branch of the Milwaukee River ranged from below the detection limit to 2.65 ng Hg L-1, 0.51 to 4.30 micrograms Cu L-1, and 0.34 to 2.33 micrograms Zn L-1. Thus, metal concentrations in ground water were sufficiently high to account for a substantial fraction of the filtrable trace metal concentration in the river. Metal concentrations in the soil ranged from 8 to 86 ng Hg g-1, 10 to 39 micrograms Cu g-1, and 15 to 84 micrograms Zn g-1. Distribution coefficients, KD, in the aquifer were 7900, 22,000, and 23,000 L kg-1 for Hg, Cu, and Zn, respectively. These values were three to 40 times smaller than KD values observed in the Milwaukee River for suspended particulate matter.

Formation of sphalerite (ZnS) deposits in natural biofilms of sulfate-reducing bacteria.

Abundant, micrometer-scale, spherical aggregates of 2- to 5-nanometer-diameter sphalerite (ZnS) particles formed within natural biofilms dominated by relatively aerotolerant sulfate-reducing bacteria of the family Desulfobacteriaceae. The biofilm zinc concentration is about 10(6) times that of associated groundwater (0.09 to 1.1 parts per million zinc). Sphalerite also concentrates arsenic (0.01 weight %) and selenium (0.004 weight %). The almost monomineralic product results from buffering of sulfide concentrations at low values by sphalerite precipitation. These results show how microbes control metal concentrations in groundwater- and wetland-based remediation systems and suggest biological routes for formation of some low-temperature ZnS deposits.

Decreased metal concentrations in ground water caused by controls of phosphate emissions

A NEW generation of phosphate-eliminating sewage treatment plants and the recent prohibition of phosphates in detergents have considerably reduced the concentrations of phosphate in surface waters1. But there has been concern that replacing phosphate in detergents with complexing agents might cause increased mobilization of heavy metals, and consequent pollution of ground waters2,3. Here we present a twelve-year analysis of phosphate, manganese and cadmium in the river Glatt, Switzerland, and in an adjacent aquifer which is infiltrated by the river water. Together with a reduction of phosphate concentrations in both river and ground water over the study period, we find lower ground water concentrations of manganese and cadmium. We postulate that lower phosphate levels have decreased the amount of oxidizable organic carbon in the river bed, and hence havecreated less reducing conditions in the infiltrating water. This in turn has resulted in decreased reductive dissolution of manganese and cadmium in the ground water. It thus appears that eliminating phosphate has led to an unexpected improvement in drinking water quality with respect to heavy metals.