Soil-plant interactions and the uptake of Pb at abandoned mining sites in the Rookhope catchment of the N. Pennines, UK--a Pb isotope study (original) (raw)
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Sources, lability and solubility of Pb in alluvial soils of the River Trent catchment, U.K
Science of The Total Environment, 2012
Alluvial soils are reservoirs of metal contaminants such as Pb that originate from many different sources and are integrated temporally and spatially through erosional and depositional processes. In this study the source, lability and solubility of Pb was examined in a range of alluvial soils from the middle and lower River Trent and its tributary the River Dove using Pb isotope apportionment and isotopic dilution. All samples were collected within 10 m of the river bank to represent the soil that is most likely to be remobilised during bank erosion. Paired samples were taken from the topsoil (0-15 cm) and subsoil (35-50 cm) to assess differences with depth. Lead concentrations in soil ranged from 43 to 1282 mg/kg. The lability of soil Pb varied between 9-56% of total metal concentration whilst Pb concentrations in pore water varied between 0.2 and 6.5 µg/L. There was little difference in the % Pb lability between paired top and sub soils, possibly because soil characteristics such as pH, iron oxides and clay content were generally similar; a result of the recycling of eroded and deposited soils within the river system. Soil pH was found to be negatively correlated with % Pb lability. Source apportionment using 206 Pb /207 Pb and 208 Pb /207 Pb ratios showed that the isotopic ratios of Pb in the total, labile and solution pools fitted along a mixing line between Broken Hill Type ('BHT') Pb, used as an additive in UK petrol, and the local coal/Sourthern Pennine ore Pb. Various anomalies were found in the Pb isotopes of the bankside alluvial soils which were explained by point source pollution. Statistically significant differences were found between (i) the isotopic composition of Pb in the total soil pool and the labile/solution pools and (ii) the isotopic composition of Pb in the labile and solution pools, suggesting an enrichment of recent non-Pennine sources of Pb entering the soils in the labile and solution pools.
Implications from concentrations and isotopic data for Pb partitioning processes in soils
Geochimica Et Cosmochimica Acta, 2002
Lead concentrations and stable isotopic measurements were examined in the different chemical fractions of Czech forest soils to investigate the mechanisms of Pb partitioning. A method of selective sequential dissolution (SSD) was employed that distinguished between five different fractions: exchangeable, surface bound, organic matter, Fe-oxides, and silicates (non-labile).
Mobility of Pb in salt marshes recorded by total content and stable isotopic signature
Total lead and its stable isotopes were analysed in sediment cores, leaves, stem and roots of Sacorconia fruticosa and Spartina maritima sampled from Tagus (contaminated site) and Guadiana (low anthropogenic pressure) salt marshes. Lead concentration in vegetated sediments from the Tagus marsh largely exceeded the levels in non-vegetated sediments. Depth profiles of 206Pb/207Pb and 206Pb/208Pb showed a decrease towards the surface (206Pb/207Pb=1.160–1.167) as a result of a higher proportion of pollutant Pb components. In contrast, sediments from Guadiana marsh exhibited low Pb concentrations and an uniform isotopic signature (206Pb/207Pb=1.172±0.003) with depth. This suggests a homogeneous mixing of mine-derived particles and pre-industrial sediments with minor inputs of anthropogenic Pb. Lead concentrations in roots of plants from the two marshes were higher than in leaves and stems, indicating limited transfer of Pb to aerial parts. A similar Pb isotopic signature was found in roots and in vegetated sediments, indicating that Pb uptake by plants reflects the input in sediments as determined by a significant anthropogenic contribution of Pb at Tagus and by mineralogical Pb phases at Guadiana. The accumulation in roots from Tagus marsh (max. 2870 μg g− 1 in S. fruticosa and max. 1755 μg g− 1 in S. maritima) clearly points to the dominant role of belowground biomass in the cycling of anthropogenic Pb. The fraction of anthropogenic Pb in belowground biomass was estimated based on the signature of anthropogenic Pb components in sediments (206Pb/207Pb=1.154). Since no differences exist between Pb signature in roots and upper sediments, the background and anthropogenic levels of Pb in roots were estimated. Interestingly, both background and anthropogenic Pb in roots exhibited a maximum at the same depth, although the proportion of anthropogenic Pb was relatively constant with depth (83±4% for S. fruticosa and 74±8% for S. maritima).
Atmospheric Environment, 2005
In a peat bog from Black Forest, Southern Germany, the rate of atmospheric Pb accumulation was quantified using a peat core dated by 210Pb and 14C. The most recent Pb accumulation rate (2.5 mg m−2 y−1) is similar to that obtained from a snowpack on the bog surface, which was sampled during the winter 2002 (1 to 4 mg m−2 y−1). The Pb accumulation rates recorded by the peat during the last 25 yr are also in agreement with published values of direct atmospheric fluxes in Black Forest. These values are 50 to 200 times greater than the “natural” average background rate of atmospheric Pb accumulation (20 μg m−2 y−1) obtained using peat samples from the same bog dating from 3300 to 1300 cal. yr B.C. The isotopic composition of Pb was measured in both the modern and ancient peat samples as well as in the snow samples, and clearly shows that recent inputs are dominated by anthropogenic Pb. The chronology and isotopic composition of atmospheric Pb accumulation recorded by the peat from the Black Forest is similar to the chronologies reported earlier using peat cores from various peat bogs as well as herbarium samples of Sphagnum and point to a common Pb source to the region for the past 150 years. In contrast, Pb contamination occurring before 1850 in southwestern Germany, differs from the record published for Switzerland mainly due to the mining activity in Black Forest. Taken together, the results show that peat cores from ombrotrophic bogs can yield accurate records of atmospheric Pb deposition, provided that the cores are carefully collected, handled, prepared, and analysed using appropriate methods.
Science of The Total Environment, 2019
Historical mining has a millennial scale history on the globe often leaving a long-lasting imprint on the environment. Previous results on trace metal concentrations in the Pyrenees, where extensive mining (Ag, Fe) occurred from the Antiquity to the 19 th century, suggest that ≥600 tons of anthropogenic lead (Pb) is stored in soils in the Haut-Vicdessos area (France). Yet the potential bioavailability of this legacy contamination to contemporary biota remains unclear. We therefore asked if previously reported high-levels of legacy Pb can be seen in other environmental compartments including aquatic biota, and how these are distributed within the biota. Based on Pbisotopic data, we also assessed if any Pb contamination found in contemporary biota can be linked to local/regional mining. Samples of sphagnum, soil, sediment, biofilm, and fish (Salmo trutta and Phoxinus phoxinus) were collected from three adjacent valleys in the Haut-Vicdessos area. Pb concentrations varied both between sites (i.e. decreasing concentrations with increasing distance from the former mine) and between within-site environmental compartments (i.e. soil > biofilm ≥ sediment > sphagnum > fish) as well as within organisms (i.e. entire organism>liver>muscle). Further, Pb-isotopic ratios (206 Pb/ 207 Pb, 208 Pb/ 207 Pb and 208 Pb/ 206 Pb) measured in soil, biofilm, and fish indicated both natural (weathering bedrock) and anthropogenic (industrial, transportation and/or former mining activities) sources of Pb-deposition to the area. Generally, body Pbconcentrations were within regulatory guidelines, yet contemporary biota in the upper Haut-Vicdessos area, and their prey, still showed a large range of Pb isotopic signatures, of which former mining activities appeared to have a strong influence. Our study showed that mining derived legacy Pb continues to affect onsite biota even if mining activities ceased >100 years ago, thus reflecting the long-lasting impact of human-environment interaction, suggesting that ecosystem conditions may remain impaired centuries after activities have ceased.