Investigating the origin of Pb pollution in a terrestrial soil–plant–snail food chain by means of Pb isotope ratios

Lead isotope ratios were used to trace the origin of Pb in a soil–plant (Urtica dioica)–snail (Cepaea nemoralis) food chain in two polluted locations in the floodplains of the rivers Meuse and Rhine (Biesbosch National Park) and one reference location in the Netherlands. Lead isotope ratios and concentrations were determined in soil, litter, plant leaves, snails, rainwater and airborne particulate matter. Anthropogenic Pb in the soils of all locations was found to be derived from deposition of Pb polluted river sediments. Discharging rivers influenced the reference location before being reclaimed from the sea. The river sediment contains anthropogenic Pb from various sources related to industrial activities in the hinterland of the rivers Meuse and Rhine. Lead in the atmosphere contributed substantially to Pb pollution and Pb transfer in plant leaves and snails in all locations. Lead pollution in plant leaves and snails can be explained from a mixture of river sediment-Pb and atmospheric Pb from various transfer routes that involve low concentrations.     

Holocene flooding history of the Lower Tagus Valley (Portugal)

The present paper aims to reconstruct the Lower Tagus Valley flooding history for the last ca. 6500 a, to explore the suitability of pollen‐based local vegetation development in supporting the reconstruction of flooding history, and to explain fluvial activity changes in terms of allogenic (climate, human impact) and autogenic (system intrinsic) processes. The flooding history has been determined by cored sedimentary records located ～18 km apart in distal, low‐energy backswamps on both sides of the Tagus channel. In these low‐energy backswamps, fine‐grained sediment layers deposited from suspended load of overbank flood water reflect periods with multiple overbank floods. By means of a multi‐proxy approach (sedimentology, magnetic susceptibility, grain size, loss‐on‐ignition, carbonate content and pollen), sedimentary and environmental changes were identified. At both sites, synchronous lithological intervals accumulated, suggesting a common origin for the changes in fluvial activity since ca. 6500 cal. a BP. Based on lithological changes, three phases of high fluvial activity (6500–5500, 4900–3500 and 1000–0 cal. a BP) and two phases of low fluvial activity (5500–4900 and 3500–1000 cal. a BP) were identified. Two periods with dominant allogenic controls on fluvial activity in the Lower Tagus Valley were identified: relative sea level (6500–5500 cal. a BP) and human impact (1000–0 cal. a BP). During the intermediate period, changes in fluvial activity may have been caused by climate (5500–1000 cal. BP), but unambiguous correlations are difficult to make. This is due to the way allogenic controls are translated through the fluvial system, the geomorphological differences between upstream and downstream studies and autogenic processes. The comparison of local vegetation development and flooding phases as reconstructed using sedimentology shows a limited added value of using local palynology as a proxy for fluvial activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Growth and ionic relations of fodderbeet and seabeet under saline environments

Growth and ionic relations of fodderbeet (Beta vulgaris) and seabeet (B.maritima) were studied in a greenhouse experiment using garden soil salinized with 200 mM NaCl. Both the species tolerated salinity level of 200 mM NaCl, but seabeet performed better than fodderbeet. Fresh weight of shoot increased significantly (P< 0.01) under higher salt concentration in both the species. Fodderbeet accumulated more biomass under saline conditions than seabeet. Salt treated plants accumulated significantly higher Na⁺ and CI^? content in shoot compared to untreated control plants. Chloride (CI^?) of seabeet root was significantly higher than shoot; however, chloride content of shoot was significantly lower in fodderbeet. The concentration of these ions was comparatively higher in seabeet root than fodderbeet in the later growth period. Potassium K⁺ content was low and revealed antagonistic effect with that of Na⁺ content. Calcium (Ca⁺²) ions were not significantly absorbed by shoot of both species. A significant effect of treatment by the root has been observed in both species. Magnesium (Mg⁺²) content of shoot were increased with the time. Seabeet has absorbed more Mg⁺² than fodderbeet. The fodderbeet showed a significant salt tolerance during five week growth period. Seabeet is comparatively more salt tolerant. Domesticated cultivars of fodderbeet like Majorai have considerable adaptability in the inland salt affected areas of Pakistan.