Summary• The extent of isotopic discrimination of transition metals in biological processes is poorly understood but potentially has important applications in plant and biogeochemical studies.• Using multicollector inductively coupled plasma (ICP) mass spectrometry, we measured isotopic fractionation of zinc (Zn) during uptake from nutrient solutions by rice ( Oryza sativa ), lettuce ( Lactuca sativa ) and tomato ( Lycopersicon esculentum ) plants.• For all three species, the roots showed a similar extent of heavy Zn enrichment relative to the nutrient solution, probably reflecting preferential adsorption on external root surfaces. By contrast, a plant-species specific enrichment of the light Zn isotope occurred in the shoots, indicative of a biological, membrane-transport controlled uptake into plant cells. The extent of the fractionation in the shoots further depended on the Zn speciation in the nutrient solution.• The observed isotopic depletion in heavy Zn from root to shoot ( − 0.13 to − 0.26‰ per atomic mass unit) is equivalent to roughly a quarter of the total reported terrestrial variability of Zn isotopic compositions ( c. 0.84‰ per atomic mass unit). Plant uptake therefore represents an important source of isotopic variation in biogeochemical cycling of Zn.

The unique archived samples from the Rothamsted Broadbalk Experiment, England, were used to evaluate long‐term effects of changing S inputs from atmospheric deposition and fertilization on soil S pools and soil S isotope ratio since 1843. The effects of changing land uses were also investigated. Large S inputs from atmospheric deposition and from sulfate fertilizers did not result in any significant accumulation of soil organic or inorganic S in the arable plots where organic C remained stable. Inputs of sulfate in excess of crop uptake were lost mainly through leaching. Organic S accumulated markedly in the arable plot receiving farmyard manure (FYM) or where arable land was allowed to revert to woodland or grassland. In the latter two systems soil organic C accumulated faster than organic S. In all soils investigated the S isotope ratio (δ34S) decreased substantially during the last 150 yr. The decrease in δ34S was greater in the woodland, grassland, and the arable FYM plot than in other arable plots receiving either inorganic fertilizers only or no fertilizers. The results indicate that atmospheric S was more depleted in 34S than the soil native S at the experimental site, and that atmospheric S was incorporated into the organic pool to varying degrees depending on the C pool. In conclusion, land use had a large effect on the S cycling in soils, which is driven mainly by soil organic C cycling. Without accumulating soil organic C, there appears to be little scope for S retention in temperate soils with neutral pH.

sions and deposition in western Europe has led to increased S deficiency in many agricultural crops, which Archived wheat (Triticum aestivum L.) grain and straw, and soil remove substantial amounts of S from the soil annually samples from the control plot of the Rothamsted Broadbalk Experiment, located in southeastern England and established in 1843, were (McGrath and Zhao, 1995;. used to investigate the effects of dramatically changing SO 2 pollution

Ganges, an ecotype of Thlaspi caerulescens from southern France accumulates both Zn and Cd to extraordinary levels in the shoots. The interactions between Zn and Cd in this ecotype were investigated using solution culture and pot experiments with soil. Results from both relatively long-term (4 weeks) and short-term (1 week) solution culture experiments indicated that Cd accumulation in the shoots was not affected by the supply of a 4 to 10fold excess of Zn, whereas the Cd concentration of the roots decreased with increasing Zn concentration in the solution. By contrast, the supply of an equimolar concentration of Cd significantly reduced the Zn concentration in both roots and shoots. However, when 4-fold more Zn than Cd was supplied, Cd-induced decrease in Zn accumulation was not observed. In soil treated with Cd or Zn, addition of one metal increased the metal concentration of the other in the soil solution. However, Zn accumulation by T. caerulescens decreased by Cd addition, whereas Cd accumulation was not affected by Zn addition. These results suggested that the Ganges ecotype of T. caerulescens displayed different uptake systems for Cd and Zn, and that Cd competed with Zn uptake while Zn did not compete with Cd uptake.