Kinetics of selenomethionine disappearance from reclaimed coal mine soils of Wyoming, U.S.A.     

S. Sharmasarkar  G. F. Vance 《Environmental Geology》1997,29(3-4):202-208

 Selenomethionine (SeM) is an organic toxicant that is present in seleniferous environments. No kinetic data is yet available regarding SeM reactions in coal mine environments, where selenium (Se) toxicity is a potential concern. A kinetic study was conducted on two reclaimed coal mine soils (Typic Torriorthents) from Wyoming having sandy and clayey textures. Four levels of SeM treatments (0, 50, 100 μM, and plant amendment from the mine vegetation) were reacted with the soils for 4, 7, 14, 28, 42, 56, and 84 days to characterize the kinetic behavior of overall SeM disappearance from soil solutions. Detection of SeM in soil solutions at the control level (0 μM SeM) indicated occurrence of indigenous SeM in the soils. In the plant-amended soil solutions, much greater concentrations of SeM were observed as compared with the soil-only systems. This indicated the plant material was a more potential source of SeM than the mine soils. A time-dependent loss in solution SeM concentrations was observed for both soils under 0, 50, 100 μM SeM treatments. For the soil-plant mixtures, the solution SeM concentration increased initially, reached a maximum after 14 days, and then decreased thereafter. In the plant-amended soil solutions, SeM concentrations at all time intervals were higher for the sandy as compared to the clayey soil. At 50 and 100 μM SeM treatments, the solution pH was linearly related to the percentages of SeM disappeared from the solutions; greater percentage of SeM was removed from solutions at comparatively lower pH levels, which was ≥90% at pH 7.7 for both soils. Solution SeM concentrations decreased exponentially with time following first-order kinetic reactions. Under all applications (except for the control), C ₀ (SeM concentration at t=0) values for the sandy soil were greater than those determined for the clayey soil, indicating higher solution SeM availability for the former and more SeM retention by the latter at t=0. Comparison of C ₀ in controls (0 μM SeM addition) suggested greater indigenous SeM in the clayey soil. For both soils, C ₀ values under different treatments followed the order, (soil+100 μM)>(soil+50 μM)>(soil+0 μM). The specific reaction rate constants (K _r) of SeM for both soils were similar (0.031 and 0.029 day^–1 for sandy and clayey soils, respectively); low K _r values indicated that SeM loss from our reclaimed coal mine soil solutions would follow rather slow kinetics. The half-life (t _0.5) of SeM varied from 15 to 55 days depending on treatment level. The knowledge obtained from this study should contribute in developing time-based Se reclamation strategies in coal mine environments. Received: 18 September 1995 · Accepted: 28 December 1995  相似文献   

贵州铜仁碧江区耕地土壤硒富集分布特征及影响因素研究     

沈小庆  洪万华  涂飞飞  杨炳南  张德实  韩姚飞  余万泽 《贵州地质》2021,38(4):480-486

硒是重要的人体必需微量元素,对特色农业发展起着重要的助力作用。碧江区土壤硒元素含量平均值超过贵州省及全国硒含量均值。富硒耕地面积达29426 8万亩,具有较大的富硒资源开发潜力。成土母岩为炭质页岩所形成的土壤中硒元素含量高于其他类型成土母岩所形成的土壤,强酸性土壤中硒元素含量平均值高于其他酸碱度等级土壤,水田中硒元素含量平均值显著高于旱地、果园、水浇地等其他类型土地。成土母质是土壤中硒元素的主要来源及影响因素,pH值、有机质、土壤质地等理化条件对土壤硒元素有一定影响。  相似文献   

An assessment of selenate co-precipitation with gypsum     

《Chemie der Erde / Geochemistry》2021,81(2):125743

In this study, we assessed the co-precipitation of selenate (SeO₄²⁻) with gypsum (CaSO₄·2H₂O) in controlled laboratory experiments. Batch testing was used to quantify the ability of CaSO₄·2H₂O to co-precipitate dissolved SeO₄²⁻ over a range of dissolved SeO₄²⁻-Se concentrations (0–50 mg/L) and under slightly acidic (pH ∼5.5–6.1) and oxic (Eh ∼416−501 mV) conditions. Aqueous samples were analyzed using inductively coupled plasma optical emission spectrometry, solid samples using X-ray diffraction and Raman spectroscopy, and digests of selected CaSO₄·2H₂O precipitates using inductively coupled plasma-mass spectrometry. The concentration of Se co-precipitated in CaSO₄·2H₂O increased linearly with dissolved SeO₄²⁻-Se concentration. The aqueous analyses and calculations based on the CaSO₄·2H₂O digest data show between 14–19 % of the dissolved Se was removed during the co-precipitation experiments. The strong linear relationship between SeO₄²⁻-Se added to the test solutions and Se co-precipitated in CaSO₄·2H₂O can be used to estimate the concentration of co-precipitated SeO₄^2- if the concentration of SeO₄^2- in the associated porewater is known, and vice versa. Results indicate that <1% of SeO₄²-Se was removed from the test solutions during co-precipitation and the mass of Se in CaSO₄·2H₂O solids was low, ranging between 0−120 μg/g. These results were used in conjunction with field- and model-derived data to show co-precipitation of SeO₄^2- with CaSO₄·2H₂O should be a minor SeO₄^2- sequestration mechanism. The findings of this study should be applicable to mined rock dumps in North America and elsewhere.  相似文献   

Characteristics of selenium migration in soil–plant system of East Meshchera and Transbaikalia     

Vadim Ermakov  Larisa Jovanovic 《Journal of Geochemical Exploration》2010

Herein some results of comparative researches to determine the parameters of selenium migration in meadow biogeocenoses of East Meshchera and East Transbaikalia are presented. The parameters of selenium mobility in soils (i.e., the element total content, plant-accumulation coefficient (Kb) and/or mobile form ratio) in Urov biogeochemical provinces of the East Transbaikalia are quite comparable to the element migration parameters found in selenium-deficient landscapes of the same area. Selenium mobility indices and ecological status are significantly higher for meadow biogeocenoses of the East Meshchera (Moscow Region) and also for limestone soils.  相似文献   

Selenium and heavy metals content in some Mediterranean soils   总被引：1，自引：0，他引：1  

L. Roca-Perez  C. Gil  M.L. Cervera  A. Gonzálvez  J. Ramos-Miras  V. Pons  J. Bech  R. Boluda 《Journal of Geochemical Exploration》2010

The study of metal contents in industrial, agricultural or/and polluted soils compared with natural or unpolluted soils is currently necessary to obtain reference values and to assess soil contamination. Nonetheless, very few works published appear in international journals on elements like Se, Li and Sr in Spanish soils. This study determines the total levels of Se, Li, Sr, As, Cd, Co, Cr, Cu, Ni, Pb, V, Zn, Fe, Mn and Ba in 14 natural (unpolluted) soils (Gypsisols, Leptosols, Arenosols and Acrisols), 14 agricultural soils (Anthrosols, Fluvisols and Luvisols), and 4 industrial–urban affected-surface soil horizons (Anthrosols and Fluvisols) of Eastern Spain. The geochemical baseline concentrations (GBC) and reference values (RV) have been established, and the relationships among elements and also between soil properties and elemental concentrations have been analysed. The RV obtained in this study were (mg kg⁻¹): Se 2.68, Li 115, Sr 298, Cd 0.97, Co 35, Cr 217, Cu 46, Ni 50, Pb 137, V 120, Zn 246, Fe 124,472, Mn 2691, and Ba 743. The RV for Se and Li were used as a preliminary approach to assess soil contamination in Spanish soils. The results confirm human impact on Sr, As, Cd, Cr, Cu, Ni, Pb and Zn soil concentrations, but evidence no deviation from natural Se, Li, Co, V, Fe, Mn and Ba concentrations. The results obtained from the statistical analysis reveal significant correlations between some elements and clay and soil organic matter (SOM) contents, indicating that metal concentrations are controlled by soil composition. One particularly interesting finding is the high correlation coefficients obtained between SOM and Se, Cd, Cr, V, Fe, and Mn, and between clay and Cd, Zn, V, Fe and Mn. Once again, these facts confirm the role of SOM and clay minerals in soil functions and that soil is an ecosystem element responsible for maintaining environmental quality.  相似文献   

Use of transfer factors to characterize uptake of selenium by plants   总被引：1，自引：0，他引：1  

C. Bitterli  G.S. Bañuelos  R. Schulin 《Journal of Geochemical Exploration》2010

The radioactive selenium isotope ⁷⁹Se can be a component of radioactive waste produced in nuclear power plants. The accidental release of ⁷⁹Se in the environment from power plants or nuclear waste repositories, and subsequent transfer of ⁷⁹Se into soils, plants and food chain, are relevant concerns in Europe. In environmental risk assessment models, the ability of plants to take up Se is often characterized by means of soil-to-plant transfer factors (TF). However, these recommendations take little or no account of the variability in plant Se accumulation among plant species and differences in Se distribution between plant parts. Also, such factors as soil type, form of Se, climatic conditions, as well as the chemical form in which Se is present in the soil, are not taken into consideration.  相似文献