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1.
Sequential leaching experiments using H2O, H2O2, NH4Cl, and HCl were performed on surface soils on an andesite substrate at four sites in the Kawakami mountainous area, central Japan. The solutions extracted from the dehydrated soil by H2O, H2O2, and NH4Cl have relatively constant ratios with respect to Ca, Mg, and Sr, while they have variable 87Sr/86Sr ratios depending on the site. The elemental ratios and Sr isotopes in the extracted solution are different from those of the soil minerals but identical to those of the soil solution and the plants. Sr isotopic data indicate that the residues after extraction from fine-grained minerals by NH4Cl and HCl are a mixture of acid-resistant minerals derived from bedrock and from arid areas in China. We suggest that there is a vital exchange of Sr and other cations between plants and the soil pool of exchangeable cations through the soil solution, while soil minerals, except chlorite, do not participate in the exchange reaction.  相似文献   

2.
《CATENA》1998,32(2):143-151
In calculating catchment weathering rates using strontium isotope ratios, one of the parameters required is the 87Sr/86Sr ratio of the streamwater. The effect of flow rate on this ratio is not well understood with conflicting reports in the literature. To provide more detailed information on the effect of flow rate on strontium isotope ratios, the 87Sr/86Sr ratio was measured in streamwater samples taken at low and high flow rates and also in samples taken at four and eight hourly intervals during two rain events in a small catchment (area 90 ha) in andesitic lavas. The 87Sr/86Sr ratio varied over a narrow range of 0.70797 to 0.70852 for a flow rate range of 6.1 to 41.51 s−1 and showed no relationship to flow rate. Weathering of non-radiogenic plagioclase feldspar in the soils controls the isotope signature of the streamwater and the constancy of the ratio with flow rate indicates that (1) more radiogenic minerals such as K-feldspar and mica do not contribute any more significantly during high flow than during low flow, and (2) from the available information, it is not necessary to take flow rate into account when using 87Sr/86Sr ratios in weathering studies in this particular catchment, although it must be emphasized that this conclusion may not apply to other catchments. The concentration of strontium in the streamwater was inversely proportional to the flowrate.  相似文献   

3.
Quinoa (Chenopodium quinoa Willd.) is a high-nutrient halophyte suitable for ?cultivating in semi-arid climates and saline soils. The current study investigated the ?effect of various water salinities (ECi) (i.e., 0.3, 10, 15, 20, and 25 dS m?1) and different ?irrigation methods (IMs) on accumulation of calcium (Ca), magnesium (Mg), ?sodium (Na), and chloride (Cl) ions in shoot (stem+leaves) of quinoa at the end of vegetation (onset of flowering) and seed at the end of seed-filling. Therefore, 30 pots (five ECi and two IM in three replications) were prepared with similar conditions. Considering that the salinity threshold value (STV) of quinoa varies during growth and is 8, 20 and 15 dSm?1 at each of ?establishment, flowering, and seed-filling growth stages, the two IMs consisted of considering STV at each growth stage (T) and permanent irrigation by ?constant levels of ECi(P). Results indicated that by increasing the ECi from 0.3 to 25 dSm?1 the amount of Na, Cl, and Mg in shoot increased 82.2%, 75.8%, and 8.7%, respectively, while Ca decreased 37.2%. In seeds, Na and Cl increased 43.3% and 50%, respectively, while Mg increased 8% and Ca did not change significantly. An increase in ECi ?significantly changed ion accumulation content, especially at ECi higher than STV, ?because it is the onset of damage due to salinity stress and particularly in? ??shoot compared to seed due to the halophytic properties of quinoa. The T ?method of irrigation was preferred due to less accumulation of Na and Cl in ?shoot and seed, and therefore less damage and loss, especially at higher ?salinities.?  相似文献   

4.
The 87Sr/86Sr ratios in rain at three sites in Japan were about 0.706 to 0.712, whereas those at one site in central Korea were higher (0.711 to 0.716), reflecting the difference in geology between the two countries. Because the 87Sr/86Sr ratios of exchangeable sites in soil minerals are indistinguishable from those of associated plants, aerosol Sr originating from both can be grouped together as plant-derived Sr. Spatial and temporal variations in 87Sr/86Sr and Sr/Ca ratios in the rain suggest the presence of plant-derived Sr and Ca in addition to Sr and Ca derived from sea-salt, acid-soluble aeolian carbonate from China, and cement-derived carbonate. However, systematic data on the 87Sr/86Sr ratios and elemental concentrations of soils, plants, fly-ash, and road dust are required to put reliable constraints on the provenance of atmospheric Ca.  相似文献   

5.
Carbonatite originating from the Lillebukt Alkaline Complex at Stjernøy in Northern Norway possesses favorable lime and potassium (K) fertilizer characteristics. However, enrichments of barium (Ba) and strontium (Sr) in carbonatite may cause an undesired uptake by plants when applied to agroecosystems. A field survey was carried out to compare concentrations of Ba, Sr, and macronutrients in indigenous plants growing in mineral soil developed on a bedrock of apatite–biotite–carbonatite (high in Ba and Sr) and of apatite–hornblende–pyroxenite (low in Ba and Sr) at Stjernøy. Samples of soil and vegetation were collected from three sites, two on carbonatite bedrock and one on pyroxenite bedrock. Ammonium lactate (AL)‐extracted soil samples and nitric acid microwave‐digested samples of soil, grasses, dwarf shrubs, and herbs were analyzed for element concentration using ICP‐MS and ICP‐OES. Concentrations of magnesium (Mg) and calcium (Ca) in both soil (AL) and plants were equal to or higher compared to values commonly reported. A high transfer of phosphorus (P) from soil to plants indicates that the apatite‐P is available to plants, particularly in pyroxenite soil. The non‐exchangeable K reservoir in the soil made a significant contribution to the elevated K transfer from soil to plant. Total concentrations of Ba and Sr in surface soil exhibited a high spatial variation ranging from 490 to 5,300 mg Ba kg?1 and from 320 to 1,300 mg Sr kg?1. The transfer of AL‐extractable elements from soil to plants increased in the order Ba < Sr < Ca < Mg < K, hence reflecting the chemical binding strength of these elements. Concentrations of Ba and Sr were low in grasses (≈ 20 mg kg?1), intermediate in dwarf shrubs and highest in herbs. Plant species and their affinity for Ca seemed more important in explaining the uptake of Ba and Sr than the soil concentration of these elements. The leguminous plant species Vicia cracca acted as an accumulator of both Ba (1.800 mg kg?1) and Sr (2.300 mg kg?1).  相似文献   

6.
Cesium and Strontium Exchange Properties of Marsh Soils The cesium and strontium exchange properties of some typical marsh soils of the estuary and lower river Weser region were described. Soil samples were taken according to the existing soil maps 1:25000 of Lower Saxony e.g. a “sea marsh soil”. a “brackish marsh soil”, and a “river marsh soil”. The exchange properties were determined by Cs/Ca and Sr/Ca exchange curves (Q/I relations) as generally used in soil potassium research. In addition to the Q/I relations the following investigations were carried out: - Cs and Sr desorption experiments (one time equilibration with Ca++ solutions) - Cs and Sr reexchange experiments (eight times equilibration with water, Ca++, Ba++, and K+ solutions) - the naturally-occuring Cs and Sr contents of the soils including amounts caused by imissions or fallout, respectively - clay mineral composition and swelling of layer silicates due to saturation with Ca++, Sr++, Cs+, and K+ ions. Q/I relations as well as desorption and reexchange experiments indicated strong cesium and low strontium fixation by the soils investigated. This was considered the reason for the stronger transfer of Sr from soil to plants as compared with Cs. Furthermore, the reexchange experiment revealed nearly complete reversibility of the Sr sorption reactions by equilibration with the divalent cations Ca++ and Ba++ and some Sr fixation after treatment with K+ solutions. However, cesium was much better reexchanged by K+ than by Ca++ and Ba++ ions. This led to the conclusion that Cs fixed in interlayer positions of clay minerals could be remobilized by potassium and ammonium fertilization. The naturally-occuring Cs contents of the soils were found to be below the detection limit of the analytical methods used. The contents of naturally-occuring exchangeable Sr, however, was in agreement with the amounts of “labile Sr” as derived from the Sr/Ca exchange curves. Concerning the cesium exchange properties a clear distinction between “sea and river marsh soils” on the one hand and “brackish marsh soils” on the other hand was established due to differences in clay mineral composition and swelling state of 1:2 layer silicates. The different cesium exchange properties of the two soil groups could also be verified by more or less pronounced hysteresis effects of sorption (Q/I relation) and desorption curves.  相似文献   

7.
Fresh snowfall was collected on the surface of 8 lakes across a 350 km west-east transect from northeastern New York state to the coast of Maine after a single storm. In addition, every snowfall event during the winter of 1993 was collected on a single lake near the center of the transect. Across the transect, midwestern sources appear to dominate Pb and Cd concentrations, while Sb appears to be derived from midwestern sources as well as local and/or industrial East Coast sources. In all samples, the highest Na, Cl and Mg concentrations reflect a marine influence, but at some transect sites roadspray aerosol appears to contribute to Na and Cl concentrations. The regional pattern of Ca, K, Mn and Sr concentrations and Mn/Sr ratios indicate that woodsmoke may be an important winter source of these elements at some sites. In all samples, H+ is strongly correlated with NO3 ? (R2 = 0.97) and mean NO3 ?/SO4 2? molar ratios of 6.4 for transect samples, and 4.7 for temporal samples, are higher than mean NO3 ?/SO4 2? reported for other precipitation studies in the same region. The contribution of NO3 ? to the snowpack greatly exceeds that of SO4 2?, and may be a major source of acidity in aquatic ecosystems during snowmelt.  相似文献   

8.
Abstract

The mineral ion contents of seven halophytic species in the family Chenopodiaceae, and associated soils were examined. Each species was found growing in soils with wide ranges of salinity, sodicity and salt ion composition. Absolute concentrations of Na, Ca, Mg, K, Cl and SO4 in shoot tissue differed significantly among species. Species were classified into two groups: (1) chloride halophytes, with ion composition dominated by Na and Cl (Atriplex patula, Chenopodium rubrum, Salicornia rubra and Suaeda depressa), and (2) alkali halophytes, with relatively high K, Mg, Ca and low Cl contents (Chenopodium salinum, Kochia scoparia and Salsola pestifer). All species accumulated ? and excluded SO4, relative to concentrations of these ions in soil. Salsola pestifer was unique in strongly excluding Na.  相似文献   

9.
Input/output hydrochemical budgets have been calculated for areas within the Loch Fleet catchment, Galloway, S.W. Scotland and the UK which were limed in April 1986. Bulk precipitation inputs and streamwater outputs are dominated by sea salt components. Calcium outputs over the first year post-liming increased dramatically and H+ ion outputs dropped. After the second year post-liming, Ca outputs have declined, although H+ outputs have remained very low and streamwater pH is still circumneutral. The continuation of budget calculations over the next few years, coupled with streamwater and soil chemistry analysis data, should allow estimates to be made of the duration over which of these land-based liming treatments may remain effective in acid mitigation.  相似文献   

10.
Base cation (BC) concentrations of rain, throughfall, percolation from leaf litter, and soil solution were periodically measured in two forests: Kannondai (red pine stand on volcanic soil) and Yasato (deciduous stands on granitic soil). Calculation of a BC budget gave the rate of BC release from soils; the BCs originated from mineral weathering and cation exchange. Weathering rates under field conditions were estimated from the Sr isotope ratios (87Sr/86Sr) of water and soil samples. Isotope ratios decreased in the order rain > throughfall > percolation > soil solution. Clay and silt had extremely high isotope ratios; this suggests that the sandy fraction, whose isotope ratio was smaller than that of the soil solution, was the main contributor to mineral weathering. Estimated BC weathering rates (kmolc·ha?1y?1) were 1.16 for Ca and 0.57 for Mg at Kannondai, and 0.82 for Ca and 0.51 for Mg at Yasato. The unexpected high weathering rate of granitic soil in Yasao was due to the wide coverage of the original parent material by volcanic ash. The contribution of cation exchange derived by subtraction was a little smaller than the weathering rates and was similar to the values estimated from a dynamic model that we developed.  相似文献   

11.
We compared the elemental composition of soil and bedrock samples to determine the extent of chemical weathering and the nature of the soil parent material in alpine soils on Vermont's highest summit. Previously it was unclear whether these soils formed through weathering of bedrock, glacial till, or eolian sediment, or solely through the accumulation of organic matter. In eighteen profiles, no evidence was found to indicate that soils have developed in glacial till, despite evidence that the mountain was completely inundated by the Laurentide Ice Sheet. In contrast, results strongly support the theory that pedogenesis in this environment involves in situ bedrock weathering under a thickening blanket of acidic organic litter. Weathering indices reveal an increase in weathering intensity upwards from the bedrock, and trends of normalized rare earth elements demonstrate a strong similarity between bedrock and soil samples. Leaching has concentrated less mobile elements such as Al, Cr, La, P, Pb, and Ti in soil horizons and removed mobile elements such as Co, Fe, K, Mg, Mn, Si, and Zn. X-ray diffraction reveals that chlorite, which is present in all bedrock samples and some saprolites, has weathered completely from upper soil horizons, and that hydrobiotite, vermiculite, kaolinite, gibbsite, and goethite have formed in the soil. Ratios of immobile elements (Ce, Cr, Nb, Ta, Ti, Y, and Zr) in soil and bedrock samples are, however, notably different. Furthermore, the moderately mobile trace elements Cu, Mo, and Sr are actually more abundant in soil than in bedrock, and soil concentrations of Zr are up to an order-of-magnitude greater than in bedrock samples. Together these data argue for at least a modest eolian influx, which may have arrived during the regression of Lake Vermont during the latest Pleistocene or from an outwash source in the immediate post-glacial period. Similarly, increased Ca and Na concentrations in soil samples may signify modern deposition of dust bearing Ca (from agricultural fields) and Na (from roads).  相似文献   

12.
‘Acid-flush’ events, monitored in an upland catchment in the Cairngorm Mountains (Scotland) at the time of the spring-thaw, are associated with an increase in stream discharge and raised concentrations of both major ions (Ca, Mg, Na, Cl, N03, and SO,) and trace-elements (Al, Cd, Cu, Fe, Mn, and Pb), in addition to H+. The streamwater chemistry is determined by the hydrological pathways which are operative in the catchment during these periods of snowmelt, and reflects both the meltwater composition and the influence of the soils within the catchment. Aluminium, in particular, is leached from the soils and high concentrations (up to 330 μg L?1) occur in the streamwaters. The presence of frozen soils, which result largely due to the influence of meteorological conditions prior to the accumulation of the snowpack, is likely to have a large impact on the Al concentrations in the streamwaters. The low concentrations of Ca monitored in the stream during the periods of snow-melt (<0.2 mg L?1) may promote subsequent toxic effects of the Al to aquatic life forms.[/p]  相似文献   

13.
Aeolian particles originating from arid areas in China, termed Kosa, are considered to be a major source of non-sea-salt Ca, a dominant base cation, in acid precipitation in northeastern Asia. We extracted evaporite minerals (halite, gypsum, and carbonate) from the surface soil collected at eight desert and loess areas in northern China with water and acetic acid. Most 87Sr/86Sr ratios of the extracted fractions fell in a restricted range (0.7115 ± 0.0015) and differed from those of bulk soils and acid-insoluble minerals (0.712–0.717). The selective dissolution of the soil carbonates in the atmosphere is consistent with two facts: (1) their 87Sr/86Sr ratios are close to the maximum 87Sr/86Sr ratios of spring precipitation in Japan, when Kosa activity is marked; and (2) their mole ratios of Mg/Ca (0.15) and Sr/Ca (0.001) are almost identical to those of precipitation in China and Japan when Kosa activity is marked. The 87Sr/86Sr, Mg/Ca, and Sr/Ca ratios in the acid-soluble components can be used as indexes of Kosa aerosols in the precipitation of the northwestern Pacific.  相似文献   

14.
The salinization process was investigated with hydrogeochemical tools to evaluate the origin of salinity in the Selçuk Plain. Na/Cl and Cl/Br molar ratios of coastal zone that covers an alluvial aquifer, karstic discharges, and a wetland are similar to the local seawater ratio. According to mixing ratios, seawater addition can reach 9–18% in both seasons at the coastal zone especially in karstic springs that are a kind of seawater–freshwater mixing points. A thematic map of the Salinization zone was constructed for the Selçuk Plain using geographical information system tools with different parameters such as major ion ratios, EC values, mixing ratios, and sodium adsorption ratio values. High correlation between Cl and Br, B, Li and Sr explains the salinization process that comes from marine intrusion. The δ 18O and δD composition of water samples varies between ?6.7‰ and ?2.9‰; ?37‰ and ?20‰, respectively. The coastal zone waters are plotted on the mixing line due to the effects of the salinization process in the plain.  相似文献   

15.
The strontium isotope ratio (87Sr / 86Sr) of brown rice (Oryza sativa L.) was determined by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in order to evaluate the values of 87Sr / 86Sr for use in the estimation of the area of rice production. Sample solutions were prepared from 5 g of rice samples using the acid (HNO3-HClO4-HF) digestion method. Removal of rubidium from the sample solutions was performed using ion-exchange resin (Dowex 50W X8). The Sr isotope ratios were determined with a precision of < 0.01% (RSD, repetitions = 60) by MC-ICP-MS. Typical analysis time for a single sample was about 15 min, reflecting the high sample throughput. The Sr isotope ratios of the Japanese rice samples ranged from 0.706 to 0.709. The Sr isotope ratios of the Chinese and Vietnamese rice samples (0.710 to 0.711) were slightly higher than those of almost all the Japanese samples. Australian rice showed the highest Sr isotope ratio (0.715 to 0.717) among all the rice samples examined. In contrast, the Sr isotope ratio of Californian rice (0.706) was lower than that of almost all the Japanese samples. The variation in the 87Sr / 86Sr ratios for the rice samples analyzed in this study clearly demonstrated that the Sr isotope ratios could provide a key information for the estimation of rice provenance.  相似文献   

16.
The accumulation and depuration of Ca and Sr were measured in populations of the earthworm Lumbricus rubellus, originating from calcareous and acidic soils, following laboratory exposure to a Sr-rich soil and a control soil. Populations from acidic soils accumulated more Sr than those from calcareous soils, when placed in a Sr-rich soil. After transferal from a Sr-rich soil to Sr-free soil, all populations depurated the majority of their body Sr (84 %-96 %) whilst maintaining their body Ca concentration; the Sr excretion was greater in the populations originating from acidic soils. ICP-MS cation analysis demonstrated the majority of Ca and Sr to be located in anterior alimentary canal and the majority of Sr was lost from this region.  相似文献   

17.
The natural Sr isotope composition of acid leached soils developed on loess, under beech forest, in central Belgium was used as a tracer of soil forming processes, in conjunction with physico‐chemical and quantitative mineralogical investigations. Attention was focused on weathering and exchange processes, with special emphasis on the origin of the current soil exchangeable fraction and the influence of the atmospheric deposition and biological cycling on the calcium exchangeable pool (Sr acts as a proxy for Ca). The determination of 87Sr/86Sr ratios was made on the bulk soil, on the clay‐ and silt‐size soil separates, on 0.1 m HCl extracts, on the labile pool, on the soil solution and on the bulk precipitation. The acid leached soil profiles are characterized by a sequence of weathering processes that is highlighted by both mineralogical and isotopic changes. From the calcareous unweathered loess (pH 7.5) to the uppermost soil horizons (pH < 4.0) the evolution of the 87Sr/86Sr isotope ratio clearly reflects: (i) the selective weathering of Ca‐plagioclase (small 87Sr/86Sr ratio) and the increasing proportion of resistant K‐ and Rb‐rich minerals (large 87Sr/86Sr ratio) in the uppermost soil horizons; and (ii) a downward translocation of clay minerals with a large isotopic ratio, a physical breakdown of muscovite and a non‐congruent chemical weathering of K‐feldspar. The influence of organic restitutions or atmospheric deposition is not significant. The comparison between the Sr isotopic signature of the soil solution, and the exchangeable and HCl‐extractible soil fractions provides information about cation exchange efficiency, soil–water interaction and the origin of the exchangeable pool.  相似文献   

18.
Natrium - (Calcium + Magnesium) - Austauschgleichgewichte in Böden . Beckett's approach has been used to describe the Na-(Ca + Mg) exchange isotherm in twenty soil samples that differed in texture and salinity. The data obtained from the isotherms were compared with the values of exchangeable sodium obtained by ammonium acetate and the concentration ratios (Na/ °Ca+Mg) calculated from the saturation paste extract. The Na-Q/I relation was always linear for each of the studied soils with no curvature at the lower values of concentration ratio. Values of - Δ Na0 obtained from the isotherms were highly correlated with exchangeable Na (r2 + 0.89). The equilibrium concentration ratios of the isotherms were similar to those obtained from the saturated paste extract in the non-saline soils, and were much lower in the case of the salt affected soils. The slope of the Na-Q/I relation appeared to be a soil characteristic not affected by either Na depletion from the soil or Na addition up to 5 me./100 g. soil. The PBCNa values were highly correlated with the C.E.C. values of the soil (r2 + 0.97).  相似文献   

19.
The effects on two‐week‐old plants of a salt‐tolerant line (Euroflor) and a salt‐sensitive (SMH‐24) line of sunflower, of varying sodium/calcium (Na/ Ca) ratios in a saline growth medium were assessed after three weeks growth in sand culture under greenhouse conditions. The different Na/Ca ratios of the salt treatment were 36.5, 74.0, and 149, at a constant concentration of 150 mol m‐3 NaCl. Euroflor was superior to SMH‐24 in fresh and dry matters of shoots and roots at varying external Na/Ca ratios. The leaf Na+ concentration in SMH‐24 increased consistently with increase in external Na/Ca ratio, whereas that in Euroflor remained almost unaffected. Although leaf chlorine (Cl‐) was significantly greater in SMH‐24 than Euroflor, there was no effect of decreasing Ca2+ concentration of the saline growth medium on the leaf Cl‐ concentrations of both lines. The lines did not differ in K+, Ca2+ or Mg2+ concentrations of both shoots and roots. The leaf K/Na and Ca/ Na ratios, K versus Na selectivity were considerably higher in Euroflor than in SMH‐24. The lines also did not differ in leaf water potential and gas exchange and these variables were not affected due to decreasing Ca2+ concentration of the saline growth medium. Stomatal conductance and transpiration remained unchanged in Euroflor, whereas those in SMH‐24 decreased significantly at the highest external Na/Ca ratio. Euroflor had significantly greater stomatal conductance and transpiration than those of SMH‐24 at almost all external Na/Ca ratios, whereas the reverse was true for water use efficiency. It was established that Euroflor was tolerant to low Ca2+ concentrations of the saline growth medium as compared with SMH‐24. This was mainly attributable to accumulation of relatively low Na+ and Cl‐ in the leaves, and maintenance of high leaf K/Na and Ca/Na ratios and K versus Na selectivity in Euroflor.  相似文献   

20.
The composition of tree rings and soils was studied at several locations affected by smelting and transportation in the vicinity of Kitwe (Copperbelt, Zambia). The contents of cobalt (Co), copper (Cu), manganese (Mn), and lead (Pb) and the 206Pb/207Pb isotope ratios in the tree rings were interpreted in relation to potential sources of contamination such as smelter production, acidification of the environment, soil composition, raw material processing, and atmospheric suspended particulate matter (SPM). The highest Co contents in the tree rings correspond to maximum ore production in the mid-1970s. Acidification through SO2 emissions is documented in the increased Mn contents from the mid-1980s. The isotopic composition of the tree rings of the studied tree species varies in the interval 1.16?C1.34 and the youngest parts of all the studied trees exhibit a low 206Pb/207Pb ratio (<1.17). The soil isotope composition varies in the range 206Pb/207Pb?=?1.18?C1.35. The Pb isotope composition in the soils and tree rings was formed by a combination of lithogenic Pb (206Pb/207Pb????1.3), Pb in processed ores (206Pb/207Pb????1.2), and SPM (automobile) Pb (206Pb/207Pb??1.1). As the soils in the distant region have high 206Pb/207Pb ratios (>1.3) in the whole profile and simultaneously the youngest parts of the tree rings of tree species growing in this soil have a low 206Pb/207Pb ratio (<1.17), it can be assumed that the Pb in the youngest parts of the tree species is derived from absorption of SPM Pb through the bark rather than root uptake. The absence of Pb with a low 206Pb/207Pb ratio in soils in the distant area is probably affected by fires in the herbaceous and bush undergrowth and plant litter, which prevents Pb from biomass from entering the soil and mobilize it back into the atmosphere.  相似文献   

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