The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Imre Varga - One of the best experts on this subject based on the ideXlab platform.
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Determination of trace metals and speciation of chromium ions in Atmospheric Precipitation by ICP-AES and GFAAS.
Talanta, 1994Co-Authors: Zs. Horváth, E. Mészáros, A. Lástity, Imre Varga, Ágnes MolnárAbstract:Abstract Sampling and analytical techniques used for determining trace metal concentrations in Atmospheric Precipitation waters collected in Hungary are presented. The results of the analyses are briefly discussed and special attention is devoted to chromium speciation. For the preconcentration of the trace metals a chelating cellulose, iminodiacetic acid ethylcellulose (IDAEC) microcolumn was used in a flow-injected system. Cd, Co, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn were determined by ICP-AES. In Precipitation water the concentrations of the trace elements were in the 0.1–50 μg/l. range. The two forms of chromium, Cr(III) and Cr(VI) were separated using IDAEC and the anion exchanger diethylamine ethylcellulose, respectively. Cr was determined by GFAAS. In Atmospheric Precipitation the concentration of Cr(III) was in the range of 0.1–0.4 μg/l. while that of Cr(VI) in the range of 0.04–0.1 μg/l.
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The role of spectrochemical analysis in the determination of the composition of Atmospheric Precipitation and aerosol samples in remote environments
Microchemical Journal, 1992Co-Authors: Zs. Horváth, Alexandra Lásztity, Imre VargaAbstract:Abstract In recent years there has been an increased interest in trace metals in Atmospheric Precipitation and air and their environmental effects. In estimating pollution it is necessary to know the background concentrations of the heavy metals as measured in remote areas far from human activities. From this standpoint spectroanalytical methods cover a wide range of concentrations and are unique in their ability to determine the composition of Precipitation and aerosol samples, including toxic trace metals. In the present study determinations of major, minor, and trace metals were performed by ICP-AES and GFAAS. Microwave digestion and flow-injection enrichment methods were designed for this purpose. From the experimental data background levels of metals in Atmospheric Precipitation and air at a remote location in Hungary were ascertained.
Jing Zhang - One of the best experts on this subject based on the ideXlab platform.
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Effect of Atmospheric Precipitation on the dissolved loads of the Dongjiang River, China.
Journal of Environmental Sciences-china, 2004Co-Authors: Jing-ying Li, Jing ZhangAbstract:The Atmospheric Precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The Atmospheric contribution to river water is estimated by reference to Cl concentration called Cl ref . The Cl ref of 41 97 μmol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of Precipitation and river water, two approaches sea salt correction and Precipitation correction were proposed in order to correct the contribution proportions of Atmospheric Precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the Atmospheric contribution ratios fluctuate from ～5% to ～20% of TDS(total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of Precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO - 3 and cation Ca 2+ and Na\++ dominating the major compositions in this basin. The estimated chemical weathering rate of 15 78—23 48 t/(km 2·a) is only 40%—60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the Precipitation chemistry has never been quantified in detail.
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Effect of Atmospheric Precipitation on the dissolved loads of the Dongjiang River, China.
Journal of environmental sciences (China), 2004Co-Authors: Jing ZhangAbstract:The Atmospheric Precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The Atmospheric contribution to river water is estimated by reference to Cl concentration called Clref. The Clref of 41.97 micromol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of Precipitation and river water, two approaches-sea salt correction and Precipitation correction were proposed in order to correct the contribution proportions of Atmospheric Precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the Atmospheric contribution ratios fluctuate from approximately 5% to approximately 20% of TDS (total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of Precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO3- and cation Ca2+ and Na+ dominating the major compositions in this basin. The estimated chemical weathering rate of 15.78-23.48 t/(km2 x a) is only 40%-60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the Precipitation chemistry has never been quantified in detail.
Zs. Horváth - One of the best experts on this subject based on the ideXlab platform.
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Determination of trace metals and speciation of chromium ions in Atmospheric Precipitation by ICP-AES and GFAAS.
Talanta, 1994Co-Authors: Zs. Horváth, E. Mészáros, A. Lástity, Imre Varga, Ágnes MolnárAbstract:Abstract Sampling and analytical techniques used for determining trace metal concentrations in Atmospheric Precipitation waters collected in Hungary are presented. The results of the analyses are briefly discussed and special attention is devoted to chromium speciation. For the preconcentration of the trace metals a chelating cellulose, iminodiacetic acid ethylcellulose (IDAEC) microcolumn was used in a flow-injected system. Cd, Co, Cu, Fe, Mn, Ni, Pb, Ti, V and Zn were determined by ICP-AES. In Precipitation water the concentrations of the trace elements were in the 0.1–50 μg/l. range. The two forms of chromium, Cr(III) and Cr(VI) were separated using IDAEC and the anion exchanger diethylamine ethylcellulose, respectively. Cr was determined by GFAAS. In Atmospheric Precipitation the concentration of Cr(III) was in the range of 0.1–0.4 μg/l. while that of Cr(VI) in the range of 0.04–0.1 μg/l.
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The role of spectrochemical analysis in the determination of the composition of Atmospheric Precipitation and aerosol samples in remote environments
Microchemical Journal, 1992Co-Authors: Zs. Horváth, Alexandra Lásztity, Imre VargaAbstract:Abstract In recent years there has been an increased interest in trace metals in Atmospheric Precipitation and air and their environmental effects. In estimating pollution it is necessary to know the background concentrations of the heavy metals as measured in remote areas far from human activities. From this standpoint spectroanalytical methods cover a wide range of concentrations and are unique in their ability to determine the composition of Precipitation and aerosol samples, including toxic trace metals. In the present study determinations of major, minor, and trace metals were performed by ICP-AES and GFAAS. Microwave digestion and flow-injection enrichment methods were designed for this purpose. From the experimental data background levels of metals in Atmospheric Precipitation and air at a remote location in Hungary were ascertained.
L. Bruce Railsback - One of the best experts on this subject based on the ideXlab platform.
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A comparison of growth rate of late Holocene stalagmites with Atmospheric Precipitation and temperature, and its implications for paleoclimatology
Quaternary Science Reviews, 2018Co-Authors: L. Bruce RailsbackAbstract:Abstract Growth rate of stalagmites can vary with many factors of physical environment, ecology, and karst hydrogeology, to the extent that growth rates calculated from a carefully selected set of data from 80 stalagmites from around the world vary by a factor of 400 from smallest to largest. Growth rates of those 80 stalagmites nonetheless collectively show correlations to Atmospheric Precipitation and temperature that are non-trivial (r2 = 0.12 and 0.20, respectively) and unlikely to have arisen randomly (p = 0.002 and 0.00002). Those global relationships are also supported by previously published studies of individual drip sites. The general trend of growth rates is not a monotonic increase with Precipitation; instead, it reaches a maximum at annual Precipitation rates between 700 and 2300 mm/year, which both counters many model predictions that growth rates should increase monotonically with drip rate and complicates use of growth rate as a proxy for past Precipitation. The general trend of growth rates among the 80 stalagmites is a monotonic increase with temperature. However, the low values of r2 in both of these general trends indicate that growth rate can be at best a qualitative rather than quantitative proxy of past conditions. Growth rate shows no statistically significant relationship to effective Precipitation, seemingly because of the confounding effect of temperature. Growth rates of aragonite-bearing stalagmites are commonly greater than rates in stalagmites in which calcite is the only carbonate mineral, suggesting both the need for careful identification of mineralogy and the special applicability of aragonitic stalagmites in high-resolution studies. Aragonite has exceptionally great frequency in settings with low effective Atmospheric Precipitation, supporting previous linkages of that mineral to warm dry environments. Closely-spaced sampling used in recent paleoclimatological studies suggests that unexploited long-term low-resolution records of past climate may exist in surprisingly small slow-growing stalagmites from exceptionally cold and/or dry regions.
Lawrence R Edwards - One of the best experts on this subject based on the ideXlab platform.
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a stalagmite record of abrupt climate change and possible westerlies derived Atmospheric Precipitation during the penultimate glacial maximum in northern china
Palaeogeography Palaeoclimatology Palaeoecology, 2014Co-Authors: Bruce L Railsback, Honglin Xiao, Fuyuan Liang, Pete D Akers, George A Brook, W M Dennis, Thomas E Lanier, Hai Cheng, Lawrence R EdwardsAbstract:Abstract The geochemistry and petrography of a stalagmite from Wanxiang Cave in central China provide a paleoclimate record of the Penultimate Glacial Maximum (PGM) suggesting unexpectedly abundant non-monsoonal Atmospheric Precipitation at the nadir of the PGM. Eleven U–Th ( 230 Th) ages from 149 to 140 ka BP place the stalagmite in Marine Isotope Stage 6b, coincident with the greatest benthic marine δ 18 O calcite values of MIS 6. Carbon and oxygen stable isotope data, measurements of layer-specific width, positions of surfaces of non-deposition or dissolution, changes in the character and thickness of seemingly annual layers, changes in concentration of organic acids within the stalagmite's calcite, and patterns in the Mg concentration of that calcite all combine to give a coherent paleoclimate record. These data suggest that the stalagmite represents a wetter period than before or after its growth, with the wettest and coldest phase at 145 to 144 ka BP. This extreme in climate yields a striking correlation with the LR04 stack of oxygen isotope records from marine benthic forams, if the latter is subjected to a 4500-year chronological adjustment previously suggested by U–Th data from corals. The timing of the Wudu stalagmite's deposition combines with findings elsewhere to suggest that the PGM was the most extreme of later Pleistocene glacial maxima. Petrography and U–Th age determinations suggest dramatic changes in climate during the PGM. At the beginning (149–146 ka BP) and end (143–140 ka BP) of the stalagmite's growth, abrupt (century-scale) drying caused lengthy hiatuses as dripwater to the stalagmite diminished. On the other hand, delivery of water to the stalagmite during the wettest phase (145–144 ka BP) caused dissolution of previous layers of the stalagmite. Enhanced Atmospheric Precipitation during the cold of a glacial maximum is unexpected because, within the spectrum of Holocene climate, cooler conditions lessen the impact of the East Asian monsoon. Changes in the character of stalagmite layers indeed suggest weakened to negligible influence of the East Asian monsoon during the nadir of the PGM. However, data from the stalagmite are compatible with Atmospheric Precipitation from westerly winds that today reach only northwestern China but that may have been deflected southward in the PGM by southward migration of the Siberian High. This unexpected significance of the Westerlies during the PGM may be a result of the hypothesized extreme nature of the PGM relative to other glacial maxima of the later Pleistocene.