Translocation of 203Hg labelled HgCl2 and CH3HgCl in an iron-humus podzol studied by radio-analytical techniques

Since increased Hg-concentrations in fish in lakes and rivers in northern Europe, northern parts of the U.S.A. and Canada were found, environmental Hg research has focused intensively on the factors determining leaching of mercury from soil into water systems. This article presents the results of a leaching experiment with undisturbed soil columns treated with HgCI₂ and CH₃HgCl using radio-analytical techniques. The columns were irrigated with rain of different acidity, rain volumes and irrigation intensities. The leaching of mercury was traced by detecting the vertical distribution of ²⁰³Hg in the soil profiles. Advantages and disadvantages of radioanalytical scanning techniques are discussed. The results of Hg leaching in the soil columns indicate a considerably stronger leaching of monomethyl mercury compared to inorganic mercury. Leaching of the two Hg-species is ruled by competition of H⁺ induced soil-Hg desorption with DOM-Hg complex formation; both being affected by rain acidity. Rain intensity had no visible effect on leaching of Hg²⁺ and CH₃Hg⁺. An extended rain duration increased the leaching of CH₃Hg⁺.     

A comparison of water soluble organic substances in acid soils under beech and spruce in NE-Bavaria

Water soluble organic substances extracted from the L, O_f, O_h, A, and B horizons of acid soils under Beech (Fagus sylvatica) and Spruce (Picea abies) were fractionated on Sephadex G-25 (medium). Infrared, ¹H NMR and ¹³C NMR spectra of the fractionated components were obtained and comparisons were made among fractions, among horizons, and between forest types. Usually, the spectra indicated that carbohydrates dominated the water soluble fractions. Substances originated from spruce exhibited more undissociated carboxylic acid character than the beech derived material. Despite many similarities, principal differences in the carbohydrate components were found among fractions, among horizons, and between vegetation types.     

Leaching of metals from the A-horizon of a spruce forest soil

The study quantifies the amount of metals (Na, K, Mg, Ca, Al, Fe, Mn, Ni, Cr, V, Cu, Zn, Cd, Pb) leached from the A-horizon of a podzolic spruce forest soil in southern Sweden during 2.5 yr, and offers statistical evidence of environmental conditions of importance to metal release. Considerable losses of Pb, Cr, Ni and V may occur from the A-horizon of forest soils under conditions favoring leaching of organic matter, Fe, and Al, i.e. during periods of comparably high soil temperature and moisture. Metals with a larger fraction present in exchangeable form (Na, Mg, Ca, Zn, Cd) are more susceptible to minor pH changes. An accelerated deposition or internal production of acidic matter therefore will reduce the retention times of these elements particularly.     

The influence of rock powders on microbial activity of three forest soils

To improve the quality of forest soils by applying basic rock powders tests were carried out in Vorarlberg (Austria) in 1987: in the vicinity of Möggers on Stagno-Mollic Gleysol under Abieti-Fagetum luzuletosum, in Nenzing on Calcaric Regosol and Cambisol under Abieti-Fagetum luzuletosum and in Montafon on Stagno-Dystric Gleysol under Homogyno-Piceetum. The effects of a low dosage of rock powder application on nitrification, basal respiration, microbial biomass, xylanase, phosphatase and protease activities, the amount of nitrate nitrogen (NO₃^?-N), and the soil pH were investigated. Additions of rock powder increased protease, NO₃^?-N content and pH, but decreased phosphatase in the A_h-horizon of the Stagno-Mollic Gleysol. After 3 years the A_h-horizon from the experimental site Nenzing showed statistically verified differences of all investigated parameters except xylanase. In the acid spruce forest soils of the Montafon site the rock powder had no statistically significant effect on microbiological parameters. Only the soil pH increased. It can be postulated that the application of rock powders furthered C- and N-mineralization. In the long run this affects the turnover of mineral nutrients in forest ecosystems.     

Atmospheric Impacts due to Anthropogenic Activities in Remote Areas: The Case Study of Admiralty Bay/King George Island/Antarctic Peninsula

The aim of the present work is to characterize the local atmospheric emissions levels and compare them to the component derived from global pollution in a remote site at South Hemisphere (Admiralty Bay located at King George Island in Antarctic Peninsula). Airborne particles, snow and soil/sediments samples were analyzed. Local-produced atmospheric aerosol dispersion was estimated for metals originated by fossil fuel burning from the permanent scientific stations using a simplified Gaussian model. Validation of atmospheric dispersion was established by in situ measurements. Soluble and insoluble particles deposited in freshly snow and airborne particles were analyzed by PIXE (Particle Induced X-Ray Emission) for the determination of the elemental mass concentration and to obtain the Mass Median Aerodynamic Diameter (MMAD). The results showed significant correlation between the concentration of atmospheric aerosol and the freshly deposited particles in the snow, and permitted an estimate of the atmospheric snow deposition factor for K, Cu, Zn, Fe, Pb, and Ti. Results of long-term aerosol data compilation suggest that besides the local aerosol sources, the continental atmospheric transport of airborne particles is not significantly affected by the airborne particles produced by local human impacts at King George Island.     

Zum Einfluß von pH und organischem Kohlenstoffgehalt auf die Löslichkeit von Eisen,Blei, Mangan und Zink in Waldböden

Influence of pH and organic carbon content on the solubility of iron, lead, manganese and zinc in forest soils Several soil factors determine the solubility of heavy metals in soils. The contents of exchangeable and in consequence potentially plant available heavy metals are mainly influenced by the pH and the content of organic carbon. Samples of the A_h-horizon from the stemflow area and from soil not influenced by stemflow water were investigated in beech forests. The solubility or iron, lead, manganese and zinc is described in relation to the pH and the content of organic carbon. Exchangeable iron and lead appear in significant amounts at pH below 3.5 and 4.5, respectively, regardless to the content of organic carbon. Manganese and zinc are exchangeable at pH below 5.0 and are leached for about 90% from the A_h-horizon at pH values below 3.0. The effects of higher soluble iron and lead contents on the distribution of herbaceous plants are discussed.     

Diversity of laccase genes from basidiomycetes in a forest soil

Fungal oxidative exo-enzymes lacking substrate specificity play a central role in the cycling of soil organic matter. Due to their broad ecological impact and available knowledge of their gene structure, laccases appeared to be appropriate markers to monitor fungi with this kind of oxidative potential in soils. A degenerate PCR-primer pair Cu1F/Cu2R, specific for basidiomycetes, was designed to assess directly the diversity of laccase genes in soils. PCR amplification of mycelial cultures and fruit-bodies of a wide spectrum of basidiomycetes, covering all functional groups (saprophytes, symbionts, and pathogens), produced multiple DNA fragments around 200 bp. A neighbor-joining tree analysis of the PCR-amplified laccase sequences showed a clear species-specificity, but also revealed that most fungal taxa possess several laccase genes showing a large sequence divergence. This sequence diversity precluded the systematic attribution of amplified laccase of unknown origin to specific taxa. Amplification of laccase sequences from DNA, extracted from a brown (moder) forest soil, showed a specific distribution of laccase genes and of the corresponding fungal species in the various soil horizons (O_h, A_h, B_v). The most organic O_h-horizon displayed the highest gene diversity. Saprophytic fungi appeared to be less widespread through the soil horizons and displayed a higher diversity of laccase genes than the mycorrhizal ones.     

Acid deposition and ion leaching from a podzolic soil under hardwood forest

The contribution of atmospheric acids to cation leaching from a podzolic soil under mature maple-birch forest in central Ontario was examined during 1983. The movement of base cations was associated largely with NO₃ ^?, SO₄ ^2? and organic acid anions in surface soil horizons, with SO₄ ^2? and NO₃ ^? below the effective rooting zone, and SO₄ ^2? and HCO₃ ^? in streamflow. Mineral soil horizons could adsorb little additional SO₄ ^2? or associated cations at current soil solution SO₄ ^2? concentrations. Therefore it is concluded that the soil in situ lacks a strong affinity for SO₄ ^2?. Current annual inputs to the forest of SO₄ ^2? and NO₃ ^? in bulk precipitation (26.4 and 18.2 kg ha^?1, equivalent to 8.8 kg S and 4.1 kg N ha^?1 , respectively) contributed significantly to cation leaching from the soil. In order to maintain exchangeable cations in soil at current levels, a rate of weathering yielding 29.6, 5.0, 4.4 and 2.2 kg ha^?1 yr^?1 of Ca²⁺, Na⁺, Mg²⁺ and K⁺, respectively, would be required.     

Chrom und Quecksilber in einem seit 80 Jahren mit städtischem Abwasser berieselten Boden

Chromium and mercury in a soil after 80 years of treatment with urban sewage water . A soil (tab. 1) which is since 80 years under irrigation with sewage water contains 112 ppm Cr and 1.5 ppm Hg (Fig. 1). The sewage water presently contains 0.07 ppm chromium and 0.002 ppm mercury. In order to study the migration and leaching of chromium in the soil experiments were carried out with ⁵¹Cr as CrO₄^2- under aerobic and ⁵¹Cr als Cr³⁺ under anaerobic conditions in undisturbed soil columns. In all cases chromium was adsorbed in the layer 0–5 cm (Fig. 2 and 3). Similar experiments with ²⁰³Hg as HgCl₂ (Fig. 4) showed that mercury ist adsorbed near the surface. These experiments confirmed our results of ground water analyses, neither chromium nor mercury contaminated the ground water.     

Aluminium chemistry in two contrasted acid forest soils and headwater streams impacted by acid deposition,Vosges mountains,N.E. France

Al chemistry was studied in two acidic watersheds, one with a podzol, the other with an acid brown soil, in the Vosges mountains (N.E. France), by analysing both leaching and centrifugation soil solutions and spring waters over 3 yr. In the podzol, Al was mobilized in the eluvial horizons under the predominant influence of organic acidity, then leached down the profile as organic and F-bound Al. Strong undersaturation with respect to proto-imogolite and imogolite showed that the proto-imogolite theory of podzolization could not apply. Al was transferred from the soil to spring water mostly as Al³⁺ and Al-F. Al³⁺, as well as additional minor species (AlOH²⁺, AlSO₄ ⁺), originated from the redissolution of the top of the spodic horizons under the influence of both soil solution acidity and the occurrence of mobile anions derived from atmospheric deposition. Conversely, in the acid brown soil, Al mobilization was regulated by nitrate and occurred mainly as Al³⁺. Most of Al was retained in the deep soil and only traces of monomeric Al reached spring water. In the podzol eluvial horizons, soil solutions were undersaturated with respect to all relevant mineral phases and their chemical composition agree with the concept of a mobilization of Al from the solid soil organic Al and a control of Al³⁺ activity by complexation reaction with the solid and soluble soil organic matter and F. In the acid brown soil, soil solutions were found to be in equilibrium with natural alunite, and the formation of this mineral, if confirmed, would account for the occurrence of 'open' vermiculites instead of the expected hydroxy-Al interlayered vermiculites. Al solubility control in surface water of both watersheds remains unclear. The Al-F species in both watersheds and the likely control of Al solubility by alunite in the acid brown soil emphasize the influence of acid deposition on Al chemistry in acid watersheds.     

Mobilität und Pflanzenverfügbarkeit von Phosphor aus organischen und anorganischen Formen in der Rhizosphäre von Lolium perenne

Mobility and availability of phosphorus from organic and inorganic forms in the rhizosphere of Lolium perenne 1.) In pots (sandwich-technique according to Helal and Sauerbeck), where the soil (A_p-horizon of an Alfisol-Udalf from loess) was separated into a root chamber and an outer chamber (up to 10 mm away from the root chamber), the phosphorus (P) availability of super-P, rock-P (Hyper-P) and organic P [myo-inositol-2-mono-P di(cyclohexylammonium) salt] was studied. P was applied at a rate of 50 mg P kg^?1 soil only in the outer chamber. This P fertilization resulted in significant increase of CAL- and water-extractable P in the treatment with organic P and super-P compared to the P₀ treatment. During 6 cuts of Lolium perenne organic P showed the same effect on the P-uptake of plants as super-P. Compared to the treatment without P, rock-P had no effect on the P-uptake. The higher P-uptake of Lolium perenne both in the super-P- and organic P-treatment was reflected at the end of the experiment only by the CAL-P content differences between root chamber and outer chamber. The highest activity of acid phosphatase, measured in air dried soil was found in the root chamber of the organic P treatment The content of EUF extractable organic P was significantly higher in the root chamber of the treatments with super-P and organic P than in the P₀- and rock-P-treatment. 2.) The P elution was studied with 2 soils (A_p-horizon of an Alfisol-Udalf from loess pH: 6.4; A_h-horizon of a basaltic brown soil pH: 5.4) under lab conditions in columns. In the super-P-and organic P-treatment leached P was mainly inorganic. In the soil with low pH value (5.4), P was leached in the treatment with super-P or organic P in a higher amount of organic P than in the soil with pH 6.4. The results of this experiment do not show in which form the applied organic P was moved to the roots or displaced in the soil.     

Effects of acid deposition on acidity and exchangeable cations in podzols of the Kola Peninsula

Response of soil and soil water of podzols in the Kola Peninsula to acid deposition was estimated under both field and laboratory conditions. A significant increasing trend of exchangeable acidity in organic (O) horizons and exchangeable Al in podzolic (E) horizons of podzols with distance from the nickel smelter was observed. The simulated rain at pH 4.5 did not alter chemical properties of soils and soil solutions. As much as 95–99% of the applied H⁺ ions were retained by soils and appeared in the percolates after a treatment period that depended on acid load and soil thickness. Ca and Mg in soil solutions were highly sensitive to acid loading. Simulated acid rain enhanced the leaching of exchangeable base cations out of root zone. Acid inputs resulted in decreased pH, amount of exchangeable base cations and base saturation, in elevated exchangeable acidity and it's Al fraction in soil solid phase. The most significant changes occurred in O and E horizons. Substantial amounts of both Ca and Mg can be lost from the root zone of podzols in the north-western Kola, subjected to acid deposition, thus leading to forest productivity damage.     

The solubility characteristics of organic Al precipitates in allophanic Bs horizons could mimic those of Al hydroxides, and indicate the solubility of associated allophanes

It is shown that Al-humate and fulvate precipitates in Bs horizons of pH > 4.6 can be the source of the soluble aluminium which is rapidly released in equilibrium studies to give log₁₀{Al³⁺} + 3pH values near 9.4 at 8°C, so that it is not necessary to postulate an anomalously reactive but sparingly soluble Al(OH)₃ phase. These Al-organic precipitates will have reached equilibrium in the natural soil environment with the more slowly reacting hydroxy-aluminium precipitates present, including proto-imogolite allophane, but can release Al³⁺ much more rapidly than the inorganic precipitates in laboratory equilibrations and soil leaching episodes that yield lysimeter waters. Equilibrium concentrations of Al reported in a range of Bs horizons indicate that the allophanes present are less soluble than proto-imogolite sols prepared in the laboratory and matured for up to 2 years.     

The migration of fallout 134Cs, 137Cs and 106Ru from Chernobyl and of 137Cs from weapons testing in a forest soil

To estimate the accumulation and vertical migration of radiocesium and radioruthenium, the activity concentrations of Chernobyl-derived ¹³⁴Cs, ¹³⁷Cs and ¹⁰⁶Ru as well as of ¹³⁷Cs from the global fallout of weapons testing observed in the upper horizons of a forest soil (Hapludult, spruce stand) were evaluated with a compartment model. The resulting residence half-times were used to estimate the mean rates of transport of these radionuclides. For Chernobyl-derived ¹³⁴Cs and ¹³⁷Cs within the time period of 200–600 days after the beginning of the fallout the rates were between 4 cm/yr (Of1-horizon) and 2 cm/yr (Oh-horizon), and for ¹⁰⁶Ru between 4 cm/yr (Of1-horizon) and 7 cm/yr (Oh-horizon). These rates, though considerably slower than observed in the same soil during the initial infiltration of these radionuclides with a rain shower, are (depending on the soil horizon) still higher by a factor of 3–6, when compared to the rates of transport of ¹³⁷Cs from the global fallout of weapons testing in the same soil. Because global fallout ¹³⁷Cs is in the soil since about 20 years, these results suggest that the fixation of radiocesium in the forest soil is a rather slow process.     

Influence of organic amendment on the adsorption and leaching of ethametsulfuron-methyl in acidic soils in China

The sorption and leaching of ethametsulfuron-methyl by an acidic soil, after organic amendment with humic acid (HA) and a commercial peat, were studied in batch and soil column experiments. Adsorption capacity (K_f) values, obtained by fitting the experimental data to the Freundlich equation, ranged from 4.39 for the original soil containing 1.02% OC to 10.56 for the organic amended soils containing 2.61% OC. The increase in herbicide adsorption by organic amendment addition to soil was attributed to the high adsorptive capacity of the insoluble organic matter added to the soil. Evidence provided by FT-IR analysis suggested multifunctional hydrogen bonds were involved in the adsorption of ethametsulfuron-methyl on organic matter. The distribution of ethametsulfuron-methyl along the soil profile, obtained from soil column experiments, indicated that the amount of ethametsulfuron-methyl retained ranged from 68.4% for the column filled with the original soil to 92.4% for that filled with the organic amended soil. Amounts of ethametsulfuron-methyl recovered in the leachates, which ranged from 7.7% (organic amended soil) to 23.7% (unamended soil) of that applied, depended upon the loading rate and the source of organic amendment. Organic amendments significantly reduced the leaching of ethametsulfuron-methyl, and humic acid showed the higher potential than peat. This research suggests that organic amendment may be an effective management practice for controlling pesticide leaching.     

Effects of High Nonexchangeable Aluminum on Decomposition and Nutrient Release from Chestnut Leaves

The effect of high nonexchangeable aluminum of a Cryptopodzolic soil derived from mica schist on decomposition and nutrient release from chestnut (Castanea sativa) leaf litter was studied in southern Switzerland using the litter bag technique. Variables studied were time (18 months), exposure (NW versus SE), and profile position of litter (L, O_f and A_h horizons). A site with a Haplumbrept (Al-poor) derived from cherty limestone provided a parent material contrast. Litter decay was chiefly controlled by microclimatic of sites rather than parent material. Litter decay differed between NW- and SE-exposed sites for L and O_f horizons. After 18 months, initial dry matter remaining in L, O_f and A_h positions was 58, 34 and 18%, respectively. All factors equal, the mobility series for nutrient release was K>Mg>Ca>P>N, but site and litter position affected element release. Only K and Mg were lost more rapidly than dry matter. Because dry matter and nutrient loss were similar for Al-rich and Al-poor sites, we conclude that Al content of soils had no influence on decomposition.     

Boron availability to plants from coal combustion by-products

Agronomic use of coal combustion by-products is often associated with boron (B) excess in amended soils and subsequently in plants. A greenhouse study with corn (Zea mays L.) as test plant was conducted to determine safe application rates of five fly ashes and one flue gas desulfurization gypsum (FDG). All by-products increased soil and corn tissue B concentration, in some cases above toxicity levels which are 5 mg hot water soluble B (hwsB) kg^?1 soil and 100 mg B kg^?1 in corn tissue. Acceptable application rates varied from 4 to 100 Mg ha^? for different by-products. Leaching and weathering of a high B fly ash under ponding conditions decreased its B content and that of corn grown in fly ash amended soil, while leaching of the same fly ash under laboratory conditions increased fly ash B availability to corn in comparison to the fresh fly ash. Hot water soluble B in fly ash or FDG amended soil correlated very well with corn tissue B. Hot water soluble B in fly ash amended soil could be predicted based on soil pH and B solubility in ash at different pH values but not so in the case of FDG. Another greenhouse study was conducted to compare the influence of FDG and Ca(OH)₂ on B concentration in spinach (Spinacia oleracea L.) leaves grown in soil amended with the high B fly ash. The Ca(OH)₂ significantly decreased tissue B content, while FDG did not affect B uptake from fly ash amended soil.     

Zur pedochemie des berylliums — untersuchungen einer bodengesellschaft im gebiet des bärhaldegranits (südschwarzwald)

The profile distribution of Be is given for a toposequence of podzols, brown earths, stagnogley, forest bog and “Ockererde” (slope gley with infiltrated Al, Mn and Fe). Analysed were the parent rock, fine earth, four fractions of mineral soil (fine skeleton, sand, silt, clay) and the needles of spruce trees.Beryllium is involved in selective weathering processes of elements. Accordingly, the Be-content increases from the fine skeleton to sand, rock, silt and clay, progressively. Through pedogenetic enrichment, Be accumulates in the mica-rich silt fraction.Uptake of Be by spruce is very low even from these acid soils. The accumulation in the needles becomes greater with increasing age.The pedochemical behaviour of Be is very similar to that of Al.Be is incorporated very little in the organic matter cycle, and is therefore not enriched in the soil humus.The brown earth has lost Be, especially in the A_h-horizon.In the A_e-horizon of the podzol, loss of Be is even greater; the loss is partly offset by Be-enrichment in the B-horizon.In the profiles of depressions, the Be-content is high and is ascribed to lateral flow from the slopes. Be-enrichment is especially high in horizons with a pH of about 5.The Be-balance of the watershed indicates an export of about 10% of the original amount.     

灌溉施肥对壤质潮土硝态氮淋溶的影响

在衡水市邓庄乡壤质潮上上进行了以灌水为主处理、氮用量为副处理,各五水平的定位试验。结果表明,氮肥用量是硝态氮淋溶损失的决定因素,冬小麦施氮150kghm-2不发生淋溶,施氮225～300kghm-2则硝态氮的淋溶增强。小麦播前基施氮肥量过高会使冬季发生硝态氮的淋溶。小麦拔节期和灌浆期灌溉一般不会引起硝态氮的淋溶损失;尽管一次灌水1350m3hm-2硝态氮的淋失量不高,但土壤剖面中的硝态氮含量显著比低灌水量的低。为降低硝态氮的损失,应控制一次灌水量不超过1050m3hm-2。雨季降水导致大量硝态氮淋溶损失,防治雨季土壤硝态氮的淋溶损失至关重要。     

Evaluating Relative Contribution of Atmospheric Mercury Species to Mercury Dry Deposition in Japan

In this study, we evaluated the relative contribution of atmospheric particulate mercury (Hg(p)) and divalent reactive gaseous mercury (RGM) to mercury dry deposition in Japan. The dry deposition fluxes (on a water surface sampler) and atmospheric PM concentrations of Hg, Cd, Cu, Mn, Ni, Pb and V, which were measured concurrently from April 2004 to March 2006 at 10 sites across the nation, were used in this evaluation. We considered that Hg(p) and RGM, but not Hg⁰, are deposited on the water surface, and that our method of sampling Hg(p) without the use of KCl-coated annular denuders enables the exclusion of a significant amount of RGM artifact. The monthly average dry deposition velocities (= deposition flux/atmospheric PM concentration) of Cd and Pb were found to be similar to each other (Cd/Pb deposition velocities?=?1.06?±?0.58). It was assumed that the deposition velocity of Hg(p) is identical to the mean deposition velocity of Cd and Pb, because the particle size distribution of Hg(p) is likely similar to those of both elements. Using this deposition velocity, the monthly dry deposition flux of Hg(p) was calculated. The average contribution (±1σ) of Hg(p) to the annual deposition flux at ten sites was 26?±?15%. The mercury dry deposition flux increased generally from spring to early summer, which was attributed mostly to the deposition of RGM. This seasonal change correlated to that in photochemical oxidant (primarily O₃) concentration in air at most sites. These suggest that mercury dry deposition in Japan is predominantly deposition of RGM, which was formed via oxidation of Hg⁰ by O₃ in the atmosphere.