FRACTIONAL COMPOSITION OF HUMUS IN SELECTED FOREST SOILS IN THE KARKONOSZE MOUNTAINS

This paper describes the fractions of humus compounds present in the organic and mineral horizons of the forest soils in the area of the Karkonosze Mountains. Soil profiles that represented the mountain Podzols and Dystric Cambisol were located on the northern slope along an altitude gradient from 890 to 1255 m a.s.l. Two soils were located under the spruce forest, and one in the subalpine meadow. Soil samples were taken both from the surface organic layers (the ectohumus layer) and from the mineral horizons. Fractionation of humus compounds was made using the modified Turin method. The soils had the texture of loamy sand and sandy loam, an acidic or strongly acidic reaction, low base saturation, and the predomination of aluminum among exchangeable cations. A significant increase in the fulvic fraction (Ia) with depth in the soil profiles was observed that confirmed the high mobility of this fraction in the acid mountain soils, higher in the forest soils, and lower in the meadow soils. The content of fraction I decreased generally with depth in the soil profile; however, a secondary increase was observed in an illuvial Bh horizon of the Podzols. Fulvic acids predominated over the humic acids and this predominance increased with depth in the soil profile. The ratio of the humic to the fulvic acids in fraction I in the ectohumus horizons was influenced by the composition of a biomass inflow. TheCHA:CFA ratio had the highest values under a spruce forest compared to a mixed stand and a subalpine meadow. In the surface horizons of the forest soils, a predominance of humic over fulvic acids was always observed, while in the subalpine meadow soils, the fulvic acids predominated over the humic acids in all soil horizons. Based on this study, it can be stated that thevegetation type and the dominant soil-forming process rather than simply climate factors influence the fractional composition of humus in the mountain soils of the Karkonosze Mountains

Effects of Chelating Compounds on Mobilization and Phytoextraction of Copper and Lead in Contaminated Soils

Six chelating compounds: ethylenediamine-tetraacetic aci

Spatial distribution of lead in the surface layers of mountain forest soils, an example from the Karkonosze National Park, Poland

), and correlated strongly with the stocks of organic matter, both being significantly higher in the lowest altitudinal zone (500-750 m a.s.l.) compared to the highest zone (1250-1380 m a.s.l.). Nevertheless, there was no simple correlation of Pb pools vs. altitude. The largest pools of Pb are stored in the layer 0-10 cm. The pools of accumulated Pb determined in this study are much higher than those assessed on the basis of available data on former and present Pb deposition rates. These findings may be assigned to a seeder-feeder effect and horizontal transport of pollutants. The highest amounts of Pb were identified in three distinct areas (hot spots), in particular in the vicinities of mountain passes, which may be explained by meteorological factors as well as by the influence of local pollution

Ecotoxicity of Pore Water in Meadow Soils Affected by Historical Spills of Arsenic-Rich Tailings

This study was carried out in Złoty Stok, a historical centre of gold and arsenic mining. Two kinds of soil material, containing 5020 and 8000 mg/kg As, represented a floodplain meadow flooded in the past by tailings spills and a dry meadow developed on the plateau built of pure tailings, respectively. The effects of soil treatment with a cattle manure and mineral fertilizers were examined in an incubation experiment. Soil pore water was collected after 2, 7, 21, 90, and 270 days, using MacroRhizon samplers and analyzed on As concentrations and toxicity, and assessed in three bioassays: Microtox, the Microbial Assay for Risk Assessment (MARA), and Phytotox, with Sinapis alba as a test plant. In all samples, As concentrations were above 4.5 mg/L. Fertilization with manure caused an intensive release of As, and its concentration in pore water of floodplain soil reached 81.8 mg/L. Mineral fertilization caused a release of As only from the pure tailings soil. The results of bioassays, particularly of Phytotox and MARA, correlated well with As concentrations, while Microtox indices depended additionally on other factors. Very high toxicity was associated with As > 20 mg/L. Despite an effect of “aging”, pore water As remained at the level of several mg/L, causing a potential environmental risk

Accumulation of Arsenic by Plants Growing in the Sites Strongly Contaminated by Historical Mining in the Sudetes Region of Poland

The uptake of As by various plants growing in highly enriched sites was examined in order to identify potential As accumulators and to assess the risk associated with As presence in plant shoots. Representative samples of 13 plant species, together with soil samples, were collected from various sites affected by historical As mining: mine and slag dumps, tailings and contaminated soils with As concentrations in a range 72–193,000 mg/kg. Potentially and actually soluble As forms, extracted with 0.43 M HNO3 and, 1M NH4NO3 were examined in relation to As concentrations in plant roots and shoots. The latter differed strongly among the species and within them and were in the ranges 2.3–9400 mg/kg and 0.5–509 mg/kg, respectively. The majority (over 66%) of plant samples had As shoot concentrations above 4 mg/kg, an upper safe limit for animal fodder. The uptake of As by plants correlated well with total and extractable soil As, though As concentrations in plants could not be predicted based on soil parameters. Equisetum spp. and C. epigejos indicated a particularly strong accumulation of As in shoots, while A. capillaris, and H. lanatus showed a limited As root-to-shoot transfer, apparently associated with species-related tolerance to As

Does Soil Drying in a Lab Affect Arsenic Speciation in Strongly Contaminated Soils?

This study examined the changes in extractability and fractionation of arsenic (As) that can be caused by the drying of strongly polluted anoxic soil samples. Two untreated and manure-amended soils were incubated for 7 and 21 days in flooded conditions. Thereafter, As water- and 1 M NH4NO3-extractability and As fractionation in a 5-step sequential extraction according to Wenzel were examined in fresh, oven-dried and air-dried samples. Soil treatment with manure considerably affected the results of the sequential extraction. Air-drying caused a significant decrease in As extractability with 1 M NH4NO3 and in As concentrations in the F1 fraction. The highest reduction of extractability (30–41%) was found in manure-treated soils. Oven-drying resulted in a smaller reduction (5–34%) of As extractability. These effects were explained by opposing processes of As mobilization and immobilization. Sequential extraction did not allow for balancing As redistribution due to drying, as As loss from the F1 fraction was smaller than the confidence intervals in the other fractions. The results showed that for the precise determination of As extractability in anoxic soils, fresh samples should be analyzed. However, oven-dried samples may be used for a rough assessment of environmental risk, As the order of magnitude of easily soluble As did not change due to drying

Does Soil Drying in a Lab Affect Arsenic Speciation in Strongly Contaminated Soils?

This study examined the changes in extractability and fractionation of arsenic (As) that can be caused by the drying of strongly polluted anoxic soil samples. Two untreated and manure-amended soils were incubated for 7 and 21 days in flooded conditions. Thereafter, As water- and 1 M NH4NO3-extractability and As fractionation in a 5-step sequential extraction according to Wenzel were examined in fresh, oven-dried and air-dried samples. Soil treatment with manure considerably affected the results of the sequential extraction. Air-drying caused a significant decrease in As extractability with 1 M NH4NO3 and in As concentrations in the F1 fraction. The highest reduction of extractability (30–41%) was found in manure-treated soils. Oven-drying resulted in a smaller reduction (5–34%) of As extractability. These effects were explained by opposing processes of As mobilization and immobilization. Sequential extraction did not allow for balancing As redistribution due to drying, as As loss from the F1 fraction was smaller than the confidence intervals in the other fractions. The results showed that for the precise determination of As extractability in anoxic soils, fresh samples should be analyzed. However, oven-dried samples may be used for a rough assessment of environmental risk, As the order of magnitude of easily soluble As did not change due to drying

The pools of soil organic carbon accumulated in the surface layers of forest soils in the Karkonosze Mountains, SW Poland

Differentiation of soil organic carbon (SOC) concentrations and pools in topsoil horizons of forest soils in the Karkonosze Mountains was examined in relation to environmental and human-induced factors, with special focus on altitudinal gradient, related climatic conditions, and a zonality of vegetation. The samples were collected from the forest litter and soil layers 0–10 cm and 10–20 cm, in 621 plots arranged in a regular network of monitoring established in the Karkonosze National Park. The concentrations of SOC were determined in laboratory and used for calculation of SOC pools. Four elevation zones were distinguished for analysis: 500–750 m, 750–1000 m, 1000–1250 m, and >1250 m. The concentrations of SOC in forest litter (38.3–44.1%) showed an insignificant increasing trend with altitude. The concentrations of SOC in the layers 0–10 cm and 10–20 cm, were in a very broad range 0.27–47.6%, thus indicating a high differentiation, and also tended to insignificantly increase along with altitude. The largest share of accumulated SOC pools was proved to be present in the layer 0–10 cm, except for the highest zone >1250 m in which forest litter contains slightly larger amounts of SOC. The pools of SOC accumulated in the 20 cm thick topsoil and forest litter turned out to vary considerably (3.6–58.2 kg·m−2), but the mean values and medians in particular elevation zones fall in a narrow range 10.5–11.9 kg·m−2, close to the values reported from the Alps. The lack of statistical significance of reported tendencies was explained by a monitoring sites-oriented random soil sampling, i.e. in forest stands of various age, species-composition and degradation degree

The Effects of Forest Litter and Waterlogging on the Ecotoxicity of Soils Strongly Enriched in Arsenic in a Historical Mining Site

This study examined the effects of waterlogging and forest litter introduced to soil on chemical properties of soil pore water and ecotoxicity of soils highly enriched in As. These effects were examined in a 21-day incubation experiment. Tested soil samples were collected from Złoty Stok, a historical centre of arsenic and gold mining: from a forested part of the Orchid Dump (19,600 mg/kg As) and from a less contaminated site situated in a neighboring forest (2020 mg/kg As). An unpolluted soil was used as control. The concentrations of As, Fe and Mn in soil pore water were measured together with a redox potential Eh. A battery of ecotoxicological tests, including a bioassay with luminescence bacteria Vibrio fischeri (Microtox) and several tests on crustaceans (Rapidtox, Thamnotox and Ostracodtox tests), was used to assess soil ecotoxicity. The bioassays with crustaceans (T. platyurus, H. incongruens) were more sensitive than the bacterial test Microtox. The study confirmed that the input of forest litter into the soil may significantly increase the effects of toxicity. Waterlogged conditions facilitated a release of As into pore water, and the addition of forest litter accelerated this effect thus causing increased toxicity