Mobility of mercury in soil as affected by soil physicochemical properties

Purpose

The interaction of mercury with organic matter was studied on three soils with distinct physical-chemical compositions (Fluvisol, Luvisol, and Chernozem) and three vermicomposts based on various bio-waste materials (digestate, kitchen waste with woodchips, and garden bio-waste).

Materials and methods

Laboratory batch experiments, in which organic matter composition was modeled by adding graded doses of vermicompost to individual soils, were carried out. The composition of organic matter in these vermicomposts was assessed via fractionation of humic acids, fulvic acids, hydrophilic compounds, and possible hydrophobic neutral organic matter. Furthermore, the samples were artificially contaminated with inorganic and organic mercury. Prepared samples were stored under constant temperature of 25 °C. The incubation experiments lasted for 56 days, in which the samples were taken ten times. During the experiments, the changes in mercury mobile phase amount were observed, and the influence of the source of contamination was evaluated.

Results and discussion

The amount of mobile mercury increased and then decreased during the time. In most of the soils and vermicompost combinations, the content of mercury bound to the soil was stable after 21 days. The effects of the mercury source on the exchangeable portion of Hg in the soils were most obvious in samples without added vermicompost. Nevertheless, differences between mobile inorganic and organic forms of Hg were lower in the case of Fluvisol compared to other soils. Moreover, in this soil, the content of available mercury was higher than from others.

Conclusions

In general, the smallest differences between mobile inorganic and organic forms of Hg were observed in the case of soil with the highest content of organic matter. Also higher doses of vermicomposts decreased the amount of mercury mobile phase available. Additionally, the largest positive influence of vermicompost dose on Hg mobility was measured in soils combined with vermicompost with the highest portion of humic acids.

     

Acidification of primeval forests in the Ukraine Carpathians: Vegetation and soil changes over six decades

Changes to vegetation and soil were assessed in primeval forests of the Eastern Carpathians after a period of 59-68 years. We hypothesized that forest ecosystems were acidified through the long-distance transport of air pollutants. A total of 141 relevés and 20 soil profiles that had been studied in 1938 in spruce- and beech-dominated forests along an altitudinal gradient ranging from 1085-1575 m a.s.l. were re-surveyed from 1997 to 2006. Relevés were analyzed using multidimensional statistics and plant community characteristics (Shannon-Wiener’s index, equitability, fidelity, Ellenberg indication values - EIV); soil reaction and sorption complex properties were analyzed in soils.A total of 159 vascular plant taxa were recorded in 1938, of which 35 were not found during the repeat survey. During the later survey, 137 taxa were found, of which 13 were new findings. The upper mineral (A) as well as cambic or spodic (B) horizons were considerably acidified in both forest types. Both active and exchange soil reaction decreased by 0.1-0.3 units on average, exchangeable acidity significantly increased and the sum of base cations decreased in both soil horizons and forest types. Base saturation decreased by more than half of original values, with a maximum decrease of 68% found in the B-horizon of spruce forests. Whereas the herb layer developed along with soils in beech-dominated forests, EIV values for soil reaction increased in spruce-dominated forests, probably due to the movement of broadleaf woody species to higher elevations or due to the higher resistance of herb species to soil acidification. Significant changes to EIVs also occurred in the beech- and/or spruce-dominated forests for the factors of nitrogen, light moisture and temperature.There was an expansion of the lower tree and shrub layers, primarily Fagus sylvatica, Picea abies and Sorbus aucuparia in intermediate and higher elevations, which can be explained by reduced cattle grazing. Also, the dissipation of Juniperus communis and marked decline of Abiesalba are interpreted as being related to gradual changes in landscape management along with the effect of acid deposition. Since 1938, all stands have shown a significant increase in nitrophilous taxa such as Rubusidaeus, Athyrium distentifolium, Urtica dioica, Calamagrostis arundinacea, Stellaria nemorum. Significant decreases in the number of species, Shannon-Wiener’s index and equitability were only observed in spruce-dominated forests. Neophyte taxa were not detected in either the 1930s or the 1997-2006 period.     

Hydrophility and Surface Molecular Structure of Sandy Podzol E with High Content of Quartz

The capillary elevation of water in an Orthic Podzol increases significantly after the removal of soil organic matter. The study of infrared spectra of humic acids and amorphous silica extracted from the investigated soil shows that their interaction lowers the ability of silica to form hydrogen bonds with water molecules. The liberation of reactive isolated Si-OH groups contributes to the increase of hydrophility of the soil.     

Impacts of otter (Lutra lutra L.) predation on fishponds: A study of fish remains at ponds in the Czech Republic

The increasing numbers of otters (Lutralutra L.), which are protected by the CzechAct of Nature and Landscape Protection, arecausing serious problems for fishpondmanagement. The diet of otters on pond farmsconsists predominantly (80%) of common carp,Cyprinus carpio, and to a lesser extentother pond fish species (perch, Percafluviatilis, zander, Stizostedionlucioperca and grass carp, Ctenopharyngodon idella). The size of carpcaptured by otters ranged between 376–683 mmTL (500 ± 88 mm) and 1,049–11,768 g(3,478 ± 2,867 g). Reconstructed originalweight and length of captured grass carp andperch were 599 and 182 mm TL, and 2,665 and163 g, respectively. In most of prey fishcorpses left by otters, only viscera andassociated parts were consumed. The weight ofindividual common carp corpses was estimated as73.0 ± 24.6 (26.3–95.9)% of theoriginal reconstructed weight, which means thatonly 27.0 ± 17.2 (4.1–73.7)% of fishbody mass was consumed by otters. In perch,62.8% of fish body mass was left unconsumed.Heavy losses have been reported also on fishstocks in ice-covered ponds during the winterperiod, when shoals of resting fish have beendisturbed and stressed due to otter hunting.     

The influence of crate height on selected biochemical indices in captive‐reared mallards

The aim of this study was to investigate the effects of crate type (particularly its height) on selected biochemical indices in captive‐reared mallards (Anas platyrhynchos). The physiological changes in response to 2‐h crating in crates of either 20 cm or 26 cm height were monitored in 6‐week‐old mallards. Plasma corticosterone concentrations showed an increase (P = 0.036) in mallards crated in crates of 26 cm height in comparison with control non‐crated birds, whereas no difference in plasma corticosterone levels was found between mallards crated in crates of 20 cm height and control non‐crated birds. Lower concentrations of plasma triglycerides (P < 0.05) and uric acid (P < 0.05) were found in crated mallards in comparison with control non‐crated birds; the height of the crates had no effect. Mallards crated in crates of 26 cm height also exhibited a higher (P = 0.032) plasma lactate dehydrogenase concentration in comparison with control non‐crated birds, whereas no difference (P > 0.05) was found in lactate dehydrogenase concentrations in mallards crated in crates of 20 cm height. Our results suggest that crating mallards in lower crates (20 cm) may be less stressful than keeping them in crates allowing vertical movements of the birds.