Impact of natural and man-made factors on migration of heavy metals in the Ardon River basin (North Ossetia)

Purpose

The main goal of the study was to evaluate biogeochemical effects of particular factors changing the structure of landscapes due to enhanced mass migration and erosion of the outcropping rocks by studying transformation of chemical composition of the draining waters and flood plain soils; chemical composition of the solid and liquid phases of the Ardon River waters; and by assessing ecological consequences and risk of contamination of the area by heavy metals.

Materials and methods

Water, soil, and biota species (plants, algae, and amphibian) were sampled at the plots located up- and downstream the mining and industrial areas of North Ossetia (the Ardon River basin) before and after the mudflow that took place in 2002. The air-dried samples were decomposed in a mixture of mineral acids. Heavy metals were determined by means of AAS with the help of AAS-80 (Hitachi) or AAS-2A (KORTEC) using standard reference materials of hair (CRM 397), plant mixture (SBMT-02), and soil (SRM 2709). Hydrochemical and biochemical analyses were performed with the help of the known methods (Kraynov and Shvets 1992; Burtis et al. 2006).

Results and discussion

The study showed that activity of the Misur Mining Combine and its Ardon-Khost tailings caused a significant local increase of Pb, Cd, Cu, and Zn content in soils, water, and biotic components as compared to the background values. The mudflow of 2002 changed the structure of landscapes and was followed by a considerable transformation of chemical composition of the downstream river waters and floodplain soils, and by invasion of particular hydrophyte species. Algae and amphibian adapted to the changed conditions and indicated both natural and anthropogenic transformation of the environment. A distinct relation between the particle size of the suspended matter in the Ardon River waters and water salinity was discovered.

Conclusions

Therefore, the Unal basin presents a vivid example of modern natural and anthropogenic evolution of Pb-Zn biogeochemical province under conditions of the extreme and dynamic geochemical environment leading to enhanced risks of ecological damage. Algae species demonstrated high adaptive and indicative capacity in case of both the fast natural and man-made impact.

     

Landscape-level effects on avifauna within tropical agriculture in the Western Ghats: Insights for management and conservation

A critical handicap to tropical biodiversity conservation efforts in agroecosystems is the unknowns regarding the influence of landscape-scale factors on the persistence of species. To address these uncertainties, we explored two essential landscape-scale questions, within India’s biologically-rich Western Ghats, examining two nearby human-dominated landscapes that dramatically differed in their pattern of land cover. First, how does the proximity of intact forest patches affect bird community composition within agricultural landscapes? Second, can simple remote sensing-derived measures (brightness, wetness, and NDVI) be used to estimate native bird species composition within those landscapes? In both landscapes, as distance to intact forest decreased, the similarity in bird community composition between agricultural areas and intact forest increased. This suggests that the retention of tropical forest bird communities within human-dominated landscapes critically depends on the maintenance of nearby intact forest. In an answer to the second question, the remote sensing measures correlated with forest-affiliated avian species richness in only one of the two landscapes, reflecting an ecological difference between the two in the response of forest bird species to local agricultural conditions. In the landscape where a correlation was found, there was high variation in vegetative structure, which strongly impacted both the remote sensing measures and forest bird species richness. In the other landscape, forest species richness strongly correlated with changes in tree species composition in the agriculture, a factor that could not be detected by the remote sensing metrics. In order to successfully conserve biodiversity in tropical agricultural landscapes, our findings show that it is essential to conserve intact forest within those landscapes and to understand the effect of local agricultural practices on species.     

Occurrence and genesis of secondary magnesium-bearing calcites in soils

The presence of magnesium-bearing calcites is indicated in soil carbonate accumulation layers and concretions. A differential solubility method permitted estimation of the mol percent magnesium-carbonate content of calcites in the presence of dolomite. The relationship between diffraction spacings and mol percent MgCO₃, of selected samples is in good agreement with that depicted by other workers for biogenic magnesium-bearing calcites.Magnesium-containing calcites are concentrated in clay (< 2 μ) and fine silt (2–10 μ) sizes of Cca horizons. Their presence in the clay fraction of Ck horizons is an indication that carbonate mineralogy may change at profile depths often considered to be unaffected by pedogenic processes.The dissolution of existing carbonates within solum horizons, the translocation of ions in solution and the reprecipitation of calcite in Cca and underlying horizons are the main processes applicable to a variety of different natural situations. The Mg level of the secondary calcites is likely regulated by the partitioning effect during their precipitation. Periodic moisture movement to greater depths and lateral movement of soil solutions serve as a regulating factor in maintaining soluble Mg at levels favorable to the precipitation of low-magnesium calcites in upland chernozemic soils of central Saskatchewan; higher magnesium contents occur in calcites occurring in subsoils underlying solonetzic and depressional chernozemic soils of the same area. Formation of magnesium-bearing calcites within concretions in soils of the Rusizi basin in Africa were likely influenced by Mg-rich ground waters; associated dolomite may also have been of a secondary nature.     

Changes in Collembola richness and diversity along a gradient of land-use intensity: A pan European study

Changes in Collembola richness and diversity along a land-use intensity gradient were studied in eight European countries (Portugal, Spain, France, Switzerland, Hungary, UK, Ireland and Finland). In each country a set of six 1 km² land-use units (LUUs) were selected forming a gradient ranging from natural forest to agricultural dominated landscapes, passing through mixed-use ones. In addition to data on Collembola, detailed information regarding landscape diversity and structure was collected for each LUU. A total of 47,774 individuals were identified from 281 species. Collembola reacted not only to changes in the diversity of the landscape, but also to the composition of that diversity and the area occupied by each land-use type at each LUU. Although species richness patterns were not concordant among the different countries, the total number of species per LUU (landscape richness) was generally higher in natural forests and mixed-used landscapes, and lower in agricultural dominated landscapes. Moreover, high richness and diversity of Collembola at each LUU were associated with a diverse landscape structure, both in terms of number of patches and patch richness. Despite this comparable species richness between mixed-use landscapes and those dominated by natural forests, average species richness on forested areas (local richness) decreased along the gradient, showing that forest patches on mixed-use landscapes support a lower richness than in landscapes dominated by forest. This aspect is important when addressing the role of native forests in structuring biodiversity in disturbed and fragmented landscapes. Although a diverse landscape can support a high biodiversity, the results suggest that intensive fragmentation should be avoided with the risk of collapsing local species richness with the consequent result for regional biodiversity.     

Dissolved organic matter in lysimetric water of mountain forest soils in the southern Sikhote Alin

The fractional composition of dissolved organic matter and the chemical nature of humic and fulvic acids were studied in lysimetric waters from forest soils of different altitudinal zones in the Sikhote Alin Range. The elemental composition, infrared absorption spectra, concentrations of acid functional groups, and pK spectra of humic and fulvic acids were determined. Fulvic acids predominated in the upper soil horizons, and fraction of nonspecific dissolved organic substances predominated in the lower mineral horizons. The portion of humic acids in the humus horizons markedly decreased from the low-mountain soils to the high-mountain soils; the nitrogen content of humic and fulvic acids decreased in the same direction. Three classes of carboxyl and phenolic groups were determined in pK-spectra of humic and fulvic acids. The soils of high-mountain zones had stronger acidic properties of humic and fulvic acids in comparison with the soils of low-mountain zones. The determined characteristics of the composition of dissolved organic matter and the trends of their changes contribute to our knowledge of pedogenetic processes in the altitudinal sequence of forest landscapes of the Sikhote Alin Range.     

Chemical, Physical, and Risk Characterization of Natural Gas Storage Produced Waters

Natural gas storage produced waters (NGSPWs) are brought to the surface when natural gas is reclaimed from underground storage. These waters may have a variety of constituents of concern that need to be treated before the water can be reused or discharged to receiving aquatic systems. The objective of this study was to characterize NGSPWs to discern potential constituents of concern that may limit surface discharge or beneficial reuse of these waters. We conducted a strategic review of literature, analyses of produced water composition records, and analyses of produced water samples provided by natural gas storage companies. Although NGSPWs varied widely in composition, primary constituents of concern included: chlorides (salinity), metals, metalloids, and organic compounds (e.g. oil and grease). Chlorides are the predominant constituent of concern in most NGSPWs. Strategies for risk mitigation of NGSPWs will need to be both robust and site specific to deal with the diverse composition of these waters.     

Scattered trees are keystone structures - Implications for conservation

Scattered trees are prominent features in many landscapes worldwide, including natural landscapes, cultural landscapes, and recently modified landscapes. The ecological importance of scattered trees is widely acknowledged in natural landscapes, but has not been sufficiently appreciated in human-modified landscapes. This paper shows that scattered trees are keystone structures in a wide range of landscapes. At the local scale, ecological functions of scattered trees include: provision of a distinct microclimate; increased soil nutrients; increased plant species richness; increased structural complexity; and habitat for animals. At the landscape scale, ecological roles include: increased landscape-scale tree cover; increased connectivity for animals; increased genetic connectivity for tree populations; and provision of genetic material and focal points for future large-scale ecosystem restoration. Furthermore, in disturbed landscapes, scattered trees often are biological legacies that provide ecological continuity through time. In combination, these ecological functions support the argument that scattered trees are keystone structures. That is, their contribution to ecosystem functioning is disproportionately large given the small area occupied and low biomass of any given tree, and the low density of scattered trees collectively. Because scattered trees fulfill unique functional roles in a wide range of scattered tree ecosystems, their loss may result in undesirable ecological regime shifts. A key management challenge in all landscapes with scattered trees is to maintain a balance between recruitment and mortality of trees in an appropriate spatial pattern. Meeting this challenge may represent an important step towards the genuine integration of conservation and production in human-modified landscapes.     

Soil salinization in different natural zones of intermontane depressions in Tuva

Soil salinization features in semidesert, dry steppe, and chernozemic steppe zones within intermontane depressions in the central part of the Tuva Republic are discussed. Chernozems, chestnut soils, and brown desert-steppe soils of these zones are usually nonsaline. However, salinization of these zonal soils is possible in the case of the presence of salt-bearing parent materials (usually, the derivatives of Devonian deposits). In different natural zones of the intermontane depressions, salt-affected soils are mainly allocated to endorheic lake basins, where they are formed in places of discharge of mineral groundwater, and to river valleys. The composition and content of salts in the natural waters are dictated by the local hydrogeological conditions. The total content of dissolved solids in lake water varies from 1 to 370 g/L; the water is usually of the sulfate–chloride or chloride–sulfate salinity type; in some cases, soda–sulfate water is present. Soil salinity around the lakes is usually of the chloride–sulfate–sodium type; gypsum is often present in the profiles. Chloride salinization rarely predominates in this part of Tuva, because chlorides are easily leached off from the mainly coarse-textured soils. In some cases, the predominance of magnesium over sodium is observed in the composition of dissolved salts, which may be indicative of the cryogenic transformation of soil salts. Soda-saline soils are present in all the considered natural zones on minor areas. It is hardly possible to make unambiguous statements about the dominance of the particular type of salinity in the given natural zones. Zonal salinity patterns are weakly expressed in salinization of hydromorphic soils. However, a tendency for more frequent occurrence of soda-saline soils in steppe landscapes and chloride–sulfate salinization (often, with participation of gypsum) in the dry steppe and semidesert landscapes is observed.     

Impact of Past Mining Activity on the Quality of Water and Soil in the High Moulouya Valley (Morocco)

Physical and chemical properties and the total content of potentially toxic metals (PTMs) in waters and soils were studied from the High Moulouya Valley (Morocco) in order to assess the impact of the past mining activity on their quality and to lay the foundations of a potential reclamation of the area. Surface water and groundwater samples were collected from the Moulouya River and mine pit lakes; tailings and soils were sampled inside and outside the mine sites of Zeïda, Mibladen, and Aouli. Both waters and soils were alkaline, due to the limestone environment, and contained Pb and Zn as main metallic contaminants. Pollution levels were highest within the Mibladen mining site, and soil pollution was mainly restricted to the areas where activities of metal concentration were carried out. Tailings and soils from these areas besides Pb and Zn were also polluted by As, Cd, and Cu showing clay fraction highly enriched in metal contaminants. At the time of study, all soils and wastes (including the highly polluted tailings) were in advanced stage of spontaneous herbaceous and arbustive revegetation. It is concluded that, in the High Moulouya Valley, the processes governing PTM transfer from the element-rich sites to the nearby environment are strongly influenced by pH, carbonate content, and semi-arid climate reducing metal mobility from the mining waste impoundments by dissolution. The transfer by wind and water erosion of metal-enriched fine waste particles is likely to be a much more important vector for metal dispersion. In this perspective, among a range of land remediation techniques available, natural and oriented revegetation could represent a low-cost and possible permanent solution.     

Formation of clay from granite and its distribution in relation to climate and topography

Chemical weathering can be approached from three interpretive points of view: distribution of the secondary minerals in landscapes, weathering of primary minerals and geochemistry of ions in solution. On granitic rocks it is posible to define both climatic and topographic sequences of distribution of clays in association with weathering products: gibbsite - kaolinite - hydrous iron oxides - hydrous manganese oxides - iron-rich montmorillonite - calcium carbonate - calcium sulfate - sodium carbonates and silicates. These stages appear as an absolute accumulation formed by filling of intergranular pores. Another sequence can be found not in intergranular pores but in the cracks and along the cleavages of primary minerals from which they are derived by relative accumulation. The order of appearance of these secondary minerals remains the same regardless of the nature of climates and the topographic position. The conditions of equilibrium are not identical in the interior of grains of different primary minerals nor in the pores outside of them and the secondary minerals found in the different situations are also not identical. This is well demonstrated by the chemistry of waters draining slopes. The equilibrium diagrams and balances between cations and silica sometimes result in disagreement, proving that equilibrium conditions are not satisfied between solutions circulating in the pores and clay minerals found inside the primary minerals.     

天然膨润土的矿物特性及其磷吸附性能研究

比较了不同天然膨润土共7个样品对不同程度磷污染水体的吸附净化性能,通过等温吸附实验,探讨了膨润土对磷的吸附机制.结果发现,供试膨润土对水体磷均有一定的吸附净化潜力,但针对不同程度磷污染水体存在一定差异,且同一属型膨润土的吸附净化能力因矿物组成差异而不同.针对模拟V类水(P 0.4 mg/L)和劣V类水(P 1.0 mg/L),BN-2的吸附净化能力最强,BN-6的吸附净化能力较差,而其余膨润土对磷的吸附净化能力稍显差异.天然膨润土对磷的吸附等温曲线符合Freundlich方程,说明膨润土对磷的吸附可能属于不均匀介质的多分子层吸附.结果表明,在针对不同程度磷污染水体时,需根据膨润土的矿物特性,使各具特殊性质的不同天然膨润土矿样得到有效的应用.     

Soils of paleocryogenic hummocky-hollow landscapes in the southern Baikal region

The features of ancient periglacial phenomena are widespread in landscapes lying beyond the modern permafrost zone. The specificity of the paleogeographic conditions in the south of the Baikal region resulted in the formation of paleocryogenic landscapes with hummocky-hollow landforms. The paleocryogenic mounds (hummocks) are of rounded or elongated shape, their height is up to 2–3 m, and their width is up to 20–25 m. They are separated by microlows (hollows). This paleocryogenic microtopography favors the differentiation of the pedogenesis on the mounds and in the hollows, so the soil cover pattern becomes more complicated. It is composed of polychronous soils organized in complexes with cyclic patterns. Light gray and gray forest soils and leached and ordinary chernozems are developed on the mounds; gray and dark gray forest soils and chernozems with buried horizons are developed in the hollows. The soils of the paleocryogenic complexes differ from one another in their morphology, physical and chemical properties, elemental composition, and humus composition. For the first time, radiocarbon dates have been obtained for the surface and buried humus horizons in the hollows. The results prove the heterochronous nature of the soils of the paleocryogenic landscapes in the south of the Baikal region.     

红河哈尼稻作梯田旅游资源价值空间差异评价

红河哈尼稻作梯田拥有丰富的自然与文化景观资源,是全球/中国重要农业文化遗产、世界文化遗产。目前该地区旅游发展水平空间极不平衡,在对其资源进行科学评价的基础上,提出差异化发展的策略是现实需要,也具有示范意义。本研究以哈尼稻作梯田十大片区所在8个乡镇的旅游资源为评价对象,根据自然景观与人文景观特征的差异,从资源特征和影响力两个方面,分别构建评价指标体系(自然景观6个指标,人文景观7个指标),采用层次分析-模糊数学分析方法对其资源价值进行评价。研究结果表明,自然景观价值方面,马鞍底乡、阿得博乡和三猛乡依托国家级保护区资源具有较明显的优势,其中马鞍底乡因景观奇特、规模宏大而优势突出,甲寅镇则因其水域和植物等组合景观而具有自然景观优势;人文景观价值方面,攀枝花乡、新街镇、甲寅镇和宝华镇因梯田而知名度高,民族文化典型而优势明显,其他乡镇也因具有优美的梯田景观、古村落、传统文化等人文景观资源而得到较高评价。哈尼稻作梯田系统的人文景观价值高于自然景观价值,但自然景观资源尚未得到开发,旅游发展水平空间差异巨大。最后,本研究根据各乡镇的资源优势,提出了各有侧重的旅游发展策略。     

Assessing the broad-scale impact of agriculturally transformed and protected area landscapes on avian taxonomic and functional richness

Anthropogenic modification of natural habitat is resulting in a widespread loss of biodiversity. One of the primary responses of human societies to biodiversity loss has been the creation of protected areas. Two of the most important questions in conservation biology are: (1) whether protected areas are playing their intended role as reservoirs of biodiversity; and (2) whether habitat outside protected areas, particularly in agricultural landscapes, plays a significant role in maintaining biodiversity and the ecosystem services that it provides. Even though empirical evidence is still lacking on the exact mapping from functional group richness to specific ecosystem services, functional groups are good indicators of ecosystem functioning and thus service provision. We classified the South African avifauna into nine functional groups and tested at a coarse grain for differences in functional group composition between landscapes containing predominantly agricultural vs. protected areas. We used a matched pair sampling design to control for confounding variance. We found that avian functional groups respond in quantitatively and qualitatively distinct ways to agriculturally dominated landscapes. Raptors and scavengers displayed the most consistent losses, while nutrient dispersers and grazers tended to increase. Spatial detrending and randomisation tests suggested that only raptors and scavengers are negatively affected by agricultural landscapes independently of spatial autocorrelation. Thus, protected area landscapes are serving as important reservoirs of functionally important upper trophic populations while agricultural landscapes facilitate the presence of species that link aquatic and terrestrial systems. These results demonstrate the potential for complementary facets of functional diversity to exist on landscapes containing vastly different land-uses.     

Characterization of Compost Leachate Fractions Using NMR Spectroscopy

A distilled water leachate was prepared from a hardwood-leaf compost. The ¹³C NMR (nuclear magnetic resonance) spectra of organic acids isolates from this leachate provided support for the hypothesis that the composition of the dissolved organic carbon (DOC) in the leachate is very similar to that in natural soil pore waters. The leachate DOC was adsorbed by a model mineral surface, and the organic coating on the surface was characterized by solid-state ¹³C NMR spectroscopy.     

Trace metal composition and speciation in street sediment: Sault Ste. Marie,Canada

Street sediment collected in Sault Ste. Marie, Ontario was examined for trace element composition (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn) and the metal partitioning to various sediment properties was determined by sequential extraction. Total Ni, Cu, Zn and Pb concentrations exceeded the lowest effect levels specified in the Ontario Provincial Sediment Quality Guidelines for Metals (Environment Ontario, 1992) and derived from bioassay studies. According to these Guidelines, the disposal of such sediment has to be guided by environmental considerations. A significant fraction of these metals was extractable in 0.5 N HCl over a 12-hour period and considered as potentially bioavailable. The major accumulative phases of toxic metals in this sediment are exchangeable, carbonate, Fe/Mn oxides and organic matter but the relative importance of each phase varied for individual metals. Approximately 20% of the total extractable Cd is found in each of these four fractions. Pb, Zn and Mn are predominantly bound to carbonates, Fe/Mn oxides and organic matter. Cu shows a high affinity for organic matter and to a lesser extent for carbonates. Elevated levels of Cd, Pb, Cu, Zn, Mn and Cr in the exchangeable and/or soluble phase suggest that sediment associated metals, mobilised from streets in Sault Ste. Marie during runoff and snowmelt, would adversely impact water quality in the receiving waters. However, large fractions of the total metal load are associated with coarser particles which are unlikely to be transported through the drainage system into receiving waters.     

白洋淀湿地景观斑块时空变化研究

景观格局变化可以深刻地反映人类活动对生态环境的影响,研究白洋淀湿地景观格局时空变化对于明晰湿地水环境质量的恶化原因具有重要意义。通过综合运用GIS技术和景观格局指数法,对白洋淀1987、1999和2007年LandsatTM遥感影像进行解译分析,研究了白洋淀20年间景观格局动态变化。结果表明：苇地、耕地和水域是淀区主导景观类型,所占比例高达86.62%~93.06%,苇地为42.74%~58.02%。淀区斑块数和密度增加了23.01%,景观破碎化程度加剧。景观均匀度指数由0.74降至0.67,多样性指数由1.44降至1.25。苇地和耕地面积增加最多,分别为18.08%和28.05%;水域和干草地减少最多,分别为35.78%和76.53%景观分维数范围为1.05~1.27,受人类影响较大;苇地从1.27降至1.19,水域从1.16降至1.09,人为影响明显增强;裸地、林地和干草地的分维数最小,分别为1.06~1.08,1.05~1.09和1.07~1.09。根据主导景观类型时空变化,将白洋淀划分为G、WG和WS区。G和WG区主导景观类型均表现出从水域到苇地再到耕地转化趋势,WS区的水面和苇地在外源调水的作用下得以维持,水域整体向东部转移。建议白洋淀湿地保护以水域、苇地和草地为核心,控制淀内及周边人类活动对自然景观的扰动。调水要充分考虑白洋淀的景观时空特征,尽量降低对重要景观类型和生物多样性的影响。     

Air Pollution Effect on the Decay of Carbonate Building Stones in Old Town of Tallinn

For a long time the local Ordovician carbonate rocks were widely used for the building of many historical buildings, churches and strongholds in Tallinn. The chemical and mineralogical composition of building stone and gypsum black crust from five historical objects of Old Town of Tallinn were examined in order to reveal the weathering behaviour of the limestone and estimate the influence of pollution on the decay processes. The ICP-MS analysis and X-ray difractometry were performed to provide a quantitative analysis of the processes, which are responsible for building stone decay. The enrichment factor and R-mode factor analyses were applied in order to improve the understanding the nature and sources of elements and assess the pollution effect. The obtained results confirmed a natural origin for Ca, Mg, Si, Al, Ti, K, Na and Fe. The black crust is elevated in Cu, Pb, Sb, Sn and Zn concentrations as a result of the pollution effect. The highest increase of Cu, Pb and Zn content was determined in the samples from gypsum crust at St. Olaf's church. The enrichment factors calculation and factor analysis confirm the input of these elements from anthropic sources. Sulphur isotope composition in damaged building stone and black crust was used to discriminate the anthropic and natural sources of sulphur. The impact of technogenous sulphur in the gypsum formation in the black crust was revealed. The contribution of sulphur dissoluted from limestone is reflected in the positive delta values of sulphur. Comparison of obtained data to those for similar objects in European cities was carried out.     

The relationship between local extinctions of grassland butterflies and increased soil nitrogen levels

In contrast to many other western European countries, the knowledge about trends in the Swedish butterfly fauna is poor. We studied the effects of habitat and species characteristics on species turnover in 13 grassland sites in southern Sweden by comparing species richness and compositions at two separate occasions with an interval of 21 years. The mean number of species per site decreased from 30 to 24, with a large variation between sites. The number of extinctions was highest in sites where the proportion of trees and shrubs had increased most, but there was no detectable effect of area or of the composition of landscapes surrounding the sites. Areas protected as nature reserves had lost as many species as unprotected areas had, indicating both the importance of proper management of nature reserves and that nature reserves alone may not be enough to inhibit regional extinction of butterfly species. Species dependent on nutrient-poor conditions tended to decrease while species dependent on nutrient-rich conditions tended to increase, indicating a negative effect of increased soil nitrogen levels resulting from active fertilizing of pastures and/or atmospheric nitrogen deposition. A regular monitoring program could show whether our results are representative for Sweden or Northern Europe.