A Simulation Framework for Assessing Physical and Wildlife Impacts of Oil and Gas Development Scenarios in Southwestern Wyoming

Foreseeable natural gas development in southwestern Wyoming has the potential to increase sagebrush fragmentation and risks to resident wildlife species. The ability to balance future development with conservation goals, however, is enhanced by advances in directional-drilling technologies that use multiple wells per pad and produce less surface disturbance than conventional drilling methods. To evaluate the conservation potential of this technology, I developed an energy footprint model that simulates well, pad, and road patterns for oil and gas recovery options that vary in well types (vertical and directional) and number of wells per pad and use simulation results to quantify physical and wildlife-habitat impacts. I applied the model to assess tradeoffs among 10 conventional and directional-drilling scenarios in a natural gas field in southwestern Wyoming. Scenarios spanned a gradient in the number of vertical and directional wells, and in number of pads (2000 to 250), but all extracted the same amount of gas over a 15-year period. Reducing pad numbers with directional-drilling technology reduced surface disturbance area and impacts on spatially extensive habitats (48–96% of study area) such as sagebrush-obligate songbird habitat, elk winter range, and sagebrush core area. Impacts declined for spatially restricted mule deer migration corridors (24% of study area) and greater sage-grouse leks until energy infrastructure densities within corridors and near leks were similar to the initial landscape. Scenario simulations and tradeoff assessments such as illustrated in this study are intended to help decision-makers identify development designs that best achieve both energy and conservation goals.     

Ants as Indicators of Exposure to Environmental Stressors in North American Desert Grasslands

The relative abundance of ant species was measured by pit-fall trapping at 44 sites in southern New Mexico and southeastern Arizona, U.S.A.. Sites were selected for study based on documentation of a history of disturbance or protection from disturbance, exposure to varying intensities of livestock grazing, dominance by an exotic species of plant and vegetation change resulting from disturbance or restoration efforts. Ant community composition, relative abundances of species, and species richness were the same on disturbed and undisturbed sites. None of the metrics based on hypothesized responses of ants to disturbance clearly distinguished between disturbed and undisturbed sites. Ant communities on sites where restoration efforts have resulted in distinct differences in vegetative cover and composition were similar to the ant communities on degraded unrehabilitated sites on the same soil type. Ant communities in riparian cottonwood gallery forests in Arizona and New Mexico were similar but differed from the assemblages in exotic salt cedar and native ash riparian woodlands. Ant species exhibited remarkable resistance to human-induced disturbances in these rangeland areas. In grasslands dominated by the South African grass, Eragrostis lehmanniana Nees, large seed harvesting ants, Pogonomyrmex spp., were greatly reduced in abundance compared to native grasslands. Other ant metrics were not different in E. lehmanniana grasslands and native grasslands. We conclude that ants cannot be used as indicators of exposure to stress, ecosystem health or of rehabilitation success on rangeland ecosystems. Ants are also not useful indicators of faunal biodiversity in rangeland ecosystems.     

Effect of urbanization on the structure and functional traits of remnant subtropical evergreen broad-leaved forests in South China

We investigated the effects of major environmental drivers associated with urbanization on species diversity and plant functional traits (PFTs) in the remnant subtropical evergreen broad-leaved forests in Metropolitan Guangzhou (Guangdong, China). Twenty environmental factors including topography, light, and soil properties were used to quantify the effects of urbanization. Vegetation data and soil properties were collected from 30 400-m² plots at 6 study sites in urban and rural areas. The difference of plant species diversity and PFTs of remnant forests between urban and rural areas were analyzed. To discern the complex relationships, multivariate statistical analyses (e.g., canonical correspondence analysis and regression analysis) were employed. Pioneer species and stress-tolerant species can survive and vigorously establish their population dominance in the urban environment. The native herb diversity was lower in urban forests than in rural forests. Urban forests tend to prefer the species with Mesophanerophyte life form. In contrast, species in rural forests possessed Chamaephyte and Nanophanerophyte life forms and gravity/clonal growth dispersal mode. Soil pH and soil nutrients (K, Na, and TN) were positively related to herb diversity, while soil heavy metal concentrations (Cu) were negatively correlated with herb diversity. The herb plant species diversity declines and the species in the remnant forests usually have stress-tolerant functional traits in response to urbanization. The factors related to urbanization such as soil acidification, nutrient leaching, and heavy metal pollution were important in controlling the plant diversity in the forests along the urban–rural gradients. Urbanization affects the structure and functional traits of remnant subtropical evergreen broad-leaved forests.     

Separate estimation of N export into baseline N leakage without disturbance and N loss due to insect defoliation in a pine forest watershed in central Japan

Pine wilt disease (PWD) is caused by a non-native pest that has spread extensively throughout Japan. Previous research has indicated that most infected trees have died and the litter deposited has resulted in changes to stream-water chemistry, particularly increased nitrate (NO ₃ ^? ) concentrations. In this study, we divided stream nitrogen (N) export into N loss due to PWD and baseline N leakage without disturbance based on long-term monitoring. The annual N export was 110.0 mol N ha^?1 year^?1 in 1990 and 749.8 mol N ha^?1 year^?1 in 1997, and had decreased to 37.0 mol N ha^?1 year^?1 in 2005. N export under PWD influence was estimated to be 3697 mol N ha^?1, and N loss due to PWD was 2810 mol N ha^?1. N loss due to PWD was three times larger than baseline N leakage for the disturbed period. These changes in plant–herbivore relationships could affect N status in a forest ecosystem. So-called “semi-natural” disturbances related to non-native species invasion and increases of atmospheric N deposition caused by human activity will increase. Long-term monitoring studies of various aspects are necessary to offer insight into this ecosystem.     

Using Multi-Scale Sampling and Spatial Cross-Correlation to Investigate Patterns of Plant Species Richness

Land managers need better techniques to assess exoticplant invasions. We used the cross-correlationstatistic, I _YZ, to test for the presence ofspatial cross-correlation between pair-wisecombinations of soil characteristics, topographicvariables, plant species richness, and cover ofvascular plants in a 754 ha study site in RockyMountain National Park, Colorado, U.S.A. Using 25 largeplots (1000 m²) in five vegetation types, 8 of 12variables showed significant spatial cross-correlationwith at least one other variable, while 6 of 12variables showed significant spatial auto-correlation. Elevation and slope showed significant spatialcross-correlation with all variables except percentcover of native and exotic species. Percent cover ofnative species had significant spatialcross-correlations with soil variables, but not withexotic species. This was probably because of thepatchy distributions of vegetation types in the studyarea. At a finer resolution, using data from ten1 m² subplots within each of the 1000 m² plots, allvariables showed significant spatial auto- andcross-correlation. Large-plot sampling was moreaffected by topographic factors than speciesdistribution patterns, while with finer resolutionsampling, the opposite was true. However, thestatistically and biologically significant spatialcorrelation of native and exotic species could only bedetected with finer resolution sampling. We foundexotic plant species invading areas with high nativeplant richness and cover, and in fertile soils high innitrogen, silt, and clay. Spatial auto- andcross-correlation statistics, along with theintegration of remotely sensed data and geographicinformation systems, are powerful new tools forevaluating the patterns and distribution of native andexotic plant species in relation to landscape structure.     

Assessment of availability, ecological feature, and habitat preference of the medicinal herb Houttuynia cordata Thunb in the Brahmaputra Valley of Assam, India

Houttuynia cordata Thunb. is a rhizome-bearing aromatic medicinal herb and is restricted to specialized moist habitats. The plant is collected from natural habitats for local consumption and trade. The status of the species and its variations in physiological performance in different habitats were studied in selected sites of geographically different areas of Brahmaputra valley in eastern India. The surveys were conducted in two different growth stages of the plant during 2005–2007. The sites where the species was encountered were marked and a distribution map was prepared. The frequency and density of the plant was higher in the moist habitats with higher organic carbon (0.85 ± 0.05%). Generally, the density, biomass production and growth had significant (P < 0.05) positive relationship with the soil physicochemical properties (linear curve fit). Soil moisture was the most dependent factor for the plant growth and the optimum growth was recorded at 78 ± 5.6% (r²?= 0.9; P ≤ 0.01). The physiological performance of the plant in all the studied sites were significantly varied (P < 0.05). The growth and development of H. cordata were also different in the flowering and senescence stages. Clay loam soil, average soil pH of 5.9, and 78% soil moisture were the favorable soil characteristics for the better growth of H. cordata and, hence, these data may be considered for conservation of the species.     

Rapid Assessment of Plant Diversity Patterns: A Methodology for Landscapes

We present a rapid, cost-efficient methodology to link plantdiversity surveys from plots to landscapes using: (1) unbiasedsite selection based on remotely sensed information; (2) multi-scale field techniques to assess plant diversity; (3)mathematical models (species-area curves) to estimate thenumber of species in larger areas corrected for within-typeheterogeneity; and (4) mathematical techniques to estimatetotal species richness and patterns of plant diversity in alandscape. We demonstrate the methodology in a 754 ha studyarea in Rocky Mountain National Park, Colorado, U.S.A.,using four 0.025 ha and twenty-one 0.1 ha multi-scalevegetation plots. We recorded 330 plant species (1/3 thenumber of plants recorded in the 1074 km² Park) in the2.2 ha area within the plots: this represents a samplingintensity of 0.29% of the 754 ha study site. We estimated 552plant species, about half the plant species recorded in the Park,in just 0.7% of the Parks area. We show how this rapid,cost-efficient methodology: (1) produces a rich informationbase on the patterns of native plant diversity and thedistribution of non-native plant species and keystoneecosystems; and (2) can be easily adapted for other nationaland state parks, national forests, wildlife refuges, and nature reserves.     

Imposex and butyltin concentrations in Bolinus brandaris (Gastropoda: Muricidae) from the northern Tunisian coast

The imposex incidence and butyltin concentration i.e. tributyltin with its di- and mono-substituted metabolites were investigated in the muricid Bolinus brandaris sampled from two sites on the northern Tunisian coast (the Lagoon of Bizerta and the small Gulf of Tunis). Both populations had imposex, with stages of imposex development varying between VDS 1 and VDS 4.3. All imposex indices (imposex frequency (I %), female penis length, female vas deferens length, vas deferens sequence index, relative penis length index, and vas deferens length index) were significantly higher in snails from the Bizerta lagoon. Butyltins were detected in the whole tissues of both sexes from the two sites. TBT levels were higher in gastropods collected from the lagoon of Bizerta (12.65 ±1.48 ng Sn g^???1 dw in female and 15.21 ±1.13 ng Sn g^???1 dw in male) than in individuals from the Gulf of Tunis (10.71 ±1.26 ng Sn g^???1 dw in female and 11.65 ±1.63 ng Sn g^???1 dw in male), corroborating the data of imposex analysis. These results confirmed that B. brandaris could be used as a bioindicator species of butyltin pollution in the studied areas. In addition, this study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet.     

Relationships of Human Disturbance, Bird Communities, and Plant Communities Along the Land-Water Interface of a Large Reservoir

We examined the relationships of humanactivity, bird communities, and plant communities along theland-water interface of Lake Texoma, a large human-madereservoir on the Texas-Oklahoma border. Measurements ofhuman activity, plant surveys, and bird surveys wereperformed at 40 paired transects, one with humandisturbance, the other undisturbed. Both principalcomponents and correspondence analyses of bird-survey dataseparated disturbed sites from paired undisturbed sites, andtypical disturbance-tolerant species from those lesstolerant of human activity. Compared to undisturbed sites,disturbed sites tended to have more individual birds persurvey, pavement, and mowed lawns, and less canopy,vegetation volume, and vegetation vertical diversity. Aprincipal components analysis of quantitative disturbancemeasurements revealed that most bird and plant measures werehighly correlated with the first disturbance component. However, the correlation between birds and human activitywas much stronger than that between birds and plants, orbetween plants and disturbance. Our data suggest that bird-species composition is regulated more by human activity thanby plant-community composition. Also, in this system, birdcommunities are a better choice than plant communities toindex the effect of human disturbance. To maintain regionaldiversity of both birds and plants, undisturbed areas shouldbe maintained around reservoirs.     

Using species spectra to evaluate plant community conservation value along a gradient of anthropogenic disturbance

The aim of this study was to assess the impact of anthropogenic disturbance on the partitioning of plant communities (species spectra) across a landcover gradient of community types, categorizing species on the basis of their biogeographic, ecological, and conservation status. We tested a multinomial model to generate species spectra and monitor changes in plant assemblages as anthropogenic disturbance rise, as well as the usefulness of this method to assess the conservation value of a given community. Herbaceous and arborescent communities were sampled in five Azorean islands. Margins were also sampled to account for edge effects. Different multinomial models were applied to a data set of 348 plant species accounting for differences in parameter estimates among communities and/or islands. Different levels of anthropogenic disturbance produced measurable changes on species spectra. Introduced species proliferated and indigenous species declined, as anthropogenic disturbance and management intensity increased. Species assemblages of relevance other than economic (i.e., native, endemic, threatened species) were enclosed not only in natural habitats, but also in human managed arborescent habitats, which can positively contribute for the preservation of indigenous species outside remnants of natural areas, depending on management strategies. A significant presence of invasive species in margin transects of most community types will contribute to an increase in edge effect that might facilitate invasion. The multinomial model developed in this study was found to be a novel and expedient tool to characterize the species spectra at a given community and its use could be extrapolated for other assemblages or organisms, in order to evaluate and forecast the conservation value of a site.     

Distributions, sources, and ecological risks of DDT-related contaminants in water, suspended particulate matter, and sediments from Haihe Plain, Northern China

The residual levels of dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs, including p,p′-DDT, DDD, and DDE) in water, suspended particulate matter (SPM), and sediments from major rivers, lakes, and reservoirs in Haihe Plain were measured with a gas chromatograph equipped with a ⁶³Ni microelectron capture detector. In the fall of 2004, the contents of the total DDXs in the water and SPM were 0.29?±?0.69 ng L^?1 and 423.13?±?577.85 ng g^?1 dry wt., respectively. In the spring of 2005, the total DDXs were 0.36?±?0.91 ng L^?1 for water and 35.93?±?62.65 ng g^?1 dry wt. for SPM. The average concentration of DDXs for sediments was 7.10?±?7.57 ng g^?1 dry wt. during the two seasons. The Eastern-Hebei-Province Coastland River System was the most polluted, which was mainly attributable to the extensive use of DDT pesticide and dicofol in that system. Recent DDT inputs still occur in some regions, as indicated by DDT/(DDD + DDE) > 1 at 29–36 % of the sites for water and 55–61 % of the sites for SPM. The potential ecological risks of DDT in the water were assessed using a species sensitivity distribution model. Only shrimp and crabs were found to have potentially affected fraction values of 1.63?×?10^?3 to 2.27?×?10^?4, with probabilities beyond the hazardous concentration for 5 % of species (HC5) values of 1.90–2.56 %, suggesting only slight risks. DDXs in the sediments of some sites were also of potential risk to benthic organism based on consensus-based sediment quality guidelines.     

The new flora of northeastern USA: quantifying introduced plant species occupancy in forest ecosystems

Introduced plant species have significant negative impacts in many ecosystems and are found in many forests around the world. Some factors linked to the distribution of introduced species include fragmentation and disturbance, native species richness, and climatic and physical conditions of the landscape. However, there are few data sources that enable the assessment of introduced species occupancy in native plant communities over broad regions. Vegetation data from 1,302 forest inventory plots across 24 states in northeastern and mid-western USA were used to examine and compare the distribution of introduced species in relation to forest fragmentation across ecological provinces and forest types, and to examine correlations between native and introduced species richness. There were 305 introduced species recorded, and 66 % of all forested plots had at least one introduced species. Forest edge plots had higher constancy and occupancy of introduced species than intact forest plots, but the differences varied significantly among ecological provinces and, to a lesser degree, forest types. Weak but significant positive correlations between native and introduced species richness were observed most often in intact forests. Rosa multiflora was the most common introduced species recorded across the region, but Hieracium aurantiacum and Epipactus helleborine were dominant in some ecological provinces. Identifying regions and forest types with high and low constancies and occupation by introduced species can help target forest stands where management actions will be the most effective. Identifying seemingly benign introduced species that are more prevalent than realized will help focus attention on newly emerging invasives.     

A study on the phytoaccumulation of waste elements in wetland plants of a Ramsar site in India

Some wetland plant species are adapted to growing in the areas of higher metal concentrations. Use of such vegetation in remediation of soil and water contaminated with heavy metals is a promising cost-effective alternative to the more established treatment methods. Throughout the year, composite industrial effluents bringing various kinds of heavy metals contaminate our study site, the East Calcutta Wetlands, a Ramsar site at the eastern fringe of Kolkata city (formerly Calcutta), India. In the present study, possible measures for remediation of contaminated soil and water (with elements namely, Ca, Cr, Cu, Pb, Zn, Mn, and Fe) of the ecosystem had been investigated. Ten common regional wetland plant species were selected to study their efficiency and diversity in metal uptake and accumulation. Results showed that Bermuda grass (Cynodon dactylon) had the highest total Cr concentration (6,601 ± 33 mg kg^???1 dw). The extent of accumulation of various elements in ten common wetland plants of the study sites was: Pb (4.4?C57 mg kg^???1 dw), Cu (6.2?C39 mg kg^???1 dw), Zn (59?C364 mg kg^???1 dw), Mn (87?C376 mg kg^???1 dw), Fe (188?C8,625 mg kg^???1 dw), Ca (969?C3,756 mg kg^???1 dw), and Cr (27?C660 mg kg^???1 dw) indicating an uptake gradient of elements by plants as Ca>Fe>Mn>Cr>Zn>Cu>Pb. The present study indicates the importance of identification and efficiency of metal uptake and accumulation capabilities by plants in relation to their applications in remediation of a contaminated East Calcutta Wetland ecosystem.     

Assessment of Robinia pseudoacacia cultivations as a restoration strategy for reclaimed mine spoil heaps

Reforestation with black locust (Robinia pseudoacacia) is considered a successful technique that is often used for the reclamation of open-cast mine areas. An alternative reclamation technique could be the natural regeneration of vegetation with spontaneous grass species. In this study, we compared the concentrations of chemical and biochemical variables in soil samples taken under black locust canopy to those from sites covered by spontaneous grass vegetation (control samples) in a time sequence of spoil deposition (0–10 years), in order to assess which of the two reclamation techniques yields higher soil quality. Soil quality refers here to the ability of soils to function ecologically. This has a special interest since the main question for the restored soils is their capacity to perform a range of ecological functions under stress or disturbance. Furthermore, we aimed at identifying the effect of vegetation type on soil ecological succession. The effect of vegetation type on primary succession becomes apparent after 2 years of reclamation. R. pseudoacacia as a nitrogen-fixing plant enriched soil with organic and inorganic nitrogen and organic matter to a greater extent than the natural grasses. It also increased the amount of soil microbial biomass and the activity of alkaline phosphatase. However, the fact that black locust failed to enhance dehydrogenase activity and actually decreased the activity of urease, activities that represent specialized niche functions and therefore, are more vulnerable to stress or disturbance, suggests that the development of an indigenous grass community in combination with organic supplements might often be more appropriate for the reclamation of similar kinds of mine areas.     

Concentrations of As, Be, Cr, Hg, Mn, and Ni in ambient air at four urban locations in Japan

The metal concentrations of As, Be, Cr, Hg, Mn, and Ni in ambient air were measured at four sites in Japan from October 1997 to March 2006. The mean metal concentration data measured from the four sites (K1, K2, M, and Y) are found on the order of Mn > Cr–Ni > As > Hg > Be. The concentrations of Mn with the highest mean value were fairly variable across four sites such as 45.9 ± 42.8 (K1), 25.6 ± 19.4 (K2), 22.5 ± 19.7 (M), and 25.4 ± 19.8 ng m^???3 (Y). In contrast, the concentrations of Be with the lowest mean value were less variable across four sites with means of 0.03 to 0.04 ng m^???3. Inspection of the seasonal patterns indicates the peak occurrence of most metals during spring, although relative dominance during winter is seen at the most polluted area (K1). Evaluation of long-term patterns indicates that the noticeably high values of metals in the early stage of study reduced gradually across the years, although the metal concentration levels in most areas were affected significantly by anthropogenic activities. However, efforts to control pollution levels seemed to gradually contribute to a decrease in metal concentration levels of all study sites through the years.     

Life-cycle impacts of wind energy development on bird diversity in Norway

While wind energy remains a preferred source of renewable energy, understanding the full spectrum of impacts are vital to balance climate-related benefits against their costs to biodiversity. Environmental impact assessments often fail to assess cumulative effects at larger spatial scales. In this respect, life cycle assessments are better suited, but have to date mainly focused on greenhouse gas emissions and energy accounting. Here, we adapt a recent global life-cycle impact assessment (LCA) methodology to evaluate collision, disturbance and habitat loss impacts of onshore wind energy development on bird species richness in Norway. The advantage of a local model for Norway is that it enables employing species distribution models to more accurately estimate the potential distribution area of species. This facilitates more realistic site- and species-specific assessments of potential impacts within a local scale but excludes habitat ranges outside Norway. Furthermore, a new characterization factor was developed for potential barrier effects. Larger onshore wind-power plants overall had greater site-specific potentially disappeared fractions (PDF) of species, while smaller plants were less efficiently located with greater impacts per GWh. Overall, Norwegian wind-power plants were sited least efficiently (PDF/GWh) regarding indirect habitat loss (2.186 × 10⁻⁹) and disturbance (1.219 × 10⁻⁹), followed by direct habitat loss (0.932 × 10⁻⁹), and finally collisions (0.040 × 10⁻⁹) and barriers (0.310 × 10⁻⁹). Vulnerability differed among bird groups with seabirds, raptors and waterfowl emerging as the most impacted groups (e.g. 5.143 × 10⁻⁹, 3.409 × 10⁻⁹ and 3.139 × 10⁻⁹ PDF/GWh for disturbance, respectively); highlighting the sympatric distribution of their habitats and the majority of Norway's onshore wind-power plants. Current practice has not succeeded in avoiding sites with higher impacts for birds, fuelling conflicts surrounding environmental concerns of onshore wind energy development in Norway. Operative LCA models can help decision-makers assessing localized life-cycle environmental impacts to support environmental-friendly wind energy production in specific regions.     

夏季典型背景及城市地区VOCs对比研究

选取武夷山、庞泉沟和长岛3个具有代表性的空气背景站点及其周边城市站点,分析研究夏季环境空气中挥发性有机污染物(VOCs)的特征。结果表明,庞泉沟、武夷山、长岛背景站点的总挥发性有机物(TVOCs)平均浓度分别为(24.71±7.89)×10^-9、(7.94±5.82)×10^-9、(11.98±5.34)×10^-9,分别比对应的城市站点低42%、43%、11%。背景站点TVOCs中的烷烃占比为67%～72%,明显高于城市站点;背景站点与城市站点TVOCs中的烯烃和芳香烃占比无显著差异;但背景站点炔烃占比(2%～3%)明显低于城市地区(10%～24%)。背景站点异戊二烯浓度在09:00—15:00出现峰值,且TVOCs浓度变化趋势与异戊二烯浓度变化趋势关联性较强,说明背景站点受自然源影响较大。臭氧生成潜势(OFP)分析结果表明,烯烃及芳香烃对背景地区与城市地区臭氧生成有较大影响,城市地区总OFP远大于背景地区,乙烯、甲苯等对城市地区OFP的贡献较大,异戊二烯对背景地区OFP的贡献较大。     

Rinodina sophodes (Ach.) Massal.: a bioaccumulator of polycyclic aromatic hydrocarbons (PAHs) in Kanpur City, India

The aim of this study is to determine the possibility of using Rinodina sophodes (Ach.) Massal., a crustose lichen as polycyclic aromatic hydrocarbons (PAHs) bioaccumulator for evaluation of atmospheric pollution in tropical areas of India, where few species of lichens are able to grow. PAHs were identified, quantified and compared to evaluate the potential utility of R. sophodes. The limit of detection for different PAHs was found to be 0.008–0.050 μg g^− 1. The total PAHs in different sites were ranged between 0.189 ± 0.029 and 0.494 ± 0.105 μg g^− 1. The major sources of PAHs were combustion of organic materials, traffic and vehicular exhaust (diesel and gasoline engine). Significantly higher concentration of acenaphthylene and phenanthrene indicates road traffic as major source of PAH pollution in the city. Two-way ANOVA also confirms that all PAHs content showed significant differences between all sampling sites (P 1%). This study establishes the utility of R. sophodes in monitoring the PAHs accumulation potentiality for development of effective tool and explores the most potential traits resistant to the hazardous environmental conditions in the tropical regions of north India, where no such other effective way of biomonitoring is known so far.     

Metal release from serpentine soils in Sri Lanka

Ultramafic rocks and their related soils (i.e., serpentine soils) are non-anthropogenic sources of metal contamination. Elevated concentrations of metals released from these soils into the surrounding areas and groundwater have ecological-, agricultural-, and human health-related consequences. Here we report the geochemistry of four different serpentine soil localities in Sri Lanka by coupling interpretations garnered from physicochemical properties and chemical extractions. Both Ni and Mn demonstrate appreciable release in water from the Ussangoda soils compared to the other three localities, with Ni and Mn metal release increasing with increasing ionic strengths at all sites. Sequential extraction experiments, utilized to identify “elemental pools,” indicate that Mn is mainly associated with oxides/(oxy)hydroxides, whereas Ni and Cr are bound in silicates and spinels. Nickel was the most bioavailable metal compared to Mn and Cr in all four soils, with the highest value observed in the Ussangoda soil at 168?±?6.40 mg kg^?1 via the 0.01-M CaCl₂ extraction. Although Mn is dominantly bound in oxides/(oxy)hydroxides, Mn is widely dispersed with concentrations reaching as high as 391 mg kg^?1 (Yudhaganawa) in the organic fraction and 49 mg kg^?1 (Ussangoda) in the exchangeable fraction. Despite Cr being primarily retained in the residual fraction, the second largest pool of Cr was in the organic matter fraction (693 mg kg^?1 in the Yudhaganawa soil). Overall, our results support that serpentine soils in Sri Lanka offer a highly labile source of metals to the critical zone.