Geochemical and Spatial Appraisal of Fluoride in the Soils of Indo‐Gangetic Plains of India Using Multivariate Analysis

The geochemical characteristics and the spatial distribution of the fluoride were studied in the soils of Indo‐Gangetic plains using multivariate analysis. The fluoride (F) distribution in soil profiles and surface soil (0–15 cm) samples were studied. It was found that total fluoride (TF) in the profiles ranged from 248 to 786 mg kg^?1 with a mean of 515.1 mg kg^?1 whereas CaCl₂ extractable soluble fluoride (F_Ca) was found to be in the range of 1.68 to 99.1 mg F kg^?1 soil. On the other hand, in surface soils, the TF and F_Ca ranged from 118 to 436 mg kg^?1 with a mean of 251.2 mg kg^?1 and 1.01 to 5.05 mg kg^?1 with a mean of 2.12 mg kg^?1, respectively, in the study area. The principal component analysis revealed that the natural weathering of fluoride bearing rock and minerals, various ion‐exchange and dissolution processes in the soil, alkalinity, sodium adsorption ratio, calcium (Ca), magnesium (Mg), and clay contents of the soil are responsible for high fluoride occurrence in the area. The fluoride contamination index developed by using these factors could explain more than 76% variance of F contamination due to F_Ca in soils. The interpolated kriged map of F_Ca in surface soil indicated a distinct loop of 1.0–2.0, 2.0–3.0, 3.0–4.0, and >4.0 mg kg^?1.     

Assessment of Metal Pollution in Water and Surface Sediments of the Seyhan River,Turkey, Using Different Indexes

The aim of this study was to assess the level of heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination and enrichment in the surface sediments of the Seyhan River, which is the receiving water body of both treated and untreated municipal and industrial effluents as well as agricultural drainage waters generated within Adana, Turkey. Sediment and water samples were taken from six previously determined stations covering the downstream of the Seyhan dam during both wet and dry seasons and the samples were then analyzed for the heavy metals of concern. When both dry and wet seasons were considered, metal concentrations varied significantly within a broad range with Al, 7210–33 967 mg kg^?1 dw; Cr, 46–122 mg kg^?1 dw; Cu, 6–57 mg kg^?1 dw; Fe, 10 294–26 556 mg kg^?1 dw; Mn, 144–638 mg kg^?1 dw; Ni, 82–215 mg kg^?1 dw; Pb, 11–75 mg kg^?1 dw; Zn, 34–146 mg kg^?1 dw in the sediments while Cd was at non‐detectable levels for all stations. For both seasons combined, the enrichment factor (EF) and the geo‐accumulation index (I_geo) for the sediments in terms of the specified metals ranged from 0.56 to 10.36 and ?2.92 to 1.56, respectively, throughout the lower Seyhan River. The sediment quality guidelines (SQG) of US‐EPA suggested the sediments of the Seyhan River demonstrated “unpolluted to moderate pollution” of Cu, Pb, and Zn, “moderate to very strong pollution” of Cr and Ni. The water quality data, on the other hand, indicated very low levels of these metals suggesting that the metal content in the surface sediments were most probably originating from fine sediments transported along the river route instead of water/wastewater discharges with high metal content.     

Chelant‐assisted Phytostabilization of Paint‐contaminated Residential Sites

Following the basic incubation study, a greenhouse experiment was conducted to elucidate the efficiency of vetiver grass (Vetiveria zizanioides L.), with or without chelating agents, in remediating lead (Pb)‐contaminated soils from actual residential sites where Pb‐based paints were used. Because the primary factor affecting Pb phytoavailability in soils is soil pH, we used two soil types widely varying in pH that have total Pb concentrations above 1500 mg kg^?1 soil. Lead‐contaminated, low pH, acidic soils were collected from residential sites in Baltimore, MD and high pH, alkaline soils were collected from residential sites in San Antonio, TX. Based on the soil characterization results, two most appropriate soils (one from each city, having similar Pb levels but variable soil physico‐chemical properties) were selected for this study. Ethylenediaminetetraacetic acid (EDTA) and [S,S′]ethylenediaminedisuccinate (EDDS) were applied at 5, 10, and 15 mmol kg^?1 soil. Lead uptake and translocation in vetiver was determined on day 10 after chelants addition. Plant and soil analysis show that EDTA treated soils have maximum Pb uptake and lower total soil Pb levels. Prediction models developed for exchangeable Pb show a strong correlation for total Pb accumulated in vetiver grass. Results of the sequential chemical extraction of the soils at both initial and final time‐points, indicates a significant mobilization of Pb by the two chelants from carbonate‐bound fraction to exchangeable pool. Information on physico‐chemical properties of contaminated residential soils help in predicting Pb phytoextraction and thus further help in calibrating a successful chelant‐assisted phytoremediation model.     

Methods of metal release assessment in soil water at anoxic sites

Metal mobility at contaminated sites can be assessed by soil water investigations or by leaching tests. Leaching tests are usually carried out in open contact with the atmosphere disregarding possible changes of redox conditions. This can affect the original metal speciation and distribution, particularly when anoxic samples are investigated. In this study, the applicability of common leaching tests (the German S4 test (S4), ammonium nitrate extraction (AmmN), and saturation soil extraction (SSE)) is tested for the assessment of zinc release from sulfide‐bearing flotation residues of a former ore mine. Results are compared to soil solution samples obtained by centrifugation and suction cups. The influence of sample storage on S4 leaching test results is investigated in a long‐term study to assess oxidation kinetics. Within the first 200 days the release of zinc increases with a slope of 0.1 mmol kg^–1 d^–1 or 6.0 mg kg^–1 d^–1, respectively. Since oxidation of the sulfide‐bearing samples leads to a significant overestimation of metal release, a feasible modification for the conduction of leaching tests for anoxic material is proposed where oxidation is prevented efficiently. The modified SSE is found to be the only of the tested leaching procedures, which can be recommended for the assessment of current soil water concentrations at anoxic sites if direct investigation of the soil water is impossible due to technical reasons.     

Sublethal and lethal effects of sediments applied to common Caribbean Reef corals in the field

Experiments to measure natural rates of sedimentation and to assess the tolerance of coral species to increased sedimentation were conducted at San Cristobal Reef, Puerto Rico. Sedimentation rates were measured over an 18 month period. Calcareous sediments were applied to colonies of Montastraea annularis, Diploria strigosa, D. clivosa, Acropora palmata and A. cervicornis in different frequencies and in different doses.Mean sedimentation rates from sediment traps were 9.6±2.4 (S.E.) mg cm^?2 · day^?1 at 10 cm above the bottom and 2.5±0.9 (S.E.) and 2.6±1.2 (S.E.) mg cm^?2 · day^?1 for two sets of traps at 50 cm above the bottom. Sediment application experiments indicated A. palmata was the least tolerant of the species tested. Although A. cervicornis and D. strigosa colonies were not significantly affected, single applications of 800 mg cm^?2 to M. annularis colonies and of 200 mg cm^?2 to A. palmata colonies caused death of underlying coral tissue. Algae colonized the smothered portions of these corals.     

Spatial and Temporal Distribution of Dust‐Bound Trace Metal Elements around Kuhdasht Watershed Area in Iran

Dust, as a source of trace metal elements, affects the health of society. The spatial and temporal concentrations of dust‐bound trace metals (Cd, Pb, Ni, Zn, Cu, and Mn) in Kuhdasht watershed (456 km²), Lorestan Province, Iran, is investigated. Dust is collected using glass traps placed in ten research stations in the region. The spatial and temporal distribution of dust trace metals are plotted using ARC‐GIS. The highest and the lowest concentrations of Zn (9751150 mg kg^?1), Pb (46.352.9 mg kg^?1), and Cd (2.443.30 mg kg^?1) are obtained in winter, of Ni (98110 mg kg^?1) and Cu in autumn (16.053.5 mg kg^?1), and of Mn in summer (385505 mg kg^?1). The spatial concentrations of dust‐bound trace metals indicate all, except Cu, show a decreasing trend from the mountains toward the plains, similar to that of soil and of dust, except for Zn, which shows higher concentrations in dust than in soil. The potential sources of dust‐bound trace metals and their rate of contamination are also investigated using the enrichment and contamination factors. The major sources of Cd and Zn in the dust of watershed are due to anthropogenic activities or from activities outside the borders.     

Transformation of Tobacco with ScMTII Gene‐Enhanced Cadmium and Zinc Accumulation

Genetic transformation is gaining importance for developing plant types suitable to metal accumulate and/or hyperaccumulate. In this study, the transgenic tobacco plant which transferred the ScMTII gene from Saccharomyces cerevisiae to wild type tobacco cultivar Petite Havana (SR1) was grown on soils with low and high cadmium (Cd) and zinc (Zn) concentrations in a growth chamber for 6 weeks and compared to wild type tobacco for Cd and Zn accumulation. Cadmium and Zn accumulations in the transgenic and wild type tobacco plants were increased with the increasing Cd and Zn concentrations. Unlike Zn, the transgenic plant accumulated significantly higher amount of Cd compared to the wild type control plants. Shoot Cd concentrations of transgenic tobacco in higher Cd dosages reached the above the hyperaccumulation threshold value of 100 mg Cd kg^?1 in the dry weight (DW). Transgenic tobacco accumulated 354, 400, 372, and 457 mg Cd kg^?1 DW, for 10, 20, 40, and 80 mg Cd kg^?1 soil treatments, respectively. These values are 3.5–4.5‐fold higher than that of Cd hyperaccumulation threshold value. With 10 mg kg^?1 Cd treatment, the bioconcentration factor (BCF) of transgenic tobacco plants for Cd reached up to 35 in which the threshold value for BCF should be at least 10. Our results showed that the transgenic tobacco may be used as a good Cd hyperaccumulator plant and for phytoextraction of Cd contaminated soils, but not for Zn.     

Packed‐Column of Granular Activated Carbons for Removal of Chemical Oxygen Demand from Industrial Wastewater

In the present study, chemical oxygen demand (COD) removal by packed‐columns of activated carbon (AC) derived from two different materials (coal activated carbon, CAC and wood activated carbon, WAC) is reported as part of an on‐site wastewater treatment system for handling small volumes of wastewater generated at wood‐floor industries for which there are no proper on‐site treatment options available in the market. The performance of the sorbents, the effect of bed depth (0.19 and 0.57 m) and volumetric load (0.10 and 0.24 m h^?1) on the breakthrough curve of sorption systems were studied. The results indicated the feasibility of using both ACs to treat these wastewaters. At the bed depth (0.57 m), volumetric load (0.24 m h^?1), and 30% breakthrough, CAC and WAC showed treatment capacity of 40.5 L kg^?1 in 250 h and 23.8 L kg^?1 in 63 h, respectively. This indicated that CAC requires longer retention times to reach a performance similar to WAC. The experimental data was fit into the bed depth‐service time model showing that under the same conditions, CAC had higher maximum sorption capacity (N₀) than WAC. Moreover, thermal regeneration at 500°C temperature could be a cost‐effective procedure since the reuse of spent AC through such regeneration process for further treatment could still achieve 90% of the initial sorption capacity, reducing then costs for the use of new sorbents and also the need for waste disposal.     

Organochlorine pesticides in soil and air at and around a compound contaminated site: vertical distribution,soil–air exchange and risk evaluation

The control of soil pollution in China has become an issue, and in this study, a compound contaminated site was selected and focus on the site and its nearby environment, organochlorine pesticides (OCPs) were investigated in both soil (top and deep soil) and air samples. The main pollutants in top soils at site are dichlorodiphenyltrichloroethane (DDTs, 0.05–104 mg/kg d.w., avg: 14.5 mg/kg d.w.) and hexachlorobenzene (HCB, 0.02–4.85 mg/kg d.w., avg: 0.72 mg/kg d.w.) which is in accordance with its production history. As for the deep soils, ΣOCPs at site were found concentrated at workshops especially the technical pesticide workshop (5.29–22.1 mg/kg d.w., avg: 9.15 mg/kg d.w.) and the history DDTs’ workshop (4.00–64.8 mg/kg d.w., avg: 20.4 mg/kg d.w). Around site, OCPs were mainly concentrated at layers of −20 cm and the −40 cm and decreased with distance being far away, at 5000 m, the ΣOCPs was comparable with normal agriculture soil (22.1−91.4 ng/g d.w., avg: 55.4 ng/g d.w.). ΣOCPs in the air samples ranged 64.6–823 ng/m³ (avg: 459 ng/m³) at site and 9.93–176 ng/m³ (avg: 50.8 ng/m³) around site which are all dominated with DDTs and HCHs. Soil–air exchange fugacity was calculated to judge the transportation of the OCPs and the results showed soils at the site and its nearby areas (within 5000 m) are releasing most of the OCPs into air, and accordingly through evaluation, inhalation was found to be the major source for human health risk, which is a great threat to the workers at site and the nearby residents.

     

Polycyclic aromatic hydrocarbons in marine sediments from the Rijeka Bay area, Northern Adriatic, Croatia, 1998-2006

The first analyses of PAHs in marine sediments within Rijeka Bay started in 1998 at three sampling sites offshore from the petroleum refinery facilities and were extended in 1999 to three more sampling points in front of the repair shipyard within the same east industrial zone. The small Svezanj cove, lying between the shipyard and the petroleum refinery was chosen as the reference point. The concentrations of PAHs were considerably higher in the shipyard environment (average: 3009-6314 μg kg⁻¹ d.w.) in comparison to the petroleum refinery area (average: 279-919 μg kg⁻¹ d.w.), while the PAHs load at reference point was close to the latter level (average: 717 μg kg⁻¹ d.w.). The Phe/Anth and Flo/Py ratios indicate the dominant pyrogenic sources, except for the results from 1999 to 2000 with dominant petrogenic origin at some sites. A declining trend of total PAHs, and consequently toxicity indices was observed at all sites.     

Levels of organochlorine compounds in an inland seal population in eastern Finland

Fourteen Saimaa ringed seals (Phoca hispida saimensis) were studied for PCB, DDT, chlordane and chlorophenol compounds in blubber, liver, muscle, heart and kidney in Lake Saimaa, eastern Finland, in 1977–1981. Both PCBs and total DDT increased on average from a good 5 mg kg^?1 in extractable fat of blubber in a new-born to a good 65 mg kg^?1 in sexually mature specimens, the maximum being 93 and 104 mg kg^?1 respectively. Concentrations of PCBs and tDDT in blubber and liver were most clearly dependent on the age and weight of the seal. Chlordanes were found in all 14 specimens (mean 0.59 mg kg^?1 in blubber), trichlorophenol in one, tetrachlorophenol in two and pentachlorophenol in all three specimens studied. Although some of the Saimaa seals had reached quite high levels of both PCBs and tDDT, the present results do not indicate that the steady decrease of the Saimaa seal population during the last two decades would have been caused by these toxins, at least not in isolation.     

Hydrological heterogeneity of an alpine stream–lake network in Switzerland

Water source and lake landscape position can strongly influence the physico‐chemical characteristics of flowing waters over space and time. We examined the physico‐chemical heterogeneity in surface waters of an alpine stream‐lake network (>2600 m a.s.l.) in Switzerland. The catchment comprises two basins interspersed with 26 cirque lakes. The larger lakes in each basin are interconnected by streams that converge in a lowermost lake with an outlet stream. The north basin is primarily fed by precipitation and groundwater, whereas the south basin is fed mostly by glacial melt from rock glaciers. Surface flow of the entire channel network contracted by ～60% in early autumn, when snowmelt runoff ceased and cold temperatures reduced glacial outputs, particularly in the south basin. Average water temperatures were ～4 °C cooler in the south basin, and temperatures increased by about 4–6 °C along the longitudinal gradient within each basin. Although overall water conductivity was low (<27 µS cm^?1) because of bedrock geology (ortho‐gneiss), the south basin had two times higher conductivity values than the north basin. Phosphate‐phosphorus levels were below analytical detection limits, but particulate phosphorus was about four times higher in the north basin (seasonal average: 9 µg l^?1) than in the south basin (seasonal average: 2 µg l^?1). Dissolved nitrogen constituents were around two times higher in the south basin than in the north basin, with highest values averaging > 300 µg l^?1 (nitrite + nitrate‐nitrogen), whereas particulate nitrogen was approximately nine times greater in the north basin (seasonal average: 97 µg l^?1) than in the south basin (seasonal average: 12 µg l^?1). Total inorganic carbon was low (usually <0·8 mg l^?1), silica was sufficient for algal growth, and particulate organic carbon was 4·5 times higher in the north basin (average: 0·9 mg l^?1) than in the south basin (average: 0·2 mg l^?1). North‐basin streams showed strong seasonality in turbidity, particulate‐nitrogen and ‐phosphorus, and particulate organic carbon, whereas strong seasonality in south‐basin streams was observed in conductivity and dissolved nitrogen. Lake position influenced the seasonal dynamics in stream temperatures and nutrients, particularly in the groundwater/precipitation‐fed north‐basin network. Copyright © 2007 John Wiley & Sons, Ltd.     

Cadmium‐Induced Physiological Response in Lonicera japonica Thunb.

Phytoremediation of Cd‐contaminated soil using hyperaccumulators has become a new promising technique. Lonicera japonica Thunb. has been reported as a new Cd‐hyperaccumulator. In this study, the effect of Cd stress duration on growth, photosynthesis and mineral nutrition of L. japonica was investigated. At 30 days after Cd stress, there was not any visual leaf symptoms in L. japonica, and an obvious stimulating effect of 10 mg kg^?1 Cd on net photosynthesis rate (P_N) was well correlated to photosynthetic pigment contents and mineral nutrition (Mg and Fe) concentrations. With Cd stress time extended, no significant differences of shoots and total biomass and P_N compared with the control was observed, indicating that L. japonica could develop effective tolerance mechanisms to avoid Cd‐induced damage to photosynthesis and growth. The photosynthetic performance remained functional through stomatal and non‐stomatal adjustments, and mineral nutrition responses. The improved growth based on shoots and total biomass and P_N by 10 mg kg^?1 Cd, as suggested by hormesis, may be beneficial to enhance the potential for phytoremediation, because it typically faced the low Cd concentrations in actual Cd‐contaminated soils. The study results indicated that L. japonica could be used for phytoremediation contaminated soils by Cd.     

The impact of typhoons on sediment connectivity: lessons learnt from contaminated coastal catchments of the Fukushima Prefecture (Japan)

Sediment connectivity characterizes the physical transfer of sediment through different geomorphic compartments in catchments due to sediment detachment, transport and deposition. Quantifying and modelling sediment connectivity is therefore a key prerequisite to improving our understanding of the dispersion of particle‐borne contaminants, especially in catchments exposed to highly erosive climates. The objective of this study is to provide novel insights into typhoon impacts on sediment connectivity from hillslopes to rivers. The dispersion of particle‐bound caesium‐137 (¹³⁷Cs) was investigated in two coastal catchments draining the main contamination plume from the Fukushima Daiichi Nuclear Power Plant accident. Five sampling campaigns were carried out from November 2011 to November 2015, after each typhoon season. The spatial and temporal evolution of ¹³⁷Cs contamination was investigated through the calculation of ¹³⁷Cs enrichment ratios in sediment relative to nearby soils. Rainfall erosivity (EI₃₀) associated with the main typhoons that occurred prior to each sampling campaign were computed, mapped, and finally used to improve a topographic‐based index of connectivity. From 2011 to 2015, mean contamination levels in Mano and Niida catchments decreased from 11.9 kBq kg^?1 to 3.3 kBq kg^?1 and from 34.1 kBq kg^?1 to 8.0 kBq kg^?1, respectively. Regional mean EI₃₀ ranged from 262 MJ mm ha^?1 h^?1 for typhoon Jelawat (in 2012) to 1695 MJ mm ha^?1 h^?1 for typhoon Roke (in 2011). Typhoons Roke (2011) and Etau (2015) showed the highest connectivity from contaminated sources to the rivers, and induced a significant export of sediment to the ocean. In 2013 a slight increase in ¹³⁷Cs levels in river sediments occurred, likely resulting from initial decontamination works and the occurrence of two consecutive typhoons. Importantly, this research provides new insights into the connectivity of the main sources of sediments contaminated with radiocaesium in Fukushima Prefecture and their temporal evolution, which will help with ongoing decontamination efforts. Copyright © 2016 John Wiley & Sons, Ltd.     

Plant Species Richness Affected Nitrogen Retention and Ecosystem Productivity in a Full‐Scale Constructed Wetland

The effects of plant species richness (SR; i.e., 1, 2, 4, 8, and 16 species per plot) on substrate nitrate and ammonium retention and ecosystem productivity in a full‐scale constructed wetland (CW) with high nitrogen (N) input were studied. Substrate nitrate (0.1–16.4 mg kg^?1) and ammonium concentrations (1.3–9.2 mg kg^?1) in this study were higher than those in other comparable biodiversity experiments. Substrate nitrate concentration significantly increased while ammonium concentration significantly decreased with the increase of plant SR (p = 0.008 and 0.040, respectively). The response of ecosystem productivity to increasing SR was unimodal with four species per plot achieving the greatest productivity. Transgressive overyielding, which was compared to the most productive of corresponding monocultures, did not occur in most polycultures. We conclude that substrate N retention was enhanced by plant SR even with high N input, and plant SR could be managed to improve the efficiency of N removals in CWs for wastewater treatment.     

Post‐fire hydrological response and suspended sediment transport of a terraced Mediterranean catchment

In July 2013, a wildfire severely affected the western part of the island of Mallorca (Spain). During the first three post‐fire hydrological years, when the window of disturbance tends to be more open, the hydrological and sediment delivery processes and dynamics were assessed in a representative catchment intensively shaped by terracing that covered 37% of its surface area. A nested approach was applied with two gauging stations (covering 1.2 km² and 4.8 km²) built in September 2013 that took continuous measurements of rainfall, water and sediment yield. Average suspended sediment concentration (1503 mg L^?1) and the maximum peak (33 618 mg L^?1) were two orders of magnitude higher than those obtained in non‐burned terraced catchments of Mallorca. This factor may be related to changes in soils and the massive incorporation of ash into the suspended sediment flux during the most extreme post‐fire event; 50 mm of rainfall in 15 min, reaching an erosivity of 2886 MJ mm ha^?1 h^?1. Moreover, hysteretic counter‐clockwise loops were predominant (60%), probably related to the increased sensitivity of the landscape after wildfire perturbation. Though the study period was average in terms of total annual precipitation (even higher in intensities), minimal runoff (2%) and low sediment yield (6.3 t km^?2 y^?1) illustrated how the intrinsic characteristics of the catchment, i.e. calcareous soils, terraces and the application of post‐fire measures, limited the hydrosedimentary response despite the wildfire impact. Copyright © 2017 John Wiley & Sons, Ltd.     

Groundwater quality in Mesogea basin in eastern Attica (Greece)

Studies on the hydrogeological conditions of the Mesogea basin in east Attica reveal that the aquifers developed on the post‐alpine formations at the inner part of the coastal brackish zone exhibit positive hydraulic head. These Neogene and Quaternary deposits present high salt concentrations. Selected points were sampled (total 85: 51 wells and 34 boreholes) in order to obtain hydrogeological and hydrochemical data for a better understanding of the structure, operation and dynamics of the aquifer of the area. Statistical methods, R‐mode factor analysis and scatter‐plot diagrams were used for the hydrochemical analysis and presentation of the data. The groundwater resources are relatively weak and there is significant quality degradation due to the geological structure of the greater area, as well as the bad management of the aquifer and anthropogenic activities. Groundwater is characterized by high salt concentrations. Electrical conductivity values range between 260 and 6970 µS cm^?1. High salt concentrations at the coastal aquifers are due to sea intrusion, whereas they are attributed to the dissolution of minerals of the geological environment in the inland area. The groundwaters of the study area can be classified into five water types: Ca–HCO₃, Mg–HCO₃, Na–HCO₃, Na–Cl and Mg–Cl. They are saturated in dolomite and calcite, whereas they are unsaturated in anhydrite. High ion concentrations, e.g. ] (0‐221 mg l^?1), ] (0·01‐1·88 mg l^?1), ] (0·01‐6·75 mg l^?1), as well as high heavy metals concentrations are attributed to anthropogenic impacts. Copyright © 2006 John Wiley & Sons, Ltd.     

Using a Simple Soil Column Method to Evaluate Soil Phosphorus Leaching Risk

The impacts of soil P leaching on water eutrophication have widely been concerned. However, there is no dependable method to quantitatively estimate the P leaching risk of soils. In this study, a simple soil column method was developed using two calcareous Fluvisols, silt loam and loam. The soil column was 20 cm in length and 5 cm in diameter, and distilled water was continuously supplied from the top. The volume and dissolved reactive P (DRP) concentrations of leachate were measured. Results showed that DRP concentrations in leachate increased slowly for the low soil Olsen‐P levels but rapidly for the high Olsen‐P levels. According to these two‐phase changes in the DRP versus soil Olsen‐P contents, the thresholds of P leaching risk were estimated to be 41.1 and 62.3 mg P kg^?1 (Olsen‐P) for silt loam and loam, respectively. The P leaching intensity of soils increased by 3‐ to 540‐fold if the soil Olsen‐P contents accumulated from 6.6 to 155.5 mg P kg^?1. The outcomes derived from this study regarding the determination of P leaching threshold and intensity by the soil column method also need a further verification on more soils with a wide range of physical and chemical properties.     

Observed Mass Balance of Mountain Glaciers and Greenland Ice Sheet in the 20th Century and the Present Trends

Glacier mass balance and secular changes in mountain glaciers and ice caps are evaluated from the annual net balance of 137 glaciers from 17 glacierized regions of the world. Further, the winter and summer balances for 35 glaciers in 11 glacierized regions are analyzed. The global means are calculated by weighting glacier and regional surface areas. The area-weighted global mean net balance for the period 1960?C2000 is ?270 ± 34 mm a^?1 w.e. (water equivalent, in mm per year) or (?149 ± 19 km³ a^?1 w.e.), with a winter balance of 890 ± 24 mm a^?1 w.e. (490 ± 13 km³ a^?1 w.e.) and a summer balance of ?1,175 ± 24 mm a^?1 w.e. (?647 ± 13 km³ a^?1 w.e.). The linear-fitted global net balance is accelerating at a rate of ?9 ± 2.1 mm a^?2. The main driving force behind this change is the summer balance with an acceleration of ?10 ± 2.0 mm a^?2. The decadal balance, however, shows significant fluctuations: summer melt reached its peak around 1945, followed by a decrease. The negative trend in the annual net balance is interrupted by a period of stagnation from 1960s to 1980s. Some regions experienced a period of positive net balance during this time, for example, Europe. The balance has become strongly negative since the early 1990s. These decadal fluctuations correspond to periods of global dimming (for smaller melt) and global brightening (for larger melt). The total radiation at the surface changed as a result of an imbalance between steadily increasing greenhouse gases and fluctuating aerosol emissions. The mass balance of the Greenland ice sheet and the surrounding small glaciers, averaged for the period of 1950?C2000, is negative at ?74 ± 10 mm a^?1 w.e. (?128 ± 18 km³ a^?1 w.e.) with an accumulation of 297 ± 33 mm a^?1 w.e. (519 ± 58 km³ a^?1 w.e.), melt ablation ?169 ± 18 mm a^?1 w.e. (?296 ± 31 km³ a^?1 w.e.), calving ablation ?181 ± 19 mm a^?1 w.e. (?316 ± 33 km³ a^?1 w.e.) and the bottom melt-21 ± 2 mm a^?1 w.e. (?35 ± 4 km³ a^?1 w.e.). Almost half (?60 ± 3 km³ a^?1) of the net mass loss comes from mountain glaciers and ice caps around the ice sheet. At present, it is difficult to detect any statistically significant trends for these components. The total mass balance of the Antarctic ice sheet is considered to be too premature to evaluate. The estimated sea-level contributions in the twentieth Century are 5.7 ± 0.5 cm by mountain glaciers and ice caps outside Antarctica, 1.9 ± 0.5 cm by the Greenland ice sheet, and 2 cm by ocean thermal expansion. The difference of 7 cm between these components and the estimated value with tide-gage networks (17 cm) must result from other sources such as the mass balance of glaciers of Antarctica, especially small glaciers separated from the ice sheet.     

Fractionation of Ni,Cr and Cu from Soil by Sequential Extraction Procedure and Determination by Inductively Coupled Plasma Optical Emission Spectrometry

Five‐step sequential extractions were employed to fractionation of Ni, Cr and Cu in soil polluted by anthropogenic activities and determine the mobility of the metals. Twelve samples were collected on an agricultural area that was located near an airport and intercity roads in Elazig‐Turkey. Exchangeable, organically bounded, carbonate bounded, adsorbed species on Fe and Mn oxides and residual species (except silicates) of Ni, Cr and Cu were extracted into solution by using CaCl₂, Na₄P₂O₇, Na₂EDTA, NH₂OH–HCl and HNO₃–H₂O₂, respectively. Mobile metal concentrations in fractions and total recoverable in soils were determined by using inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Total recoverable Ni, Cr and Cu concentrations were in the range of 40–119, 45–126 and 23–72 mg kg^?1, respectively. It was observed that total concentrations of metals in some of the samples were higher than the permitted values. The sum of the mobile percentages of metals was found to be lower than 50%. The Ni, Cr and Cu percentages for exchangeable species are in the ranges of 0.18–1.64, 0.03–0.59 and 0.42–2.53%, respectively.