Imidacloprid, a water-soluble neonicotinoid pesticide used globally in many applications, has been the subject of numerous studies (1) to determine its sublethal effects (5–100 ppb, LD₅₀∼200 ppb) on honeybees. This study was undertaken to determine, by ELISA assay, the presence of imidacloprid in water sources potentially frequented by honeybees in urban, suburban, and rural environments across the state of Maryland. Eighteen sites (six samples/site) were chosen which spanned diverse habitats including golf courses, nursery, livestock and crop farms, residential neighborhoods, and cityscapes. Hives were present either at or within 0.5 miles of each site. Imidacloprid was quantifiable in 8 % of the samples at sublethal levels (7–131 ppb). They were not clustered at any one type of site. Results for 13 % of the samples were at the threshold of detection; all others were below the detection limit of the assay (<0.2 ppb).

Parts of the Czech Republic received extreme loading of acid deposition from coal combustion in the second half of the twentieth century. Although associated Hg deposition was not directly measured, Hg deposition rates calculated from peat cores approach 100 μg m⁻² year⁻¹. We quantified the soil concentrations and pools of Hg with carbon (C), sulfur (S), and nitrogen (N)—elements closely associated with soil organic matter at five sites across the Czech Republic—four sites known for extreme deposition levels of S and N compounds in the twentieth century, and one site relatively less impacted. The site-specific means of O-horizon Hg concentrations ranged from 277 to 393 μg kg⁻¹, while means of Hg concentrations in mineral soil ranged from 22 to 95 μg kg⁻¹. The mean Hg/C ratio across sites increased from ∼0.5 μg Hg g⁻¹C in the Oi-horizon to ∼5 μg Hg g⁻¹C in the C-horizon due to the progressive mineralization of soil organic matter. The soil Hg/C increase was accompanied by a soil C/N decrease, another indicator of soil organic matter mineralization. Soil Hg/C also increased as soil C/S decreased, suggesting that Hg was stabilized by S functional groups within the soil organic matter. Mineral soil Hg pools (8.9–130.0 mg m⁻²) dominated over organic soil Hg pools (5.3–10.1 mg m⁻²) at all sites. Mineral soil Hg pools correlated more strongly with total soil S and oxalate-extractable Fe than with total soil C. Total soil Hg pools could be accounted for by a time period of atmospheric inputs that was short relative to the age of the soils. The cross site variability of Hg soil pools was not sensitive to the local Hg deposition history but rather related to the capacity of soil to store and stabilize organic matter.

Urban stormwater runoff is contaminated by nutrients that wash off of roadways, parking lots and lawns during storms. In-ground permeable filter systems that consist of carefully selected filter material have the potential to remove these nutrients from the run-off. In this paper, four filter materials, calcite, zeolite, sand and iron filings, were investigated using laboratory batch tests to evaluate their efficiency in the removal of nitrate and phosphate from the simulated stormwater at different initial concentrations under the same 24-h exposure time period. The range of removal for nitrate was from 39 % to 65 % for calcite, from 42 % to 77 % for zeolite, from 40 % to 70 % for sand, and from 74 % to 100 % for iron filings. The removal of phosphate ranged from 35 % to 41 % for calcite, 59 % to 100 % for zeolite, 49 % to 100 % for sand, and 73 % to 100 % for iron filings. The removal of nitrate is mainly attributed to electrostatic adsorption, except when iron filings were used as a filter material where additional processes such as electrochemical reduction, ligand complexation and precipitation may have contributed to the higher nitrate removal. Phosphate removal is also attributed to electrostatic adsorption in all filter materials; however, at higher phosphate concentrations, the precipitation process may be the dominant process for all of the filter materials except calcite. The Langmuir and Freundlich isotherms fitted the observed nonlinear adsorption results, but the mechanism of removal of phosphate changed from adsorption to precipitation at concentrations higher than 1 mg/l in zeolite, sand, and iron filings; therefore, the adsorption models are valid below this concentration limit. A typical application of these batch adsorption test results is presented in the design of a field in-ground permeable filter system.

Acidification of lakes and rivers is still an environmental concern despite reduced emissions of acidifying compounds. We analysed trends in surface water chemistry of 173 acid-sensitive sites from 12 regions in Europe and North America. In 11 of 12 regions, non-marine sulphate (SO₄*) declined significantly between 1990 and 2008 (−15 to −59 %). In contrast, regional and temporal trends in nitrate were smaller and less uniform. In 11 of 12 regions, chemical recovery was demonstrated in the form of positive trends in pH and/or alkalinity and/or acid neutralising capacity (ANC). The positive trends in these indicators of chemical recovery were regionally and temporally less distinct than the decline in SO₄* and tended to flatten after 1999. From an ecological perspective, the chemical quality of surface waters in acid-sensitive areas in these regions has clearly improved as a consequence of emission abatement strategies, paving the way for some biological recovery.

Redox conditions play an outstanding role in controlling the behaviour of trace elements in soil environments. They are not only sensitive to water saturation but also to soil temperature because many redox reactions are mediated by microorganisms. In this study, we investigated the influence of oxidising (oxygen predominant), weakly reducing (Mnᴵᴵᴵ,ᴵⱽreduction) and moderately reducing (Feᴵᴵᴵreduction) conditions at three temperature regimes (7, 15 and 25 °C) on the solubility of ten trace elements. Multimetal-contaminated topsoil (pH 5.8) from a floodplain in Germany was investigated with the following aqua regia-soluble concentrations: Zn 903, Cu 551, Cr 488, Pb 354, Ni 93.5, As 35.7, Co 22.4, Sb 20.5, Cd 8.3 and Mo 6.5 mg kg⁻¹. Soil suspensions were held at fixed redox potential in microcosm experiments, sampled at every third day and analysed for trace elements. Time to achieve weakly and particularly moderately reducing conditions was temperature dependent and increased in the order 25 °C < 15 °C < 7 °C. Under oxidising conditions, the solubility of the trace elements was low. Reductive dissolution of Mn oxides under weakly reducing conditions was accompanied by a release of Co and Mo. Reductive dissolution of Fe oxides (and of remaining Mn oxides) under moderately reducing conditions additionally led to a release of As, Cd, Cr, Ni and Pb, whereas Cu and Zn were hardly affected. Antimony revealed a different behaviour because, after a first increase, a continuous decrease in its concentration was observed soon after the onset of weakly reducing conditions. We conclude that soil temperature should be considered as a master variable, to distinguish between weakly and moderately reducing soil conditions, and that it is necessary to keep element-specific behaviour in mind when dealing with the effects of redox conditions in soils on trace element solubility.

The use of magnetic micro- and nanoparticles for the removal of pollutants from wastewater is gaining increasing attention. Here, amine-functionalized magnetic microparticles (AFMMs) and carboxylic-functionalized magnetic microparticles (CFMMs) were synthesized by modifying the surface of Fe₃O₄with amino and carboxyl groups for fast and efficient removal of textile dyes from aqueous solution. The functionalized magnetic microparticles were characterized by TEM, SEM, FTIR, and VSM. The adsorption experiments were carried out by varying the regulating parameters like solution pH and adsorbent dosage and analyzed in terms of kinetic and isotherm models. It was demonstrated that simple electrostatic interactions between functionalized magnetic microparticles and adsorbates played a dominating role in the adsorption of textile dyes. The positively charged AFMMs adsorbed the negatively charged dyes vat blue (VB) and direct violet (DV) at pH 6 with the maximum removal percentages of 95.72 and 97.29 %, respectively. The maximum removal percentages of cationic dyes methylene blue (MB) and azure A chloride (AA) on the negatively charged CFMMs were 92.28 and 92.22 % at pH 11, respectively. Moreover, the adsorbed dyes could be desorbed completely from the surface of CFMMs at a lower pH, and AFMMs also allowed rapid removal of VB and DV in different water samples. All the results in the present work demonstrated that the functionalized magnetic microparticles as efficient, magnetically separable adsorbents are attractive for the removal of dye pollutants.

Silver-doped TiO₂(Ag-TiO₂) immobilized onto polystyrene (PS) waste was prepared using a thermal attachment method. Its efficiencies as a photocatalyst under UVA light (λ = 365 nm) for the removal of Cr(VI), methylene blue, Escherichia coli, and Aspergillus niger from water were studied. The results showed that Ag-TiO₂-PS material removes pollutants at significantly high rates and especially posseses strong disinfection properties. The morphological study of Ag-TiO₂-PS material was carried out using X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscopy. The catalyst can be prepared using waste PS employing a simple immobilization method and it is highly effective for the removal of biological and chemical impurities from drinking and underground water supplies.

The comparative effectiveness for hexavalent chromium reduction and removal from irrigation water, using three selected plant species (Phragmites australis, Salix viminalis, and Ailanthus altissima) planted in soil contaminated with hexavalent chromium, has been studied in the present work. The above plant species were irrigated, in a continuous mode, with water, contaminated with 10 mg/L of hexavalent chromium. Hexavalent chromium and total chromium have been measured in all plant tissues species and in the drainage water. Total chromium removal from water was ranging from 56 % (Phragmites) to 70 % (Salix). After 360 days of growth, the chromium content of the contaminated soil dropped from 70 (initial) to 32, 36, and 41 mg Cr/kg₍dᵣy ₛₒᵢₗ₎, for Salix, Phragmites, and Ailanthus, respectively. Salix and Phragmites accumulated the highest amount of chromium in the roots (2,029 and 1,800 mg Cr/kg₍dᵣy ₜᵢₛₛᵤₑ₎, respectively), compared with 358 mg Cr/kg₍dᵣy ₜᵢₛₛᵤₑ₎for Ailanthus roots. Most of chromium was found in trivalent form in all plant tissues. Ailanthus had the lowest affinity for Crⱽᴵreduction in the root tissues. Phragmites indicated the highest chromium translocation potential, from roots to stems, while Salix indicated the highest chromium translocation from roots to leaves. Toxicity effects, expressed as root growth rate inhibition, indicated that Salix is the most chromium-tolerant species, with Ailanthus in the antipode.

Tungsten (W) concentrations were measured along with arsenic (As) in groundwaters from the Murshidabad district of West Bengal, India. Tungsten concentrations range from 0.8 to ~8 nmol kg⁻¹(0.15–1.5 μg kg⁻¹) in the circumneutral pH (average pH ~ 7.3) Murshidabad groundwaters, and attain concentrations as high as 14 nmol kg⁻¹(2.5 μg kg⁻¹) in local ponds (n = 2). Total dissolved As concentrations (AsT) range from 0.013 to 53.9 μmol kg⁻¹(<1 to 4,032 μg kg⁻¹), and As(III) predominates in Murshidabad groundwaters accounting for 70 %, on average, of As in solution. Tungsten concentrations in Murshidabad groundwaters are low compared to alkaline groundwaters (pH > 8) from the Carson Desert in Western Nevada, USA, where W concentrations are reported to reach as high as 4,036 nmol kg⁻¹(742 μg kg⁻¹). Although W is positively correlated with As in groundwaters from the Carson Desert, it is not correlated with AsTor As(III) in Murshidabad groundwaters, but does exhibit a weak relationship with As(V) in these groundwaters. Surface complexation modeling indicates that pH related adsorption/desorption can explain the geochemical behavior of W in Murshidabad groundwaters. However, the model does not predict the high As concentrations observed in Murshidabad groundwaters. The high As and low W concentrations measured in Murshidabad groundwaters indicate that either As and W originate from different sources or are mobilized by different biogeochemical processes within the Murshidabad aquifers. Mobilization of As in Murshidabad groundwaters is presumed to reflect reductive dissolution of Fe(III) oxides/oxyhydroxides and release of sorbed and/or coprecipitated As to the groundwaters. Multivariate statistical analysis of groundwater composition data indicate that W is associated with Mn and Cl⁻, which may point to a Mn oxide/oxyhydroxide, clay mineral, and/or apatite source for W in the Murshidabad sediments.

Recent scientific findings and legislations have clearly highlighted the need for comprehensive approaches and methods to evaluate natural dust contributions to an urban atmosphere. The evaluation of chemical compositions of airborne aerosols is of these methods that may employ several advanced analytical techniques and processes. In this paper, an episodic appearance of Saharan dust incursion over a megacity (Istanbul, Turkey) was investigated using size segregated particulate matter (PM) samples in fine and coarse fractions collected between February 27 and March 8, 2009. The Saharan impact was investigated using satellite observations, backward air trajectory statistics, and chemical analyses of the collected samples. In the chemical analyses, Fourier transform infrared coupled with attenuated total reflectance (ATR-FTIR) spectroscopic method was used to determine the functional groups, namely, alcohols, ammonium, aliphatic carbons, carbonyls, organonitrates, nitrate, silicate, silica, kaolinite, and calcium carbonate. Among all the measured functional groups, it was clearly seen that the intensities of IR peaks related to silicate, silica, kaolinite, and calcium carbonate were associated with the increased mass concentrations during the impact period. The observed IR peaks at 1,030 and 800 cm⁻¹for silicate ions in the samples can be used as an indicator of the large dust incursion into the atmosphere (e.g., Saharan dust episodes observed in Istanbul). This study showed that the ATR-FTIR spectroscopic method is a fast and convenient method to identify these peaks and the IR method in general is useful for identifying a large dust incursion into the atmosphere.