We have conducted an interlaboratory comparison study for total mercury and methylmercury analysis in natural (unspiked) water samples annually for the past 4 years. The samples were primarily freshwater, with the exception of one coastal seawater sample in 2014. The study provided participants with an opportunity to assess the quality of their measurements and the intercomparability of their data with their peers. Data on analytical methods used were collected and used to determine whether any methods yield biased results and should be discontinued. The majority of participants received performance scores of 3 or higher, indicating satisfactory performance and results close to the consensus means. However, the coefficients of variation between labs were greater than 20 % in most cases, which may not be sufficiently precise for multilaboratory environmental research, where the processes being studied may vary by 20 % or less. Total mercury analysis methods that do not use gold amalgamation were shown to be underperforming relative to those that do. No significant correlation was observed between sample storage time or temperature and total mercury recovery. Methylmercury analysis methods that do not use distillation performed poorly relative to those that use distillation.

A kinetic study of the photocatalytic degradation of the pharmaceutical clofibric acid is presented. Experiments were carried out under UV radiation employing titanium dioxide in water suspension. The main reaction intermediates were identified and quantified. Intrinsic expressions to represent the kinetics of clofibric acid and the main intermediates were derived. The modeling of the radiation field in the reactor was carried out by Monte Carlo simulation. Experimental runs were performed by varying the catalyst concentration and the incident radiation. Kinetic parameters were estimated from the experiments by applying a non-linear regression procedure. Good agreement was obtained between model predictions and experimental data, with an error of 5.9 % in the estimations of the primary pollutant concentration.

We highlighted some of the key problems associated with the use of beneficial microorganisms for improving adaptation of plants to soils, polluted with heavy metals (HMs), especially Cd. Inoculation of pea line SGE and its Cd-tolerant mutant SGECdᵗ with nodule bacteria Rhizobium leguminosarum bv. viciae demonstrated that nodulation process may be disturbed at Cd concentrations below threshold toxicity levels for each partner and the plant genotype plays a major role in nodulation under Cd stress. A comparative mathematical analysis of available information about Cd tolerance, accumulation of HMs (Cd, Cr, Cu, Ni, Pb, Sr and Zn), response to mycorrhizal fungus Glomus sp. and 15 phenotypic traits of 99 pea varieties revealed that (1) the Cd-sensitive varieties were more efficient in exploring the protective potential of symbiosis to compensate their deficit in Cd tolerance and (2) correlations between the studied traits exist and can be helpful for selection of plant-microbe systems adapted to polluted soils. In pot experiment with 11 varieties of Indian mustard, the plant growth-promoting effect of rhizobacterium Variovorax paradoxus 5C-2 negatively correlated with Cd tolerance and shoot Cd concentration of the plants grown in Cd-supplemented soil. In an outdoor pot experiment, inoculation of willow with the ectomycorrhizal fungus Pisolithus tinctorius and a cocktail of rhizobacteria stimulated root exudation, decreased soil pH and increased Cd mobilization in soil and Cd uptake by plants, but decreased plant growth at a moderate contamination level (25 mg Cd kg⁻¹). Opposite effects were observed in highly contaminated soil (77 mg Cd kg⁻¹). We propose a preliminary systematic framework of interactions between these factors that determine the success of microbial inoculation aimed at improving crop performance on HM-polluted soils or enhancing phytoremediation.

In this work, the removal of methylene blue by Bacillus thuringiensis (Bt) 016 was investigated through batch experiments and microscopic investigations. It was found that methylene blue could not affect the growth of B. thuringiensis 016 at the concentration ranging from 5 to 25 mg/L, and be removed with the increase of biomass. Further studies indicated that Bt 016 biomass possessed strong ability of methylene blue biosorption with a quick process. Twenty-five milligrams of methylene blue per liter could be completely biosorbed within 2 h. The pH value could affect the removal of methylene blue in a large extent. UV–visible, Fourier transform infrared (FT-IR) spectroscopy analyses, and microscopic investigations suggested that the removal of methylene blue could be divided into two steps as follows: (1) rapid biosorption of methylene blue on Bt 016 biomass through electrostatic attraction or chelating activity of functional groups; (2) methylene blue was further degraded by Bt 016 through enzyme-mediated or couple with the metabolism process.

The Ría de Huelva is one of the most polluted areas in Western Europe because of the high acid mining activity together with the chemical industries located in its margins. This strong anthropogenic pressure results in the liberation of high concentrations of metals and rare earth elements (REEs) to the Ría. In this work, an Itrax™ Core Scanner (Itrax) has been used for the first time to detect and to study REEs distribution in a sediment core. Its high sensitivity (until 5 μg·g⁻¹for Er) was confirmed by comparing its semi-quantitative results with concentration values obtained from inductively coupled plasma mass spectrometry (ICP-MS). In this way, establishing equivalences between Itrax continuous data and concentration data have been possible to detect pollution levels caused by REEs and related trace elements along the whole sediment core reducing the discrete analyses and therefore saving time and money. Moreover, Itrax was confirmed as a fast screening and monitoring tool to study REEs fractionation patterns and to identify the environmental changes responsible of these patterns.

Representative sediment samples rich in nitrogen and phosphorus (both continuous and intermittently submerged) were used to conduct dynamic water level (WL) regulation experiments with various WL velocity modes (0, 3, and 6 cm/day). The experiments lasted three WL regulating cycles (6 months), and each single cycle included four WL dynamic phases: decline, stable, ascend, and re-stable. During the experiment, a greater nutrient stock caused higher nutrient release fluxes for continuously submerged sediments when compared to corresponding intermittently submerged sediments regardless of WL regulation. Moreover, continuous submerged sediment nutrient release showed a similar “U” pattern to the intermittently submerged sediment, and nutrient concentrations within the water phase generally increased with rising WL and decreased with dropping WL. Rapid WL regulation such as 6 cm/day promoted nitrogen release, and slow WL regulation at 3 cm/day favored phosphorus leaching. When three WL regulation cycles were finished, WL regulation of 6 cm/day resulted in 18 and 25 % decline of sediment mean organic matter (OM) content for continuous and intermittently submerged sediment, respectively. However, increased WL regulation cycles impacted on sediment nitrogen and phosphorus stock in different manners. For example, a WL regulation of 6 cm/day led to a 582 mg/kg decline and 322 mg/kg increase for intermittently submerged sediment in terms of total nitrogen (TN) and total phosphorus (TP) content, respectively. Results indicated that direct WL regulation insignificantly affected sediment nutrient release, but changed the overlying water conditions such as pH and redox potential (redox), and then indirectly changed the nutrient release dynamics.

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that mediates many of the toxic effects of dioxin-like compounds (DLCs) and some polycyclic aromatic hydrocarbons (PAHs). Strong AHR agonists, such as certain polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), cause severe cardiac teratogenesis in fish embryos. Moderately strong AHR agonists, such as benzo[a]pyrene and β-naphthoflavone, have been shown to cause similar cardiotoxic effects when coupled with a cytochrome P450 1A (CYP1A) inhibitor, such as fluoranthene (FL). We sought to determine if weak AHR agonists, when combined with a CYP1A inhibitor (FL) or CYP1A morpholino gene knockdown, are capable of causing cardiac deformities similar to moderately strong AHR agonists (Wassenberg and Di Giulio Environ Health Perspect 112(17):1658–1664, 2004a; Wassenberg and Di Giulio Res 58(2–5):163–168, 2004b; Billiard et al. Toxicol Sci 92(2):526–536, 2006; Van Tiem and Di Giulio Toxicol Appl Pharmacol 254(3):280–287, 2011). The weak AHR agonists included the following: carbaryl, phenanthrene, 2-methylindole, 3-methylindole, indigo, and indirubin. Danio rerio (zebrafish) embryos were first exposed to weak AHR agonists at equimolar concentrations. The agonists were assessed for their relative potency as inducers of CYP1 enzyme activity, measured by the ethoxyresorufin-O-deethylase (EROD) assay, and cardiac deformities. Carbaryl, 2-methylindole, and 3-methylindole induced the highest CYP1A activity in zebrafish. Experiments were then conducted to determine the individual cardiotoxicity of each compound. Next, zebrafish were coexposed to each agonist (at concentrations below those determined to be cardiotoxic) and FL in combination to assess if CYP1A inhibition could induce cardiac deformities. Carbaryl, 2-methylindole, 3-methylindole, and phenanthrene significantly increased pericardial edema relative to controls when combined with FL. To further evaluate the interaction of the weak AHR agonists and CYP1A inhibition, a morpholino was used to knockdown CYP1A expression, and embryos were then exposed to each agonist individually. In embryos exposed to 2-methylindole, CYP1A knockdown caused a similar level of pericardial edema to that caused by exposure to 2-methylindole and FL. The results showed a complex pattern of cardiotoxic response to weak agonist inhibitor exposure and morpholino-knockdown. However, CYP1A knockdown in phenanthrene and 3-methylindole only moderately increased pericardial edema relative to coexposure to FL. AHR2 expression was also knocked down using a morpholino to determine its role in mediating the observed cardiac teratogenesis. Knockdown of AHR2 did not rescue the pericardial edema as previously observed with strong AHR agonists. While some of the cardiotoxicity observed may be attributed to the combination of weak AHR agonism and CYP1A inhibition, other weak AHR agonists appear to be causing cardiotoxicity through an AHR2-independent mechanism. The data show that CYP1A is protective of the cardiac toxicity associated with weak AHR agonists and that knockdown can generate pericardial edema, but these findings are also suggestive of differing mechanisms of cardiac toxicity among known AHR agonists.

In this study, stable carbon and nitrogen isotope ratios in the samples of pine needles collected in 2013 and 2014 from heavily urbanized area in close proximity to point-source pollution emitters, such as a heat and power plant, nitrogen plant, and steelworks in Silesia (Poland), were analyzed as bio-indicators of contemporary environmental changes. The carbon isotope discrimination has been proposed as a method for evaluating water-use efficiency. The measurement of carbon and nitrogen isotopes was carried out using the continuous flow isotope ratio mass spectrometer. The isotope ratio mass spectrometer allows the precise measurement of mixtures of naturally occurring isotopes. The δ¹⁵N values were calibrated relative to the NO-3 and USGS34 international standards, whereas the δ¹³C values were calibrated relative to the C-3 and C-5 international standards. The strong year-to-year correlations between the δ¹³C in different sampling sites, and also the inter-annual correlation of δ¹⁵N values in the pine needles at each of the investigated sampling sites confirm that the measured δ¹³C and δ¹⁵N and also intrinsic water-use efficiency (iWUE) trends are representative of the sampling site. Diffuse air pollution caused the variation in δ ¹³C, δ¹⁵N, and iWUE dependent on type of emitter, the localization in the space (distance and direction) from factories and some local effect of other human activities. The complex short-term variation analysis can be helpful to distinguish isotopic fractionation, which is not an effect explainable by climatic conditions but by the anthropogenic effect. Between 2012 and 2014, an increase in iWUE is observed at leaf level.

As rice paddies are widespread sources of water pollution in the agricultural regions of the Asian monsoon area, a mechanistic understanding of nutrient loss from paddies is critical for water quality management. A 2-year experiment was conducted in a typical monsoon-affected rice field to improve our understanding of the impacts of rainfall and agricultural management practice on nitrogen (N) and phosphorus (P) loss. Samples of paddy drainage water were collected during rainfall events (n = 25) and analyzed for total N (T-N) and total P (T-P) concentrations. The impacts of rainfall (amount, duration, and intensity) and agricultural management practice (transplanting and fertilization) on the event mean concentration (EMC) and loss of nutrient were assessed using regression analyses. The results showed that T-N and T-P concentrations were affected by agricultural practice; meanwhile, loss of T-N and T-P was correlated with rainfall characteristics. Specifically, the EMC of T-N but T-P was negatively (p < 0.001) correlated with the number of days after agricultural practice in both years, which likely represents a decrease in nutrient availability in paddy water over time. Loss of T-N and T-P was positively (p < 0.01) correlated with rainfall amount, and this suggests that the rainfall-runoff process is a key driver of nutrient loss in the study area. Our results suggest that rainfall amount and days after transplanting need to be taken into account when estimating nutrient loss from rice paddies in monsoon regions.

Three commercial electrodes, Ta-Ir/TiO₂, Rh-Ir/TiO₂, and PbO₂/TiO₂, were used as electrochemical anodes, and their performance was evaluated by the electrochemical oxidation of ammonia at neutral pH in a continuous electrochemical quadrangular reactor. Based on the cyclic voltammetry scans and volt-ampere relation analysis, in direct oxidation, the oxygen evolution from H₂O₂decomposition was completely inhibited, and more•OH radicals could be then generated over PbO₂/TiO₂and in the presence of powder activated carbon (PAC). PbO₂/TiO₂can be indicated as an appropriate for the direct electrooxidation of ammonia in an unpacked bed reactor. While the efficiency for direct oxidation of ammonia was similar for the three anodes in a PAC packed reactor due to the presence of PAC could avoid short circuit and enhance electric efficiency. In indirect oxidation mediated by active free chlorine, Rh-Ir/TiO₂was the most effective in ammonia removal when chloride was present in the reaction system, and the disappeared ammonia was mainly transferred to N₂, and only a small part was converted into nitrate (there was no nitrite detected during the reaction). The results indicated that Rh-Ir/TiO₂had the highest oxidation capability for ammonia compared with Ta-Ir/TiO₂and PbO₂/TiO₂. Hence, Rh-Ir/TiO₂based on a PAC packed bed reactor provides an alternative for the treatment of ammonia wastewater with high chloride concentration.