As freshwater bodies become enriched in nutrients, there is a shift in the phytoplankton community toward dominance by cyanobacteria. Cyanobacterial blooms are a significant problem in water supply reservoirs worldwide because some species can release toxic compounds and are also associated with the production of bad odor and taste. The aims of this paper were to elucidate the mechanism inducing the development of cyanobacterial blooms and to understand the species succession during the bloom, as well as the influence of abiotic factors on the species composition. Total phosphorus level and parameters related to seasonality, i.e., temperature and solar radiation, were the factors triggering the development of the blooms. Blooms were dominated by Microcystis natans and Anabaena circinalis. Phosphorus was an important limiting factor for Anabaena development but never limited Microcystis growth. Water temperature was optimum until end of February for Anabaena, whereas Microcystis growth was slightly limited since water temperature never reached the optimal. Solar radiation was more limiting than temperature, and the decrease in light had a strong role in the bloom decline. Four species of cyanobacteria recorded in Paso de las Piedras reservoir are potentially toxic: Snowella fennica, Microcystis aeruginosa, Planktothrix agardhii, and A. circinalis, being the last one as the most abundant species during the blooms. Considering the Alert Level Framework for cyanobacteria, alert level 2 was exceeded only during blooms while alert level 1 was exceeded during almost all the year.

Forest and peatland fires in Indonesia emit large quantities of smoke leading to poor air quality across Equatorial Asia. Marlier et al (2015 Environ. Res. Lett. 10 085005) explore the contribution of fires occurring on oil palm, timber (wood pulp and paper) and natural forest logging concessions to smoke emissions and exposure of human populations to the resulting air pollution. They find that one third of the population exposure to smoke across Equatorial Asia is caused by fires in oil palm and timber concessions in Sumatra and Kalimantan. Logging concessions have substantially lower fire emissions, and contribute less to air quality degradation. This represents a compelling justification to prevent reclassification of logging concessions into oil palm or timber concessions after logging. This can be achieved by including logged forests in the Indonesian moratorium on new plantations in forested areas.

Chelating reagents impregnated or incorporated into solid sorbents have been widely used in the preconcentration of metal species. In this work, polystyrene-divinylbenzene functionalized with 2-hydroxyacetophenone was used for the preconcentration and determination of cadmium, cobalt, and nickel in sediment samples by flame atomic absorption spectrometry. The sorbent was characterized by infrared spectroscopy and scanning electron microscopy. The influence of variables on the extraction of the metal ions was studied. Under optimized conditions, the method showed enrichment factors of 20 (Cd), 37 (Co), and 32 (Ni) and detection limits of 0.1 (Cd), 0.8 (Co), and 0.6 μg L⁻¹(Ni). The accuracy of the method was tested by analysis of a certified reference material composed of inorganics in marine sediment (NIST 2702). The method was applied to the determination of cadmium, cobalt, and nickel in real sediment samples. Cadmium and cobalt were not found in the sediment samples. Nickel was found in two samples (5.2 and 8.2 μg g⁻¹).

The ability of untreated and acid-treated biomass from Pistia stratiotes (PL and APL, respectively) and Eichhornia crassipes (ELS and AELS, respectively) to remove color from anaerobically digested sugar cane stillage (ADS) was investigated. The effects of pH (3–8), particle size (< 0.75, 0.75–1, 1–4 mm), and biomass concentration (5–15 g/L) on decolorization of ADS were assessed using untreated biomass. After acid modification of biomass (acid-treated), the effects of pH (3–8), biomass concentration (6–10 g/L), time (20–480 min), and ADS dilution (non-diluted, 1:2, 1:10, 1:20) on color removal from ADS were evaluated. Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) analyses were also performed. A clear effect of particle size on ADS decolorization was found (21.04 ± 0.75 and 27.87 ± 0.30 % for 0.75–1 and <0.75 mm, respectively, for ELS; 31.65 ± 0.23 and 37.82 ± 0.53 for 1–4 and 0.75–1 mm, respectively, for PL). Decolorization also increased when the untreated biomass concentration was higher (15.41 ± 0.3 and 27.89 ± 0.2 % for 5 and 10 g/L, respectively, for ELS; 15.61 ± 0.11 and 33.06 ± 1.09 % for 5 and 10 g/L, respectively, for PL). The use of acid-treated biomass enhanced the effect of pH on color removal (48.30 ± 1.27 and 12.96 ± 0.27 % for pH of 3 and 7, respectively, for AELS; 47.11 ± 1.72 and 6.62 ± 0.21 % for pH of 3 and 7, respectively, for APL). The highest rate of color removal obtained using acid-treated biomass was 55.58 ± 1.82 and 56 ± 0.77 % for AELS and APL, respectively. The FTIR spectra analysis suggested the electrostatic attraction between protonated carboxylic groups on biomass and anionic colored compounds as being one of the adsorption mechanisms for ADS decolorization. The use of dry biomass from invasive macrophytes is an effective alternative for color removal from ADS.

In the European registration procedure for pesticides, microcosm and mesocosm studies are the highest aquatic experimental tier to assess their environmental effects. Evaluations of microcosm/mesocosm studies rely heavily on no observed effect concentrations (NOECs) calculated for different population-level endpoints. Ideally, a power analysis should be reported for the concentration–response relationships underlying these NOECs, as well as for measurement endpoints for which significant effects cannot be demonstrated. An indication of this statistical power can be provided a posteriori by calculated minimum detectable differences (MDDs). The MDD defines the difference between the means of a treatment and the control that must exist to detect a statistically significant effect. The aim of this paper is to expand on the Aquatic Guidance Document recently published by the European Food Safety Authority (EFSA) and to propose a procedure to report and evaluate NOECs and related MDDs in a harmonised way. In addition, decision schemes are provided on how MDDs can be used to assess the reliability of microcosm/mesocosm studies and for the derivation of effect classes used to derive regulatory acceptable concentrations. Furthermore, examples are presented to show how MDDs can be reduced by optimising experimental design and sampling techniques.

Four kinds of surfactants were used to increase accessibility of pyrene and cadmium (Cd) in simulated pyrene, Cd, and pyrene-Cd soils in this study. Tea saponin (TS) at 40 mg L⁻¹groups (exchangeable fraction of Cd and bioaccessible fraction of pyrene were 8.96 and 36.93 mg kg⁻¹) showed more preferable potential application in improving solubilization capability than other surfactants. The morphology of Cd was transformed from Fe-Mn oxides (8.86 to 7.61 and 8.67 to 7.99 mg kg⁻¹in Cd and pyrene-Cd soil) and associated to carbonates fractions (4.46 to 4.36 and 4.28 to 4.36 mg kg⁻¹in Cd and pyrene-Cd soil) to exchangeable fraction with adding TS. These two morphological changes were important processes in the solubilization of Cd. The morphology of pyrene was transformed from associated fraction (72.15 to 61.95 and 71.02 to 63.48 mg kg⁻¹in pyrene and pyrene-Cd soil) to bioaccessible fraction (26.66 to 33.71 and 26.91 to 36.93 mg kg⁻¹in pyrene and pyrene-Cd soil) with adding TS. This morphological transformation was important in the improving of solubilization capacity of pyrene. In contrast, the solubilization of pyrene was promoted in the presence of Cd in pyrene-Cd soil (the bioaccessible fractions were 33.71 and 36.93 mg kg⁻¹in pyrene and pyrene-Cd soil), but the solubilization of Cd was hindered in the presence of pyrene (the exchangeable fractions of Cd were 8.86 and 8.67 mg kg⁻¹in Cd and pyrene-Cd soil). These findings will be beneficial for application of surfactants in soil remediation.

Malathion is an organophosphate insecticide registered for use in cities throughout North America to control adult mosquitoes. The objective of this study was to determine the impact of urban malathion applications on the levels of malathion detected in bulk deposition. In 2010, malathion was applied by the City of Winnipeg’s Insect Control Branch for a total amount of 6632 kg in the city, as well as by the general public in relatively small amounts. In 2011, no malathion was applied by the city. Malathion was detected in 41 % of the samples in 2010 with deposition rates ranging from 0.5 to 107.7 μg/m²/week. Only 9 % of the samples contained malathion in 2011 with deposition rates always being <0.4 μg/m²/week. Between 6 and 25 % of the samples in 2010 exceeded the toxicological threshold levels of malathion to a range of freshwater amphipods, water fleas, and stoneflies, including Daphnia magna which is a bioindicator of good environmental health. The weekly maximum malathion concentration detected in this study (5.2 μg/L for a week in June 2010) was at least 26 times greater than the maximum concentration of malathion reported in other atmospheric deposition studies. For the two insect management areas (7.4 and 37.6 km²) where the bulk deposition samplers had been placed, calculations suggested that between 1.2 and 5.1 % of the malathion applied by the city became bulk deposition. Percutaneous absorption by humans of malathion in rainfall is unknown.

The internal concentration represented by the critical body residue (CBR) is an ideal indicator to reflect the intrinsic toxicity of a chemical. Whilst some studies have been performed on CBR, the effect of exposure route on internal toxicity has not been investigated for fish. In this paper, acute toxicity data to fish comprising LC₅₀ and LD₅₀ values were used to investigate CBR. The results showed that exposure route can significantly affect the internal concentration. LD₅₀ and CBR calculated from LC₅₀ and BCF both vary independently of hydrophobicity as expressed by log Kₒw; conversely, LC₅₀ is related to log Kₒw. A poor relationship was observed between LC₅₀ and LD₅₀, but the relationship can be improved significantly by introduction of log Kₒw because log CBR is positively related to log LD₅₀. The parallel relationship of log CBR-log Kₒw and log LD₅₀-log Kₒw indicates that LD₅₀ does not reflect the actual internal concentration. The average LD₅₀ is close to the average CBR for less inert and reactive compounds, but greater than the average CBR for baseline compounds. This difference is due to the lipid fraction being the major storage site for most of the baseline compounds. Investigation on the calculated and observed CBRs shows that calculated CBRs are close to observed CBRs for most of compounds. However, systemic deviations of calculated CBRs have been observed for some compounds. The reasons for these systemic deviations may be attributed to BCF, equilibrium time and experimental error of LC₅₀. These factors are important and should be considered in the calculation of CBRs.

The paper presents the results of antimony removal from the Dúbrava water resource using a pilot plant system capable of taking samples from different heights of adsorption materials. The adsorbents GEH, CFH12, CFH18, and Bayoxide E33 and two experimental stainless columns with bleeder valves located at heights of 20, 45, and 70 cm of the adsorption media and 91 cm (GEH), 94 cm (CFH18), 87 cm (CFH12), and 87 cm (Bayoxide E33) filter media high were used. The results of the experiments show that the most suitable material for removing antimony from water is GEH. For an antimony concentration of 78.4–108.0 μg/L in raw water and a filtration rate of 5.6–5.9 m/h, the limit concentration of 5 μg/L at the outlet of the 70-cm high adsorption media was reached at the bed volume 1788. In a case when the media height was 91 cm, the antimony concentration in the treated water would reach the limit value of 5 μg/L after a 672-h operation of the stainless column at the bed volume 4256. Under these conditions, the adsorption capacity was calculated at 184 μg/g. The adsorption capacities and bed volumes of the other adsorbents were lower in comparison to GEH.

This paper proposes an extraction procedure for the speciation analysis of inorganic antimony in sediment samples using slurry sampling and hydride generation atomic absorption spectrometry. The optimization step of extraction of the species was performed employing a full two-level factorial design (2³) and a Box-Behnken matrix where the studied factors in both experiments were: extraction temperature, ultrasonic radiation time, and hydrochloric acid concentration. Using the optimized conditions, antimony species can be extracted in closed system using a 6.0 M hydrochloric acid solution at temperature of 70 °C and an ultrasonic radiation time of 20 min. The determination of antimony is performed in presence of 2.0 M hydrochloric acid solution using HG AAS by external calibration technique with limits of detection and quantification of 5.6 and 19.0 ng L⁻¹ and a precision expressed as relative standard deviation of 5.6 % for an antimony solution with concentration of 6.0 μg L⁻¹. The accuracy of the method was confirmed by analysis of two certified reference materials of sediments. For a sample mass of sediment of 0.20 g, the limits of detection and quantification obtained were 0.70 and 2.34 ng g⁻¹, respectively. During speciation analysis, antimony(III) is determined in presence of citrate, while total antimony is quantified after reduction of antimony(V) to antimony(III) using potassium iodide and ascorbic acid. The method was applied for analysis of six sediment samples collected in São Paulo Estuary (Bahia State, Brazil). The antimony contents obtained varied from 45.3 to 89.1 ng g⁻¹ for total antimony and of 17.7 to 31.4 ng g⁻¹ for antimony(III). These values are agreeing with other data reported by the literature for this element in uncontaminated sediment samples.