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A miniaturized QuEChERS extraction method followed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed to analyze thiamethoxam and imidacloprid in 0.3 g of lyophilized Africanized honey bees (Apis mellifera L.). The work aimed to estimate honey bees' exposure to pesticides at the nanogram/gram (ng g−1) levels, using small sample and reagent quantities. Low amounts of solvents and salts were employed – 15× less than used in traditional methods. Average recoveries ranged from 64.5% to 99.7%, with repeatability below 20% for samples spiked at 3 and 167 ng g−1. LOD and LOQ were 0.7, and 3 ng g−1 for both pesticides. Applying the proposed approach, honey bee samples from different apiaries from the State of São Paulo (Brazil) were analyzed. The pesticides were detected in concentrations between 7.0 and 27.0 ng g−1. Thus, the proposed method can be used as a greener alternative to analyze the two neonicotinoids at trace levels in small quantities of bees, consequently saving chemicals and waste. [ABSTRACT FROM AUTHOR]

Toxicities of bisphenol A (BPA) and nonylphenol (NP) to the neotropical freshwater cladocerans Ceriodaphnia silvestrii and Daphnia similis were studied under laboratory conditions. Acute exposures to BPA generated mean 48-h EC50 values of 14.44 (6.02-22.85) mg L−1 for C. silvestrii and 12.05 (1.73-22.37) mg L−1 for D. similis. When the organisms were exposed to acute doses of NP, mean 48-h EC50 values were 0.055 (0.047-0.064) mg L−1 (C. silvestrii) and 0.133 (0.067-0.200) mg L−1 (D. similis). Ceriodaphnia silvestrii was also tested in chronic bioassays, which resulted in mean 8-d IC25 values of 2.43 (2.16-2.69) mg L−1 BPA [no observed effect concentration (NOEC): 1.38 mg L−1] and 0.020 (0.015-0.026) mg L−1 NP (NOEC: 0.015 mg L−1). These laboratory tests are valuable to broaden the understanding of the environmental threat posed by BPA and NP in aquatic ecosystems, and to increase the knowledge about the sensitivity of neotropical indigenous species to these contaminants. In addition to the laboratory bioassays, species sensitivity distributions were used to suggest protective concentrations of BPA and NP to prevent adverse effects on freshwater organisms. According to the obtained results, concentrations lower than 36.47 µg L−1 BPA and 1.39 µg L−1 NP are not expected to adversely impact aquatic organisms in natural ecosystems. [ABSTRACT FROM AUTHOR]

An old landfill leachate was pre-treated in a pilot-scale aerated packed tower operated in batch mode for total ammoniacal nitrogen (TAN) removal. The stripped ammonia was recovered with a 0.4 mol L−1H2SO4solution, deionized water and tap water. Ca(OH)2(95% purity) or commercial hydrated lime was added to the raw leachate to adjust its pH to 11, causing removal of colour (82%) and heavy metals (70–90% for Zn, Fe and Mn). The 0.4 mol L−1H2SO4solution was able to neutralize 80% of the stripped ammonia removed from 12 L of leachate. The effectiveness of the neutralization of ammonia with deionized water was 75%. Treating 100 L of leachate, the air stripping tower removed 88% of TAN after 72 h of aeration, and 87% of the stripped ammonia was recovered in two 31 L pilot-scale absorption units filled with 20 L of tap water. [ABSTRACT FROM PUBLISHER]

To boost crop yield, sugarcane growers are using increasing amounts of pesticides to combat insects and weeds. But residues of these compounds can pollute water resources, such as lakes, rivers and aquifers. The present paper reports the results of a study of water samples from the Feijão River, which is the source of drinking water for the city of São Carlos, São Paulo, Brazil. The samples were evaluated for the presence of four leading pesticides – ametryn, atrazine, diuron and fipronil – used on sugarcane, the dominant culture in the region. The samples were obtained from three points along the river: the headwaters, along the middle course of the river and just before the municipal water intake station. The pesticides were extracted from the water samples by solid-phase extraction (SPE) and then analyzed by liquid chromatography with diode array detection (LC-DAD). The analytical method was validated by traditional methods, obtaining recovery values between 90 and 95%, with precision deviations inferior to 2.56%, correlation coefficients above 0.99 and detection and quantification limits varying from 0.02 to 0.05 mg L−1 and 0.07 to 0.17 mg L−1, respectively. No presence of residues of the pesticides was detected in the samples, considering the detection limits of the method employed. [ABSTRACT FROM AUTHOR]

This study aims to verify the influence of the apparent molecular size of aquatic humic substances (AHSs) on the effectiveness of coagulation with aluminium sulphate and ferric chloride. Coagulation-filtration tests using the jar test and bench-scale sand filters were carried out with water samples having a true colour of approximately 100 Hazen units and prepared with AHSs of different molecular sizes. Stability diagrams are presented showing regions of≥90% and≥95% apparent colour removal delineated for each water sample using plots of total metal ion concentration (Al3+ and Fe3+) versus coagulation pH. To achieve the same degree of colour removal, the water samples with smaller apparent molecular sizes and a higher percentage of fulvic acids required higher dosages of both aluminium sulphate and ferric chloride. [ABSTRACT FROM PUBLISHER]