The effects of field-realistic doses of imidacloprid on Melipona quadrifasciata (Apidae: Meliponini) workers

Environmental Science and Pollution Research - The presence of Brazilian native bees can improve tomato production by increasing pollination effectiveness. However, the extensive use of pesticides...     

Simple biotoxicity tests for evaluation of carbonaceous soil additives: establishment and reproducibility of four test procedures

Biochar derived from pyrolysis has received much attention recently as a soil additive to sequester carbon and increase soil fertility. Hydrochar, a brown, coal-like substance produced via hydrothermal carbonization, has also been suggested as a beneficial soil additive. However, before soil application, both types of char need to be tested for potential toxic effects. The aim of this study was to develop simple, inexpensive, and easy-to-apply test procedures to identify negative effects of chars but not to provide false-negative results. The following tests, based partly on ISO norm biotoxicity test procedures, were chosen: (i) cress germination test for gaseous phytotoxic emissions; (ii) barley germination and growth test; (iii) salad germination test; and (iv) earthworm avoidance test for toxic substances. Test reproducibility was ensured by carrying out each test procedure three times with the same biochar. Several modifications were necessary to adapt the tests for biochars/hydrochars. The tested biochar did not induce negative effects in any of the tests. In contrast, the beet-root chip hydrochar showed negative effects in all tests. In an extension to the regular procedure, a regrowth of the harvested barley shoots without further nutrient additions yielded positive results for the hydrochar, which initially had negative effects. This implies that the harmful substance(s) must have been degraded or they were water soluble and leached. Tests with a biochar and hydrochar showed that the proposed modified quick-check test procedures provide a fast assessment of risks and effects of char application to soils within a short period of time (<2 wk).     

Monitoring of polychlorinated biphenyl contamination and estrogenic activity in water, commercial feed and farmed seafood

We evaluated the concentration and congener distribution of seven "target" polychlorinated biphenyls (PCBs) present in water collected in different aquaculture farms of the Mediterranean area, commercial feeds, and farmed seafood. PCBs were present in feed and in tissues of all the analysed organisms at levels ranging from 1.96 ng g(-1) to 124.00 ng g(-1) wet weight, and in 10.5% of the water samples, at levels from under detection limit to 33.0 ng l(-1) with total PCB concentrations significantly higher in samples from the Tyrrhenian Sea than the Adriatic Sea. PCB congener distribution in tissues resembled that of feed, suggesting that commercial feed is an important source of PCBs. The estrogenicity of organic extracts of the samples was also evaluated by using an in vitro yeast reporter assay. Estrogenic activity higher than 10% of the activity induced by 10 nM 17 beta-estradiol was observed in 20.0% of seafood samples and 15.8% of water samples. Seafood and water samples from the Tyrrhenian Sea were more frequently estrogenic than the Adriatic ones (16.45 versus 4.08%). A significant correlation of total PCB concentrations on biological activity was observed for sea bass and mussels from the Adriatic Sea (p < 0.045 and p < 0.04, respectively), and for sea bass of the Tyrrhenian Sea (p = 0.05). These results indicate the need of an integral approach in the exposure assessment to potential toxic compounds for human via food.     

The equivalence of diffusive samplers to reference methods for monitoring O3, benzene and NO2 in ambient air

A study of the equivalence to the reference methods of the Radiello samplers for ozone (O(3)) and benzene as well as the membrane-closed Palmes tube (MCPT) for nitrogen dioxide (NO(2)) is presented. These samplers benefit from new model equations capable of estimating their uptake rate. For O(3), the aim here was to demonstrate the equivalence for the reference period of 8 h and 120 microg m(-3), the target value of the 3rd European Daughter Directive. For benzene, the demonstration of equivalence to the annual limit value of 5 microg m(-3) of the 2nd European Daughter Directive was examined. In the case of NO(2), the equivalence to the annual limit value of the 1st European Daughter Directive (40 microg m(-3)) was considered. Results show that the radial sampler for O(3) fails to meet the Data Quality Objective (DQO) for continuous monitoring. However, with an expanded uncertainty of less than 30%, the O(3) diffusive sampler fulfils the DQO for indicative measurements. For benzene, the Radiello sampler exposed for 7 days gave satisfying results showing the ability of the sampler to meet the DQO of the reference method. Nevertheless, the field tests should be complemented by measurements for a wider range of benzene concentrations. In the case of NO(2), all the results of the laboratory and field experiments respected the requirements necessary for the demonstration of equivalence. Overall, these findings thus show that the Radiello sampler and the MCPT are equivalent to the reference methods only for assessment of benzene and NO(2), respectively.     

Removal of fenhexamid and pyrimethanil from aqueous solutions by clays and organoclays

The ability of a sodium montmorillonite (CLONa) and two commercial available organoclays having interlayer organic cations possessing different functional groups (CLO20A and CLO30B) was investigated for adsorbing two pesticides namely fenexamid (FEX) and pyrimethanyl (PMT). The two organoclays displayed a higher affinity with the pesticides than the unmodified clay, but the improvement in adsorption capacity varied according to the characteristics of the pesticide and the interlayer organic cation. FEX was adsorbed to a greater extent than PMT by both organoclays, which may be due to the higher hydrophobicity of FEX thereby indicating considerable hydrophobic interaction between the adsorbent/adsorbate systems. Our findings may find application in the removal of water-soluble pesticides from aquifers.     

Importance of fish gender as a factor in environmental monitoring of mercury

Total mercury concentrations were determined in the gonadal tissues of 15 female and 10 male European perch (Perca fluviatilis) from one location of the stream “Jevanský potok” located about 30 km from Prague (Czech Republic). Tissue samples were frozen at ?26 °C in polypropylene containers until further processing, which was carried out using an Advance Mercury Analyser (single purpose atomic absorption spectrometer). Mercury concentrations were present in all analysed gonad samples, and ranged from 2.3 to 12.7 μg/kg wet weight. However, we determined a mean Hg concentration (9.45 μg/kg) in male gonads that was 2.4 times greater than that of female gonads (3.9 μg/kg). This is an important finding when taking into account fish sex in environmental pollution monitoring (especially for mercury contamination).     

Existential threat and compliance with pro-environmental norms

Recent research on the effects of personal threat suggests that perceived threat might enhance pro-environmental behavior when pro-environmental norms are in focus. In three experiments we found support for the latter assumption, showing that mortality salience and salience of pro-environmental norms interacted in predicting pro-environmental attitudes and information search (Study 1), sustainable behavior in a forest management game (Study 2), as well as pro-environmental intentions and behavior (Study 3). Specifically, mortality salience increased pro-environmental conduct only when pro-environmental norms were salient. Moreover, norm salience only had an effect on pro-environmental attitudes and behavior when the threat of personal mortality was salient. We discuss the implications of these results for both terror management theory and the promotion of pro-environmental behaviors.     

Hydrolytic degradation of azimsulfuron, a sulfonylurea herbicide

The chemical degradation of the herbicide azimsulfuron was investigated in aqueous solutions at different pH values. The hydrolysis rate, determined by HPLC analyses, was pH dependent and was much faster in acidic than in neutral or weakly basic conditions. The metabolites formed at different pH values were compared with standards when possible or isolated and identified using ESI-LC-MS/MS, (1)H NMR and (13)C NMR. The two main products of hydrolysis in mild acidic solution were identified as 2-amino-4,6-dimethoxy-pyrimidine and 2-methyl-4-(2-methyl-2H-tetrazol-5-yl)-2H-pyrazole-3-sulfonamide, both produced as a result of the sulfonylurea bridge cleavage. Under basic conditions, a new product, a substituted 2-pyrimidinamine, deriving from the contraction of the sulfonylurea bridge, was isolated and completely characterized for the first time.     

Spectroscopic and conformational properties of size-fractions separated from a lignite humic acid

A lignite humic acid (HA) was fractionated by preparative high performance size-exclusion chromatography (HPSEC) in seven different size-fractions. The size-fractions were characterized by cross polarization (CP) magic angle spinning (MAS) (13)C NMR spectroscopy and a further analytical HPSEC elution under UV and fluorescence detection. The alkyl hydrophobic components mainly distributed in the largest molecular-size-fraction, whereas the amount of oxidized carbons increased with decreasing size of fractions. Cross polarization time (T(CH)) and proton spin-lattice relaxation time in the rotating frame (T(1rho)(H)) were measured from variable contact time (VCT) experiments. The bulk HA was characterized by the shortest T(CH) values and the longest T(1rho)(H) values which suggested, respectively, one. an aggregation of components in a large conformation that favored a fast H-C cross polarization, and, two. consequent steric hindrances that prevented fast local molecular motions and decreased proton relaxation rates. Conversely, the separated size-fractions showed longer T(CH) values and shorter T(1rho)(H) values than the bulk HA, thereby indicating that they were constituted by a larger number of mobile molecular conformations. The UV and fluorescence absorptions were both low in the large size-fractions that mainly contained alkyl carbons, whereas they increased in the olephinic- and aromatic-rich fractions with intermediate molecular-size, and decreased again in the smaller fractions which were predominantly composed by oxidized carbons. These results support the supramolecular structure of humic substances and indicate that the observed variation in conformational distribution in humic association may be used to explain environmental processes with additional precision.