Effect of pH and the role of organic matter in the adsorption of isoproturon on soils

Equilibrium measurements were carried out with the herbicide isoproturon on natural adsorbents (brown forest-, chernozem-, sandy soils and quartz) in different buffered media (pH 5, 7, 8 phosphate buffer). Adsorption isotherms were fitted by a multi-step adsorption equation providing numerical information used in the environmental propagation models and risk assessment works. In the adsorption of the slightly polar isoproturon the dissolved organic matter of the soil and the pH play an important role. At molecular level, results are interpreted by taking into consideration the hydrophobic interaction and the formation of hydrogen bonds between the surface and the solute. The observed adsorption behavior indicates that the organic matter content of the soils and its soluble fulvic acid, alkaline soluble humic acid and insoluble humin fractions were considerable different. The chernozem soil containing the highest amount of insoluble organic fraction proved to be a very efficient adsorbent. The brown forest and the sandy soils exhibit rather similar adsorbent properties but at pH 7 the latter containing more fulvic acid adsorbs less isoproturon due to the enhanced solubility of the soil organic matter. In alkaline conditions the negatively charged solute and the surface repel each other and the hydrophobic interactions are also weaker than in neutral media.     

Heavy metals monitoring at a Mediterranean natural ecosystem of Central Italy. Trends in different environmental matrixes

The study deals with the evaluation of the impact of heavy metal pollution on a Mediterranean natural ecosystem, and presents the results derived from a monitoring of heavy metals in different environmental matrixes (atmospheric dry depositions, suspended particulate matter (SPM) and stemflow of forest trees). Two sites in Castelporziano Presidential Estate (Rome), one internal and one near the sea-side, were chosen in order to assess the differences in pollutant load. Results showed that heavy metal contamination can arise from local anthropogenic activities, in particular road traffic, and long-range pollution, from industrial and artisan activities near Rome.     

采用联用技术测定中国海产品中砷的形态

1　IntroductionAtthebeginningof2 0 thcentury ,highlevelsofarsenic～mg·kg-1 werefoundinmarineorga nisms,whichattractedalotofattention ,becausearsenicisoneofthemostnotoriouselementsonaccountofitshumantoxicity.Forthisreason ,thedeterminationofthetotalamount…     

Adsorption of propisochlor on soils and soil components equation for multi-step isotherms

Static equilibrium measurements were performed for the study of propisochlor on three different kinds of soils at pH = 7.0 at 25 degrees C. The concentration of herbicide was changed from 30 to 300 mumol/l. The obtained two-step adsorption isotherms cannot be evaluated by using the Freundlich or Langmuir equations. New equation has been derived by making use of the usual mass balance and equilibrium relationships of the adsorption and by considering the possibility of the formation of associates of the hydrophobic solute molecules. The characteristic model parameters of each step of the adsorption isotherm were estimated for the studied systems by a non-linear least square regression. The calculated curves fit well to the experimentally obtained two-step isotherms and the parameters of the model can be used for the characterization of the pesticide-soil interactions and consequently the mobility of the propisochlor in soil/water systems.     

Idiothetic orientation of a wandering spider: Compensation of detours and estimates of goal distance

Summary The wandering spider Cupiennius salei Keys uses idiothetic orientation, i.e., memorized information about its own previous movements, to retrieve lost prey. Spiders, having been chased away from a prey fly, return to the capture site (the goal) over a distance of more than 75 cm even though all external orientation cues were precluded. This behavior and its sensory basis were examined by varying the proprioceptive and motor command inputs to the memory and by ablating particular lyriform slit sense organs on the legs of the spider.The success rate of returns to the goal after rectilinear chases over 6 discrete distances ranging from 20 cm to>41 cm declines with increasing distances. At distances>41 cm, more than 50% of the performances of intact spiders are nevertheless successful, in that the animals approach the capture site as close as 5 cm (or less).Animals that have been operated on (lyriform organs on all femora destroyed) are much less successful even at short distances. The mean starting angles of the returns by intact spiders and by those operated on do not differ signficantly. Walking error e _n for each segment of the entire return path shows that intact animals deviate little from the ideal return route and correctly estimate the distance to the goal. The operated spiders tend to drift off the ideal return route, while their distance estimates remain largely accurate.Returns after curvilinear chases through a semicircular corridor do not retrace the curved path; instead the spiders take a shortcut. Of all performances by intact and by control spiders (with sham operations) 85% are successful. By contrast, most of the 8 groups with sensory ablations have a success rate of less than 50%.Compensation for the semicircular detours is not quite complete: the mean starting directions of returns are biased, pointing to the corridor, and the shape of many return paths reflects the curved corridor shape. Spiders with unilateral ablations of their femoral lyriform organs show low success rates only if the operated legs are on the inner curve perimeter during the chase, while their return parameters resemble those of the intact group in the reverse situation (operated legs on outer perimeter). These side-specific ablation effects, which are correlated with the geometrical situation existing while idiothetic information is gathered and memorized, suggest that the idiothetic memory depends at least partly on input from proprioceptors.     

Characteristics and predictors of recidivist drink-drivers

Objective: The current study compared characteristics of nonrecidivist versus recidivist drink-drivers and of recidivists in their first versus second appearance at Back on Track (BOT), the remedial measures program for impaired drivers in Ontario, Canada.

Methods: Information from 59,134 convicted drivers who participated in BOT between 2000 and 2010 was examined to identify drivers who completed the program a second time following reconviction.

Results: A total of 586 recidivists were identified. Compared to nonrecidivist drivers, recidivists at first attendance were more likely to be male and had higher scores on measures of alcohol dependence and adverse legal consequences of substance use. Compared to nonrecidivist drivers, recidivists at second attendance were significantly older, had a higher income, were more likely to be retired, and were less likely to be employed part-time. They had fewer legal problems. Recidivists reported fewer drinking days and fewer drinks per occasion but greater use of benzodiazepines than nonrecidivists and had higher scores on a measure of future risk of alcohol- and drug-related problems. Comparison of recidivists' characteristics at first versus second attendance confirmed many of these findings, with second-time recidivists reporting fewer drinks per drinking day and greater use of benzodiazepines and having higher scores on a measure of future substance use problems than first-time recidivists.

Conclusions: Results suggest that identification of drivers at increased risk of recidivism may be possible at first program attendance by examining indicators of increased alcohol-related problems. In addition, recidivists appear to show a greater readiness to change at second attendance. Implications for remedial program development and recommendations for future research are discussed.     

Assessing the estrogenic potency in a Portuguese wastewater treatment plant using an integrated approach

The estrogenic potency of a wastewater treatment plant(WWTP) was evaluated using chemical and biological analyses,which showed that after the station treatment processes some of the selected endocrine disruptor compounds(EDCs) were still present in the treated effuent(e.g.,bisphenol A,alkylphenols,estrone) .Thus,the most common endocrine EDCs were identified and quantified and the overall estrogenicity of the treated effuent assessed by integrating the results.Male goldfish(Carassius auratus) were used as biological indicators in a 28-day experiment.Vitellogenin(Vtg) ,gonadosomatic and hepatosomatic indices,steroids(17β-estradiol and 11-ketotestosterone) and histopathology were biomarkers used in fish to evaluate WWTP treated effuent estrogenicity,in combination with instrumental analyses.The results showed a significant increase(P0.01) in plasma and liver Vtg,which were significantly correlated(r=0.66;P0.01) .The gonadosmatic index was significantly(P0.01) reduced in exposed fish.The steroid analyses revealed significant elevations in 17β-estradiol and depressed 11-ketotestosterone concentrations.The histological examinations show changes in exposed fish gonads,such as regressed testes and in some cases(43%to 75%) the development of ovo-testis in fish exposed to 50% and 100% treated effuent.