Strategically designed sample composition for fastest screening of polychlorinated biphenyl congeners in water samples

A new strategy for preparing composite samples of special interest and applicability in environmental screening studies is presented. The use of supersaturated experimental design matrices to conduct the sample composition of water sample specimens in screening studies is demonstrated. In contrast to well known conventional sample composition, this strategic approach provides analytical objects allowing the accurate prediction of analyte concentration levels in the original individual sample specimens while fixing the number of experiments to be carried out down to the very number of sample specimens. This will be of special importance when dealing with analytes that require complicated, labour intensive and expensive analytical processes. To reach this goal, two main conditions must be fulfilled. The first one is the sparsity effect (Pareto principle) which holds for the specimens in the sampling campaign. This means that the number of really anomalous or contaminated specimens, as compared to the total number of specimens to be analysed, is low. In environmental screening studies, frequently this situation can be reasonably assumed. The second condition is to have an effective manner to develop and solve the experimental designs required to build-up the composite samples. The challenging problem of screening PCBs in water samples has been tackled to show the usefulness of this strategic approach by combining chemometrically assisted sample composition and rapid analysis using solid-phase microextraction of the composite samples.     

Micro-evolutionary change in host response to a brood parasite

The relationship between brood parasites and their hosts is usually assumed to result in coevolution, and documentation of changes in extant populations should thus be possible. Here we describe how the ejection rate of eggs of an obligate brood parasite, the great spotted cuckoo Clamator glandarius, by its host, the magpie Pica pica, has recently increased in an area in southern Spain. The ejection rate of great spotted cuckoo eggs in naturally parasitized nests of the magpie increased at a rate of 0.5% year' during the period 1982–1992. This result was verified in a number of field experiments using nonmimetic and mimetic model eggs. The rate of increase in ejection rate was 4.7% year^-1 for mimetic eggs and 2.3% year^-1 for nonmimetic eggs. There were clear differences in parasitism by the great spotted cuckoo between study plots and years, which makes comparisons of rates of parasitism between areas difficult without considering temporal variation. The recent increase in the ejection response of magpies to great spotted cuckoo eggs was not due to magpies using the abundance of cuckoos as a cue to the intensity of parasitism.     

Direct measurements of urban OH reactivity during Nashville SOS in summer 1999

Emissions of volatile chemicals control the hydroxyl radical (OH), the atmosphere's main cleansing agent, and thus the production of secondary pollutants. Accounting for all of these chemicals can be difficult, especially in environments with mixed urban and forest emissions. The first direct measurements of the atmospheric OH reactivity, the inverse of the OH lifetime, were made as part of the Southern Oxidant Study (SOS) at Cornelia Fort Airpark in Nashville, TN in summer 1999. Measured OH reactivity was typically 11 s(-1). Measured OH reactivity was 1.4 times larger than OH reactivity calculated from the sum of the products of measured chemical concentrations and their OH reaction rate coefficients. This difference is statistically significant at the 1sigma uncertainty level of both the measurements and the calculations but not the 2sigma uncertainty level. Measured OH reactivity was 1.3 times larger than the OH reactivity from a model that uses measured ambient concentrations of volatile organic compounds (VOCs), NO, NO2, SO2, and CO. However, it was within approximately 10% of the OH reactivity from a model that includes hydrocarbon measurements made in a Nashville tunnel and scaled to the ambient CO at Cornelia Fort Airpark. These comparisons indicate that 30% of the OH reactivity in Nashville may come from short-lived highly reactive VOCs that are not usually measured in field intensive studies or by US EPA's Photochemical Assessment Monitoring Stations.     

Volatile organic compounds produced during the aerobic biological processing of municipal solid waste in a pilot plant

The volatile organic carbon (VOC) and odours emitted during the aerobic biological processing of municipal solid waste (MSW) was studied in a pilot-scale reactor. VOCs were detected by different techniques on solid waste samples and the outlet air stream, before and after a biofilter. Organic compounds (alpha-pinene, beta-myrcene, D-limonene) were also measured in condensate water and leachate from the process. Results showed uniformity in the composition of the air in the solid waste samples, air sampled during the process and condensed water, indicating a matrix-derived origin of these compounds. Leachates, however, contained substances with a quite different molecular structure from the compounds identified in the gaseous fraction. Most of the substances in the gaseous effluent had a hydrocarbon-like structure, mainly terpenoids. The odour produced and detected through olfactometry agreed with GC-MS analyses. This was true above all for terpenes.     

Antioxidant enzymes in the digestive gland of the common musselMytilus edulis

Antioxidant enzymes function to remove deleterious reactive oxygen species, including the superoxide anion radical and H₂O₂. Subcellular distributions and optimal and other properties of catalase (EC. 1.11.1.6), superoxide dismutase (SOD; EC. 1.15.1.1), selenium-dependent glutathione peroxidase (Se-GPX; EC. 1.11.1.9) and total glutathione peroxidase (GPX) activities were determined in the digestive gland of the common musselMytilus edulis L. by spectrophotometric and cytochemical/electron microscopic (catalase) techniques. Assay conditions for Se-GPX and total GPX activities were determined which optimized the difference between the non-enzymic and enzymic rates of reaction. General peroxidase activity (guaiacol as substrate) (EC. 1.11.1.7) was not detectable in any subcellular fraction. Catalase was largely, if not totally, peroxisomal, whereas SOD and GPX activities were mainly cytosolic. Distinct mitochondrial (Mn-SOD) and cytosolic (CuZn-SOD) SOD forms were indicated. Catalase properties were consistent with a catalase, rather than a catalase-peroxidase. The pH-dependence and temperature-dependence of GPX activity were different with H₂O₂ or CHP as substrate, and these and other observations indicate the existence of a distinct Se-GPX. Under saturating or optimal (GPX) assay conditions, the apparent Michaelis constantsK _m (mM) were: catalase, 48 to 68 (substrate, H₂O₂); Se-GPX, 0.11 (H₂O₂) and 2.0 (glutathione); and total GPX, 2.2 (eumene hydroperoxide) and 1.2 (glutathione). Calculated catalase activity was 2 to 4 orders of magnitude greater than Se-GPX activity over an [H₂O₂] of 1 to 1000 M. The results are discussed in relation to theoretical calculations of in vivo oxyradical production and phylogenetic differences in antioxidant enzyme activities.     

Honeybees modify gustatory responsiveness after receiving nectar from foragers within the hive

Food quality is a relevant characteristic to be transferred within eusocial insect colonies because its evaluation improves the collective foraging efficiency. In honeybees, colony mates could directly acquire this resource characteristic during trophallactic encounters with nectar foragers. In the present study, we focused on the gustatory responsiveness of bees that have unloaded food from incoming foragers. The sugar sensitivity of receiver bees was assessed in the laboratory by using the proboscis extension response paradigm. After unloading, hive bees were captured either from a colony that foraged freely in the environmental surroundings or from a colony that foraged at an artificial feeder with a known sucrose solution. In the first situation, the sugar sensitivity of the hive bees negatively correlated with the sugar concentration of the nectar crops brought back by forager mates. Similarly, in the controlled situation, the highest sucrose concentration the receivers accepted during trophallaxis corresponded to the highest thresholds to sucrose. The results indicate that first-order receivers modify their sugar sensitivity according to the quality of the food previously transferred through trophallaxis by the incoming foragers. In addition, trophallaxis is a mechanism capable of transferring gustatory information in honeybees. Its implications at a social scale might involve changes in the social information as well as in nectar distribution within the colony.     

Stable isotopes changes in the adductor muscle of diseased bivalve Ruditapes philippinarum

In this article, we show how a disease could bias stable isotope analyzes of trophic networks and propose a strategy in the choice of tissues to be analyzed. In the past few years, a new pathology (brown muscle disease or BMD) affecting the posterior adductor muscle of Ruditapes philippinarum has emerged in Arcachon Bay. BMD induces a necrosis of muscle tissues which become infused by conchiolin and hence calcified. As muscle of mollusks are often used for trophic food webs studies through stable isotopic analyzes, this work investigated the effect of BMD on carbon and nitrogen isotopic ratios of anterior and posterior adductor muscles of clams collected in February and August 2007. Infected clams displayed a lower condition index and a posterior adductor muscle δ¹³C enrichment of 1.2‰ in February and 0.7‰ in August. δ¹⁵N of posterior muscles was however not affected by the disease. Anterior muscle of diseased clams remained healthy and displayed the same isotopic signature as both posterior and anterior muscular tissues of healthy clam. Acidification significantly depleted δ¹³C in posterior muscles of infected clams, suggesting calcification, contrary to anterior muscles of infected clam and to both muscles of healthy clams, where no effect was observed. An X-ray diffractometry analysis confirmed the presence of CaCO₃ (aragonite). Trophic food web studies relying on stable isotope ratios should utilize only healthy animals or anterior adductor muscles when expertise in mollusk pathology is lacking.     

Realizing the potential of GIS in community-based management of protected areas

SUMMARY

This paper explores the roles GIS technology can play in support of land management, focusing in particular on its application in protected environments such as Biosphere Reserves. These ecologically significant areas present complex planning situations since, unlike areas set aside solely for conservation, they must continue to support human populations that depend on natural resources for their economic and social well being. In situations such as marginal tropical locations, land managers often face major economic and political disincentives to the conservation of precious natural resources. The necessity for community participation and local expertise in the planning process becomes increasingly critical as GIS evolves from a basic presentation aid for spatial data to a synthesizing problem-solving tool. Coupled with enhanced community participation is the opportunity for greater education of stakeholders; the potential for GIS to serve as a medium for information gathering and dissemination is discussed. A case study in the Sierra de Manantlán Biosphere Reserve (SMBR), México, is presented.     

Effect of surfactant-coated iron oxide nanoparticles on the effluent water quality from a simulated sequencing batch reactor treating domestic wastewater

This study was conducted to evaluate the effect of commercially available engineered iron oxide nanoparticles coated with a surfactant (ENP_Fe-surf) on effluent water quality from a lab-scale sequencing batch reactor as a model secondary biological wastewater treatment. Results showed that ∼8.7% of ENP_Fe-surf applied were present in the effluent stream. The stable presence of ENP_Fe-surf was confirmed by analyzing the mean particle diameter and iron concentration in the effluent. Consequently, aqueous ENP_Fe-surf deteriorated the effluent water quality at a statistically significant level (p < 0.05) with respect to soluble chemical oxygen demand, turbidity, and apparent color. This implied that ENP_Fe-surf would be introduced into environmental receptors through the treated effluent and could potentially impact them.