Polychlorinated biphenyls in contaminated soil samples evaluated by GC-ECD with dual-column and GC-HRMS

We present and compare results obtained from the analysis of polychlorinated biphenyls (PCBs) of a limited number of contaminated soil samples collected in three areas of Basilicata region (south of Italy). The levels of PCBs were evaluated by using two analytical methods: (i) parallel dual-column gas-chromatography with dual electron capture detectors (GC-ECD) and (ii) gas-chromatography coupled to high-resolution mass spectrometry (GC-HRMS) via electron impact ionization (EI) in the multiple ion monitoring mode (MIM, two ions per compound). Two extraction methods prior to sample cleanup were also examined: microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE). The MAE was the extraction procedure adopted using acetone/n-hexane (1:1, v/v) as it is mainly characterized by higher sample throughput and allowed reduced consumption of organic solvents. While extraction and analysis of spiked soil samples showed the applicability of both methods, systematic differences between the results were obtained for the sum of PCBs as a result of some non-detected congeners by GC-ECD compared with GC-HRMS. Indeed, high resolution MS using EI mode (electron energy 40eV) with a resolving power of 10,000 provides additional information about the contamination pattern. The GC-ECD screening of 11 soil samples led to just one sample non-compliant to as it was close to the guide value for soils fixed by the Italian legislation (i.e., 60ppb for private or urban soil). Using GC-HRMS, the amount of all PCBs found ranged from 5.4 to 127ppb with five soil samples non-compliant to the guide value. The number of identified congeners ranged from 1 to 9 and 9 to 18 using dual-column GC-ECD and GC-HRMS, respectively.     

Intermediate distributions and primary yields of phenolic products in nitrobenzene degradation by Fenton's reagent

Nitrobenzene thermal degradation was investigated using the Fenton reagent in different experimental conditions. Reaction products were analyzed by HPLC, GC-MS, LC-MS and IC. The products obtained at different nitrobenzene conversion degrees show that degradation mainly involves successive hydroxylation steps of the aromatic ring and its subsequent opening followed by oxidation of corresponding aliphatic compounds. Our results show as primary reaction products: 4-nitrophenol, 3-nitrophenol, 2-nitrophenol, phenol and 1,3-dinitrobenzene, indicating that both hydroxylation and nitration reactions are involved. The formation of phenolic products can be explained by postulating an initial step of HO() addition to nitrobenzene ring. The mechanisms of primary reaction pathways are discussed and a detailed kinetic analysis to obtain the true primary yields of phenolic products is proposed. The relative yields observed for nitrophenol isomers do not follow the expected orientation according to deactivating characteristics of the nitro group but significantly depend on Fe(+2), Fe(+3), H(2)O(2) and O(2) concentrations. The understanding of the effect of reaction conditions on the relative product distribution benefits the application of Fenton and Fenton-like systems to waste water treatment.     

Effects-directed analysis of organic toxicants in wastewater effluent from Zagreb, Croatia

The organic toxicants present in the effluent of the main sewer of the city of Zagreb, Croatia were isolated and identified through the use of effects-directed characterisation techniques. At the time of investigation, the wastewater effluent received no treatment and was comprised of a mixture of effluent from domestic and industrial sources. The organic load of the wastewater was isolated by solid phase extraction and toxicity profiles obtained using reverse-phase HPLC. All procedures were evaluated through the analysis of a series of reference compounds of widely differing polarity. Toxicity profiles for EROD activity (CYP1A induction), vitellogenin induction (estrogenic activity), cytotoxicity (membrane stability and metabolic inhibition) were obtained using a rainbow trout (Oncorhynchus mykiss) primary hepatocyte bioassay. The suite of bioassays showed biological responses after exposure to the raw extracts for all the endpoints tested. However, a combination of mixture toxicity and cytotoxicity in the complex raw extract had some masking effect on the sub-lethal responses of vitellogenin and EROD induction. Bioassay testing of the fine fractions obtained by HPLC produced a range of endpoint-specific toxicity profiles for each sample. A number of compounds were identified by the use of GC-MS and LC-MS/MS as responsible for the observed effects. The steroid estrogens 17 beta-estradiol and estriol were identified by LC-MS/MS as estrogen receptor agonists in two of the estrogenic fractions. In addition, GC-MS analysis identified different alkylphenols, benzophenone and methylparaben which also contributed to the estrogenic activity of the sample. Polycyclic aromatic hydrocarbons (PAHs), alkyl substituted PAHs, nitro-polycyclic aromatic compounds (nitro-PACs), carbazoles and alkyl substituted carbazoles and other known CYP1A inducers were identified by GC-MS analysis as responsible for some of the observed EROD activity. Some active compounds remain unidentified.     

Removal of Prussian blue from contaminated soil in the rhizosphere of cyanogenic plants

The fate of radiolabeled cyanide in soil was investigated during exposure to cyanogenic plant species, sorghum (Sorghum bicolor var. P721) and flax (Linum usitassimum var. Omega-Gold), in fully-contained growth chambers. Labeled cyanide was subject to microbial transformation, assimilation by plant roots, incorporation and biodegradation in plant tissue. For this study, (14)C-labeled cyanide was added to soil, and distribution of (14)C activity was assessed before plant establishment and after harvest. After 3 months of plant growth, 7% of the (14)C-labeled cyanide was converted to (14)CO(2) with sorghum and 6% with flax, compared with only 2% conversion in unplanted soil. A small amount of unaltered cyanide was shown to be accumulated by the plants (approximately 140 mg cyanide/kg plant or <0.1% of the total). Results from this experiment demonstrate the potential of cyanogenic plants for use in phytoremediation of cyanide-contaminated soil.     

Metal capital sustaining a North American city: Iron and copper in New Haven, CT

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.     

Cost-benefit approaches to territoriality: A test with forest primates

Summary Defense of an area has often been suggested to be more likely when the area contains critical resources which are available more continously, more reliably, or in greater concentration. We report a case in which field experiments and observations of two closely related primate species do not support these expectations. Among other possibilities, the results may indicate conflicting strategies of spacing between males and females.     

Evidence for obligate monogamy in the Djungarian hamster,Phodopus campbelli: pup survival under different parenting conditions

Summary Two recent studies have described pregnancy blocking responses in female Djungarian hamsters, Phodopus campbelli, under conditions where the potential for paternal investment by the male is low (Wynne-Edwards and Lisk 1984; Wynne-Edwards et al. 1987). If this pattern of pregnancy block is adaptive, solitary females should have a low probability of successfully rearing a litter without investment by their mate. The present study was designed to compare the relative reproductive success of solitary females with that of paired females. Weights and survivorship were determined daily from birth through weaning (day 18 after birth) for litters of Djungarian hamster pups raised by solitary females (Solitary females), male-female pairs (Pairs), or female-female pairs consisting of the experimental female and her unmated littermate sister (Sisters). Unmated littermate sisters were included in the design to differentiate between the contribution of the mate and the contribution of another conspecific adult to the reproductive success of the experimental female. As predicted by the hypothesis that the pattern of incidence of pregnancy block was adaptive (Wynne-Edwards et al. 1987), the presence of the mate significantly affected the reproductive success of the female. Pairs were very successful, raising 95% of pups and 100% of litters to weaning. Solitary females were significantly less successful, raising only 47% of pups and 77% of litters with 16% of litters intact on day 18. A littermate sister did not compensate for the absence of the mate. Sisters raised only 61% of pups and 73% of litters with 36% of litters intact on day 18. Pup survival and weights were independent of sex. However, for pups that were still alive on day 18, weight distributions did not differ significantly across the three parenting conditions. Likewise, the proportion of best pups alive on day 18 (with weights exceeding a threshold of 11.5 g) did not differ significantly across groups. Differences between parenting conditions lay in the survivorship of pups rather than in the quality of the pups that survived. This study provides evidence that the presence of the mate is essential for high female reproductive success even under the ideal climate and nutritional conditions of the laboratory. Thus, the Djungarian hamster is a strong candidate for a small mammalian species with obligate monogamy as the optimal mating system.     

Foliar absorption of intercepted rainfall improves woody plant water status most during drought

A large proportion of rainfall in dryland ecosystems is intercepted by plant foliage and is generally assumed to evaporate to the atmosphere or drip onto the soil surface without being absorbed. We demonstrate foliar absorption of intercepted rainfall in a widely distributed, continental dryland, woody-plant genus: Juniperus. We observed substantial improvement in plant water status, exceeding 1.0 MPa water potential for drought-stressed plants, following precipitation on an experimental plot that excluded soil water infiltration. Experiments that wetted shoots with unlabeled and with isotopically labeled water confirmed that water potential responded substantially to foliar wetting, that these responses were not attributable to re-equilibration with other portions of the xylem, and that magnitude of response increased with water stress. Foliar absorption is not included in most ecological, hydrological, and atmospheric models; has implications for interpreting plant isotopic signatures; and not only supplements water acquisition associated with increases in soil moisture that follow large or repeated precipitation events, but also enables plants to bypass soil water uptake and benefit from the majority of precipitation events, which wet foliage but do not increase soil moisture substantially. Foliar absorption of intercepted water could be more important than previously appreciated, especially during drought when water stress is greatest.