Leaf accumulation of trace elements and polycyclic aromatic hydrocarbons (PAHs) in Quercus ilex L

Quercus ilex L. leaves were collected four times in one year at six urban sites and one remote area in order to determine trace element and PAH accumulation through concomitant analyses of unwashed and water-washed leaves. Both unwashed and washed leaves showed the highest amounts of trace elements and PAHs in the urban area. Unwashed leaves showed greater differences between urban and remote areas and among the urban sites than washed leaves for trace element and PAH concentrations. Water-washing resulted in a significant (P<0.001) decrease in leaf concentrations of Cr, Cu, Fe, Pb, V and Zn. By contrast, Cd and total PAH concentrations showed no differences between unwashed and washed leaves.     

Seasonal Variation of Toxic Benzene Emissions in Petroleum Refinery

Petroleum refineries are largest chemical industries that are responsible for the emission of several pollutants into the atmosphere. Benzene is among the most important air pollutants that are emitted by petroleum refineries, since they are involved in almost every refinery process. Volatile organic compounds (VOCs) are a major group of air pollutants, which play a critical role in atmospheric chemistry. These contribute to toxic oxidants, which are harmful to ecosystem, human health and atmosphere. The variability of pollutants is an important factor in determining human exposure to these chemicals. The ambient air concentrations of benzene were measured in several sites around the Digboi petroleum refinery, near the city of Gowahati in northeast India, during winter and summer 2004. The seasonal and spatial variations of the ambient air concentrations of this benzene were investigated and analyzed. An estimation of the contribution of the refinery to the measured atmospheric levels of benzene was also performed. The ambient air mixing ratios of benzene in a large area outside the refinery was generally low, in ppbv range, much lower than the ambient air quality standards. This article presents the temporal and spatial variation of air pollution in and around petroleum refinery and showed that no health risk due to benzene is present in the areas adjacent to the refinery.     

Impact of continental margins in the Mediterranean Sea: Hints from the surface colour and temperature historical record

The surface colour and temperature fields of the Mediterranean Sea, as appearing in time series, of basin-wide images available in the CZCS (1979–1985) and AVHRR (1982–1991) historical archives, differentiate between basin interior and continental margins affected by coastal patterns, river plumes, and mesoscale features. The original data were processed to apply calibration factors, to correct for atmospheric contamination, and to estimate chlorophyll-like pigment concentration and surface temperature. Composites were derived, as monthly and annual means, using a fixed equal-area projection with a 1-km² pixel grid. Enhanced pigment values and lower temperatures along the northern coastal areas (i.e. the Ligurian, Provençal and Balearic basins, as well as the Adriatic, and Aegean Seas) have been associated with the impact of runoff from continental margins (i.e. both a direct impact due to the sediment load and one induced on the planktonic flora by the associated nutrient load) and with vertical mixing due to the prevailing winds (i.e. the Mistral in the northwest, the Bora in the Adriatic, the Etesians in the Aegean). The pattern of increasing pigments and decreasing temperatures in seen to develop in the monthly images from the coastal zone towards the open sea from summer to winter, and then back from winter to summer. The southern coastal areas show different values, namely lower pigments and higher temperatures (except in areas where the data are altered by signal contamination). It is suggested that differences in geomorphology and meteorology of the basin margins have an impact on both water biogeochemistry and dynamics, influencing the biooptical and thermal properties of the various sub-basins, and of the entire Mediterranean region.     

Elemental (C, N and P) analysis of metamorphosing bonefish (Albula sp.) leptocephali: relationship to catabolism of endogenous organic compounds, tissue remodeling, and feeding ecology

Whole-body carbon (C), nitrogen (N) and phosphorus (P) content, and stable-isotope composition (¹³C:¹²C and ¹⁵N:¹⁴N), were followed during metamorphosis of bonefish (Albula sp.) larvae (leptocephali). Metamorphosing larvae depend entirely on endogenous carbon compounds (some of which contain N and P) as an energy source. Two fundamental questions are (1) Do the demands of extensive tissue remodeling during metamorphosis require the efficient retention of N and P during the catabolism of carbon compounds? (2) What effect does the lack of feeding have on stable-isotope composition? Our results showed that both C and N decreased by ～35 to 40%, reflecting the utilization of neutral lipid (triacylglycerols) and N-containing compounds (phosphatidylethanolamine and keratan sulfate glycosaminoglycan) as energy sources, and indicating that larvae have little or no capacity to retain N. Evidence suggested that collagen breakdown, measured as a loss of hydroxyproline content, also contributed to N loss. Stable-isotope ratios, expressed as ¹³C and ¹⁵N, showed no statistically significant differences in early and advanced metamorphosing larvae. In contrast to C and N, phosphorus was conserved during metamorphosis and most probably is utilized in the increased bone mineralization occurring in advanced larvae. We show, however, that advanced larvae are P-limited and that normal ossification is dependent upon a supply of exogenous P obtained after the resumption of feeding. The N:P ratio of 12.3 in early larvae decreased to 8.1 in advanced larvae owing to the conservation of P as N was lost. The mean ¹⁵N value in early metamorphic larvae (11.6‰) is consistent with results from other studies, and provides further support for the view that premetamorphic leptocephali feed at a very low trophic level.     

Effects of productivity on biodiversity in forest ecosystems across the United States and China

In the global campaign against biodiversity loss in forest ecosystems, land managers need to know the status of forest biodiversity, but practical guidelines for conserving biodiversity in forest management are lacking. A major obstacle is the incomplete understanding of the relationship between site primary productivity and plant diversity, due to insufficient ecosystem‐wide data, especially for taxonomically and structurally diverse forest ecosystems. We investigated the effects of site productivity (the site's inherent capacity to grow timber) on tree species richness across 19 types of forest ecosystems in North America and China through 3 ground‐sourced forest inventory data sets (U.S. Forest Inventory and Analysis, Cooperative Alaska Forest Inventory, and Chinese Forest Management Planning Inventory). All forest types conformed to a consistent and highly significant (P < 0.001) hump‐shaped unimodal relationship, of which the generalized coefficients of determination averaged 20.5% over all the forest types. That is, tree species richness first increased as productivity increased at a progressively slower rate, and, after reaching a maximum, richness started to decline. Our consistent findings suggest that forests of high productivity would sustain few species because they consist mostly of flat homogeneous areas lacking an environmental gradient along which a diversity of species with different habitats can coexist. The consistency of the productivity–biodiversity relationship among the 3 data sets we examined makes it possible to quantify the expected tree species richness that a forest stand is capable of sustaining, and a comparison between the actual species richness and the sustainable values can be useful in prioritizing conservation efforts.     

Application of activated M/ZnO (M = Mn,Co, Ni,Cu, Ag) in photocatalytic degradation of diazo textile coloring dye

Activated ZnO powder has been prepared by procedures involving first its dissolution in nitric acid, then simultaneous treatment by adding NH₄OH and CO₂ bubbling leading to precipitation as Zn(OH)CO₃ (ZH) and further thermal decomposition of ZH at 400 °C. The gas evolution leads to formation of pores and increase in the specific surface area. Chemically activated M/ZnO powders doped with Mn, Co, Ni, Cu, and Ag have been obtained by the impregnation method. The samples have been characterized by ultraviolet-visible (UV-Vis) spectroscopy, diffuse reflectance (DR) UV-Vis, X-ray diffraction (XRD), single point Brunauer–Emmet–Teller (BET), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) methods. The experiments have shown that metal-doped activated ZnO powders possess higher photocatalytic activities in oxidative discoloration of model contaminant textile coloring dye Reactive Black 5 in slurry reactor compared to that of the pure ZnO. The XRD and XPS data have shown the presence of defects, nonstoichiometricity implying the formation of solid solutions. Copper-doped (1.5 wt%) activated ZnO (Cu²⁺ replaces Zn²⁺) is outstanding in its photocatalytic performance in discoloration of the dye due to the higher specific surface area and improved charge carrier separation.     

Differences in phosphorus translocation contributes to differential arsenic tolerance between plants of Borreria verticillata (Rubiaceae) from mine and non-mine sites

We have identified new arsenic-tolerant plant species Borreria verticillata (Rubiaceae) that has mine and non-mine populations at a highly contaminated site (CS) and an uncontaminated site (UCS), respectively, in Brazil. Plants of B. verticillata from both sites were cultivated at different As and P concentrations. At low P concentration, CS plants showed reduced As uptake, higher P translocation to shoots, higher constitutive levels of phenolic compounds in roots, and higher tolerance to this metalloid. At the lowest P and highest As concentration, CS plants showed higher biomass. In addition, CS plants showed higher P uptake in the absence of As, suggesting that more efficient P translocation could contribute more to tolerance than decreased As uptake. In contrast, at low P concentration, UCS plants showed higher As content in shoot and root, increase in phenol levels in roots, reduction in dry biomass, and decrease of the effective efficiency of photochemical reactions and the electron transport rate. Under higher P concentrations, the decrease in As uptake was similar in both populations. The differences between the two populations with respect to As and P uptake suggest that altered kinetic properties or expression of P transporters contribute to higher As tolerance in B. verticillata from CS. As a ruderal and As-tolerant plant, B. verticillata could be successfully used for the revegetation of contaminated soils.     

Green synthesis of silver nanoparticles by microorganism using organic pollutant: its antimicrobial and catalytic application

A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of AgNO₃ using culture supernatant of phenol degraded broth is reported in this work. The synthesis was observed within 10 h, and AgNPs showed characteristic surface plasmon resonance around 410 nm. Spherical nanoparticles of size less than 30 nm were observed in transmission electron microscopy. X-ray diffraction pattern corresponding to 111, 200, 220, and 311 revealed the crystalline nature of the as-formed nanoparticles. It was found that the colloidal solution of AgNP suspensions exhibited excellent stability over a wide range of ionic strength, pH, and temperature. The effect of pH and ionic strength indicated that stabilization is due to electrostatic repulsion arising from the negative charge of the conjugate proteins. The AgNPs showed highly potent antimicrobial activity against Gram-positive, Gram-negative, and fungal microorganisms. The as-prepared AgNPs showed excellent catalytic activity in reduction of 4-nitrophenol to 4-aminophenol by NaBH₄. By manufacturing magnetic alginate beads, the reusability of the AgNPs for the catalytic reaction has been demonstrated.     

Toward a new understanding of the links between poverty and illegal wildlife hunting

Conservation organizations have increasingly raised concerns about escalating rates of illegal hunting and trade in wildlife. Previous studies have concluded that people hunt illegally because they are financially poor or lack alternative livelihood strategies. However, there has been little attempt to develop a richer understanding of the motivations behind contemporary illegal wildlife hunting. As a first step, we reviewed the academic and policy literatures on poaching and illegal wildlife use and considered the meanings of poverty and the relative importance of structure and individual agency. We placed motivations for illegal wildlife hunting within the context of the complex history of how wildlife laws were initially designed and enforced to indicate how hunting practices by specific communities were criminalized. We also considered the nature of poverty and the reasons for economic deprivation in particular communities to indicate how particular understandings of poverty as material deprivation ultimately shape approaches to illegal wildlife hunting. We found there is a need for a much better understanding of what poverty is and what motivates people to hunt illegally.