Anaerobic degradation of naphthalene in a fluvial aquifer: a radiotracer study

A radiotracer study was conducted in a creosote-contaminated aquifer beneath the Fraser River, British Columbia Canada to investigate the in situ degradation of naphthalene. The groundwater is anaerobic, with abundant methane, ferrous iron and carbon dioxide. This study followed earlier work at the site where the contaminant distribution could only be explained by invoking a mass loss through degradation, even though extensive field and laboratory microcosm studies closer to the source zone onshore could not confirm degradation. Accordingly, 14C-naphthalene was injected into the aquifer offshore, further from the source zone where modeling suggested degradation was occurring. During the 230-day monitoring period, 14CO2 was detected, confirming the degradation of the radio-labeled naphthalene tracer. A zero-order degradation rate of naphthalene of 5 microg/L-day was estimated based on the decrease in 14C-naphthalene concentration with time. While the degradation pathway could not be determined from the radiotracer study alone, the geochemistry of the site suggests that either iron reduction or methanogenesis is the terminal electron accepting processes responsible for naphthalene oxidation.     

Derivation of a household-level vulnerability index for empirically testing measures of adaptive capacity and vulnerability

Recent studies have projected significant climate change impacts in Africa. In order to understand what this means in terms of human well-being at local level, we need to understand how households can cope and adapt. This need has led many authors to argue for approaches to adaptation that are based on vulnerability analysis. Vulnerability is one of the key terms in the climate change literature, but little progress has been made in the field of its quantification. Typically, indicators are combined according to a weighing scheme, with the identification of indicators and the weighing schemes based on expert judgment rather than empirical evidence. In addition, most quantitative assessments are applied to countries or other administrative units, whereas managing climate risk has traditionally been the responsibility of households. We therefore focus on the adaptive capacity of households. We analyze the coping strategies and vulnerability to climatic stresses of agro-pastoralists in Mozambique and test the validity of a number of commonly used vulnerability indicators. We derive a household-level vulnerability index based on survey data. We find that only 9 out of 26 indicators tested exhibit a statistically significant relationship with households’ vulnerability. In total, they explain about one-third of the variation in vulnerability between households, confirming the need for more research on underlying determinants and processes of vulnerability. With inclusion of local knowledge, our study findings can be used for local targeting, priority setting and resource allocation. Complemented with studies analyzing climate change impacts and findings from country-level adaptive capacity studies, governmental policy can be informed.     

Illicit crops and armed conflict as constraints on biodiversity conservation in the Andes region

Coca, once grown for local consumption in the Andes, is now produced for external markets, often in areas with armed conflict. Internationally financed eradication campaigns force traffickers and growers to constantly relocate, making drug-related activities a principal cause of forest loss. The impact on biodiversity is known only in general terms, and this article presents the first regional analysis to identify areas of special concern, using bird data as proxy. The aim of conserving all species may be significantly constrained in the Santa Marta and Perijá mountains, Darién, some parts of the Central Andes in Colombia, and between the middle Mara?ón and middle Huallaga valleys in Peru. Solutions to the problem must address the root causes: international drug markets, long-lasting armed conflict, and lack of alternative income for the rural poor.     

Modeling inorganic aerosols and their response to changes in precursor concentration in Mexico City

Based on data from the 1997 Investigación sobre Materia Particulada y Deterioro Atmosférico-Aerosol and Visibility Evaluation Research (IMADA-EVER) campaign and the inorganic aerosol model ISORROPIA, the response of inorganic aerosols to changes in precursor concentrations was calculated. The aerosol behavior is dominated by the abundance of ammonia and thus, changes in ammonia concentration are expected to have a small effect on particle concentrations. Changes in sulfate and nitrate are expected to lead to proportional reductions in inorganic fine particulate matter (PM2.5). Comparing the predictions of ISORROPIA with the observations, the lowest bias and error are achieved when the aerosols are assumed to be in the efflorescence branch. Including crustal species reduces the bias and error for nitrate but does not improve overall model performance. The estimated response of inorganic PM2.5 to changes in precursor concentrations is affected by the inclusion of crustal species in some cases, although average responses are comparable with and without crustal species. Observed concentrations of particle chloride suggest that gas phase concentrations of hydrogen chloride may not be negligible, and future measurement campaigns should include observations to test this hypothesis. Our ability to model aerosol behavior in Mexico City and, thus, design control strategies, is constrained primarily by a lack of observations of gas phase precursors. Future campaigns should focus in particular on better understanding the temporal and spatial distribution of ammonia concentrations. In addition, gas phase observations of nitric acid are needed, and a measure of particle water content will allow stable versus metastable aerosol behavior to be distinguished.     

Comparative studies on the concentrations of some elements in the urban air particulate matter in Lodz City of Poland and in Milan,Italy

Urban air particulate matter (APM) was collected at two sampling sites in the city of Lodz, Poland in March, May and July 2001. The concentrations of several trace elements (TEs) as well as heavy metals were determined by neutron activation analysis (NAA). It was found that for many elements, the contribution of the blank values arising from the filtering material is very high, especially for glass fiber filters. The results obtained for Lodz were compared to those obtained for Milan, Italy. The data of Lodz are, in general, lower than those found in Milan downtown in the winter season. The influence of three coal-fired power plants located within the city of Lodz on the concentration of trace elements in APM was also considered.     

Multiple regression analysis of the sources of variation in orientation of two sympatric sandhoppers, <Emphasis Type="Italic">Talitrus saltator</Emphasis> and <Emphasis Type="Italic">Talorchestia brito</Emphasis>, from an exposed Mediterranean beach

Two sympatric species from an exposed sandy beach in north-western Tunisia, the sandhoppers Talitrus saltator (Montagu) and Talorchestia brito Stebbing, were compared as regards orientation under natural conditions. Sets of experiments were carried out on the beach using two experimental arenas, one permitting the view of both the sky and landscape and the other of the sky only. Replicates were made at different hours of the day, in different days and period of the year and with various climatic conditions. Multiple regression models were fitted to the angular data obtained. These models allow an estimate of the trends of variation depending on a combination of factors. The simultaneous effects of environmental factors influencing orientation were quantified for each species. The sun was confirmed as the major orientation cue in these populations, but the concentration of directional choices was enhanced by the landscape vision. The climatic factors affected orientation in different ways depending on the time of day and year. When the two species were compared, Talitrus saltator showed a higher flexibility of response than Talorchestia brito under the same environmental conditions, supporting the hypothesis of a higher level of terrestrialization of the former species.