PAHs Contamination in Bank Sediment of the Yamuna River, Delhi, India

This study was performed to elucidate the distribution, concentration trend and possible sources of PAHs in bank sediment of river Yamuna in Delhi, India. The levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were analyzed during pre-monsoon, monsoon and post-monsoon seasons in the sediment fraction < 53 μm. Reference standards and internal standards were used for identification and quantification of PAHs by HPLC. The sum of 16 PAH compounds ranged from 4.50 to 23.53 μg/g with a mean concentration of 10.15 ± 4.32 μg/g (dry wt.). Among 5 sites studied, the site, Income Tax Office (ITO) was found to be the hotspot attaining highest concentration. Predominance of 2–4 ring PAHs suggests a relatively recent local sources of PAHs in the study area. Moreover, molecular indices based source apportionment also illustrates pyrogenic source fingerprint of PAHs. No significant temporal trend was observed.     

Preparation of 2-mercaptobenzothiazole-derivatized mesoporous silica and removal of Hg(ii) from aqueous solution

Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second reaction a multifunctionalized N,S donor compound (2-mercaptobenzothiazol) was incorporated to obtain the functionalized silicas denoted as MBT-SBA-15-Het and MBT-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MBT-SBA-15-Hom or MBT-MCM-41-Hom. The functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions at pH 6 contaminated with Hg(ii) at room temperature. Results obtained indicate that mercury adsorption was higher in the mesoporus silicas prepared by the homogeneous method, and the maximum adsorption value (0.24 +/- 0.02 mmol Hg(ii) g(-1)) was obtained for MBT-SBA-15-Hom. The chemically stability in acid medium of the functionalized silicas, possibility its regeneration washing with concentrate HCl, resulting in the reuse of the adsorbent material for several cycles.     

SAOZ measurements of NO2 at Aberystwyth

We present in this paper fifteen years' measurements, from March 1991 to September 2005, of stratospheric NO2 vertical columns measured by a SAOZ zenith-sky visible spectrometer. The instrument spent most of its time at Aberystwyth, Wales, with occasional excursions to other locations. The data have been analysed with the WinDOAS analysis program with low-temperature high-resolution NO2 cross-sections and fitting a slit function to each spectrum. Because of a change in detector in May 1998 there is some uncertainty about the relative changes before and after this date, which are partially constrained by the results of an intercomparison exercise. However, the effect of the Mt Pinatubo aerosol cloud is very evident in the data from 1991-94, with a decrease of 10% in NO2 in the summer of 1992 (the SAOZ was located in Lerwick, Scotland during the winter of 1991-92 and observed very low NO2 values but these cannot be directly compared to the Aberystwyth data). To focus more on interannual and long-term variations in NO2, a seasonal variation comprising an annual and semi-annual component was fitted to the morning and evening twilight separately from 1995 to the present. This fit yielded average NO2 columns of 4.08 x 10(15) cm(-2) and 2.68 x 10(15) cm(-2) for the evening and morning twilight, respectively, with a corresponding annual amplitude of +/-2.08 x 10(15) cm(-2) and +/-1.50 x 10(15) cm(-2). Departures from the fitted curve show a trend of 6% per decade, consistent with that reported elsewhere, for the period 1998-2003, but in the past two years a distinct interannual variation of amplitude of approximately 8% has emerged.     

Community-Based Environmental Management in Atlantic Canada: The Impacts and Spheres of Influence of the Atlantic Coastal Action Program

The Atlantic Coastal Action Program (ACAP) is a unique, community-based program initiated by Environment Canada in 1991 to help Atlantic Canadians restore and sustain watersheds and adjacent coastal areas. ACAP is the eastem-most Environment Canada Ecosystem Initiative. The ACAP family is currently made up of 14 ecosystem-based organizations in the four Atlantic provinces. Each one of these non-profit organizations operates independently, but is formally linked under the umbrella of ACAP to represent a force stronger than the individual parts. In Environment Canada's experience, the program consistently demonstrates the value of a community-based approach and produces results on an ecosystem basis. This paper will examine some of the impacts of ACAP in terms of economics, credible community science, and environmental results which most often align with Environment Canada's objectives. It will explore the influences of the community-based approach to environmental management on multiple scales (local, regional, etc.). Through examples, the paper will demonstrate the effectiveness of ACAP in influencing some of the policies, programs and attitudes of various levels of government and industry in the region, as well as describe how the community-based model has been exported internationally. The paper will conclude with a discussion on a planned path forward for ACAP.     

A Simulation Study to Assess the Sensitivity of a Forest Health Monitoring Network to Outbreaks of Defoliating Insects

The sensitivity of the United States Forest Health Monitoring network to outbreaks of defoliating insects was examined by means of a simulation study. A model constructed specifically for the study was used to generate a wide variety of defoliation patterns in forested landscapes. Forest configuration was that of Minnesota, USA, as expressed by the GAP land cover classification. Combinations of model parameters were based on a Latin Hypercube sample. The relationship between the average number of plots defoliated and outbreak characteristics was then examined via multiple regression. Both theoretical and model results pointed to a strong, linear relationship between the average number of plots defoliated and outbreak size. Model results provided additional insight, suggesting a significant relationship between the average number of plots defoliated and other outbreak characteristics after outbreak size was taken into account.     

Organochlorine Pesticide Residues in Milk and Blood of Women from Anupgarh, Rajasthan, India

Anupgarh is the most fertile area of Rajasthan state where a variety of seasonal crops are grown. The availability of three manmade canals has enhanced the agricultural activities in this area. The farmers use huge amounts of pesticides to increase the crop productivity. Exposure of humans to these hazardous chemicals occurs directly in the fields and indirectly due to consumption of contaminated diet, or by inhalation or by dermal contact. The organochlorine pesticides are reported to be lipophilic and their presence in human milk and blood has been documented in different parts of the world. Blood and milk samples were collected from lactating women who were divided into four groups on the basis of different living standards viz residence area, dietary habits, working conditions and addiction to tobacco. The level of total organochlorine pesticides in blood ranged from 3.319mg/L—6.253mg/L while in milk samples it ranged from 3.209Mdash;4.608 mg/L. The results are in concurrence with the reports from other countries.     

Kinetics and thermodynamic studies of Methyl Orange removal by polyvinylidene fluoride-PEDOT mats

We report the preparation of poly(3,4-ethylene dioxythiophene) (PEDOT)-modified polyvinylidene fluoride electrospun fibers and their use as a novel adsorbent material for the removal of the anionic dye Methyl Orange (MO) from aqueous media. This novel adsorbent material can be used to selectively remove MO on a wide pH range (3.0–10.0), with a maximum capacity of 143.8 mg/g at pH 3.0. When used in a recirculating filtration system, the maximum absorption capacity was reached in a shorter time (20 min) than that observed for batch mode experiments (360 min). Based on the analyses of the kinetics and adsorption isotherm data, one can conclude that the predominant mechanism of interaction between the membrane and the dissolved dye molecules is electrostatic. Besides, considering the estimated values for the Gibbs energy, and entropy and enthalpy changes, it was established that the adsorption process is spontaneous and occurs in an endothermic manner. The good mechanical and environmental stability of these membranes allowed their use in at least 20 consecutive adsorption/desorption cycles, without significant loss of their characteristics. We suggest that the physical-chemical characteristics of PEDOT make these hybrid mats a promising adsorbent material for use in water remediation protocols and effluent treatment systems.     

A kinetic analysis of solid waste composting at optimal conditions

Six municipal solid waste (MSW) and yard waste components (food waste, mixed paper, yard waste, leaves, branches, grass clippings) were aerobically decomposed to measure the extent of decomposition under near optimal conditions. Decomposition was characterized by at least two principal stages, for most components, as was indicated by the carbon dioxide production rates. An aerobic biodegradation conceptual model is presented here based on the principle that solids hydrolysis is the rate-limiting step during solid waste composting. The mineralizable solid carbon of each solid waste component was assumed to comprise the readily, the moderately and the slowly (or refractory) hydrolysable carbons, each hydrolyzing at different rates to aqueous (water soluble) carbon. Aqueous carbon mineralizes to CO2 at rapid rates that are not rate-limiting to the process. Solids hydrolysis rate constants were calculated after fitting the experimentally determined carbon dioxide production rate data to model results. Hydrolysis rates for the readily hydrolysable carbon in all components ranged from approximately 0.06 to 0.1 d(-1); hydrolysis rates for the moderately hydrolysable carbon ranged from 0.005 to 0.06 d(-1). Leaves, branches and grass clippings did not have a readily hydrolysable carbon fraction, whilst the leaves and branches had the largest slowly hydrolysable carbon fractions (70%, 82%, respectively, of the total solid organic carbon). Grass and yard waste did not contain slowly hydrolysable carbon fractions. Food waste had the largest readily hydrolysable carbon fraction and produced the highest amount of CO2 among all substrates. Moderately hydrolysable solid carbon fractions ranged from 16% to 90% of the total solid organic carbon for all substrates used.     

Modelling Phosphorus Retention in Lakes and Reservoirs

Steady-state models for the prediction of P retention coefficient (R) in lakes were evaluated using data from 93 natural lakes and 119 reservoirs situated in the temperate zone. Most of the already existing models predicted R relatively successfully in lakes while it was seriously under-estimated in reservoirs. A statistical analysis indicated the main causes of differences in R between lakes and reservoirs: (a) distinct relationships between P sedimentation coefficient, depth, and water residence time; (b) existence of significant inflow–outflow P concentration gradients in reservoirs. Two new models of different complexity were developed for estimating R in reservoirs: , where τ is water residence time (year), was derived from the Vollenweider/Larsen and Mercier model by adding a calibrated parameter accounting for spatial P non-homogeneity in the water body, and is applicable for reservoirs but not lakes, and , where [P_in] is volume-weighted P concentration in all inputs to the water body (μg l⁻¹), was obtained by re-calibrating the OECD general equation, and is generally applicable for both lakes and reservoirs. These optimised models yield unbiased estimates over a large range of reservoir types.     

Implications of changing national policies on land use in the Chittagong Hill Tracts of Bangladesh

Land use in the Chittagong Hill Tracts (CHT) of Bangladesh had undergone changes over the past several centuries. The landscape, which was mostly covered with forest with interspersed shifting cultivation plots until the beginning of the colonial period, has gradually changed into a landscape with a blend of land uses. Overall, the forest area has gradually declined, while the area under shifting cultivation and sedentary agriculture has expanded. The process of the change was multi-directional. National forestry, land use, land taxation, population migration policies, and development activities, such as construction of a hydroelectric dam and roads, played an important role in this process. Shifting cultivation had inflicted little damage on the forest until the beginning of the colonial period. The pace of deforestation accelerated with the nationalization of forests which abolished tribal people's customary use and management rights to the forest, and allowed large-scale commercial logging both legally and illegally. The pace was further intensified by the policy encouraging population migration to CHT and construction of a reservoir on the Karnafuli River. Efforts were made to replace shifting cultivation with more productive types of sedentary agriculture. However, much change could not take place in the absence of secure land rights, supportive trade policies, and the required support services and facilities, including infrastructure. Locationally suitable land use evolved in areas where transportation facilities were available and farmers were granted land title with the necessary extension services and credit facilities. These findings have important policy implications for the promotion of environmentally and economically sound land use in CHT.