Computational analysis of turbulence enhancement in a compression ignition engine with modified inlet design

Environmental Science and Pollution Research - This study aims to enhance the turbulence of direct injection (DI) diesel engine by modifying the inlet manifold design with an inclined nozzle-like...     

Macrobenthos response to sewage pollution in a tropical inshore area

Organic sewage pollution is the major stressor that affects benthic communities in the coastal waters. In the present study involving a once-off sampling (July–August 2003) of a sewage treatment plant (STP) outfall and areas 6 km farther into the sea, we tried to estimate the severity of organic pollution on marine macrobenthos over a pollution gradient in the inshore waters (station depths, 5–30 m) off a heavily urbanized tropical city, on the east coast of India. Multivariate ordination analyses revealed two different groups of faunal assemblages. Group I is associated with sites impacted by the sewage outfall and group II with the locations 3–6 km away in the open sea. Polychaetes and amphipods were the predominant fauna with significant taxonomic differences between the assemblages. Despite the homogeneity in sediment texture, the two-fold increase in sediment organic matter near the sewage outfall area supported r-strategists, while group II locations favoured K-strategists. Approximation through benthic opportunistic polychaetes amphipods (BOPA) index and information on the key taxa responsible for the observed assemblage patterns corroborated these findings. Thus, the present findings revealed how organic sewage pollution influences benthic diversity in coastal waters by supporting communities of opportunistic characteristics. We advocate inclusion of community traits and compatible analytical tools (statistical approaches) in studies of similar nature so that the observations could be compared and broad remedial measures could be evolved.     

Effects of transgenic Bt cotton on soil fertility and biology under field conditions in subtropical inceptisol

Although there is large-scale adoption of Bt cotton by the farmers because of immediate financial gain, there is concern that Bt crops release Bt toxins into the soil environment which reduces soil chemical and biological activities. However, the majorities of such studies were mainly performed under pot experiments, relatively little research has examined the direct and indirect effects of associated cover crop of peanut with fertilization by combined application of organic and inorganic sources of nitrogen under field conditions. We compared soil chemical and biological parameters of Bt cotton with pure crop of peanut to arrive on a valid conclusion. Significantly higher dehydrogenase enzyme activity and KMnO₄-N content of soil were observed in Bt cotton with cover crop of peanut over pure Bt cotton followed by pure peanut at all the crop growth stages. However, higher microbial population was maintained by pure peanut over intercropped Bt cotton, but these differences were related to the presence of high amount of KMnO₄-N content of soil. By growing cover crop of peanut between Bt cotton rows, bacteria, fungi, and actinomycetes population increased by 60%, 14%, and 10%, respectively, over Bt cotton alone. Bt cotton fertilized by combined application of urea and farm yard manure (FYM) maintained higher dehydrogenase enzyme activity, KMnO₄-N content of soil and microbial population over urea alone. Significant positive correlations were observed for dry matter accumulation, dehydrogenase enzyme activity, KMnO₄-N content, and microbial population of soil of Bt cotton, which indicates no harmful effects of Bt cotton on soil biological parameters and associated cover crop. Our results suggest that inclusion of cover crop of peanut and FYM in Bt cotton enhanced soil chemical and biological parameters which can mask any negative effect of the Bt toxin on microbial activity and thus on enzymatic activities.     

Corrigendum

Corrigendum

Corrigendum     

Assessment of Calibration Parameters for an Aerial Gamma Spectrometry System using Monte-Carlo Technique

During a radiation emergency subsequent to a nuclear accident orweapon fallout, quick assessment of the ground contamination andthe resulting exposure is of prime importance in planning and execution of effective counter measures. For an online assessmentof ground contamination, it is essential to calibrate the detector system for several parameters viz. the source energy,source deployment matrix, the flight altitude and position abovethe contaminated surface. This article discusses the methodology to predict all the necessary parameters like photon fluence atvarious altitudes, the photo-peak counts in different energy windows, Air to Ground Correlation Factors (AGCF) and the doserate at any height due to air scattered gamma ray photons. Themethodology includes generation of theoretically simulated gammaspectra at a required detector position for a given source distribution on the ground using Monte-Carlo method provided by general purpose coupled neutron/photon transport code (MCNP CCC-200). Thus generated gamma spectra are analyzed to arrive at the required parameters mentioned above.     

Zooplankton community structure across an eddy-generated upwelling band close to a tropical bay-mangrove ecosystem

Mesoscale eddies in the world’s oceans are ubiquitous and bring about episodic pulses of nutrients into the photic zone. Transient in nature, the role of eddy pumping in coastal enrichment via plankton production, and subsequent organic flux is not yet fully realised. In the context of a cyclonic cold-core eddy that propagates annually under the influence of the East India Coastal Current and enriches coastal waters in the western Bay of Bengal north of 16°N, a detailed study on zooplankton community structure along with phytoplankton composition and associated water quality was undertaken during April–May 2002 coinciding with the spring intermonsoon. Zooplankton samples were collected at 32 hydrographically different (salinity 24.5–35.6 PSU) GPS fixed locations representing bay-mangrove areas and nearshore waters (30 m) close to the River Godavari, which is one of India’s largest estuarine systems. During the study, the bay-coastal waters were typified by elevated nutrient levels (nitrate 10.73–22.04 μM), high salinity (27.98–35.52 PSU), and relatively low temperatures (30.63–31.40°C). Altogether, 95 zooplankton taxa were encountered with copepods forming the predominant population. Agglomerative Hierarchical Cluster Analysis (AHCA) and Non-metric Multidimensional Scaling (NMDS) based on Bray–Curtis similarity (PRIMER) analysis revealed appreciable alterations in zooplankton structure across bay-mangrove locations and coastal waters (Stress 0.11; ANOSIM test Global R: 0.94, P = 0.1%). Similarity Percentage (SIMPER) analysis revealed zooplankton associations through “discriminating species” for each location (Kakinada Bay, Cluster I, 27.9 ± 3.0 PSU; upwelling band, cluster II, 35.5 ± 0.2 PSU; offshore waters, cluster III, 34.2 ± 0.4 PSU; mangrove outlets, cluster IV, 32.7 ± 1.3 PSU and mangrove creeks, cluster V, 33.5 ± 0.6 PSU). The index of multivariate dispersion (IMD) illustrated high variability in zooplankton standing stock for mangrove/sea locations relative to the bay. Concurrent observations on phytoplankton revealed the importance of diatoms (r: 0.640, P ≤ 0.05). Within the eddy-generated band of upwelled water, a significant top-down control of diatoms by herbivorous zooplankton resulted in a comparative increase in abundance of dinophyceans. Based on zooplankton abundance data and species association patterns, it was possible to distinguish different zooplankton/copepod communities in accordance with mesoscale variability in physical, chemical and biological processes under tropical conditions. This was confirmed through canonical correspondence analysis (CCA) that represented coastal-offshore waters and the Bay environment in this area.     

Airborne black carbon concentrations over an urban region in western India—temporal variability, effects of meteorology, and source regions

This study characterizes over 5 years of high time resolution (5 min), airborne black carbon (BC) concentrations (July 2003 to December 2008) measured over Ahmedabad, an urban region in western India. The data were used to obtain different time averages of BC concentrations, and these averages were then used to assess the diurnal, seasonal, and annual variability of BC over the study region. Assessment of diurnal variations revealed a strong association between BC concentrations and vehicular traffic. Peaks in BC concentration were co-incident with the morning (0730 to 0830, LST) and late evening (1930 to 2030, LST) rush hour traffic. Additionally, diurnal variability in BC concentrations during major festivals (Diwali and Dushera during the months of October/November) revealed an increase in BC concentrations due to fireworks displays. Maximum half hourly BC concentrations during the festival days were as high as 79.8 μg m^?3. However, the high concentrations rapidly decayed suggesting that local meteorology during the festive season was favorable for aerosol dispersion. A multiple linear regression (MLR) model with BC as the dependent variable and meteorological parameters as independent variables was fitted. The variability in temperature, humidity, wind speed, and wind direction accounted for about 49% of the variability in measured BC concentrations. Conditional probability function (CPF) analysis was used to identify the geographical location of local source regions contributing to the effective BC measured (at 880 nm) at the receptor site. The east north-east (ENE) direction to the receptor was identified as a major source region. National highway (NH8) and two coal-fired thermal power stations (at Gandhinagar and Sabarmati) were located in the identified direction, suggesting that local traffic and power plant emissions were likely contributors to the measured BC.     

Protein Metabolic Response to Carbon Tetrachloride in A Freshwater Fish, Sarotherodon Mossambicus

Exposure of a freshwater teleost, Sarotherodon mossambicus, to a sublethal concentration (26 ppm) of carbon tetrachloride for periods up to 30 days led to significant changes in the soluble protein fractions (albumin and globulins) and free amino acid content. the decrease in total protein content was greater in liver than in muscle. the protein loss was expected due to the impairement of protein synthetic activity during stress conditions.     

Analysis of climate trends in North Carolina (1949-1998)

North Carolina has one of the most complex climates in the United States (U.S.). Analysis of the climate in this state is critical for agricultural and planning purposes. Climate patterns and trends in North Carolina are analyzed for the period 1949-1998. Precipitation, minimum temperature, and maximum temperature are analyzed on seasonal and annual time scales using data collected from the National Weather Service Cooperative Observer Network. Additionally, changes in patterns of occurrence of the last spring freeze and first fall freeze are investigated. Linear time series slopes are analyzed to investigate the spatial and temporal trends of climate variability in North Carolina. Spatial analysis of climate variability across North Carolina is performed using a geographic information system.While most trends are local in nature, there are general statewide patterns. Precipitation in North Carolina has increased over the past 50 years during the fall and winter seasons, but decreased during the summer. Temperatures during the last 10 years are warmer than average, but are not warmer than those experienced during the 1950s. The warm season has become longer, as measured by the dates of the last spring freeze and first fall freeze. Generally, the last 10 years were the wettest of the study period.These conclusions are consistent with earlier studies that show that the difference between the maximum and minimum temperatures is decreasing, possibly due to increased cloud cover and precipitation. Similarly, these results show that temperature patterns are in phase with the North Atlantic Oscillation and precipitation patterns appear to be correlated with the Pacific Decadal Oscillation.