Interaction of free-living marine nematodes in the artificial mangrove environment (southeast coast of India)

Free-living marine nematode diversity was analyzed between Avicennia marina and Rhizophora mucronata mangrove covers of the Vellar Estuary (southeast coast of India). A total of 4,976 specimens of free-living marine nematodes were collected in 56 species. Comparatively, a higher species richness was obtained for A. marina (52 species) than for R. mucronata (44 species), whereas 40 species commonly existed in both mangrove covers. A higher density of nematodes was found in sediments of sandy nature, whereas there was lower total organic carbon compared to silt/clay composition; epigrowth feeders were dominant over the other feeding groups based on organic enrichment in surface sediments. Principal component analysis clearly explained the relationship between the environmental parameters of various months. Higher R values of analysis of similarities revealed significant differences in nematode assemblages between months, and it was quite evident by non-metric multidimensional scaling. Diversity indices showed higher values in the dry months. RELATE analysis explained serial changes in nematode species composition between months, and a relationship between biotic and abiotic variables was clarified using the BIO-ENV procedure. Viscosia spp., Metachromadora spp., Theristus spp., and Sphaerolaimus spp. were candidate species of A. marina leaf interaction by observation.     

Heavy metal enrichment in the seagrasses of Lakshadweep group of islands—A multivariate statistical analysis

An assessment on heavy metal (Al, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn) accumulation by seven seagrass species of Lakshadweep group of islands was carried out using multivariate statistical tools like principal component analysis (PCA) and cluster analysis (CA). Among all the metals, Mg and Al were determined in higher concentration in all the seagrasses, and their values varied with respect to different seagrass species. The concentration of the four toxic heavy metals (Cd, Pb, Zn and Cu) was found higher in all the seagrasses when compared with the background values of seagrasses from Flores Sea, Indonesia. The contamination factor of these four heavy metals ranged as Cd (1.97–12.5), Cu (0.73–4.40), Pb (2.3–8.89) and Zn (1.27–2.787). In general, the Pollution Load Index (PLI) calculated was found to be maximum for Halophila decipiens (58.2). Results revealed that Halophila decipiens is a strong accumulator of heavy metals, followed by Halodule uninervis and Halodule pinifolia, among all the tested seagrasses. Interestingly, the small-leaved seagrasses were found to be efficient in heavy metal accumulation than the large-leaved seagrass species. Thus, seagrasses can better be used for biomonitoring, and seagrasses can be used as the heavy metal sink as the biomass take usually long term to get remineralize in nature.     

Ecotoxicological effects of trace element contamination in talitrid amphipod Orchestia montagui Audouin, 1826

Environmental Science and Pollution Research - This study deals with the evaluation of trace element bioaccumulation and histological alterations in the hepatopancreas of the supralittoral amphipod...     

Petroleum hydrocarbon concentrations in ten commercial fish species along Tamilnadu coast,Bay of Bengal,India

Background, aim, and scope  

The aim of the present study was to evaluate the distribution of petroleum hydrocarbons in ten commercial fish species and water samples in three estuaries along Tamilnadu coast, Bay of Bengal, India.     

Preliminary investigation on the impact of engineered PVP-capped and uncapped silver nanoparticles on Eudrilus eugeniae,a terrestrial ecosystem model

Environmental Science and Pollution Research - Recently, the production of silver nanoparticles and their commercial products has generated increased concern and caused a hazardous impact on the...     

Impact of hydrogeochemical processes and its evolution in controlling groundwater chemistry along the east coast of Tamil Nadu and Puducherry,India

Environmental Science and Pollution Research - The present study area falls beside the coastal zone of Tamil Nadu, and Puducherry is characterized by varied geological formations that mostly...     

Experimental investigation on mechanical and metallurgical properties of super duplex stainless steel joints using friction welding process

Friction welding is one of the most economical and highly practicable methods in joining similar and dissimilar metals. In this study, high-quality welds are produced in the super duplex stainless steel by continuous drive friction welding successfully. Design of experiment was done using central composite design of response surface methodology. In the present work, the microstructure and mechanical properties of friction welded super duplex stainless steel (UNS S32760) were examined. The base material has a microstructure consisting of the ferrite matrix with austenite islands. Ferrite content was analyzed through the phase analyzer software and found that it is in the range of 42–55% in all weld metals. The phases were further analyzed through X-ray diffraction method. All the weld metals have higher hardness than the base metals. Weld transverse tensile failures consistently occurred away from the weld zone and exhibit more hardness, yield and ultimate tensile strengths than the base material. The austenite content increases with nitrogen concentration. Nitrogen could enhance the yield stress and ultimately tensile strength of super duplex stainless steel. Secondary phase precipitation is not observed in the welded joint probably due to the shorter heating times.     

Uptake of Aromatic Hydrocarbon Vapors (Benzene and Phenanthrene) at the Air-Water Interface of Micron-Size Water Droplets

Abstract

Uptake of aromatic hydrocarbon vapors (benzene and phenanthrene) by typical micrometer-sized fog-water droplets was studied using a falling droplet reactor at temperatures between 296 and 316 K. Uptake of phenan-threne vapor greater than that predicted by bulk (air-water)-phase equilibrium was observed for diameters less than 200 μm, and this was attributed to surface adsorption. The experimental values of the droplet-vapor partition constant were used to obtain the overall mass transfer coefficient and the mass accommodation coefficient for both benzene and phenanthrene. Mass transfer of phenanthrene was dependent only on gas-phase diffusion and mass accommodation at the interface. However, for benzene, the mass transfer was limited by liquid-phase diffusion and mass accommodation. A large value of the mass accommodation coefficient, α = (1.4 ± 0.4) × 10^?2 was observed for the highly surface-active (hydrophobic) phenanthrene, whereas a small α = (9.7 ± 1.8) × 10^?5 was observed for the less hydrophobic benzene. Critical cluster numbers ranging from 2 for benzene to 5.7 for phenanthrene were deduced using the critical cluster nucleation theory for mass accommodation. The enthalpy of mass accommodation was more negative for phenanthrene than it was for benzene. Consequently, the temperature effect was more pronounced for phenanthrene. A linear correlation was observed for the enthalpy of accommodation with the excess enthalpy of solution. A natural organic carbon surrogate (Suwannee Fulvic acid) in the water droplet increased the uptake for phenanthrene and benzene, the effect being more marked for phenanthrene. A characteristic time constant analysis showed that uptake and droplet scavenging would compete for the fog deposition of phenanthrene, whereas deposition would be unimpeded by the uptake rate for benzene vapor. For both compounds, the characteristic atmospheric reaction times were much larger and would not impact fog deposition.     

The role of soil humic and fulvic acid in the sorption of endosulfan (alpha and beta)

The sorption behaviour of alpha- and beta-endosulfan in soil organic matter was investigated using standard soil humic acid (HA) and soil fulvic acid (FA) with a modified solubility enhancement method and a dialysis bag technique. For HA, all the experiments were conducted at an ionic strength of 0.001 mol/L, in both the presence and absence of calcium and at an ionic strength of 0.01 mol/L. For FA, the experiments were conducted at two ionic strengths: 0.001 mol/L (with calcium) and 0.01 mol/L. This study is the first to describe the striking differences in the sorption behaviours of the two stereoisomers of endosulfan in HA and in FA. The sorption coefficients of alpha-endosulfan in HA and FA were significantly higher than those of beta-endosulfan. Beta-endosulfan has comparable sorption coefficients (1.5–5.4 L/g) in HA and in FA. Ionic strength and the presence of calcium have no significant effect on the sorption of beta-endosulfan in HA. However, calcium can significantly (p=0.01) enhance the solubility of alpha-endosulfan in HA. Changes in ionic strength by one order of magnitude also affect the solubility of alpha-endosulfan in HA. The sorption coefficients of alpha-endosulfan in HA (10–36 L/g) were greater than those in FA (9–14 L/g). The chirality of the alpha-isomer was hypothesised to be the primary reason behind its higher sorption in soil organic matter relative to the beta-isomer. In the presence of dissolved HA and FA found in natural soil environments, solubility of endosulfan can be increased by five times than the aqueous solubility of endosulfan without HA and FA.     

Hepatoprotective and antioxidant effects of Bridelia retusa against carbon tetrachloride-induced hepatotoxicity

The aim of present study was to validate hepatoprotective and antioxidant activities of the bark of Bridelia retusa. The aqueous ethanol extract of B. retusa exhibited highest in vitro hepatoprotective effects as evident from the significantly reduced serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) into the incubation medium of rat hepatocytes with carbon tetrachloride (CCl₄), over the other organic extracts (chloroform, ethylacetate, and methanol). CCl₄ administered through subcutaneous injection produced a marked elevation in the serum levels of GOT, GPT, lactate dehydrogenase, alkaline phosphatase, bilirubin, thiobarbituric acid reactive substances, and decreased in the levels of reduced glutathione, superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and total protein content. The biochemical activities were normalized in the pretreatment of rats induced by CCl₄ with different doses (250 and 500 mg kg^?1) of the aqueous ethanol extract of B. retusa. Histopathological changes induced by CCl₄ were also significantly attenuated by aqueous ethanol extract of B. retusa treatment. The activity of the aqueous ethanol extract of B. retusa at the dose of 500 mg kg^?1 was comparable to the standard drug, silymarin (25 mg kg^?1). The overall data indicated that B. retusa possesses a potent protective effect against CCl₄-induced hepatic damage and oxidative stress.