Visitor impact on rocky shore communities of Qeshm Island, the Persian Gulf, Iran

The influence of visitors on macroinvertebrates of rocky intertidal shores was investigated in southern coasts of the Qeshm Island, the Persian Gulf, Iran. Qeshm Island located at the Strait of Hormuz, with an area of 1,491 km², is the largest island in the region. This island consists of a number of important natural habitat types including creeks, mangroves, corals, and sandy, muddy, and rocky shores that accommodate diverse marine flora and fauna communities. Two rocky shores were selected at the touristic beaches being visited regularly, and further two control locations selected at pristine shores. Intertidal macroinvertebrates were collected from six microhabitats including rock platforms, cobbles, boulders, crevices, sea walls, and rock pools during two different periods representing high and low tourist seasons. Species richness, density, and assemblage structure in heavily visited shores were compared with that of control locations. Striped barnacles (Balanus amphitrite) were present on platforms of all locations, thus the changes in their size were used as the obvious contrast associated with visitor’s impact. A total of 70 macroinvertebrate species from 11 phyla were recorded. Significant differences were detected in taxonomic richness, density, and assemblage structure of macroinvertebrates between heavily visited and pristine shores, suggesting that macroinvertebrates were adversely affected by visitors’ impact at heavily visited shores. The test of changes in species richness, density, and assemblage structure from high to low seasons yielded mixed results. The significant changes in density and assemblage structure from high to low seasons were only observed in one heavily visited shore. A significant reduction in size of striped barnacles was observed only in one heavily visited shore. The opportunistic or fugitive species (e.g., small macroalgae and barnacles) were dominant macroinvertebrates on heavily visited shores indicating early succession stage. The results presented here showed that macroinvertebrates were adversely affected by human activities in subtropical rocky shore.     

Preparation and investigation of poly(methylmethacrylate) nano-capsules containing haloxyfop-R-methyl and their release behavior

Abstract

In this study, the preparation and characterization of haloxyfop-R-methyl herbicide loaded in poly(methylmethacrylate) (PMMA) nano-capsules by emulsion polymerization and its release behavior were investigated. The chemical characterizations of PMMA/haloxyfop-R-methyl nano-capsules were confirmed by FT-IR spectroscopy method, and the surface morphology was studied by field emission scanning electron microscopy and transmission electron microscopy. Also, the herbicide loading and encapsulation efficiency were analyzed for the herbicide-loaded nano-capsules. The release rate of PMMA/haloxyfop-R-methyl nano-capsules was determined by UV-visible spectroscopy. The thermal properties and thermal stability of nano-capsules were explored by the thermal gravimetric analysis method. The diameter of the nano-capsules was in the range of 100–300?nm. Increasing the amount of herbicide in nano-formulations significantly affected the surface of the nano-capsules and reduced their surface smoothness. Triton-X100 was identified as the best surfactant for the preparation of nano-capsules, and the sample containing the lowest herbicide content showed the best performance in terms of encapsulation and loading efficiency. This sample showed a steady-state release rate during the six days.     

A Computational Fluid Dynamic Model for Prediction of Organic Dyes Adsorption from Aqueous Solutions

Modelling of the removal of synthetic dyes from aqueous solutions by adsorbents is important to develop an appropriate treatment plan using adsorption process. This paper presents a computational fluid dynamic model incorporating the Langmuir isotherm scheme and second-order kinetic expression to describe the adsorption process. The governing equation of the model was numerically solved using PHOENICS software to simulate synthetic dyes adsorption from the aqueous system. The experimental results presented in this study and taken from the literature for the removal of synthetic dyes were compared with those results predicted by the numerical model. The predicted outputs of the model match the experimental measurements satisfactory. A sensitivity analysis of the major parameters that influence the percent of dye removal from solution phase has been carried out. Three of the main parameters taken into account were the kinetic rate constant, amount of dye adsorbed at equilibrium and the Langmuir isotherm constant. It was found that the model is most sensitive to the amount of dye adsorbed at equilibrium. This effect is most obvious at the early stages of the adsorption process when the rate of dye removal is very fast. Quantification of the reaction mechanism allows developing an appropriate remediation strategy based on the adsorption process.     

Geochemical characterisation of pyrite oxidation and environmental problems related to release and transport of metals from a coal washing low-grade waste dump, Shahrood, northeast Iran

Pyrite oxidation and release of the oxidation products from a low-grade coal waste dump to stream, groundwater and soil was investigated by geochemical and hydrogeochemical techniques at Alborz Sharghi coal washing plant, Shahrood, northeast Iran. Hydrogeochemical analysis of water samples indicates that the metal concentrations in the stream waters were low. Moreover, the pH of the water showed no considerable change. The analysis of the stream water samples shows that except the physical changes, pyrite oxidation process within the coal washing waste dump has not affected the quality of the stream water. Water type was determined to be calcium sulphate. The results of the analysis of groundwater samples indicate that the pH varies from 7.41 to 7.51. The concentrations of the toxic metals were low. The concentration of SO4 is slightly above than its standard concentration in potable water. It seems that the groundwater less affected by the coal washing operation in the study area. Geochemical analysis of the sediment samples shows that Fe concentration decreases gradually downstream the waste dump with pH rising. SO(4) decreases rapidly downstream direction. Copper, Zn and Co concentrations decrease with distance from the waste dump due to a dilution effect by the mixing of uncontaminated sediments. These elements, in particular, Zn are considerably elevated in sediment sample collected at the nearest distance to the waste dump. There is no doubt that such investigations can help to develop an appropriate water remediation plan.     

Limitations of habitats as biodiversity surrogates for conservation planning in estuaries

Increasing pressures on global biodiversity and lack of data on the number and abundance of species have motivated conservation planners and researchers to use more readily available information as proxies or surrogates for biodiversity. “Habitat” is one of the most frequently used surrogates but its assumed value in marine conservation planning is not often tested. The present study developed and tested three alternative habitat classification schemes of increasing complexity for a large estuary in south-east Australia and tested their effectiveness in predicting spatial variation in macroinvertebrate biodiversity and selecting estuarine protected areas to represent species. The three habitat classification schemes were: (1) broad-scale habitats (e.g., mangroves and seagrass), (2) subdivision of each broad-scale habitat by a suite of environmental variables that varied significantly throughout the estuary, and (3) subdivision of each broad-scale habitat by the subset of environmental variables that best explained spatial variation in macroinvertebrate biodiversity. Macroinvertebrate assemblages differed significantly among the habitats in each classification scheme. For each classification scheme, habitat richness was significantly correlated with species richness, total density of macroinvertebrates, assemblage dissimilarity, and summed irreplaceability. However, in a reserve selection process designed to represent examples of each habitat, no habitat classification scheme represented species significantly better than a random selection of sites. Habitat classification schemes may represent variation in estuarine biodiversity; however, the results of this study suggest they are inefficient in designing representative networks of estuarine protected areas.     

Photodestruction of Acid Orange 7 (AO7) in aqueous solutions by UV/H2O2: influence of operational parameters

The photodestruction of Acid Orange 7 (AO7), an anionic acidic dye, was studied in the UV/H2O2 process. H2O2 and UV light have a negligible effect when they were used on their own. Removal efficiency of AO7 was sensitive to the operational parameters such as initial H2O2 concentration, initial AO7 concentration, pH and different light sources. The photodestruction of AO7 was inhibited by addition of EtOH as an electron scavenger. The semi-logarithmic graphs of the concentration of AO7 versus time (t<30 min) were linear, suggesting pseudo-first order reactions (k(optimum)=0.105 min(-1)). A simple kinetic model is proposed which is in agreement with experimental results.