EFFECT OF WATERSHED SUBDIVISION ON SWAT FLOW,SEDIMENT, AND NUTRIENT PREDICTIONS1

ABSTRACT: The size, scale, and number of subwatersheds can affect a watershed modeling process and subsequent results. The objective of this study was to determine the appropriate level of subwatershed division for simulating flow, sediment, and nutrients over 30 years for four Iowa watersheds ranging in size from 2,000 to 18,000 km² with the Soil and Water Assessment Tool (SWAT) model. The results of the analysis indicated that variation in the total number of subwatersheds had very little effect on streamflow. However, the opposite result was found for sediment, nitrate, and inorganic P; the optimal threshold subwatershed sizes, relative to the total drainage area for each watershed, required to adequately predict these three indicators were found to be around 3, 2, and 5 percent, respectively. Decreasing the size of the subwatersheds below these threshold levels does not significantly affect the predicted levels of these environmental indicators. These threshold subwatershed sizes can be used to optimize input data preparation requirements for SWAT analyses of other watersheds, especially those within a similar size range. The fact that different thresholds emerged for the different indicators also indicates the need for SWAT users to assess which indicators should have the highest priority in their analyses.     

Non-powered hand tool improvement research for prevention of work-related problems: a review

Purpose. In lower-middle-income countries, most of the work is performed manually using non-ergonomic hand tools which results in work-related health problems. Using hand tools designed in line with ergonomic principles may play an important role in reducing work-related health concerns significantly. Methods. Scientific databases (PubMed, EBSCOhost) and e-publishers were searched for articles from 1985 to 2015 using the following keywords: ‘hand tool’, ‘ergonomics’, ‘usability’ and ‘design’. After applying selection criteria to 614 articles, 58 articles related to the physical design of hand tools were selected. Results. Seventeen articles were related to hand tool improvement in the manufacturing sector. Musculoskeletal disorders were found to be the most frequently occurring work-related health problems. Most of the articles focused on product and qualitative variables for improvement in hand tools, while few articles considered human and task variables. Conclusions. Literature shows that hand tool improvement studies have been given less importance in low-income and lower-middle-income countries. However, some work of significance is reported in the agriculture sectors of these countries. Hence, it is concluded that ergonomic intervention in hand tools is much needed for those industries which employ traditional methods of working.     

Carbon density and accumulation in agroecosystem of Indo-Gangetic Plains and Vindhyan highlands,India

In agroecosystems, the annual carbon (C) inputs to soil are one of the most promising greenhouse gas mitigation options. Net primary productivity (NPP) provides the inputs of C in ecosystems that can potentially be sequestered in soil organic matter. In this study, we estimates the C density and accumulation rate in rice–wheat agroecosystem at four sites of Indo-Gangetic Plains and Vindhyan highlands through amalgamation of ground truth (GT) and remote sensing (RS) approach. In addition to this, we validated field-measured aboveground net production (ANP) with remotely sensed SPOT-Vegetation data. ANP of the sites ranged from 6.8 to 11.1 and 3.3 to 8.8 t-C ha^?1 year^?1 for GT and RS, respectively. Both estimates (GT and RS) were linearly and significantly related with each other (y?=?1.33x???5.82, R ²?=?0.93, P?=?0.04; where x?=?GT ANP and y?=?RS ANP). For the whole region, total NPP (rice?+?wheat) was ranged from 7.9 to 12.5 t-C ha^?1 year^?1. The C accumulation potential of the present agroecosystems was 9.1 and 1.9 t-C ha^?1 year^?1 in the form of ANP and belowground NPP (BNP), respectively. The aboveground C stock of agroecosystem allocated in foliage (7.8 %), stem (57.6 %), and grain (35.1 %). Survey about the fate of post-harvested materials indicated that aboveground portion of the crop is almost used completely within the year for different purposes including human consumption and cattle feeding. Therefore, only BNP and litter contribute to long-term C sequestration. Since agroecosystem has enormous potential to sequester C, better management of aboveground portion NPP of the crop may enhance C sequestration potential of agroecosystem.     

A Time-Dependent System for Evaluating Groundwater Contamination Hazard Rating of Municipal Solid Waste Dumps

In developing countries, several old municipal solid waste dumps (unlined landfills) exist adjacent to large cities, releasing contaminants to the underlying aquifer, thus posing the hazard of groundwater contamination. These uncontrolled waste dumps need to be prioritized in terms of the groundwater contamination hazard posed by them, so that necessary control and remedial measures can be undertaken in a phased manner. This paper presents a time-dependent system for evaluating groundwater contamination hazard rating of municipal solid waste dumps. The system is based on source–pathway–receptor relationships and evaluates the relative value of hazard posed by a site over its entire leaching life, on a scale of 0–1,000. The system parameters have been selected based on literature and expert opinions. The Delphi technique is used to derive the relative importance weights of the system parameters. The proposed system is compared with six selected existing hazard rating systems. The comparison, made by way of score range analysis, shows that the proposed system exhibits a much wider range of hazard scores for various scenarios of site conditions, and hence the proposed system is more sensitive to varied site conditions. The application of different systems to six municipal solid waste dumps located in four cities of India shows that, whereas the existing systems individually produce clustered scores and return the same rank to more than one site, the proposed system produces significantly varying scores and return different ranks to different sites. This demonstrates that the proposed system improves decision making and makes a better basis for prioritization of municipal solid waste dumps for adopting control and remedial measures.     

Solvent tolerant marine bacterium Bacillus aquimaris secreting organic solvent stable alkaline cellulase

The organic solvent tolerant bacteria with their physiological abilities to decontaminate the organic pollutants have potentials to secrete extracellular enzymes of commercial importance. Of the 19 marine bacterial isolates examined for their solvent tolerance at 10 vol.% concentration, one had the significant tolerance and showed a relative growth yield of 86% for acetone, 71% for methanol, 52% for benzene, 35% for heptane, 24% for toluene and 19% for ethylacetate. The phylogenetic analysis of this strain using 16S rDNA sequence revealed 99% homology with Bacillus aquimaris. The cellulase enzyme secreted by this strain under normal conditions showed an optimum activity at pH 11 and 45 °C. The enzyme did show functional stability even at higher pH (12) and temperature (75 °C) with residual activity of 85% and 95% respectively. The enzyme activity in the presence of different additives were in the following order: Co⁺² > Fe⁺² > NaOCl₂ > CuSO₄ > KCl > NaCl. The enzyme stability in the presence of solvents at 20 vol.% concentration was highest in benzene with 122% followed by methanol (85%), acetone (75%), toluene (73%) and heptane (42%). The pre-incubation of enzyme in ionic liquids such as 1-ethyl-3-methylimidazolium methanesulfonate and 1-ethyl-3-methylimidazolium bromide increased its activity to 150% and 155% respectively. The change in fatty acid profile with different solvents further elucidated the physiological adaptations of the strain to tolerate such extreme conditions.     

UV-irradiation assisted functionalization and binding of Pd nanoparticles in polycarbonate membranes for hydrogen separation

Environmental Science and Pollution Research - For hydrogen-based energy systems development, purified hydrogen (H2) is a basic requirement and it can be achieved by using the H2-selective...     

Microbial and size characterization of airborne particulate matter collected on sticky tapes along US–Mexico border

Particulate matter(PM) emissions from various sources can affect significantly human health and environmental quality especially in the Chihuahuan Desert region along US–Mexico border. The objective of this study was to use the low-cost sticky tape method to collect airborne PM for size characterization and identification of fungal spores. Sticky tape samplers were placed at 1.0 and 2.0 m above the ground surface at experimental sites in Ciudad Juárez, Mexico and at 0.6, 1.2 and 1.8 m at New Mexico sites, USA. Soil samples were collected in both countries to determine fungal diversity, texture and moisture content Dust particles collected from all of the experimental sites had a dominant texture of clay( 0.002 mm). The dominant textures identified from soil samples collected from the US and Mexican sites were loam and sandy clay loam, respectively. Alternaria, Penicillium and Fusarium were frequently found funguses in the US sites while Alternaria and Aspergillus were commonly observed in the Mexican sites. The sticky tapes also showed a similar diversity of fungal microorganisms present in the airborne PM at both Mexico and US sites Alternaria, Penicillium and Aspergillus were the three groups of airborne fungal microorganisms consistently present in the US and Mexican sites. The low-cost sticky tape method has the potential to be used for characterizing different airborne microorganisms and dust particles.     

Occurrence,toxicity and remediation of polyethylene terephthalate plastics. A review

Environmental Chemistry Letters - Polyethylene terephthalate is a common plastic in many products such as viscose rayon for clothing, and packaging material in the food and beverage industries....     

Nerve conduction studies in sprayers occupationally exposed to mixture of pesticides in a mango plantation at Lucknow,North India

In this study, nerve conduction, organochlorine (OC) pesticide residues in blood and cholinesterase activity levels of pesticide sprayers employed in mango plantations at Lucknow, North India, were determined. Fifty-two sprayers from mango plantations who regularly spray mixture of pesticides like organophosphates (OP), OCs, and carbamates were considered as exposed group. Eighteen subjects with similar socio-economic status of exposed group, who do not handle pesticides, were selected as controls. Questionnaire-based interviews related to personal and occupational histories of the study subjects were carried out. Sprayers did not use any personal protective equipment during pesticide handling. The blood-pesticide analyses of sprayers show higher mean values of hexachlorohexane (HCH), γ-HCH, δ-HCH, total HCH, op-DDT compared with the controls. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activites were significantly reduced among sprayers. Risk of motor nerve conduction deficits was observed in sprayers with low AChE activity. Negative correlation of motor and sensory nerve conduction deficits was observed with the duration of exposure and age among sprayers. The study demonstrated that the prolonged exposure to mixture of pesticides, ergonomic factors, decline in cholinesterase activity may lead to nerve conduction dysfunction. The findings suggest the need for controlled use of pesticides in the plantation and indicated the need for training and implementation of hygiene practices like proper usage of personal protective equipments.