Atrazine and alachlor transport in claypan soils as influenced by differential antecedent soil water content

Increased attention to ground water contamination has encouraged an interest in mechanisms of solute transport through soils. Few studies have investigated the effect of the initial soil water content on the transport and degradation of herbicides for claypan soils. We investigated the effect of claypan soils at initial field capacity vs. permanent wilting level on atrazine and alachlor transport. The soil studied was Mexico silt loam (fine, smectitic, mesic Aeric Vertic Epiaqualf) with a subsoil clay content, primarily montmorillonite, of >40%. Strontium bromide, atrazine, and alachlor were applied to plots; half were at field capacity (Wet treatment), and half were near the permanent wilting point (Dry treatment). Soil cores were removed at selected depths and times, and cores were analyzed for bromide and herbicide concentrations. Bromide, atrazine, and alachlor were detected at the 0.90-m depth in dry plots within 15 d after experiment initiation. Bromide was detected 0.15 m deeper (P < 0.05) in the Dry compared with the Wet treatment at 1, 7, and 60 d after application and >0.30 m deeper (P < 0.01) in the Dry treatment at 15 and 30 d after application; similar treatment results were found for atrazine and alachlor, although on fewer dates with significant differences. The mobility order of the applied chemicals was bromide > atrazine > alachlor. The atrazine apparent half-life was significantly longer in the Dry plots compared with the Wet plots. The retardation factor determined from the relative velocity of each herbicide to that of bromide was higher for alachlor than for atrazine. This study identifies the impact that shrinkage cracks have for different moisture conditions on preferential transport of herbicides in claypan soils.     

Generalized gene expression programming models for estimating reference evapotranspiration through cross-station assessment and exogenous data supply

Environmental Science and Pollution Research - Adopting methodologies utilizing exogenous data from ancillary stations for determining crop water requirement is a suitable approach to exempt local...     

Aldicarb and carbofuran transport in a Hapludalf influenced by differential antecedent soil water content and irrigation delay

Pesticide use in agroecosystems can adversely impact groundwater quality via chemical leaching through soils. Few studies have investigated the effects of antecedent soil water content (SWC) and timing of initial irrigation (TII) after chemical application on pesticide transport and degradation. The objectives of this study were to investigate the effects of antecedent soil water content (wet vs dry) and timing of initial irrigation (0h Delay vs 24h Delay) on aldicarb [(EZ)-2-methyl-2-(methylthio)propionaldehyde O-methylcarbamoyloxime] and carbofuran [2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate] transport and degradation parameters at a field site with Menfro silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf) soils. Aldicarb and carbofuran were applied to plots near field capacity (wet) or near permanent wilting point (dry). Half of the dry and wet plots received irrigation water immediately after chemical application and the remaining plots were irrigated after a 24h Delay. The transport and degradation parameters were estimated using the method of moments. Statistical significance determined for SWC included averages across TII levels, and significance determined for TII included averages across SWC levels. For the dry treatment, aldicarb was detected 0.10 m deeper (P<0.01) on two of the four sampling dates and carbofuran was detected at least 0.10 m deeper (P<0.05) on all of the sampling dates compared to the wet treatment. Pore water velocity was found to be higher (P<0.10) in the dry vs wet treatments on three of four dates for aldicarb and two of four dates for carbofuran. Retardation coefficients for both pesticides showed similar evidence of reduced values for the dry vs wet treatments. These results indicate deeper pesticide movement in the initially dry treatment. For aldicarb and carbofuran, estimated values of the degradation rate were approximately 40-49% lower in the initially dry plots compared to the initially wet plots, respectively. When the initial irrigation was delayed for 24h, irrespective of antecedent moisture conditions, a 30% reduction in aldicarb degradation occurred. This study illustrates the deeper transport of pesticides and their increased persistence when applied to initially dry soils.     

Interaction between meteorological parameters and COVID-19: an ecological study on 406 authorities of the UK

Environmental Science and Pollution Research - Understanding the factors affecting COVID-19 transmission is critical in assessing and mitigating the spread of the pandemic. This study investigated...     

Use of recycled plastics in wood plastic composites – A review

The use of recycled and waste thermoplastics has been recently considered for producing wood plastic composites (WPCs). They have great potential for WPCs manufacturing according to results of some limited researches. This paper presents a detailed review about some essential properties of waste and recycled plastics, important for WPCs production, and of research published on the effect of recycled plastics on the physical and mechanical properties of WPCs.     

Effects of aerobic exercise on histopathology and toxicology of ZnO and nano ZnO in male rats

The effects of four weeks of aerobic exercise on histopathological and toxicological effects induced by nano ZnO and ZnO powders in male rats were evaluated. Tissue sections of liver and kidneys of ZnO and nano ZnO rats showed some histopathological changes, which were partly reverted by exercise. ZnO and nano ZnO treatments caused an increase in the level of tumor necrosis factor-α, while the mean of Interleukin 10 was declined. Exercise training enhanced the mean value of and declined mean level of in rats treated with ZnO and nano ZnO. The ZnO and ZnO groups demonstrated the highest means of insulin resistance, low density lipoprotein, cholesterol, triglyceride levels and lower mean value of compared to the other groups, while exercise resulted in improvement in mean of these factors.     

Distribution,geochemistry, and mineralogy of aerosols in the Angouran Mine area,northwest Iran

The Angouran Mine, located in northwest Iran, is the largest Zn–Pb producer in the Middle East. This study was designed to investigate the distribution, geochemistry, and mineralogy of the aerosols in the mining area and to assess their likely health impacts on the local residents. For this purpose, 36 aerosol samples were collected from 2014 to 2015 at nine sites located in mine district and upwind and downwind directions. The concentration of potentially toxic elements in the aerosols was determined using AAS instrument. Size, morphology, and mineralogy of the particles were studied using SEM and EDX spectra. The results indicate that the amount of total suspended particles in upwind, mine district, and downwind sites is 95.5, 463.4 and 287.5 µg/m³, respectively. The concentrations of PM_2.5 in the three locations are 8.9, 134.7, and 51.8 µg/m³, whereas the PM₁₀ contents are 2.9, 74.4, and 15.5 µg/m³, respectively. These observations point to the impact of mining activities on the concentration of aerosols in the local atmosphere. The values of air quality index also show the probable effects of the mining activities on the health of the local populations, especially for allergic peoples. The average concentration of Zn in the samples collected from the mining district (290 µg/kg) is much higher than its value in the upwind sites (27 µg/kg). The highest concentration of As (70 µg/kg), Cd (10 µg/kg), and Pb (3 µg/kg) is in downwind sites, which shows the negative impact of mining activities on the local air quality. Temporally, the highest concentration of the studied elements is recorded in spring season, especially for PM_2.5 collected in downwind stations. Based on the results of SEM and EDX spectra, three groups of minerals, i.e., carbonates, silicates, and sulfides, are present in the aerosol particles, confirming the local source for the aerosols. SEM analyses showed that the aerosol particles with dissimilar chemical composition have different morphologies such as irregular, rounded, elongated, and angular. On the basis of the results, the mining activities in the Angouran Zn–Pb Mine may have various short- and long-term consequences on the public health, especially due to high amount of the finer particles (PM_2.5) and the higher concentration of the potentially toxic elements in PM_2.5 which can penetrate into the lungs.

     

Optimal water resources allocation in transboundary river basins according to hydropolitical consideration

Environment, Development and Sustainability - Water resources allocation policies can create cooperation or tension among different stakeholders in a large basin. Thus, integrated water resources...     

Application of ultrasound irradiation in landfill leachate treatment

Environmental Science and Pollution Research - Landfilling is known to be the most widely used method in municipal solid waste management in many countries. Landfill leachate containing different...     

Effect of Thermo-Mechanical Degradation of Polypropylene on Hygroscopic Characteristics of Wood Flour-Polypropylene Composites

In this research, the influence of thermo-mechanical degradation of polypropylene (PP) on water absorption and thickness swelling of beech wood flour–PP composites were studied. For this purpose, a virgin PP was thermo-mechanically degraded by two times extrusion under controlled conditions. The results showed that the melt flow index, water absorption and thickness swelling of PP significantly increase by extrusion and re-extrusion. The virgin PP and degraded polypropylene were compounded with wood flour (at 60% by weight wood flour loading) in a counter-rotating twin-screw extruder in presence or absence of MAPP to produce wood flour–PP composites. From the results, the composites containing recycled PP exhibited higher water absorption and thickness swelling. The use of MAPP decreased water absorption and thickness swelling in composites made of virgin or recycled PP.