Minimizing drift and exposure from knapsack sprayers

Abstract

An improved drift shield for attaching to the lance of conventional knapsack sprayer to reduce wind induced drift and operator exposure was designed and tested. The drift shield consists of a conical wire frame covered with polythene and has an annular opening at the point of attachment to the lance which allows air to be drawn into the shield while spraying. Tests conducted with winds in the range of 1.25–5.75 m/s show that wind can increase the width of spray swath from an unshielded lance, up to 4.3 times the normal swath in no‐wind condition. Use of a conventional shield contained the swath width within 3.5 times and the improved shield restricted the swath width to 3.1 times the normal swath. Spray deposit from an unshielded lance, within the normal swath decreased to as low as 45%, due to wind effects. However, use of the conventional, and the improved shields enhanced the spray deposit to 54.2% and 68%, respectively. The improved drift shield improved the spray pattern displacement (SPD) significantly (P<0.05) compared with the conventional shield and the unshielded lance when the wind speed exceeded 1.25 m/s. The improved shield decreased the off target drift by as much as 63% compared with the unshielded spray. It also decreased the quantity of pesticide deposit on the operator's body by 41–84% and thereby reduced exposure and improved safety.     

Bioaugmentation of polyethylene succinate-contaminated soil with Pseudomonas sp. AKS2 results in increased microbial activity and better polymer degradation

Pseudomonas sp. AKS2 isolated from soil degrades polyethylene succinate (PES) efficiently in the laboratory. However, this organism may not be able to degrade PES with similar efficiency in a natural habitat. Since in situ remediation is preferred for the effective removal of recalcitrant materials like plastic, in the current study, bioaugmentation potential of this organism was investigated. To investigate the potential of the AKS2 strain to bioaugment the PES-contaminated soil, a microcosm-based study was carried out wherein naturally attenuated, biostimulated, and AKS2-inoculated (bioaugmented) soil samples were examined for their ability to degrade PES. The results showed better degradation of PES by bioaugmented soil than other microcosms. Consistent with it, a higher number of PES-degrading organisms were found in the bioaugmented microcosm. The bioaugmented microcosm also exhibited a higher level of average well color development in BiOLOG ECO plate assay than the other two. The corresponding Shannon–Weaver index and Gini coefficient revealed a higher soil microbial diversity of bioaugmented microcosm than the others. This was further supported by community-level physiological profile of three different microcosms wherein we have observed better utilization of different carbon sources by bioaugmented microcosms. Collectively, these results demonstrate that bioaugmentation of PES-contaminated soil with AKS2 not only enhances polymer degradation but also increases microbial diversity. Bioaugmentation of soil with AKS2 enhances PES degradation without causing damage to soil ecology. Thus, Pseudomonas sp. AKS2 has the potential to be implemented as a useful tool for in situ bioremediation of PES.     

Feral swine disturbance at important archaeological sites

Feral swine are well known as environmentally destructive invasive animals in many areas around the world, where they degrade native habitats, harm rare plant and animal species, damage agricultural interests, and spread disease. We provide the first quantification of their potential as agents of disturbance at archaeological sites. Our study was conducted in south-central Florida at Avon Park Air Force Range, a base comprising over 40,000 ha and containing many archaeological sites. To determine the identifiable prevalence of feral swine disturbance, we examined 36 sites registered with the Florida State Historic Preservation Office and also eligible for inclusion in the National Register of Historic Places (NRHP). Moreover, we evaluated the extent of swine disturbance at a prehistoric site of extraordinary significance to Florida’s prehistory, “Dead Cow.” Fifteen of the 36 NRHP-eligible sites (42 %) had some level of swine disturbance, including 14 of 30 (47 %) sites known to have artifacts within 20 cm of the surface (well within swine rooting depths). At the Dead Cow site, we documented disturbance at 74 % of shovel test points. Sites with shallow artifact depositions appeared highly vulnerable to disturbance by feral swine, threatening destruction of artifact stratigraphy and provenience. Our observations likely are a minimal representation of accumulated damage. These irreplaceable sites tell the area’s land use story across the millennia. That they are under threat from feral swine should serve broad notice of potential threats that feral swine may pose to archaeological sites globally, making effective swine management imperative for site protection.     

Low-density polyethylene degradation by Pseudomonas sp. AKS2 biofilm

Polyethylene materials are a serious environmental concern as their nondegradable nature allows them to persist in the environment. Recent studies have shown that polyethylene can be degraded by microbes at a very slow rate, whereby detectable changes are evident after several years. In the present study, we report the degradation of low-density polyethylene by Pseudomonas sp. AKS2. Unlike the previous reports, degradation by Pseudomonas sp. AKS2 is relatively fast as it can degrade 5?±?1 % of the starting material in 45 days without prior oxidation. This degradation can be altered by agents that modulate hydrophobic interaction between polythene and the microbe. As mineral oil promotes hydrophobic interactions, it enhances bacterial attachment to the polymer surface. This enhanced attachment results in increased biofilm formation and enhanced polymer degradation. In contrast, Tween 80 reduces bacterial attachment to the polymer surface by lowering hydrophobic interactions and thereby reduces polymer degradation. Thus, this study establishes a correlation between hydrophobic interaction and polymer degradation and also relates the biofilm formation ability of bacteria to polymer degrading potential.     

Trace metals, anions and polybromodiphenyl ethers in settled indoor dust and their association

Contaminants in settled indoor dust are potentially health hazardous to human. Thus, identification and quantification of toxic chemicals in settled indoor dust is of great concern. In this study, the levels of major anions ( $ \mathrm{C}{{\mathrm{l}}^{-}},\mathrm{N}{{\mathrm{O}}_2}^{-},\mathrm{B}{{\mathrm{r}}^{-}},\mathrm{N}{{\mathrm{O}}_3}^{-},\mathrm{P}{{\mathrm{O}}_4}^{3-}\,\mathrm{and}\,\mathrm{S}{{\mathrm{O}}_4}^{2- } $ ), trace metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, As and Pb) and polybromodiphenyl ethers (PBDEs) in settled office and home dust were determined and correlations between the contaminants investigated. Depending on the available materials in both microenvironments, the most possible sources were identified. The results showed that the settled office dusts (n?=?6 pooled samples from 85 offices) were more contaminated than home dusts (n?=?8 homes). For anions, $ \mathrm{S}{{\mathrm{O}}_4}^{2- } $ and Cl^– accounted for 87 and 97 % of the total office and home dust contaminants, respectively. For trace metals, Fe, Cu, Zn and Mn, accounted for 98 % of the contaminants in both office and home dust samples. Fe exhibited the highest percentage of 76.7 and 87.3 % in office and home dust samples, respectively. For PBDEs, the mean concentrations detected in office and home dust ranged between 5.8–86.3 and 1.5–20.6 ng?g^?1, respectively. The log-transformed correlation between the total concentrations of trace metals and major anions detected in offices and homes was positive for offices and negative for homes with a statistically significant values (r?=?0.73, p?<?0.01; r?= ?0.22, p?<?0.01, respectively). The daily exposure rates determined for the most hazardous such as As, Cd, Pb and PBDEs congeners, relative to the individual concentrations reported in the literature in settled indoor dust, were found very lower. Therefore, maybe it is possible to expect less potential health risk. Investigation of formation of coordination compounds between trace metals and PBDEs congeners is possible; however, this requires further study.     

PAH air pollution at a Portuguese urban area: carcinogenic risks and sources identification

This study aimed to characterize air pollution and the associated carcinogenic risks of polycyclic aromatic hydrocarbon (PAHs) at an urban site, to identify possible emission sources of PAHs using several statistical methodologies, and to analyze the influence of other air pollutants and meteorological variables on PAH concentrations.The air quality and meteorological data were collected in Oporto, the second largest city of Portugal. Eighteen PAHs (the 16 PAHs considered by United States Environment Protection Agency (USEPA) as priority pollutants, dibenzo[a,l]pyrene, and benzo[j]fluoranthene) were collected daily for 24 h in air (gas phase and in particles) during 40 consecutive days in November and December 2008 by constant low-flow samplers and using polytetrafluoroethylene (PTFE) membrane filters for particulate (PM₁₀ and PM_2.5 bound) PAHs and pre-cleaned polyurethane foam plugs for gaseous compounds. The other monitored air pollutants were SO₂, PM₁₀, NO₂, CO, and O₃; the meteorological variables were temperature, relative humidity, wind speed, total precipitation, and solar radiation. Benzo[a]pyrene reached a mean concentration of 2.02 ng?m^?3, surpassing the EU annual limit value. The target carcinogenic risks were equal than the health-based guideline level set by USEPA (10^?6) at the studied site, with the cancer risks of eight PAHs reaching senior levels of 9.98?×?10^?7 in PM₁₀ and 1.06?×?10^?6 in air. The applied statistical methods, correlation matrix, cluster analysis, and principal component analysis, were in agreement in the grouping of the PAHs. The groups were formed according to their chemical structure (number of rings), phase distribution, and emission sources. PAH diagnostic ratios were also calculated to evaluate the main emission sources. Diesel vehicular emissions were the major source of PAHs at the studied site. Besides that source, emissions from residential heating and oil refinery were identified to contribute to PAH levels at the respective area. Additionally, principal component regression indicated that SO₂, NO₂, PM₁₀, CO, and solar radiation had positive correlation with PAHs concentrations, while O₃, temperature, relative humidity, and wind speed were negatively correlated.     

Synergistic effect of Eugenia jambolana Linn. and Solidago canadensis Linn. leaf extracts with deltamethrin against the dengue vector Aedes aegypti Linn. at Mysore

With the goal in mind to minimize the application of environmentally hazardous chemical insecticides, the larvicidal activity of two plant extracts along with deltamethrin was studied at University of Mysore. The extracts of Solidago canadensis and Eugenia jambolana were employed for working out the synergistic efficacy against Aedes aegypti larvae, as the extracts of both the plants exhibited high efficacy when applied individually. The deltamethrin when analyzed separately, LC₅₀ and LC₉₀ values were 0.00045 and 0.00148 ppm, respectively. Synergistic studies with two plant extracts on deltamethrin revealed S. canadensis as more effective with synergistic factor(SF) of 4.090 for LC₅₀ value and 4.781 for LC₉₀ followed by E. jambolana with SF 1.80 for LC₅₀ and 2.467 for LC₉₀ at 1:1 ratio of the phytoextracts and deltamethrin. Thus, S. canadensis was found to be a better larvicidal and synergistic agent. Combination of phytochemical and insecticide were found to be more effective than insecticides or phytochemicals alone which could be a good ecofriendly and cost-effective approach to reduce the dose of chemicals with high residual effect to be applied in vector control programs.     

Cadmium (Cd2+) removal by nano zerovalent iron: surface analysis, effects of solution chemistry and surface complexation modeling

Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd²⁺ ions by nZVI through adsorption. Cd²⁺ adsorption decreased in the presence of competitive cations in the order: Zn²⁺?>?Co²⁺?>?Mg²⁺?>?Mn²⁺?=?Cu²⁺?>?Ca²⁺?>?Na²⁺?=?K⁺. Higher concentrations of Cl^? significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd²⁺ adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI–Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions.     

Approximation and spatial regionalization of rainfall erosivity based on sparse data in a mountainous catchment of the Yangtze River in Central China

In densely populated countries like China, clean water is one of the most challenging issues of prospective politics and environmental planning. Water pollution and eutrophication by excessive input of nitrogen and phosphorous from nonpoint sources is mostly linked to soil erosion from agricultural land. In order to prevent such water pollution by diffuse matter fluxes, knowledge about the extent of soil loss and the spatial distribution of hot spots of soil erosion is essential. In remote areas such as the mountainous regions of the upper and middle reaches of the Yangtze River, rainfall data are scarce. Since rainfall erosivity is one of the key factors in soil erosion modeling, e.g., expressed as R factor in the Revised Universal Soil Loss Equation model, a methodology is needed to spatially determine rainfall erosivity. Our study aims at the approximation and spatial regionalization of rainfall erosivity from sparse data in the large (3,200 km²) and strongly mountainous catchment of the Xiangxi River, a first order tributary to the Yangtze River close to the Three Gorges Dam. As data on rainfall were only obtainable in daily records for one climate station in the central part of the catchment and five stations in its surrounding area, we approximated rainfall erosivity as R factors using regression analysis combined with elevation bands derived from a digital elevation model. The mean annual R factor (R _a) amounts for approximately 5,222 MJ?mm?ha^?1?h^?1?a^?1. With increasing altitudes, R _a rises up to maximum 7,547 MJ?mm ha^?1?h^?1 a^?1 at an altitude of 3,078 m a.s.l. At the outlet of the Xiangxi catchment erosivity is at minimum with approximate R _a?=?1,986 MJ?mm?ha^?1?h^?1?a^?1. The comparison of our results with R factors from high-resolution measurements at comparable study sites close to the Xiangxi catchment shows good consistance and allows us to calculate grid-based R _a as input for a spatially high-resolution and area-specific assessment of soil erosion risk.     

Performance of a naturally growing Parmelioid lichen Remototrachyna awasthii against organic and inorganic pollutants

The present study aims to assess the level and possible sources of organic and inorganic pollutants in Mahableshwar city in Western part of India and their effect on naturally growing foliose lichen Remototrachyana awasthii (Hale & Patw.) Divakar & A. Crespo. This lichen species growing abundantly in the area was collected from eight different sites on the basis of anthropogenic activities detected in the area. The concentration of inorganic heavy metals (Al, As, Cd, Cr, Fe, Pb, Mn, and Zn) and polycyclic aromatic hydrocarbons (PAHs) were analyzed and correlated with photosynthetic pigments (Chl a, Chl b, total chlorophyll, and carotenoid) together with chlorophyll degradation and protein contents. The concentration of most of the metals at different sites was significantly greater than at the control site (P?<?0.001). The highest metal content was found at Bus Stand and Panchgani, a tourist place that experiences heavy traffic activities. The concentration of PAHs, particularly of two-and three-ringed PAHs, was also found to be the highest in samples collected at Bus Stand area. The chlorophyll degradation and protein content were found to be the most sensitive parameters to assess the vitality of lichen thallus against wide range of air pollutants. The effectiveness of R. awasthii as a biomonitor will be investigated in the near future by comparing this species with other biomonitors.