The thermal behavior of dilute (5000-50 ppm) solutions of tri- and tetrachlorobenzene in mineral oil, silicone oil, and tetrachloroethylene (TCE) has been investigated. Although pyrolyses or combustion of neat chlorobenzenes readily forms significant yields of PCDDs/PCDFs, corresponding treatment of dilute solutions was generally non-productive. This result is consistent with the proposition that, under the conditions studied, the rate-limiting step for PCDD/PCDF formation is bimolecular in chlorobenzene. In contrast, earlier studies of PCBs implied a rate-limiting step that was unimolecular in chloroaromatics. Combustion of dilute solutions of chlorobenzenes in tetrachloroethylene did produce detectable concentrations of PCDF; this result reflects combination of chlorobenzene and TCE- or TCE-derived species. 相似文献
Irrigation system performance regards as a function of climatic conditions. The present study was carried out to study this phenomenon. Sugar beet and sesame corps were cultivated during two agricultural seasons of 2017/2018 and 2018/2019 irrigated with drip and sprinkler systems. The drip and sprinkler systems performance was evaluated in terms of hydraulic characteristics added to irrigation water requirements. The recorded monthly values were compared to the traditional estimation method. The results revealed that irrigation system efficiency was increased by increasing ambient temperature for the drip irrigation system, and vice versa was noticed with the sprinkler irrigation system. Emission uniformity and application efficiency of emitters were increased by increasing ambient temperature. While the sprinkler flow rate and distribution uniformity were decreased by increasing ambient temperature. For drip irrigation system, the average total amount of irrigation water requirements using traditional estimation for sugar beet (2372 m3/fed) was less than the actual calculated (2439 m3/fed), while for sesame crop, the traditional estimation method (2556 m3/fed) was higher than actual calculated (2477 m3/fed). Using a sprinkler system, the average total amount of irrigation water requirements by the traditional estimation (2689 and 2897 m3/fed) was less than the actual calculated (2709 and 3044 m3/fed) for sugar beet and sesame crops, respectively. So, it is important to consider the effects of climatic conditions through the agricultural season.
Field observations of the Asian longhorned beetle (Anoplophora glabripennis) mating behavior in China suggested that a female-produced contact pheromone was almost certainly involved in sex recognition. Gas chromatography–mass spectrometry (GC-MS) analysis of A. glabripennis adults' whole body cuticular extracts indicates that a series of long-chain hydrocarbons comprise the cuticular waxes of both sexes. Although for the most part the GC profiles are similar for the two sexes, five monounsaturated compounds were consistently more abundant in samples from females than in those from males. These compounds were identified as (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-7-pentacosene, (Z)-9-heptacosene, and (Z)-7-heptacosene in the approximate ratio of 1:2:2:8:1, respectively. Antennal and palpi contact to a polypropylene micro-centrifuge tube coated with a synthetic mixture of the five compounds stimulated copulatory behavior in males.Electronic Supplementary Material Supplementary material is available for this article if you access the article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
The present investigation was an attempt to compare the within-watershed prioritization capabilities of a physical model based SDSS with the SYI and RPI model based subjective-SDSS, conventionally devised for between-watershed prioritizations, by All India Soil Survey and Land Use Planning Division of Ministry of Agriculture, Government of India. Application of these two approaches on a test watershed situated in Damodar-Barakar catchment in India, the second most seriously eroded area in the world, demonstrated that the proposed physical model based SDSS was capable of realistically and logically mimicking the sub-watershed-scaled water and soil losses thereby suggesting its immense application potential for priority area identification within the test watershed. In contrast to the proposed physical method, the subjective approaches, which assigned totally reverse priorities to about 67–93% of the test-sub-watersheds, were observed to be incapable of realistically assessing the impact of topography and varied land use and soil types in the test watershed on their sub-watershed scaled run-off and soil loss generating potential. Besides, the physical approach could be used for assessing the annual dynamics of the total water and sediment yields, under prevailing resource management systems in the test watershed with good to moderately good correlation coefficients of 0.83 and 0.65; model efficiency coefficients of 0.54 and 0.70; mean relative errors of –4.28% and –17.97% and root mean square prediction errors of 71.8 mm and 9.63 t/ha, respectively. 相似文献
Rubber leaf powder(an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(Ⅱ) ions from aqueous solution was evaluated.The interactions between Pb(Ⅱ) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared(FT-IR) spectroscopy,scanning electron microscopy(SEM) coupled with X-ray energy dispersive spectroscopy(EDX).The effects of several important parameters which can affect adsorption capacity such as pH,adsorbent dosage,initial lead concentration and contact time were studied.The optimum pH range for lead adsorption was 4-5.Even at very low adsorbent dosage of 0.02 g,almost 100% of Pb(Ⅱ) ions(23 mg/L) could be removed.The adsorption capacity was also dependent on lead concentration and contact time,and relatively a short period of time(60-90 min) was required to reach equilibrium.The equilibrium data were analyzed with Langmuir,Freundlich and Dubinin-Radushkevich isotherms.Based on Langmuir model,the maximum adsorption capacity of lead was 95.3 mg/g.Three kinetic models including pseudo first-order,pseudo second-order and Boyd were used to analyze the lead adsorption process,and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99. 相似文献
The study was conducted to investigate people’s forest dependency and contributions of forests to the livelihoods in the three hill districts of Chittagong Hill Tracts (CHT), Bangladesh. The study revealed that forest resources contribute significantly to rural community’s livelihoods and economic well-being. Using generalized logistic regressions, this study has also investigated the socioeconomic factors that affect people’s dependency on forest resources of CHT. The study revealed that people’s income from forest and forest-related occupation was positively aligned with their forest dependency. However, their education level significantly reduced their dependency on forest resources. Thus, educating the forest-dependent people and supporting alternative income generation activities should be appreciated for effective forest management in CHT. This study will be helpful to forest and environmental policy makers for CHT. 相似文献
Environmental Geochemistry and Health - Vertical heavy metal profiling reflects the history of the deposition of metals and helps to understand the characteristics of accumulation in various layers... 相似文献
The present study investigated the chemical composition of wet atmospheric precipitation over Dhanbad, coal city of India.
The precipitation samples were collected on event basis for three years (July 2003 to October 2005) at Central Mining Research
Institute. The precipitation samples were analyzed for pH, conductivity, major anions (F, Cl, NO3, SO4) and cations (Ca, Mg, Na, K, NH4). The pH value varied from 4.01 to 6.92 (avg. 5.37) indicating acidic to alkaline nature of rainwater. The pH of the rainwater
was found well above the reference pH (5.6), showing alkalinity during the non-monsoon and early phase of monsoon, but during
the late phase of monsoon, pH tendency was towards acidity (<5.6~pH) indicating the non-availability of proper neutralizer
for acidic ions. The observed acidic events at this site were 91, (n = 162) accounting 56% for the entire monitoring months. The (NO3 + Cl)/SO4 ratio in majority of samples was found below 1.0, indicating that the acidity is greatly influenced by SO4. The calculated ratio of (Ca + NH4)/(NO3 + SO4) ranges between 0.42–5.13 (average 1.14), however in most of the samples, the ratio is greater than unity (>1.0) indicating
that Ca and NH4 play an important role in neutralization of acidic ions in rainwater. Ca and SO4 dominate the bulk ionic deposition and these two ions along with NH4 accounts 63% of the annual ionic deposition. 相似文献
Wet and dry deposition samples were collected in the capital of Jordan, Amman. Concentrations of Al, Ba, Bi, Cd, Co, Cr, Cu,
Mn, Mo, Ni, Pb, Sb, V, Zn, Fe, Sr, Mg2+, Ca2+, Na+, K+, Cl−, NO3− and SO42−, along with pH were determined in collected samples. Mean trace metal concentrations were similar or less than those reported
for other urban regions worldwide, while concentrations of Ca2+ and SO42− were among the highest. High Ca2+ concentrations were attributed to the calcareous nature of the local soil and to the influence of the Saharan dust. However,
high SO42− concentrations were attributed to the influence of both anthropogenic and natural sources. Except for Cl−, NO3−, SO42− and Cu, monthly dry deposition fluxes of all measured species were higher than wet deposition fluxes. The annual wet deposition
fluxes of trace metals were much lower than those reported for other urban areas worldwide. 相似文献
Many drainage schemes and salinity control projects have been executed world wide. Pipe drainage has widely been used in Pakistan,
Egypt and India to control waterlogging. The impact of pipe drainage on land and water was evaluated in this paper using data
of three pipe drainage projects in Pakistan namely Khushab Salinity Control and Reclamation Project, Fourth Drainage Project
in Faisalabad and Swabi Salinity Control and Reclamation Project. Data by regular monitoring of these projects were collected.
The effect of pipe drainage on water table depth at these three locations has been compared. Water quality and soil salinity
improvement due to the pipe drainage has also been investigated. Data, related to water table depths and discharges from drain
pipes/wells, was collected. Observation wells, installed at various places by the Water and Power Development Authority, were
used for collection of this data. To evaluate the impact of the projects on salinity, soil samples from all the three locations
were tested. A questionnaire was prepared to get the view of the people about the projects. It was revealed that in these
areas, due to subsurface pipe drainage, the percentage of the abandoned land has been considerably decreased. Over drainage
was observed in a few places of the projects. The farmers at such places were asked to change their cropping patterns. Ultimately,
there has been an increase in area under cultivation, crop yields and cropping intensity in the projects’ area. 相似文献