Adsorbent selection for endosulfan removal from water environment

In the present study, an attempt was made to select a low cost adsorbing material for the removal of endosulfan [C,C'-(1,4,5,6,7,7-hexachloro-8,9,10- trinorborn-5-en-2,3-ylene)(dimethylsulphite)] from water. Various low cost adsorbents like wood charcoal, kimberlite tailings, silica, macro fungi sojar caju were tried with activated charcoal as reference material. The above materials were selected from various sources encompassing organic, inorganic, clayey, and biological sources. For the selection of suitable adsorbent for endosulfan uptake, maximum adsorption capacity (Qmax) was chosen as the parameter. Kinetic profiles of removal were generated for all the materials to assess the equilibrium time. Equilibrium studies were carried out for all materials to assess the adsorption equilibrium model that they followed. The model that gave the best correlation coefficient by linear regression analysis, was adopted for the calculation of Qmax of the corresponding adsorbent material. Using linearised forms of equilibrium models like Langmuir, BET, and Freundlich, maximum adsorptive capacities were determined. Activated charcoal showed the best adsorptive capacity with Qmax of 2.145 mg/g followed by wood charcoal 1.773 mg/g, sojar caju 1.575 mg/g, kimberlite tailings 0.8821 mg/g, and silica 0.3231 mg/g. Albeit activated charcoal gave better performance, it was not considered as a candidate material because of its high cost. Wood charcoal was the next best adsorbent with Qmax 1.773 mg/g. Therefore, wood charcoal was chosen as the best material for endosulfan removal. The study of physical and chemical characteristics of wood charcoal revealed that it is a potential adsorbent and can even be improved further.     

Petroleum hydrocarbons in the nearshore marine sediments of the United Arab Emirates

The concentrations of total petroleum hydrocarbons (TPH) were determined in nearshore sediment samples collected from 28 sampling sites along the United Arab Emirates shorelines on the Arabian Gulf, the Gulf of Oman and seven major creeks (khors) extending from them. Concentrations were highly variable and ranged between <0.4 and 212 microg g(-1) dry weight, and the highest values obtained were in the top sediment (1 cm) layer near a fuel filling station and port areas. Locally high levels of TPH were found in Dubai, Sharjah and Ajman semi-enclosed creeks where boat activities and land-based wastewater discharges are most common. Data support the premise that port activities, fuel filling stations and land-based wastewater discharges are major sources of pollution in the study area. Correlations with sediment grain size, total organic carbon (TOC) and distance from pollution sources are discussed.     

大空间火灾烟气流动的动态显示研究

讨论了火灾烟气流动过程的计算机动态模拟方法。利用Ｄｅｌｐｈｉ可视化编程工具,建立了一个融区域模拟计算和计算机动态显示于一体的火灾发展的模拟软件,并以中国科技大学的大空间建筑火灾实验厅为对象,对典型火灾羽流及烟气层的发展过程进行了动态显示。     

Subsurface nutrient modelling using finite element model under Boro rice cropping system

Boro rice, an emerging low-risk crop variety of rice, cultivated using residual or stored water after Kharif season. To enhance the quality and production of rice, potassium (K) and phosphorus (P) are the common constituents of agricultural fertilizers. However, excess application of fertilizers causes leaching of nutrients and contaminates the groundwater system. Therefore, assessment and optimization of fertilizer dose are needed for better management of fertilizers. Towards this, the present study determines the path, persistence, and mobility of K and P under the Boro rice cropping system. The experimental site consisted of four plots having Boro rice with four different fertilizer doses of nitrogen (N), P, K viz. 100%, 75%, 50%, and 25% of the recommended dose. Disturbed soil samples were analysed for K and P from pre-sown land to tillering stage at 0–5, 5–10, 10–15, 15–30, 30–45, and 45–60 cm depths. Simultaneously, K and available P were also simulated in the subsurface soil layers through the HYDRUS-1D model. The statistical comparisons were made with RMSER, E, and PBIAS between the modelled values and laboratory-measured values. Although, the results showed that all the treatments considered had agreeable simulations for both K and P, the K simulations were found to be better as compared to P simulations except for 25% where P simulations outperformed K. The simulated concentration at all doses was found most appropriate when measured for the subsurface layers (up to 45 cm), while showed an underestimation in the bottom layers (45–60 cm) of soil.

     

Acute toxicity of two insecticides to tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri

Acute toxicity and presumable harmless concentration of two commercial insecticides, Furadan 3G and Malataf 50E were reported for tubificid worms, Tubifex tubifex and Limnodrilus hoffmeisteri. L. hoffmeisteri were found more susceptible to both the insecticides; the Furadan was found to be more toxic than Malataf to tubificid worms. Analysis of variants showed a significant difference between safe concentrations of the same insecticide to different species.     

Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: Study design, sample generation, collection, and preparation

A major diesel emissions research program has been initiated by the U.S. Environmental Protection Agency to assess the human health risk associated with increased use of diesel automobiles. This program is intended to establish the mutagenic and carcinogenic potency of complex organics associated with diesel particles as well as comparative particle-bound organics from other environmental emissions for which human epidemiological data are available. The mobile source samples selected for this study were collected from a heavy-duty diesel engine, a series of light-duty diesel passenger cars, and a gasoline catalyst automobile. The comparative source samples incorporated into the study were cigarette smoke condensate, coke oven emissions, roofing tar emissions, and benzo(a)pyrene. The samples were tested using three mutagenic assays and four carcinogenic assays as prescribed by a test matrix. This report describes the study design, particle generation, and sample collection and preparation. A brief summary of the bioassays is also included.     

Preparation of size-selected fibers and fibrous aerosols for biological experiments

A size-selective procedure was developed for the preparation of fiber fractions of uniform size of chrysotile, crocidolite, amosite, and glass. The raw material was first ground to a suitable fineness, then suspended in liquids by ultrasonic agitation and separated by fiber diameter by means of slow sedimentation. The fractionation by fiber length was done by a vibrating sieve method. Fibrous aerosols of different size distributions could be prepared by using a vibrating bed aerosol generator.     

Fertility and air pollution: Some empirical findings

This paper attempts to explain regional differences in fertility rates in the standard metropolitan statistical areas of the United States through socioeconomic factors and air pollution. An important feature of this study is that it uses the most recent data pertaining to a homogeneous sample of observations within a country rather than using data for different countries. Statistical results suggest that given other factors, fertility and the level of air pollution have an inverse relationship. This quantitative effect is statistically significant but the absolute impact is rather low. Our results also suggest that an increase in the level of income, relative education of females, temperature, and the availability of physicians would in the long run reduce fertility rates in the urban areas of the United States.     

Transport of particulate matter in natural waters — modelling and in situ-measurements

The significant processes controlling the fate of particulates are convection an dispersion on one hand, and sedimentation on the other hand. Due to inteparticulated reactions, larger aggregates can be formed from smaller units thus changing the sedimentation characteristics. These phenomena are summarized in a mathematical model whereby hydrodynamic effects as well as the control mechanisms of the dissolved phase are included. A relationship was derived on the basis of energy considerations leading to the formulation of a critical sedimentation velocity of the suspensa, which determines the transport capacity of the flowing system. The sedimentation term is calculated from the above discussed transport capacity, hydro-dynamic parameters and suspending media properties. Aggregation effects are taken into account as an increase of sedimentation velocities of the particles. The equations are solved in a particular computational routine such that the horizontal distribution of suspended solids in a natural system can be describe as function of the above discussed phenomena. The model was tested with in situ-measurements. It was found that the observed processes are described satisfactorily by this model.