Cytotoxicity assessment of monocrotophos in Paramecium caudatum and Oxytricha fallax

Experiments were conducted to evaluate the toxic effects ofmonocrotophos in ciliate models Paramecium caudatum and Oxytricha fallax. In acute toxicity studies higherconcentrations of monocrotophos caused marked increase in mobility of cells exhibiting rocking movements within two mins of exposure but were decreased after 30 mins. LC50 value by mortality curve for 3 hr acute toxicity test of Oxytricha fallax and Paramecium caudatum was found 307.744 +/- 33.27 mg l(-1) and 332.284 +/- 57.52 mg l(-1) respectively. Oxytricha fallax was found sensitive than Paramecium caudatum to monocrotophos. In acute exposure cells showed deformities such as swelling, oval shaped deformity and in higher concentrations shortening of longitudinal axis with blackening of cytoplasm occurred. The length of paramecia was reduced prominently. Similarly enlargement of contractile vacuole and stress egestion of food vacuoles was also observed. The morphological studies showed the changes in shape, size, colour and width of Paramecia and Oxytricha. Frequencies of macronuclear aberrations were significant showing deformities such as rod shaped, elongation, fragmentation, diffusion and total absence of nucleus and were concentration dependent. The data provided in the present study on interaction of pesticides with nuclear structure can be of immense value because most of these pesticides have been reported to have carcinogenic, mutagenic and teratogenic properties.     

A review on bisphenol A occurrences,health effects and treatment process via membrane technology for drinking water

Massive utilization of bisphenol A (BPA) in the industrial production of polycarbonate plastics has led to the occurrence of this compound (at μg/L to ng/L level) in the water treatment plant. Nowadays, the presence of BPA in drinking water sources is a major concern among society because BPA is one of the endocrine disruption compounds (EDCs) that can cause hazard to human health even at extremely low concentration level. Parallel to these issues, membrane technology has emerged as the most feasible treatment process to eliminate this recalcitrant contaminant via physical separation mechanism. This paper reviews the occurrences and effects of BPA toward living organisms as well as the application of membrane technology for their removal in water treatment plant. The potential applications of using polymeric membranes for BPA removal are also discussed. Literature revealed that modifying membrane surface using blending approach is the simple yet effective method to improve membrane properties with respect to BPA removal without compromising water permeability. The regeneration process helps in maintaining the performances of membrane at desired level. The application of large-scale membrane process in treatment plant shows the feasibility of the technology for removing BPA and possible future prospect in water treatment process.     

Artificial neural network based maximum power point tracking controller for photovoltaic standalone system

This article presents a two-stage maximum power point tracking (MPPT) controller using artificial neural network (ANN) for photovoltaic (PV) standalone system, under varying weather conditions of solar irradiation and module temperature. At the first-stage, the ANN algorithm locates the maximum power point (MPP) associated to solar irradiation and module temperature. Then, a simple controller at the second-step, by changing the duty cycle of a DC–DC boost converter, tracks the MPP. In this method, in addition to experimental data collection for training the ANN, a circuit is designed in MATLAB-Simulink to acquire data for whole ranges of weather condition. The whole system is simulated in Simulink. Simulation results show small transient response time, and low power oscillation in steady-state. Furthermore, dynamic response verifies that this method is very fast and precise at tracking the MPP under rapidly changing irradiation, and has very low power oscillation under slowly changing irradiation. Experimental results are provided to verify the simulation results as well.     

Assessment of heavy metals in water,sediment, Anabas testudineus and Eichhornia crassipes in a former mining pond in Perak,Malaysia

The concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sn and Zn were analysed in water, sediment, muscle of climbing perch fish (Anabas testudineus), and tissue of water hyacinth plants (Eichhornia crassipes) collected from a former tin-mining pond in Perak, Malaysia. The monitoring was performed during the minimum and maximum rainfall periods. The concentrations of As, Cr, Fe, Ni, Pb and Zn in water exceeded the permissible limits set by the Interim National Water Quality Standards for Malaysia (INWQS). The risk index (RI) values determined for As, Cd, Cr, Cu, Hg, Pb and Zn in sediment presented a low degree of ecological risk. The order of the top three heavy metals measured in fish muscle was Zn?>?Fe?>?Al. The estimated daily intake (EDI) of As and Cr exceeded the allowable limits in both rainfall periods. The bioconcentration factor (BCF) and translocation factor (TF) values of Zn in water hyacinth were 24.865 and 3.214, respectively. The concentrations of Cu and Zn in the plant tissue were significantly correlated (p?<?.05) with the concentrations of heavy metals in water. Overall, climbing perch and water hyacinth are excellent bioindicators of environmental impacts on water bodies.     

不同降水下覆盖与缓释肥减量对油菜土壤微生物群落结构的影响

为探讨沟垄集雨、秸秆覆盖和减量缓释肥集成技术对油菜土壤微生物群落结构的影响,在大田定位试验条件下,设置3种栽培方式（秸秆覆盖、沟垄集雨、传统平作）和4种施肥水平（习惯施肥、缓释肥减量20%、缓释肥减量40%、不施肥）,比较分析2016~2017年（多雨年份）和2017~2018年（季节性干旱年份）这2种不同降水年型下油菜土壤微生物群落结构对集成技术的响应.结果表明,不同降雨条件下,秸秆覆盖+缓释肥减量20%（J80）与沟垄覆盖+缓释肥减量20%（M80）较习惯栽培（PC）更利于土壤微生物生长.在多雨年型和季节性干旱年型下,J80与M80能平均分别提高微生物量碳9.94%和10.32%;提高土壤微生物量氮2.38%和1.19%.多雨年型下,土壤微生物磷酸脂肪酸（PLFA）总量较干旱年型降低30.75%,覆盖能有效提高土壤PLFA质量摩尔浓度.多雨年型下土壤细菌、真菌PLFA质量摩尔浓度较干旱年型平均减少33.67%和53.21%;而放线菌PLFA增加13.04%.微生物群落对异常降水具有敏感响应.多雨气候会造成细菌/真菌升高;干旱气候则会增加直链饱和脂肪酸/直链单不饱和脂肪酸及直链单不饱和脂肪酸/环丙烷脂肪酸.通过秸秆覆盖与缓释肥的集成技术,能稳定异常降水下的土壤微环境,缓解水分和养分胁迫,为油菜稳产和可持续发展提供有效途径.     

TiO2/Ag modified penta-bismuth hepta-oxide nitrate and its adsorption performance for azo dye removal

A modified hydrophilic penta-bismuth hepta-oxide nitrate (Bi₅O₇NO₃) surface was synthesized via a precipitation method using TiO₂ and Ag as modified agents. The synthesized product was characterized by different analytical techniques. The removal efficiency was evaluated using mono-and di-sulphonated azo dyes as model pollutants. Different kinetic, isotherm and diffusion models were chosen to describe the adsorption process. X-ray photoelectron spectroscopy (XPS) results revealed no noticeable differences in the chemical states of modified adsorbent when compared to pure Bi₅O₇NO₃;however, the presence of hydrophilic centres such as TiO₂ and Ag developed positively charged surface groups and improved its adsorption performance to a wide range of azo dyes. Dyes removal was found to be a function of adsorbent dosage, initial dye concentration, solution pH and temperature. The reduction of Langmuir 1,2-mixed order kinetics to the second or first-order kinetics could be successfully used to describe the adsorption of dyes onto the modified adsorbent. Mass transfer can be described by intra-particle diffusion at a certain stage, but it was not the rate limiting step that controlled the adsorption process. Homogenous behavior of adsorbent surface can be explored by applying Langmuir isotherm to fit the adsorption data.     

Comparison of a plant based natural surfactant with SDS for washing of As(Ⅴ) from Fe rich soil

This study explores the possible application of a biodegradable plant based surfactant, obtained from Sapindus mukorossi, for washing low levels of arsenic （As） from an iron （Fe） rich soil. Natural association of As（Ⅴ） with Fe（Ⅲ） makes the process difficult. Soapnut solution was compared to anionic surfactant sodium dodecyl sulfate （SDS） in down-flow and a newly introduced suction mode for soil column washing. It was observed that soapnut attained up to 86% efficiency with respect to SDS in removing As. Full factorial design of experiment revealed a very good fit of data. The suction mode generated up to 83 kPa pressure inside column whilst down-flow mode generated a much higher pressure of 214 kPa, thus making the suction mode more efficient. Micellar solubilisation was found to be responsible for As desorption from the soil and it followed 1st order kinetics. Desorption rate coefficient of suction mode was found to be in the range of 0.005 to 0.01, much higher than down-flow mode values. Analysis of the PT-IR data suggested that the soapnut solution did not interact chemically with As, offering an option for reusing the surfactant. Soapnut can be considered as a soil washing agent for removing As even from soil with high Fe content.     

Determination of total hydrocarbon concentration in coastal waters and sediments off the east coast of Peninsular Malaysia

To determine the level of total hydrocarbon concentrations (THCs) along the eastern coastal regions of Peninsular Malaysia, samples of subsurface seawater (1 m) and surface sediments were collected from several sampling stations between June and August 1993. THCs in seawater and sediments as determined by fluorescence spectroscopy ranged from 1.4 to 21.8 µg L-1 (Seligi crude oil equivalents) and from 0.79 to 20.0 mg kg-1 (dry weight Seligi crude oil equivalents) respectively. In comparison to results obtained in similar surveys in Malaysian waters, the levels of THCs found in the present study were significantly lower indicating lower hydrocarbon contamination in the area studied.     

Trends in the use of Fenton,electro-Fenton and photo-Fenton for the treatment of landfill leachate

Advanced oxidation processes (AOPs) such as Fenton, electro-Fenton and photo-Fenton have been applied effectively to remove refractory organics from landfill leachate. The Fenton reaction is based on the addition of hydrogen peroxide to the wastewater or leachate in the presence of ferrous salt as a catalyst. The use of this technique has proved to be one of the best compromises for landfill leachate treatment because of its environmental and economical advantages. Fenton process has been used successfully to mineralize wide range of organic constituents present in landfill leachate particularly those recalcitrant to biological degradation. The present study reviews the use of Fenton and related processes in terms of their increased application to landfill leachate. The effects of various operating parameters and their optimum ranges for maximum COD and color removal are reviewed with the conclusion that the Fenton and related processes are effective and competitive with other technologies for degradation of both raw and pre-treated landfill leachate.     

Environmental toxicology and associated human health risks

Environmental Science and Pollution Research -