Investigation of acute toxicity of chlorpyrifos-methyl on guppy Poecilia reticulata

Static bioassays were made to determine acute toxicity of chlorpyrifos-methyl, a wide spectrum organophosphorus insecticide and potential toxic pollutant of aquatic ecosystem, Guppy fish (Poecilia reticulata). Bioassays were made at a regulated temperature of 22+/-1 degrees C and were repeated three times. Lethal doses of the insecticides were determined using LC50 software programme of U.S. EPA based on Finney's Probit Analysis statistical method. The 96 h LC50 value and 95% confidence limit of chlorpyrifos-methyl for Guppy was estimated as 1.79 (1.47-2.10) mg/l. The fish exposed to chlorpyrifos-methyl exhibited behavioral changes in the form of neurotoxin toxicity: less general activity than control group, loss of equilibrium, erratic swimming and staying motionless at a certain location generally at mid-water level for prolonged periods. The 1 mg/l (lowest) concentration had similar behavior (NOEC) with the control group.     

Microwave plasma conversion of volatile organic compounds

A microwave-induced, steam/Ar/O2, plasma "torch" was operated at atmospheric pressure to determine the feasibility of destroying volatile organic compounds (VOCs) of concern. The plasma process can be coupled with adsorbent technology by providing steam as the fluid carrier for desorbing the VOCs from an adsorbent. Hence, N2 can be excluded by using a relatively inexpensive carrier gas, and thermal formation of oxides of nitrogen (NOx) is avoided in the plasma. The objectives of the study were to evaluate the technical feasibility of destroying VOCs from gas streams by using a commercially available microwave plasma torch and to examine whether significant byproducts were produced. Trichloroethene (TCE) and toluene (TOL) were added as representative VOCs of interest to a flow that contained Ar as a carrier gas in addition to O2 and steam. The O2 was necessary to ensure that undesirable byproducts were not formed in the process. Microwave power applied at 500-600 W was found to be sufficient to achieve the destruction of the test compounds, down to the detection limits of the gas chromatograph that was used in the analysis. Samples of the postmicrowave gases were collected on sorbent tubes for the analysis of dioxins and other byproducts. No hazardous byproducts were detected when sufficient O2 was added to the flow. The destruction efficiency at a fixed microwave power improved with the addition of steam to the flow that passed through the torch.     

Levels of PCDDs and PCDFs in Korean river sediments and their detection by biomarkers

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) are a group of toxic halogenated aryl hydrocarbons inducing various physiological disorders against biological organisms. Here, we investigated their levels in sediment samples taken from 12 different rivers in Korea. The levels of PCDD/PCDFs in sediment samples were expressed as concentrations and international TEQ values. Among 17 PCDD/PCDFs selected as target compounds in this study, the 1,2,3,4,7,8-HxCDD and OCDD were found in all river sediments with significant variation in various congener profiles of PCDD/PCDFs in sediments. PCDD/PCDFs could be monitored by sensitive biomarkers using insect immune system. Out of 12 river sediment samples, the biomarkers reported four spots (up, middle, and down Singil sites and Ansan) as putative contamination areas. When comparing both chemical and biological monitoring results, two methods agreed three spots of Singil as contamination areas (above 10ppt levels) as well as six river sediment samples as relatively less-contaminated areas, but differed in the results in Ansan and Miho, probably due to relative non-specificity of biomarkers. Despite some disparity between bio- and chemical monitoring results, the biomarkers can be recommended as a device warning the contamination of dioxins in the environment because of a fast and inexpensive detection method.     

Road-deposited sediments mediating the transfer of anthropogenic organic matter to stormwater runoff

Environmental Geochemistry and Health - It has been regarded that road-deposited sediment (RDS) is one of the important sinks of anthropogenic pollutants as well as the major source of pollutants...     

Evaluation of the potential methane yield of industrial wastewaters used in bioreactor landfills

To increase the moisture content of waste disposed in a bioreactor landfill, it is critical to secure the moisture source. In this study, industrial wastewater was evaluated as a potential moisture source for a bioreactor landfill with respect to the impact on methane generation. Industrial wastewater samples were collected from fishery, brewery and dairy industries. These samples were tested for basic water chemistry parameters, heavy metals, and methane generation using the regular and modified biochemical methane potential (BMP) assays. Despite high sodium and total phosphate concentrations in the fishery wastewater, a significant methane yield was observed (0.313?m³ CH₄/kg COD). However, a relatively large amount of fishery wastewater added at the phase of methane generation acceleration adversely affected microbial activity. Samples from the brewery and dairy wastewater did not indicate significant inhibitory effects on methane generation in either the regular or the modified BMP assay. This study demonstrates the utility of wastewater as an alternative to traditional moisture sources when used to enhance methane production in a bioreactor landfill.     

Quantifying the efficiency of soil sampling designs: A multivariate approach

The objective of this paper is to quantify and compare the loss functions of the standard two-stage design and its composite sample alternative in the context of multivariate soil sampling. The loss function is defined (conceptually) as the ratio of cost over information and measures design inefficiency. The efficiency of the design is the reciprocal of the loss function. The focus of this paper is twofold: (a) we define a measure of multivariate information using the Kullback–Leibler distance, and (b) we derive the variance-covariance structure for two soil sampling designs: a standard two-stage design and its composite sample counterpart. Randomness in the mass of soil samples is taken into account in both designs. A pilot study in Slovenia is used to demonstrate the calculations of the loss function and to compare the efficiency of the two designs. The results show that the composite sample design is more efficient than the two-stage design. The efficiency ratio is 1.3 for pH, 2.0 for C, 2.1 for N, and 2.5 for CEC. The multivariate efficiency ratio is 2.3. These ratios primarily reflect cost ratios; influence of the information is small.     

Prenatal diagnosis of 46, XX/47, XXY mosaicism: A case report

A case of 46,XX/47,XXY mosaicism was diagnosed at 22 gestational weeks by amniocentesis and fetal blood sampling. After genetic counselling, the couple elected to have the pregnancy terminated. Culture of the fetal skin and both gonads confirmed the prenatal diagnosis. In external appearance, the abortus had no remarkable findings except hypospadia. Histology of both gonads showed testicular tissue without evidence of ovarian components.