Levels and Trophic Transfer of Selected Pesticides in the Lake Ziway Ecosystem.

The levels of 30 selected pesticides and trophic biomagnification of DDT were investigated in biota samples of the Lake Ziway in the Rift valley region, Ethiopia. Carbon source and trophic position were calculated by using C and N stable isotopes, individually, and trophic magnification factors (TMFs) were inferred. Only DDT and its metabolites were quantified in all samples analyzed.

Small-scale Farmer Pesticide Knowledge and Practice and Impacts on the Environment and Human Health in Ethiopia.

Background: Inappropriate use and application of pesticides in Ethiopia pose a major threat to the health of farmers and the environment.

Objective: The present study aimed to assess the level of knowledge, attitudes, and practices of small-scale vegetable farmers towards the use of pesticides in Ethiopia along the Lake Ziway watershed.

Methods: This was a cross-sectional study involving a total of 210 farmers randomly selected during a period of pesticide application from a purposively selected village located in the immediate vicinity of Lake Ziway, Ethiopia.

The effect of freezing and thawing on water flow and MCPA leaching in partially frozen soil.

Limited knowledge and experimental data exist on pesticide leaching through partially frozen soil. The objective of this study was to better understand the complex processes of freezing and thawing and the effects these processes have on water flow and pesticide transport through soil. To achieve this we conducted a soil column irrigation experiment to quantify the transport of a non-reactive tracer and the herbicide MCPA in partially frozen soil.

An integrated approach for assessing influence of agricultural activities on pesticides in a shallow aquifer in south-eastern Norway.

The study examines the influence of agricultural activities on pesticides in groundwater in an area with fluvial deposits of sand with a top layer of sandy silt and silt, intensive cultivation of potatoes and cereals, and drinking water supplies of households from local groundwater wells. Information about local agricultural practice and washing sites for pesticide spraying equipment, properties of soils and deeper deposits, hydrogeology and groundwater flow, simulations of pesticide leaching, and contents of pesticides and nitrate in groundwater samples from drinking water wells was used to explore extension and reasons of pesticide contamination of groundwater. Pesticides were found in a majority of the sampled wells.

Organochlorine pesticides and polychlorinated biphenyls in fish from Lake Awassa in the Ethiopian Rift Valley: human health risks.

Dietary intake of fish containing organic contaminants poses a potential threat to human health. In the present work, an assessment has been carried out to look at the human health risk associated with consumption of fish contaminated with organochlorine pesticides (OCPs) and polychlorinated biphenyles (PCBs) in certain fish species collected from Lake Hawassa, Ethiopia. The health risk assessment was made by comparing the concentrations of OCPs and PCBs in fish muscle tissues with reference doses given in the USEPA guidelines.

Effects of picoxystrobin and 4-n-nonylphenol on soil microbial community structure and respiration activity.

There is widespread use of chemical amendments to meet the demands for increased productivity in agriculture. Potentially toxic compounds, single or in mixtures, are added to the soil medium on a regular basis, while the ecotoxicological risk assessment procedures mainly follow a chemical by chemical approach. Picoxystrobin is a fungicide that has caused concern due to studies showing potentially detrimental effects to soil fauna (earthworms), while negative effects on soil microbial activities (nitrification, respiration) are shown to be transient.

Bioaccumulation of persistent organic pollutants (POPs) in fish species from Lake Koka, Ethiopia: The influence of lipid content and trophic position.

The concentrations and bioaccumulation of persistent organic pollutants (POPs) were determined in four fish species from Lake Koka, Ethiopia, representing 2-3 levels in the food chain of the lake. Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, polychlorinated biphenyls (PCBs) and chlorpyrifos were identified, with DDTs as the most predominant pesticide, with concentration ranging from 0.05 to 72.

Metribuzin transport in undisturbed soil cores under controlled water potential conditions: experiments and modelling to evaluate the risk of leaching in a sandy loam soil profile.

Background: Mobility of pesticides in soils is often evaluated and characterised in the surface soil layers rather than at different depths where soil characteristics such as soil organic matter, microbial biomass or clay contents can strongly change pesticide behaviour. The objective of this work was to characterise the reactivity of the herbicide metribuzin in three main soil horizons found in the 0-80 cm profile of an alluvial soil of southern Norway under dynamic transport conditions.

Results: A laboratory infiltrometer was used to perform percolation experiments in soil cores sampled in the three horizons Ap, Bw and Bw/C, at a fixed matric potential of -10 cm, thus preventing pores of equivalent radii higher than 0.

Bioaccumulation of organochlorine pollutants in the fish community in Lake Arungen, Norway.

Organochlorine pollutants in the major fish species (pike Esox lucius, perch Perca fluviatilis, and roach Rutilus rutilus) of Lake Arungen, Norway, were investigated after an extensive removal of large pike in 2004. The organochlorine pollutants detected in fish liver samples in 2005 were dichlorodiphenyltrichloroethane (DDTs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), and heptachlor epoxide (HCE). DDTs were the dominant among all analyzed OCs.

Effect of freezing and thawing on microbial activity and glyphosate degradation in two Norwegian soils.

Little research has been done on pesticide dissipation in cold climates and there is a need to focus on the influence of climate on pesticide degradation in soil. Glyphosate, N-(phosphonomethyl)glycine, is a herbicide frequently used for controlling perennial weeds through application after harvest and was used as a model compound for this study. The effect of freeze-thaw activity on the availability of glyphosate in soil, and consequently its mineralization by soil microorganisms, was studied through laboratory incubations of repacked soil cores treated with 14C-labelled glyphosate and subjected to different freeze-thaw treatments.