Arsenic contamination of soils and agricultural plants through irrigation water in Nepal.

This study monitored the influence of arsenic-contaminated irrigation water on alkaline soils and arsenic uptake in agricultural plants at field level. The arsenic concentrations in irrigation water ranges from <0.005 to 1.014 mg L(-1) where the arsenic concentrations in the soils were measured from 6.1 to 16.7 mg As kg(-1). The arsenic content in different parts of plants are found in the order of roots>shoots>leaves>edible parts. The mean arsenic content of edible plant material (dry weight) were found in the order of onion leaves (0.55 mg As kg(-1))>onion bulb (0.45 mg As kg(-1))>cauliflower (0.33 mg As kg(-1))>rice (0.18 mg As kg(-1))>brinjal (0.09 mg As kg(-1))>potato (<0.01 mg As kg(-1)).

Treatment of landfill leachate by irrigation and interaction with landfill gas.

The treatment efficiency of landfill leachate irrigation and the effect of landfill gas addition were investigated in a vegetated compost/gravel substrate by monitoring soil moisture content, drainage water volume and quality in a two years lysimeter experiment. Landfill leachate irrigation exceeding 350 mm increased soil moisture and drainage volumes owing to the deterioration of the vegetation resulting from high sodium chloride inputs. Even so sodium chloride was lost in between the irrigation periods, the total reduction of the landfill leachate volume by irrigation decreased from 71% in the first year to 38% in the second year. Landfill gas addition also increased drainage volumes, but was less pronounced. Twenty-two percent of magnesium was retained under landfill leachate irrigation, while decreasing pH values, redox potential and high initial concentrations in the substrate released calcium, iron and potassium. Ninety-eight percent of ammonium was removed by irrigation, but 44% of the applied ammonium was leached as nitrate after oxidation took place due to a decreased uptake after the vegetation deteriorated. Landfill gas fumigation influenced landfill leachate treatment by decreasing the redox potential and the pH and increasing the drainage water content, which improved the retention of total nitrogen and sulfate, but increased the release of iron, calcium and magnesium. To conclude, landfill leachate irrigation is a valuable treatment option to minimize leachate quantities and remove ammonium independent from the presence of landfill gas if salt accumulation is avoided.

Certification of the European reference soil set (IRMM-443--EUROSOILS). Part I. Adsorption coefficients for atrazine, 2,4-D and lindane.

The European Commission has characterised and certified a set of six European soils (the EUROSOILS) under the number IRMM-443. After a successful validation and trial period with a preliminary batch it was decided to produce a new batch of certified reference materials. Part I of this paper describes the certification of adsorption coefficients for atrazine, 2,4-D and lindane in these soils. The adsorption coefficients were determined according to OECD Test Guideline 106. Additionally, the underlying principles for the value assignment process according to the GUM and their practical application to the numerical data obtained during the certification exercise according to ISO Guide 34 and 35 are discussed.

Certification of the European Reference Soil Set (IRMM-443--EUROSOILS). Part II. Soil-pH in suspensions of water and CaCl2.

IRMM-443 re-groups a set of six European Reference Soils (EUROSOILS), which had been certified for their adsorption coefficients for atrazine, 2,4-D and lindane (Certification of the European Reference Soil Set (IRMM-443-EUROSOILS)-Part I. Adsorption coefficients for atrazine, 2,4-D and lindane. Sci Total Environ, in press). The certification of these parameters was complemented by an additional certification of pH in suspension as well by the determination of indicative values for total nitrogen, organic and total carbon content. While Part I explained the principles of the value assignment process and discussed their application to the adsorption coefficients, Part II presents the certified values for pH as well as the indicative values for N(tot), C(tot) and C(org). In addition, the assessment of uncertainty components for stability and homogeneity, which have been included in the final uncertainty budget, is discussed.