• Comparison of methods for enumeration of total coliforms and Escherichia coli in water samples in the Netherlands

      Schets FM; Nobel PJ; Strating S; Mooijman KA; Engels GB; Brouwer A; MGB (Rijksinstituut voor Volksgezondheid en Milieu RIVMKiwaPWN, 2001-05-28)
      The new European Drinking Water Directive (December 1998) defines a reference method for estimating the concentration of coliforms and Escherichia coli in drinking water. Laboratories may use other methods, but should demonstrate that results obtained are at least as reliable as those produced with the reference methods. Three Dutch laboratories participated in a European trial, in which a protocol for comparing enumeration methods for total coliform bacteria and Escherichia coli in water samples was tested. Besides the membrane filtration method on Lactose TTC agar with Tergitol 7 (LTTC) described in ISO 9308-1, and the Colilert(R) method, the Dutch laboratories included membrane filtration methods on Laurylsulphate Agar (LSA), Chromocult(R) Coliform Agar (CCA) and the E. coli Direct Plating method. On LTTC37 significantly more total oliforms were enumerated than on LSA37; however, the LTTC method was found suitable for analysing very clean (drinking) water samples only, due to its lack of selectivity. The DP method (or Rapid Test in ISO 9308-1) is the best method for enumeration of E. coli, while the Colilert(R) method produces 12,5 % false negative E. coli results.<br>
    • Evaluatie duurzame gewasbescherming 2006: milieu

      van der Linden AMA; van Beelen P; van den Berg GA; de Boer M; van der Gaag DJ; Groenwold JG; Huijsmans JFM; Kalf DF; de Kool SAM; Kruijne R; Merkelbach RCM; de Snoo GR; Vijftigschild RAN; Vijver MG; van der Wal AJ; LER (Rijksinstituut voor Volksgezondheid en Milieu RIVMAlterraCBSCLMCMLKiwaPDPPOPRIRIZA, 2007-01-16)
      The Dutch plant protection policy aims at reaching sustainable agriculture in the Netherlands. Operational goals with respect to the environment for the year 2010 compared to the year 1998 are: a reduction of 95% of the environmental impact on surface water and a reduction of 95% of bottle-necks in the production of drinking water from surface water. Midterm goals are 75% and 50% respectively. The calculated environmental impact as a result of drift emissions to surface water was reduced with 86%. Drift reduction measures, imposed since 2000, contributed most to this calculated reduction. The second most important contribution came from the use of less toxic plant protection products. Concentrations of plant protection product residues measured in surface waters declined over the study period, but still concentrations above maximum permissible levels occurred in 2004. The number of bottle-necks in the production of drinking water from surface water was diminished from 33 to 27; the midterm goal was not met. This was partly due to non-agricultural use of plant protection products and foreign sources. Experiments show that changes in plant protection strategies and management at the farm level may further reduce the environmental impact of plant protection products. Implementation of these innovations requires widespread dissemination of the results.
    • Nutrienten in bodem en grondwater: Kwaliteitsdoelstellingen en kwaliteit 1984-2000

      Willems WJ; Fraters B; Meinardi CR; Reijnders HFR; van Beek CGEM; LBG (Rijksinstituut voor Volksgezondheid en Milieu RIVMKiwa, 2003-01-15)
      This report is one of the background reports of the evaluation report "MINAS en Milieu" It deals with the impact of fertiliser- and manure application in agriculture on the quality of soil (phosphrus) en groundwater (phosphorus/nitrogen). It is based on monitoring data carried out in the period 1984-2000. The report describes the actual status of quality standards with respect to nutrients. The agricultural soils in the Netherlands are in general phosphorus-rich. Nitrate concentrations in groundwater are high in shallow groundwater (in 2000 in sandy areas ca 125 mg/l: more than twice the standard value) but show a decrease since 1995, due to lower N-surpluses in dairy farming. At greater depths, concentrations are lower due to a combination of slow travel time, hydrology and decay (denitrification). In certain areas the abstracted groundwater for public water supply shows an increase of co-products of denitrifiaction e.g. sulphate, metals (nickel) and hardness.<br>