PEARL model for pesticide behaviour and emissions in soil-plant systems : description of the processes in FOCUS PEARL v 1.1.1

The use of pesticides in agriculture presents risks to the environment, which are increasingly evaluated by using computation models. The new PEARL model simulates the behaviour of pesticides in soil-plant systems and their emissions to the environment. The pesticide model is used in combination with the hydrological model SWAP. Various agricultural situations and ways of applying the pesticides can be simulated. The model accounts for different sorption mechanisms, in equilibrium and non-equilibriumdomains of the soil. Pesticide transport in the liquid and gas phases is described by the convection-dispersion-diffusion type equation, which is supplemented with sink terms. Comprehensive reaction schemes are processed in matrix form. The rate in first-order transformation kinetics is dependent on temperature, soil moisture content and depth in the soil. Besides computing persistence and distribution of the pesticidal compounds in soil, the model computes volatilization into the air, lateral drainage to water courses and leaching to groundwater

Manual of PEARLNEQ v4

This document describes a PEARLNEQ-PEST combination, which can be used to estimate the parameters for long-term sorption kinetics in the PEARL model on the basis of an incubation experiment for a certain soil and a certain pesticide. The combination provides also the transformation half-life at reference temperature (when long-term sorption kinetics are included in PEARL, the definition of this half-life changes so it has to be recalculate

Partial Validation of the Dutch Model for Emission and Transport of Nutrients (STONE)

The Netherlands has to cope with large losses of N and P to groundwater and surface water. Agriculture is the dominant source of these nutrients, particularly with reference to nutrient excretion due to intensive animal husbandry in combination with fertilizer use. The Dutch government has recently launched a stricter eutrophication abatement policy to comply with the EC nitrate directive. The Dutch consensus model for N and P emission to groundwater and surface water (STONE) has been developed to evaluate the environmental benefits of abatement plans. Due to the possibly severe socioeconomic consequences of eutrophication abatement plans, it is of utmost importance that the model is thoroughly validated. Because STONE is applied on a nationwide scale, the model validation has also been carried out on this scale. For this purpose the model outputs were compared with lumped results from monitoring networks in the upper groundwater and in surface waters. About 13,000 recent point source observations of nitrate in the upper groundwater were available, along with several hundreds of observations showing N and P in local surface water systems. Comparison of observations from the different spatial scales available showed the issue of scale to be important. Scale issues will be addressed in the next stages of the validation study

De consequenties van de Europese bodemrichtlijn voor het Nederlandse beleid

Deze publicatie beoogt het Nederlandse Kabinet, Parlement, belangengroepen en andere EU-landen te informeren over drie vragen: 1. Wat zijn de bodemproblemen in Nederland? 2. Wat doet het bestaande Nederlandse bodembeleid daaraan? 3. Hoe sluit de voorgestelde Kaderrichtlijn Bodem (KRB) aan op dat bestaande beleid

Op zoek naar de "ware" neerslag en verdamping; toetsing van de met het STONE 2.1-instrumentarium berekende verdamping aan literatuurgegevens en aan regionale waterbalansen, en de gevoeligheid van het neerslagoverschot op de uitspoeling van nutriënten

Het neerslagoverschot is van grote invloed op de door het STONE-instrumentarium berekende N- en P-belasting van grond- en oppervlaktewater. Naar de hiervoor meest bepalende processen neerslag en verdamping, zoals die voor STONE 2.1 als randvoorwaarden worden opgelegd of worden berekend, is een beperkte gevoeligheidsanalyse uitgevoerd. Daaruit volgt dat het niveau van de potentiële verdamping van grasland systematisch te hoog wordt berekend. De vergelijking met de verdampingsreducties volgens de HELP-tabel indiceren een te geringe berekende reductie voor droogtegevoelige zandgronden. Ook is een vergelijking gemaakt met gegevens uit de literatuur en met de verdamping als restpost van de waterbalansen van een aantal gebieden. Voor het Holocene deel van Nederland is er een goede overeenkomst; voor het Pleistocene deel van Nederland is de verdamping als restpost van de waterbalans enigszins lager dan de door STONE 2.1 berekende verdamping. Door het gedateerd zijn van historische gegevens en door de onbetrouwbaarheid van de waterbalansen zijn dit geen harde conclusie

Pesticide leaching to the groundwater in drinking water abstraction areas; analysis with the GeoPEARL model

In the new Dutch decision tree for the evaluation of pesticide leaching from soils, leaching to the shallow groundwater is assessed with the spatially distributed model GeoPEARL. The relative vulnerability of the groundwater in the drinking water abstraction areas is estimated. The general conclusion is that the groundwater within the drinking water abstraction areas as a whole is up to five times more vulnerable to pesticide leaching than the groundwater in Dutch agriculture. The higher vulnerability of the groundwater in the drinking water abstraction areas is primarily caused by lower soil organic matter contents

Guidance proposal for using available DegT50 values for estimation of degradation rates of plant protection products in Dutch surface water and sediment

The degradation rate of plant protection products and their transformation products in surface water and sediment may influence their concentrations in Dutch surface water. Therefore the estimation of these rates may be an important part of the assessment of the exposure of aquatic organisms. We propose a stepped sequence of studies for estimating the rate in water going from simple and conservative to more sophisticated and more realistic studies. The sequence includes: - studies on hydrolysis and photolysis; - studies with fresh surface water in the dark; - water-sediment studies in the dark or in light; - studies with algae and macrophytes; - outdoor studies in realistic surface water systems. The usefulness of these studies for the exposure assessment in Dutch surface water is discussed