In the framework of the project Area Atlas, about 50 maps, spread over about 150 digital files were collected for several types of area-specific policy. The aim of the project was to overview the existing maps and files as completely as possible. The files, including the file manipulation and presentation program ArcView version 1, have been made available on CD-ROM but exclusively to the contributors of this project. A cumulation map for area-specific policy has been derived using 25 maps suitable for this purpose. From this, it appears that at some locations a maximum of 17 different area-specific policies are applicable.

In this analysis of the economic impact of reductions in nitrate leaching on dairy farms in the Netherlands, a non-linear optimisation model was developed to describe the production and purchase of fodder (maize, grass and concentrates) and the resulting nitrate leakage for various grazing systems and groundwater classes. The analysis focused on the central eastern part of the Netherlands, where nitrate leakage is a serious problem. The model minimised economic costs, with constraints for production, feed requirements and mass balances for fodder, as well as for nitrate leaching (the maximum admissible rate is 34 kg N ha exp. -1yr exp. -1). Economic costs were shown to be attributable to the increased costs of fodder and processing of manure when nitrate restrictions are tightened. For some groundwater classes with shallow groundwater the costs shown were negligible. For areas with deep groundwater, it was in some cases difficult - if not impossible - to achieve maximum admissible nitrate leaching. Model results indicated a reduction in the financial balance of NLG 0 to NLG 549 per hectare.

This report gives the results of a monitoring program on nematodes, coupled with a soil quality monitoring program on the same 200 plots in the Netherlands. The sampling interval is five years. This report deals with the data of the two first years and gives also results of the effects of different levels of manure on the number and the species composition of the nematodefauna. In 1993 and 1994 samples were taken from plots of 55 farms with dairy-cattle on grasslands with sandy soils. The farms had different numbers of cattle (mainly cows) per ha. This leads to differences in the amounts of manure per ha which was supposed to be by the concentrations of phosphate. The species composition changes by a change in the phosphate concentration. Eucephalobus mucronatus becomes more abundant if the phosphate concentration increases, as Aphelenchus, Eucephalobus paracornutus and Prismatolaimus decrease. The total numbers of nematodes do not change significantly. The trophic diversity index decreases when the concentration of phosphate increases, as does the total number of plant feeding and hyphal feeding nematodes, while the total number of bacterial feeders stays on the same level.

No Observed Effect Concentrations of species or processes are used to derive statistical sensitivity distributions. Hazardous Concentrations (HC5 and HC50) derived from these distributions define the ecotoxicological risk limits. The project 'Validation of Toxicity Data and Risk Limits for Soils' was set up to evaluate the ecological relevance of (1) laboratory toxicity data and (2) ecotoxicological risk limits, and to identify which factors introduce uncertainties. Toxic effects of zinc and other metals were studied on selected species (Trifolium pratense, Folsomia candida, Enchytraeus crypticus, Eisenia andrei) and on microbial degradation activities. Differences in bioavailability between soil types were found to be of prime importance in laboratory-to-field extrapolation of toxicity data. Studies with mixtures suggested that each contaminant should be taken into account in risk assessment. Variable exposure conditions appeared to modulate toxicity moderately. Toxic effects of zinc on community endpoints were determined at an experimental field plot and a heavy-metal contaminated field site using enchytraeids, nematodes and micro-organisms. No or weak responses were found at the HC5 level, while measurable effects were present at the HC50 level. This was confirmed by data from the literature. The scientific underpinning of HC values may be improved if toxicity-modulating factors such as bioavailability are taken into account in the interpretation of laboratory toxicity data and if long-term effects of contaminants are focused on.<br>

The present Dutch intervention values for mineral oil (i.e. 'Total Petroleum Hydrocarbons') have been reviewed with respect to fractions of TPH and using ecotoxicological and human toxicological data. It is found that review of TPH-fractions is significant with respect to both human and ecological risks, since risks by exposure to TPH-fractions could be more pronounced. It is concluded that the present method could underestimate the (non-carcinogenic) human-toxicological risk of TPH in light fuels (=C12) like petrol. Replacing this method by a method to distinguish aliphatic and aromatic fractions and to adopt the 10 indicative levels presented for TPH fractions is recommended. Especially aliphatic fractions (to EC12) and aromatic fractions (to EC16) are relevant with respect to the (non-carcinogenic) human risk. Since there are insufficient reliable ecotoxicological data to calculate ecotoxicological risk-levels, it is recommended to first identify relevant TPH fractions to describe terrestrial exotoxicological effects of petroleum hydrocarbons and then to generate the necessary ecotoxicological data to derive HC50 values (ecotoxicological-based serious soil concentrations).<br>

This report includes information with respect to soil protection on industrial sites. Essential is to define which industrial activities need protection and how to make it adequate protection. Protection options may have a general character, like waste prevention or environmental care, or directly be related to soil or groundwater (like impermeable floors and groundwater monitoring). In this report the emphasis on the later. Dutch policy, legislation and regulation with respect to the subject is presented. To support authorities and industry in their performance, National Guidelines on Soil protection will be developed. To support the development of these Guidelines, all relevant documents have been traced (included in the appendices).

The impact of dispersion on the concentration of pesticide in the saturated groundwater was studied using scenario-type computer simulations for an area in the eastern part of the Netherlands (Lochem). The simulations demonstrated concentrations to decrease with depth; however, the rate of reduction is not systematic and varies throughout the area. On the boundaries between maize-land and grassland the reduction is considerable. In other parts of the area the reduction is limited and the concentrations gradually approach input concentrations, especially for long-term applications (i.e. > 10 years). The decrease in concentration by dispersion is based on the mixing of contaminated water with water from the surrounding areas. Therefore, the reduction for diffuse contamination or in cases where the load is maintained at a certain level for a long period of time, will be low. The most important effect of dispersion is the leveling out of peaks. The final rate of dilution depends highly on the situation in the surrounding area. Occurrence of dispersion itself is no guarantee that concentrations at a depth of 10 m will be reduced to below the threshold level, when they are above the threshold level in the uppermost groundwater.

In view of a revision of the Dutch Soil Protection act, proposals are presented in this report for human toxicologically based intervention values for soil and groundwater, calculated from human toxicological guideline values and human exposure. To this purpose the exposure model CSOIL is presented and discussed. This model has been developed to quantify the exposure due to soil contamination. Moreover, the uncertainties of the model calculations are discussed. The CSOIL model is not only used for the derivation of intervention values, but is also used, in combination with measurements in contact media, for the calculation of the actual human exposure to determine the priority of remediation.<br>

The multistress model, SMART-MOVE, was developed to forecast changes in the plant species composition occurring in the Netherlands due to acidification, eutrophication and desiccation. The model consists of: (1) SMART2, a soil module used for calculating changes pH, groundwater level and nutrient availability and (2) MOVE, a vegetation module, consisting of regression equations describing the relation between environmental factors and the probability of plant species occurrence. The environmental factors are represented by average Ellenberg indication values. Since management practices also determine the occurrence of plant species, this study investigated the possibility of using indication values for light and sensitivity to mowing to describe the effects of management on the vegetation. Four categories of management (high, medium and low intensity of management, and forest management) were defined on an ordinal scale. Calibration was carried out with the use of indication values for light, sensitivity to mowing and nitrogen availability. From this analysis, probability equations were derived, describing for each category -given the indication values- the probability of a record belonging to that category. A management scale was defined on the basis of these probability equations for use as model input. For this calibration, a set of 500 records was used. Extending the regression model with indication values for light and sensitivity to mowing resulted in a significant improvement of regression equations describing the relation between environmental factors and the probability of occurrence. Indication values for light, nitrogen availability and sensitivity to mowing can be used to describe the effect of management on species occurrence. Extending the model with these values will enable SMART-MOVE to predict the effects of management and succession on a national scale.

It is possible to make rapid field measurements of nitrate using the Nitrachek. Within the context of subproject Field measurements/Quality Assurance (712602), measurements have been carried out to establish the comparability of the Nitrachek field measurements with spectrofotometric laboratory measurements. The Nitrachek field measurements have shown good agreement with spectrofotometric laboratory measurements. A number of characteristics have also been determined for the nitrate measurement using Nitrachek. The various characteristics include extend of measurement (5 - 440 mg.l-1), repeatability (16 mg.l-1) and within-laboratory-reproducibility (74 mg.l-1). Different measurement methods for Nitrachek measurements are tested for comparability. The dip method is a method in which the test strip is dipped into the solution and measured, while the drop method a drop (standard, 10 mul) of the solution is applied to the test strip and measured. The accuracy of the drop method is better than that of the dip method. For a maximum error of 10% by a confidence interval of 95%, four measurements for each method are necessary to assure this quality. For a drop method with a sample amount of 8 mul there should be three measurements. The Nitrachek measurement is interfered with by nitrite. The determination of the presence of nitrite gives some important information on the reliability of the nitrate measurement.