Slooff W; Beelen P van; Annema JA; Janus JA (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1994-06-30)
This document contains data on mercury concerning the sources and distribution, and the risks based exposure levels and hazardous concentrations. The autonomous developments in the emissions are also described and an insight is given into any possible technical measures for further emission control.Mercury is one of the heavy metals. In the Netherlands mercury is obtained as a byproduct (several tonnes) in the natural gas extraction and the primary zinc production. In 1990 its use amounted to 13 tonnes, 40% of which was applied as amalgam in dentistry, 20% in batteries and 40% in measuring equipment, incandescent lamps and in the chloralkali industry. An amount of approximately 40 tonnes of mercury is landfilled annually with waste (based on 1990 data). A major cause of the relatively high amount of mercury waste is the non-intentional mercury flow: mercury as an unintended byproduct in various base materials. This non-intentional flow is responsible for more than 50% of the mercury occurring in waste.The emission to air amounted to approximately 4 tonnes (particularly from waste incineration and the chloralkali industry), to water amounted to approximately 1 tonne (especially from the phosphorous fertilizer industry and dentistry), to the soil to approximately 1.2 tonne (especially by application of fertilizer on agricultural land).The contribution to the mercury load from abroad is considerable. For surface water this is estimated at 75% (based on 1990 data). The deposition is also mainly determined by the background level and thus constitutes the major load of the soil in the Netherlands.
Vaal MA; Folkerts AJ (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1998-05-31)
Aquatic microbiotests were selected and evaluated for their potential usefulness in measuring ecotoxicity in monitoring programs. Microbiotests are tests with aquatic invertebrates that demand a shorter exposure period and a smaller test volume than conventional aquatic ecotoxicity test methods. Microbiotests evaluated were the Thamnotox F test, the Rotox F test, the Algaltoxkit F test, the Microtox test and the Daphnia IQ test. They were tested with a reference toxicant (a metal salt), and, except for the Algaltoxkit F, with two defined mixtures of chemicals. One mixture contained toxicants with a non-specific mode of action and the other pesticides. The sensitivity and reproducibility of the microbiotests were compared with the conventional short-term tests on Daphnia magna and a fish species. Since the loss of even moderately volatile organic compounds from the original microbiotest containers appeared to be considerable, it could therefore result in a serious underestimation of toxicity when used in monitoring programmes. Modification of the test containers of the Thamnotox F and Daphnia IQ tests resulted in an improvement of the test performance. Along with the Microtox test, they form a good base for a test battery. The Rotox F test in its present form, appeared to be less useful because of its low sensitivity. At present, no suitable algal microbiotest is operational. Because of their ecological function as primary producers, algae need to be included in the test battery.
Bakker J; Meent D van de (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-06-30)
The algorithm for the calculation of the Potentially Affected Fraction (PAF) as described by Hamers et al. (1995) was performed on 49 substances (heavy metals, pesticides and priority substances). The toxic stress of both individual substances (PAF) and all substances together (Itox ) was calculated. Concentrations in the surface water compartment and soils were calculated from recent emission data with the SimpleBox model version 2.0. In addition the toxic stress caused by substances calculation for the year 1995. The algorithm used and described in this report will be proposed for the calculation of the PAF and Itox in future.
Klepper O; Meent D van de (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-06-30)
The Potentially Affected Fraction (PAF) is the fraction of species exposed above the no-effect concentration (NOEC). The PAF is a measure that allows a comparison in toxic stress between substances and areas. In the report the PAF is calculated for four heavy metals (cadmium, copper, lead and zinc) and a selection of agricultural pesticides in the Netherlands. PAF values are between 5-50% for large areas, with the highest values in the sandy areas in the middle and southern provinces, and major toxicants copper and zinc.
Notenboom J; Verschoor A; Linden A van der; Plassche E van de; Reuther C (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1999-11-19)
The ecotoxicological risk concept is considered to be the basis for setting environmental quality objectives for pesticides in groundwater. Ecotoxicological critical concentrations for groundwater can be derived through several exploratory approaches. These approaches will be subsequently compared (focusing mainly on the Netherlands but bringing the European Union standard for pesticides in groundwater into the relevant context ) with critically reviewed groundwater monitoring data. Furthermore, aldicarb, atrazine and MITC results of geographic modelling are ecotoxicologically evaluated. The study focuses mainly on the Netherlands but the European context is not forgotten. Many reported groundwater monitoring data are strongly correlated. Therefore the assessment of the extent of groundwater contamination should be based on the number of localities where pesticides have been detected. Shallow Dutch groundwater monitoring data reveal that aldicarb, 1,3-dichloropropene, 1,2-dichloropropane, dinoseb, dinoterb, ethoprophos and MITC are ecotoxicologically the most hazardous pesticides. Of the pesticides found in monitoring programs critical levels are lower than 0.1 4g/l for aldicarb and aldicarb sulfoxide, dinoseb, dinoterb, ethoprophos, heptachlor, MITC, parathion ethyl and pirimicarb. If ecotoxicological risk levels for groundwater are desired they should be derived from standard aquatic toxicity data, and the ecological characteristics of the system should be taken into account in the extrapolation. It was not found meaningful to develop ecotoxicity tests based on specific groundwater organisms.
Meent D van de (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1999-09-30)
PAF is the fraction of species for which, at ambiant concentrations in the environment, the No Observed Effect Concentration (NOEC) is exceeded. PAF is interpreted as a measure of toxic stress on exosytems. PAF is calculated from measured concentrations in the environment, using the substance-characteristic Species Sensitivity Distribution (SSD). PAF;s are calculated for singel chemicals, and combiPAF's for mixtures of chemicals. In surface water, combiPAF is determined experimentally. PAF is applied to compare chemicals and locations, on the basis of their toxic stress. By far the most important application of PAF is the calculation of toxic stress from mixtures of chemicals. Application of the combiPAF calculation to measured concentrations of heavy metals and pesticides in Dutch soils and surface waters shows that sometimes NOECs are exceeded for over half of the species. It is recommended to concentrate the ong-going PAF research onto (i) quatification of the relationship between toxic stress and observed effects on exosystems, and (II) reconciliation of calculated combiPAF with measured PAF in water. This would enable further development of an indicator of toxic effects as a monitor of exosystem toxification.
Traas, TP; Posthuma L; Notenboom J; Zwart D de; Klepper O; Aldenberg T (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-08-31)
This reports deals with the definition of a research program for ecological consequences of exceedance of quality objectives. Methods are available for estimating the Potentially Affected Fraction (PAF) of species, the 'thermometer' for toxic stress. Translating the PAF to ecologically relevant effects is illustrated by comparing NOEC exceedance with acute mortality in laboratory experiments. The calibration of potential effects on structure of the ecosystem, is illustrated by analysis of ecological effects at two contaminated sites. A research program is defined to underpin the calibration in terms of ecosystem processses and Life Support Functions.
Posthuma L; Gestel CAM van; Smit CE, Bakker DJ; Vonk JW (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1998-06-30)
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.
Otte JG; Grinsven JJM van; Peijnenburg WJGM; Tiktak A (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1999-12-10)
Sorption isotherms for metals in soil obtained in the laboratory generally underpredict the observed metal content in the solid phase in the field. Isotherms based on in-situ data are therefore required. The aim of this study is to obtain field-based sorption isotherms for Cd, Cu, Pb and Zn as input for the heavy-metal accumulation model SOACAS. Two types of sorption isotherms were fitted using field data sets in this research: the Freundlich type, with one solid-phase fraction was fitted by Stepwise Linear Regression (LR), and a model with two solid phase mass fractions, a reactive fraction and a non-reactive fraction, was fitted with Nonlinear Least Squares Regression (NLSSR). From the results of the LR and the NLLSR fits of the Hoop-Janssen data set, the generally explained variance for the Zn models is shown to be the highest, followed by the Cd models. The explained variance of the Cu and Pb models is lower. The performance of the LR models and the NLLSR models is comparable. The NLLSR fits of the 2-phase isotherms of the Hoop-Janssen data set almost never include a statistically significant inert metal fraction. This implies that a 2-phase model can, in most cases, not be derived from this data set. The LR models derived from field data (this research) predicts the observed metal content in the solid phase in the field best compared with isotherms derived from batch data. The extension of the field partition data set and quality improvement is recommended for future research.
Lijzen JPA; Meulen GRB ter; Vries W de (Rijksinstituut voor Volksgezondheid en Milieu RIVM, 1997-06-30)
This Guideline will be useful for limiting, constructing, managing or purchasing agricultural land on behalf of the Netherlands' National Ecological Network. The soils of agricultural areas are often slightly polluted, possibly even so polluted that objectives for development of natural areas can not be achieved. Therefore the Guideline should determine whether a location has enough potential for realizing the intended objectives, considering the soil pollution, and whether construction and management of the area could improve opportunities. This is done by means of an ecotoxicological risk assessment. This is based on 'bioavailable' fractions of the soil contaminants, since land-use changes can lead to changes in soil conditions (pH, redox, organic matter) which can change the bioavailable fractions. The framework of the Guideline consists of the following six modules: 1) actual conditions and basic data, 2) the desired development and corresponding scenarios, 3) prognosis of future soil conditions, 4) prognosis of future available fractions of the contaminants, 5) ecotoxicological risk assessments, and 6) the integration of the modules and other relevant factors, and final assessment.
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