Assessment of the entry of PPP in groundwater in Germany

Transcription

1 Assessment of the entry of PPP in groundwater in Karin Aden Chemistry Division, Braunschweig, Wolfgang Koch Federal Environmental Agency (UBA) Berlin, Aden 1

2 Entry routes of PPP in groundwater leaching in soil bank-infiltration from surface water entry of PPP in surface water via - drift (buffer zones can be considered) - runoff (buffer zones can be considered) - drainage Aden 2

3 Tiered approach: Computer calculation (PELMO 3.00, national scenario) conc. < 0.1 µg/l Lysimeter or field leaching study Registration conc. 0.1 µg/l conc. 0.1 µg/l No registration Explanation of findings of PPP in groundwater Post-registration monitoring in groundwater Aden 3

4 1 st step: PELMO calculation One realistic worst case scenario: - Soil Borstel - Hamburg climate (normal: 778 mm or wet: 872 mm) - Plant parameters and interception comparable with FOCUS - Simulation of 10 years Output used for the decision: Highest annual average concentration Aden 4

5 2 st step: Lysimeter or field leaching study Studies with sandy soil (>70% sand, <10% clay, C org <1.5%, minimum 800 mm precipitation + irrigation) Lysimeter is preferred: - mass balance (distribution of 14 C in soil, plant, water) - unknown metabolites can be identified in the leachate - NIR in leachate can trigger further (ecotox-) studies - calculation of annual average concentrations is simple Aden 5

6 Lysimeter (Führ et al. 1988/89: Jahresbericht der KFA Jülich GmbH) Aden 6

7 Risk assessment of metabolites in groundwater PEC GW of metabolites were obtained from model calculation or lysimeter/field leaching studies. The relevance of the metabolites (c 0.1µg/l) was evaluated - biological activity - ecotoxicological relevance (TER values) - toxicological relevance (toxicology comparable or higher than the parent substance) Aden 7

8 Conclusions The use of the tiered approach was able to protect the groundwater in on a high level! The number of findings of PPP in groundwater is low. Nearly all of the finding can be explained by: - misuse of the PPP - non-valid analytical methods - accidents - direct contamination of wells - finding of PPP, which were banned in, e. g. atrazine Aden 8

9 - Currents activities Question Can FOCUS-PELMO be used in the German tiered approach? (Are the calculations conservative enough?) Comparison of the national scenario with FOCUS-PELMO 1. Step Model calculations with PELMO national scenario and with PELMO-FOCUS 2. Step Comparison of the calculations with lysimeter studies Aden 9

10 - Currents activities Comparison of the national scenario with FOCUS-PELMO Main differences between the models/scenarios Climate file repeated use of one year 20 years real weather Input values (DT 50, K OC ) No/simple correction of DT 50 values FOCUS guidance Degradations factors in the layer of the Borstel soil 1, 0.16, 0.09, 0.13, 0, 0 1, 0.5, 0.3, 0.3, 0.3, 0 Output max. annual average concentration of 1 year 80 th perc. of 1, 2 or 3 years, depending on the application pattern Aden 10

11 Questions to be discussed Which results should be used in the evaluation process, if one model predicts > 0.1µg/l and one <0.1µg/l, e. g. PRZM and PEARL? How to deal with FOCUS calculations which show lower concentrations than a lysimeter or a field leaching study? Acceptance of higher tier approaches used in FOCUS calculations (adaptation of micro-organism, increased sorption with time)? Is the identification of DT 50 values (standardised to 20 C, 100% FC) from field studies (inverse modelling) and the use in FOCUS models acceptable? Is this acceptable as 1 st step or as a higher tier calculation? Aden 11