Leachate ecotoxicity - characterization and risk assessment Olof Berglund Chemical Ecology & Ecotoxicology Department of Ecology Lund University Leachate ecotoxicity • To compare toxic potency of different leachates, and effects of treatment methods - combine chemical and toxicological characterization • For environmental risk assessments -use ecotoxicological approaches with endpoints on population, community or ecosystem level Source • How do you estimate leachate toxicity? • How do you assess impact on recipient? Leachate Recipient • Chemical and toxicological characterization • Environmental risk assessments Landfill leachates • Complex mixture of organic and inorganic constituents • Characterization of leachates • Information needed for: – selection of treatment methods – risk assessments of landfill emissions Xenobiotic organic compounds Baun et al. 2004 Pesticides Phtalates Baun et al. 2004 What information? • Information on compounds present and concentrations • Limitations in traditional chemical analyses - time, money and detection limits • Biological effects - toxicity and environmental impact Leachate toxicity • To predict leachate toxicity both toxicological and chemical characterization required • Toxicological - we cannot analyze and detect everything • Chemical - toxicity tests do not reveal the identity of the potential problematic compounds Battery-of-tests approach Exposure Test Organism Endpoint time MicrotoxTM bacteria 15 min luminescence Selenastrum algae 96h growth mortality Daphnia zooplankton 48h (immobility) LC50 test 48 h + + Daphnia magna Dead or Alive? 100 Landfill 1 Landfill 2 50 % response Concentration of leachate LC50 LC50 Battery-of-tests approach Exposure Test Organism Endpoint time MicrotoxTM bacteria 15 min luminescence Daphnia zooplankton 48h immobility Selenastrum algae 96h growth • Several tests - differences in sensitivity Mode of operation • Combine chemical and toxicity characterization to attribute toxicity to specific compounds • Concentration addition (toxic units) – measured concentrations – literature EC50 values – leachate toxicity tests • Rank analysis between leachate toxicity and compound concentrations Contribution to toxicity 4-chlorphenol 4-chlor-o/m- cresol Landfill 6 Camphor • Identify problematic Naphtalene Other compounds • Concentration addition Unknown 4-chlor-o/m- cresol 1. Determine concentrations Landfill 8 Camphor of compounds Naphtalene 2. EC50 values from literature 3. Compare with leachate toxicity tests Unknown 1-Methylnaph 2-Methylnaph Other Baun et al. 2004 Rank analysis Leachate Benzene toxicity NH conc Cd conc 4 conc test 6 Landfill 1 5 1 5 3 5 4 Landfill 2 3 5 3 1 NH4 conc 3 Cd conc Benzene conc Landfill 3 2 2 1 5 2 Landfill 4 1 4 2 4 1 Landfill 5 4 3 4 2 0 0123456 Leachate toxicity test Benefits and drawbacks - chemical and toxicological characterization • Quick, simple and • pH, ammonium, inexpensive chloride (buffering and extraction can partially solve problem) • Compare toxic potency of different leachates • Misses chronic effects (e.g. Bisphenol A) • Identify problematic compounds • Limited relevance to environmental risk assessments Ecotoxicology Ecosystems Responses at different Community organizational levels composition Population changes Whole organism responses Biochemical/physiological changes Pollutant Increasing importance Compare exposure and organizational level 48h months, years, decades single species ecosystems What do we want to protect? • Acute, single species tests, few endpoints - problems with extrapolations to ecosystems • For environmental risk assessments (ERAs) population growth is the first relevant endpoint – community composition, ecosystem structure and function are the ultimate • In ERAs we don’t care about individuals! • Few links between standardized endpoints and population growth How do (should) we assess risks for recipient ecosystems? • Multi-species toxicity testing in mesocoms or in situ – Chronic – Direct and indirect effects Direct and indirect effects • Direct – Acting directly on sites of action in and on the organism + -- + -- • Indirect – Result of changes in the chemical, physical and/or biological environment – Could be both positive and + + negative - - – Trophic cascades How do (should) we assess risks for recipient ecosystems? • Multi-species toxicity testing and in situ or in mesocoms – Chronic – Direct and indirect effects • Population- and community ecology theory Putting ecology into toxicity testing • Life-history traits and population growth (Euler-Lotka equation) – EC50 s for relevant endpoints (life-history traits) – Calculate effect on population growth Individual-level vs population growth rate (λ) sensitivity Polychaete exposed to nonylphenol (174 µg/g) -tj -ta 1 = n Sj λ + Sa λ change relative to control trait (%) juvenile survival (Sj ) 0 adult survival (Sa ) 0 time to first reproduction (tj) +17 time between broods (ta) +25 total number of offspring per -78 individual (n) population growth rate (λ) -24 Forbes & Calow 2002 Individuals versus ecosystems • In many cases population growth less sensitive than individual life history variables Density depending factors -1 0.3 density 0.2 K 0.1 0.0 -0.1 Population growth rate, r, day Log population density (# L-1) time Individuals versus ecosystems • In many cases population growth less sensitive than individual life history variables • But, in several cases toxicity will increase in population and community context 6.5 mg/L 100 75 no predator Community predator 50 25 context 0 1.6 mg/L • Presence of a predator 100 75 no predator predator increases the toxicity of 50 pesticides 25 – Green frogs 0 – Predator cue 100 0.3 mg/L Survival (%) 75 – Carbaryl (insecticide) no predator predator 50 25 0 • Carbaryl 50 times more 100 0 mg/L toxic in combination with 75 no predator predator predation stress! 50 25 0 1 3 5 7 9 1 3 5 1 1 1 Day Reylea 2003 Putting ecology into toxicity testing • Life-history traits and population growth – EC50 s for relevant endpoints (life-history traits) – Calculate effect on population growth • Species interactions and community ecology -direct and indirect effects • Environmental risk assessments on recipient ecosystems Summary - Leachate ecotoxicity • To compare toxic potency of different leachates, and effects of treatment methods - combine chemical and toxicological characterization • For environmental risk assessments -use ecotoxicological approaches with endpoints on population, community or ecosystem level .