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,Population growth 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