What is a pesticide? Pesticides as a water quality indicator. Pesticides Sales in Alberta. Pesticide Types

Transcription

1 What is a pesticide? Pesticides as a water quality indicator Red Deer River Watershed Alliance Community Forum September 21-23, 2010 Sarah Depoe Alberta Agriculture and Rural Development A pesticide is a chemical or microbiological substance that is designed to kill pests. Pesticides by definition are toxic because they poison the pest. Pesticides include insecticides, herbicides, fungicides and rodenticides. Common examples are RoundUp, Killex, Weed and Feed, and 2,4-D. Pesticide Types Herbicides to control weeds Insecticides to control insects Fungicides to control certain types of plant diseases Rodenticides to control mice and other rodents Also includes sanitizers for swimming pools and spas to control micro-organisms Pesticides Sales in Alberta In 2003, a total of over 9 million kg of pesticide active ingredient was sold in, or shipped to Alberta % of pesticide sales in the agriculture sector Pesticides sold were predominantly herbicides, 77.3%. Insecticides and fungicides comprised, 4.7% and 3.4% of sales, respectively. Cited from Byrtus,

2 Pesticide Registration in Canada Pesticides are stringently regulated in Canada. Before a product is registered for use, it must undergo a rigorous scientific assessment (epidemiology and toxicity studies). Only use registered pesticides for the pests and treatment areas listed on the label, and use them according to the label directions. Where are pesticides used? Agricultural Use = Majority Crop land Urban and Municipal Use Households Public lands Golf courses Rights-of-ways for roads, electrical power lines, water and gas lines and railways Industrial and Forestry Use What is the fate of a pesticide? Why are pesticides important from a water quality perspective? They are not naturally occurring in the environment They are inherently toxic, but do vary in their persistence and toxicity Pesticides in water could affect water used for Supporting Aquatic life Irrigation Uses Livestock Drinking Water Human Drinking Water 2

3 Other water quality considerations Toxicity to non-target organisms Common example: frogs and other amphibians Some pesticides are carcinogens and endocrine disrupters Significance of additives and breakdown products.? Synergistic or cumulative effects? Are pesticides detected in surface water in Alberta? Provincial-scale river monitoring Major River Systems (AENV) Upstream and downstream of urban centres Agricultural Streams (ARD) Watersheds with different agricultural intensities Water treated for human consumption (tap water) (AENV) Alberta River Water Quality Index: Pesticides River Water Quality Index Pesticides 2,4D Triallate Picloram Malathion Bromoxynil Diuron Chlorpyrifos Diazinon MCPP Atrazine Dicamba Methoxychlor Cyanazine Dichlorprop Imazamethabenz Lindane MCPA The River WQI evaluates how many pesticides are present, how often and in what concentration 3

4 Pesticide Detection Frequency in Agricu Streams One or more pesticides were detected 61% of samples collected from 1999 to of 1627 samples By Agricultural Intensity 24% 50% 80% 91% Pesticide Compounds Thirty-seven (37) of the 68 compounds analyzed were detected at least once from 1999 to 2006 Detections included: 29 of 40 herbicides 4 of 20 insecticides 4 of 8 fungicides Most frequently detected Herbicides: 2,4-D, MCPA, Clopyralid, Dicamba, Triclopyr, Picloram and Imazemethabenz-methyl, and MCPP. Insecticide: Gamma-benzenehexachloride (Lindane) Source: Lorenz et al Fungicide: Iprodione 30.4% 16.4% 14.6% 13.5% 13.2% 9.8% 49.5% Top 8 compounds - All herbicides - Top pesticide sales: 2,4-D and MCPA (kg ai (2003)) Total number of individual pesticide compounds detected in each stream from 1999 to 2006 LOW MOD HIGH IRR 9.6% Blindman River & Ray, Threehills, Renwick, Haynes Creek 4

5 Multiple Pesticide Detections A water sample was more likely to contain multiple pesticide compounds when it came from a watershed with high intensity dryland or irrigation agriculture. Median # of cmpds detected per sample LOW MOD HIGH IRR Compliance with WQ Guidelines Nine compounds (7 herbicides / 2 insecticides) exceeded guidelines for either irrigation use or the protection of aquatic life (PAL) All guidelines for livestock drinking water were met With the exception of MCPA and dicamba, a very small proportion of samples (<1 %) exceeded guidelines over the 8 year monitoring period (1999 to 2006) Compliance with WQ Guidelines cont d Pesticides in treated drinking water 1995 to % of 1788 samples at least one detection 63 compounds analyzed, 19 detected 100% compliance with Drinking Water Guidelines 15 herbicides 4 insecticides PAL= protection aquatic life IRRIG=irrigation Source: Byrtus et al

6 Summary Questions? Pesticides are present in surface and treated water in AB in low concentrations. With the exception of irrigation guidelines, water quality guidelines are typically met. It is not uncommon for multiple pesticides to be present. Cumulative or synergistic effects may be important. Land activities (agric, urban, municipal, industrial) do influence on pesticide occurrence in surface water, air & rain. Thank you! Sarah Depoe Water Quality Specialist What is the fate of a pesticide? Chemical or microbial breakdown Attached to soil or sediment particles Absorbed by vegetation Vaporized from soil or plant canopy Transported though air during spraying Washed off in surface runoff Leached through soil 6