Evaluation of buffer zone effectiveness in mitigating the risks associated with agricultural runoff in Prince Edward Island.

To minimize the risk posed by runoff from row crops, Prince Edward Island introduced buffer legislation in 2000. The legislation mandates 10-m and 20-m buffers, respectively, for moderate sloped (i.e. <5%) and steep sloped (i.e. >5%) agricultural fields that border streams. Since 2001, Environment Canada has been evaluating the effectiveness of various buffer widths on operational farms in reducing toxicity and contaminant concentrations in runoff. Sample collectors, placed in 44 fields at the field edge (0m), 10m and at distances out to 30m, collected overland flow following rainfall-induced runoff events. Samples were collected within 24 hours of an event and analysed for seven pesticides (endosulfan, chlorothalonil, carbofuran, linuron, metribuzin, metalaxyl, mancozeb), water quality parameters and Daphnia magna toxicity. The 10-m buffer required for moderate sloped fields was effective at reducing contaminant concentrations but not always to less than lethal concentrations to Daphnia magna. Limited data beyond 10m for fields of both slope types precluded making recommendations on a suitable buffer width for shallow sloped fields and evaluating the effectiveness of 20-m buffers for steep sloped fields. When paired data were combined and statistically tested for all fields, the studied pesticides underwent a 52-98% and 68-100% reduction in aqueous and particulate concentrations within 10m and 30m, respectively. In addition, by 10m, soluble phosphorus, nitrate-nitrogen and total suspended solids were reduced by 34%, 38% and 64%, respectively. Results suggest buffer zones on operational farms are capable of achieving contaminant reductions comparable to those reported for controlled experiments. Inconsistent siting of sample collectors beyond 10m limited the evaluation of the effects of field slope and buffer width on buffer effectiveness on working farms. Future studies on buffer efficiency on operational farms should focus on building the data set beyond 10m and evaluating load reductions.

[1]  M. G. Dosskey,et al.  Filter strip performance and processes for different vegetation, widths, and contaminants , 1999 .

[2]  M. Dosskey,et al.  Toward Quantifying Water Pollution Abatement in Response to Installing Buffers on Crop Land , 2001, Environmental management.

[3]  Awwa,et al.  Standard Methods for the examination of water and wastewater , 1999 .

[4]  H. J. Bennett,et al.  Toxicity of selected chemicals to certain animals. , 1965, Journal - Water Pollution Control Federation.

[5]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[6]  I. Schlosser,et al.  Water Resources and the Land-Water Interface , 1978, Science.

[7]  Peter S Cornish,et al.  Vegetated biofilters: The relative importance of infiltration and adsorption in reducing loads of water-soluble herbicides in agricultural runoff , 2006 .

[8]  J. T. Cole,et al.  Influence of Buffers on Pesticide and Nutrient Runoff from Bermudagrass Turf , 1997 .

[9]  C. D. S. Tomlin,et al.  The Pesticide Manual , 2003 .

[10]  M. Lydy,et al.  Synergistic toxicity of atrazine and organophosphate insecticides contravenes the response addition mixture model , 1997 .

[11]  N. Syversen,et al.  Effect and design of buffer zones in the Nordic climate: The influence of width, amount of surface runoff, seasonal variation and vegetation type on retention efficiency for nutrient and particle runoff , 2005 .

[12]  L. Krutz,et al.  Reducing herbicide runoff from agricultural fields with vegetative filter strips: a review , 2005, Weed Science.

[13]  D. Shaw,et al.  Metolachlor and metribuzin losses in runoff as affected by width of vegetative filter strips , 1998, Weed Science.

[14]  V. Norris,et al.  The use of buffer zones to protect water quality: A review , 1993 .

[15]  M. Lydy,et al.  Increased toxicity to invertebrates associated with a mixture of atrazine and organophosphate insecticides , 2002, Environmental toxicology and chemistry.

[16]  L. E. Asmussen,et al.  Reduction of 2,4‐D Load in Surface Runoff Down a Grassed Waterway , 1977 .

[17]  L. Krutz,et al.  Infiltration and adsorption of dissolved atrazine and atrazine metabolites in buffalograss filter strips. , 2003, Journal of environmental quality.

[18]  G. Zanin,et al.  Performance of a narrow buffer strip in abating agricultural pollutants in the shallow subsurface water flux. , 2004, Environmental pollution.

[19]  Marc Voltz,et al.  Using grassed strips to limit pesticide transfer to surface water: a review , 2005 .

[20]  Hans-Georg Frede,et al.  Mitigation strategies to reduce pesticide inputs into ground- and surface water and their effectiveness; a review. , 2007, The Science of the total environment.

[21]  Benoit Real,et al.  The Use of Grassed Buffer Strips to Remove Pesticides, Nitrate and Soluble Phosphorus Compounds from Runoff Water , 1997 .

[22]  C. Seybold,et al.  Abating endosulfan from runoff using vegetative filter strips: the importance of plant species and flow rate , 2003 .

[23]  B. Stein,et al.  Herbicide transport by surface runoff and herbicide retention in a filter strip — Rainfall and runoff simulation studies , 1997 .

[24]  David D. Bosch,et al.  HERBICIDE TRANSPORT IN A MANAGED RIPARIAN FOREST BUFFER SYSTEM , 1997 .

[25]  Steven K. Mickelson,et al.  Herbicide Retention by Vegetative Buffer Strips from Runoff under Natural Rainfall , 1996 .

[26]  David R. Shaw,et al.  Perennial grass filter strips for reducing herbicide losses in runoff , 2001, Weed Science.

[27]  R. P. Trussell.  The Percent Un-Ionized Ammonia in Aqueous Ammonia Solutions at Different pH Levels and Temperatures , 1972 .

[28]  T. Collier,et al.  The Synergistic Toxicity of Pesticide Mixtures: Implications for Risk Assessment and the Conservation of Endangered Pacific Salmon , 2008, Environmental health perspectives.

[29]  Saied Mostaghimi,et al.  Vegetative Filter Strips for Agricultural Nonpoint Source Pollution Control , 1989 .

[30]  J. W. Gilliam,et al.  Sediment and Chemical Load Reduction by Grass and Riparian Filters , 1996 .

[31]  L. E. Asmussen,et al.  Trifluralin Movement in Runoff from a Small Agricultural Watershed , 1980 .

[32]  E. Webster,et al.  Impact of Vegetative Filter Strips on Herbicide Loss in Runoff from Soybean (Glycine max) , 1996, Weed Science.

[33]  Steven K. Mickelson,et al.  Contributing Area and Concentration Effects on Herbicide Removal by Vegetative Buffer Strips , 1996 .

[34]  L. Krutz,et al.  Adsorption and desorption of metolachlor and metolachlor metabolites in vegetated filter strip and cultivated soil. , 2004, Journal of environmental quality.