by Kaylynne Marquez, EVIO Labs Eugene
A Look at the Problem
The legalization of Cannabis in states like Oregon, Washington and Colorado have led to large scale grow operations, both indoor and outdoor. And just as with any other form of agriculture, the demand for higher yields is ever-growing. Inappropriate management and irrigation technology, in all forms of agriculture, can lead to chemical run-off from cultivation sites to nearby natural water sources, contaminating rivers, lakes and streams. Water with dissolved pesticides entering the soil can also leach contaminates deep into the groundwater supply through the vertical descending displacement of materials through the soil profile. These contaminated water sources can then cause secondary contamination of crops.
Groundwater can move freely under the influence of gravity, and often will move horizontally towards stream channels. The degree to which applied pesticides reach the groundwater is determined by factors like land-management practices, chemical and biological degradation rates and hydrogeological conditions like the thickness of the unsaturated zone of the soil profile, which can vary between different soil types (Toccalino et al. 2014).
Variations in soil types can influences water contamination. Some soils may be more susceptible to the leaching of pesticides as water infiltrates the surface horizons. Infiltration is the process in which water falling onto the ground enters the soil through absorption. The rate of infiltration decreases as the soil becomes more saturated, and once the soil is fully saturated, infiltration can no longer proceed and the water is transported across the top of the soil as surface run-off.
A study by the U.S. Geological Survey’s (USGS) National Water-Quality Assessment (NAWQA) Program tracked changes in pesticide concentrations in U.S. groundwater over the course of nearly two decades, from 1993 through 2011. The assessment by Toccalino and her team revealed that pesticide concentrations infrequently surpassed human-health standards. However, there may still be a concern for secondary contamination of crops like Cannabis, which could potentially lead to detections of pesticides in flower samples submitted for regulatory analytical testing.
Drawing water from wells for use in agriculture without proper filtration could be problematic. Wells draw water from deep below the soil surface where groundwater moves freely. Using contaminated groundwater to supply water through an incorrectly maintained delivery system could potentially cause secondary contamination. The cleanup of contaminated groundwater is nearly impossible and contamination can proceed for many years.
Surface Run-Off Contamination
New research on surface run-off by Jan Vymazal and Tereza Březinová (2015) shows promise in how cultivators might prevent and limit water run-off while using plants to clean contaminated surface run-off water.
Attempts to prevent run-off from farms using vegetated ditches and fabricated wetlands alongside fields have been more popularized due to the increasing knowledge and awareness of the hazards of contamination. Wetland vegetation had been used sporadically in the past to remove excess fertilizers, but has only become more accepted in the last ten years or so for removing pesticides. Because surface run-off almost immediately enters waterways, the risk of pesticide contamination is much higher than the slower, albeit irreversible, contamination through a soil profile once it meets the groundwater.
Preventing Water Contamination and Secondary Contamination of Cannabis
Greater awareness of the types and characteristics of chemicals, soil and water sources used when cultivating Cannabis, and any other crop for that matter, will help prevent further contamination of the waterways we all share. Water can be tested for pesticides to ensure against secondary contamination of Cannabis through pesticide tainted water.
Understanding varying pesticide solubility and degradation rates will help growers better understand how to apply such chemicals without adding the unnecessary stress of contamination to local water sources. Integrating manufactured wetlands and other bioremediation tools in the cultivation area can also help enhance the quality of our water. Utilizing integrated pest management plans can help reduce the need for chemical interventions during cultivation, thus limiting future water contamination.
Limiting or eradicating the usage of pesticides in agriculture may have adverse results on crop yield, but on the other end of the spectrum, increasing pesticide use to further increase yield may present disastrous consequences for our environment. The balance lies in arming oneself with the knowledge about these compounds and how they affect other systems to allow for the use of such products in a responsible manner.
Soil and water are not endless resources, and ancient civilizations that have destroyed the soil and water sources in which they relied upon should serve as a reminder that no amount of technology can resolve the issue of using a resource quicker than it can be replenished or purified.
Laboratory Manager and Quality Officer
EVIO Labs Eugene
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Hwang JI, Lee SE, Kim JE (2015) Plant uptake and distribution of endosulfan and its sulfate metabolite persisted in soil. PLoS ONE 10(11): e0141728.
Toccalino PL, Giolliom RJ, Lindsey BD, Rupert MG (2014) Pesticides in groundwater of the United States: decadal-scale changes, 1993-2011. Groundwater 52(1): 112-125
Vymazal J, Březinová T (2015) The use of constructed wetlands for removal of pesticides from agricultural runoff and drainage: A review. Environment International 75: 11-20
Ms. Marquez began working as a Cannabis testing laboratory technician for Oregon Analytical Services in 2014. In 2016 she became responsible for the management of back-office operations of the laboratory, including quality assurance, compliance, and procurement. She also provides microbiological testing services for the lab.
Prior to joining OAS and the EVIO Labs group, she worked with Dr. Alan Shanks at The Shanks Lab at the Oregon Institute of Marine Biology on a variety of research projects. She also worked as a Naturalist where she provided educational tours elucidating the ecology of the Pacific Northwest through Whale Research EcoExursions. She was selected to work as intern in the highly competitive Centers for Ocean Sciences Education Experience (COSEE) where she stayed on as a lab technician. Her work included deployment of oceanographic instruments and microscopy work at sea.
Ms. Marquez has prior experience working for a financial investment firm where she worked as assistant to the President performing documentation and staffing tasks. A member of the Phi Theta Kappa Honor Society, Kaylynne Marquez is currently completing her degree in Biology at the University of Oregon.