Attenuation of insecticide impact by a small wetland in a stream draining a horticultural basin in Argentina

Multiple pesticides occurrence, fate, and environmental risk assessment in a small horticultural stream of Argentina

Peri-urban horticulture is crucial to local populations, but a global paucity of information exists regarding the contamination of the associated waterways because of this activity. The aim of this study was to assess pesticide pollution of surface water, suspended particulate matter and bottom sediments from the Carnaval Creek Basin (La Plata, Buenos Aires, Argentina) - a representative system of waterways surrounded by horticultural production - by over 40 selected herbicides, insecticides, and fungicides by gas-chromatography-time-of-flight mass spectrometry and ultraperformance liquid chromatography tandem mass spectrometry. Six sampling campaigns were conducted biannually from 2015 to 2017. Glyphosate and (aminomethyl)phosphonic acid (AMPA), surprisingly, were the most frequently detected pesticides, in concentrations comparable to those reported in areas with genetically modified extensive crops (maximum in water, 20.04 and 4.86 μg·L^-1; in sediment, 1146.5 and 4032.7 μg·kg_dw^-1, respectively). The insecticides chlorpyrifos, cypermethrin and λ-cyhalothrin were detected in more than 30% of the samples. The concentrations tended to greatly exceed those previously reported - by up to more than 800 times for chlorpyrifos in water (maximum 2.645 μg·L^-1) and more than 400 times for lambda-cyhalothrin in sediments (maximum 2607.7 μg·kg_dw^-1). The total pesticide concentration in surface water was found to be influenced by precipitation regimes but was independent of the season of the year, with precipitations of more than 140 mm diluting the pesticide concentrations to levels below detection limits. An environmental risk assessment performed with the pesticide concentrations of pesticides in surface water revealed that the surrounding horticultural activity posed a high risk for aquatic biota, with 30% of the samples exceeding the threshold value by more than a thousand times. We conclude that pesticides from horticultural use are a major threat to small streams and their biodiversity. This work provides valuable information that is scarce regarding the impact on watercourses exclusively as a consequence of horticulture.

A Literature Review of Wetland Treatment Systems Used to Treat Runoff Mixtures Containing Antibiotics and Pesticides from Urban and Agricultural Landscapes

Wetland treatment systems are used extensively across the world to mitigate surface runoff. While wetland treatment for nitrogen mitigation has been comprehensively reviewed, the implications of common-use pesticides and antibiotics on nitrogen reduction remain relatively unreviewed. Therefore, this review seeks to comprehensively assess the removal of commonly used pesticides and antibiotics and their implications for nitrogen removal in wetland treatment systems receiving non-point source runoff from urban and agricultural landscapes. A total of 181 primary studies were identified spanning 37 countries. Most of the reviewed publications studied pesticides (n = 153) entering wetlands systems, while antibiotics (n = 29) had fewer publications. Even fewer publications reviewed the impact of influent mixtures on nitrogen removal processes in wetlands (n = 16). Removal efficiencies for antibiotics (35–100%), pesticides (−619–100%), and nitrate-nitrogen (−113–100%) varied widely across the studies, with pesticides and antibiotics impacting microbial communities, the presence and type of vegetation, timing, and hydrology in wetland ecosystems. However, implications for the nitrogen cycle were dependent on the specific emerging contaminant present. A significant knowledge gap remains in how wetland treatment systems are used to treat non-point source mixtures that contain nutrients, pesticides, and antibiotics, resulting in an unknown regarding nitrogen removal efficiency as runoff contaminant mixtures evolve.