Large Scale Risks from Agricultural Pesticides in Small Streams

Abstract

Small streams are important refuges for biodiversity. In agricultural areas, they may be at risk from pesticide pollution. However, most related studies have been limited to a few streams on the regional level, hampering extrapolation to larger scales. We quantified risks as exceedances of regulatory acceptable concentrations (RACs) and used German monitoring data to quantify the drivers thereof and to assess current risks in small streams on a large scale. The data set was comprised of 1 766 104 measurements of 478 pesticides (including metabolites) related to 24 743 samples from 2301 sampling sites. We investigated the influence of agricultural land use, catchment size, as well as precipitation and seasonal dynamics on pesticide risk taking also concentrations below the limit of quantification into account. The exceedances of risk thresholds dropped 3.7-fold at sites with no agriculture. Precipitation increased detection probability by 43%, and concentrations were the highest from April to June. Overall, this indicates that agricultural land use is a major contributor of pesticides in streams. RACs were exceeded in 26% of streams, with the highest exceedances found for neonicotinoid insecticides. We conclude that pesticides from agricultural land use are a major threat to small streams and their biodiversity. To reflect peak concentrations, current pesticide monitoring needs refinement.

Pesticides from the EU First and Second Watch Lists in the Water Environment

“…The investigation of large-scale risks from agricultural pesticides in small streams in Germany shows a positive relationship between agricultural land use and the number of regulatory acceptable concentration (RAC) exceedances. [3] The catchment size had no statistically significant effect on the number of RAC exceedances, however previous studies showed that small streams are more polluted than bigger streams. [88][89][90] Additionally, precipitation before sampling had a stronger effect than during sampling on the probability of exceeding LOQ.…”

“…Additionally, precipitation before sampling had a stronger effect than during sampling on the probability of exceeding LOQ. Among the fifteen compounds with the highest observed RQ in small streams, thiacloprid, imidacloprid, and clothianidin had the highest values …”

“…Among the fifteen compounds with the highest observed RQ in small streams, thiacloprid, imidacloprid, and clothianidin had the highest values. [3] Among 123 samples of surface water taken in 2006 and 2007 from intensively exploited arable lands in Wielkopolska Province in Poland, 36 contained residues of insecticides used for the protection of rape plantations. [91] Contamination with thiamethoxam and acetamiprid was detected in 17.1 and 11.4% of the water samples, respectively, with the highest concentration of acetamiprid (1.34 mg L À1 ) in a sample from a field watercourse taken in spring 2007.…”

Aquatic risks from human pharmaceuticals—modelling temporal trends of carbamazepine and ciprofloxacin at the global scale

“…Ecoregions are distinct geospatial units that represent unique patterns of environmental and ecological variables. As such, ecoregions are considered particularly useful for risk assessment and conservation planning at a larger scale (Schäfer et al 2013, Szöcs et al 2017. The AR for each freshwater ecoregion b (AR b ) was calculated as the average risk-quotient over its total water volume (equation (5)).…”

Effectiveness of Grassed Buffer in Reducing Spinosad Runoff: Real Data and FOCUS Output

“…Pesticides runoff to surface water poses a risk to the aquatic environment, and recent studies show that pesticides from agricultural land use are a major threat to small streams and their biodiversity [1] [2].…”