Nontargeted chemical analysis for the evaluation of ecosystem functions in natural and agricultural waterways

Abstract

Agriculture supports growing human populations and exerts pressures on the natural processes that occur in neighboring ecosystems. While it is impossible to eliminate the impacts of agriculture and other anthropogenic activities, measuring and evaluating ecosystem functions in agricultural and natural landscapes is essential for developing agricultural practices that replicate or preserve these functions more effectively. This study uses a novel application of multivariate statistical tools on a Nontargeted chemical dataset to holistically evaluate and compare chemical factors (patterns) in both agricultural (irrigation canal) and more natural systems (rivers, springs, and a lake) in Klamath County, Oregon. Using NMF (non-negative matrix factorization), three major chemical factors were extracted from nontargeted data from surface water samples (n = 180). One factor (NMF1) was most dominant across all samples (> 80%); NMF1 was associated with 47 suspect screening compounds, including biocides and pharmaceuticals. Longitudinal samples along three waterways (an irrigation canal transect, the Lost River, and the Klamath River) were evaluated for changes in chemical composition and compared to lake samples. Lake samples were distinguishable from the waterways, suggesting the presence of different ecosystem functions in standing versus flowing water. However, there were no apparent trends in chemical composition as water flowed away from a standing source