Land use, geology and soil properties control nutrient concentrations in headwater streams

Faruk Djodjic,Magdalena Bieroza,Lars Bergström

doi:10.1016/j.scitotenv.2021.145108

Faruk Djodjic, Magdalena Bieroza + Show 1 more

Open Access

https://doi.org/10.1016/j.scitotenv.2021.145108

Copy DOI

Abstract

Nutrient losses from headwater catchments (<50 km2) cause eutrophication problems downstream. Catchment properties are strongly reflected in the levels of nutrient concentrations in headwater streams. Based on measurements of total and dissolved nitrogen (TN, DN) and phosphorus (TP, DP) in 235 small headwater streams, we showed that proportion of arable land in a catchment had the strongest positive effect on nutrient concentrations, with coefficient of determination (R2) of 0.54, 0.64, 0.45, and 0.51 for TN, DN, TP, and DP, respectively. In contrast, increased proportion of forest and wetland led to lower nutrient concentrations in streams. The geological composition of catchments had a major influence on the soil properties. In turn, certain soil properties, such as clay content and content of aluminum (Al), an important binding agent of P, influenced losses of particulate P (PP) and DP, respectively. Consequently, by using soil properties as a link between geology and water quality, areas potentially sensitive to nutrient losses were identified by classifying bedrock categories into three geological groups. Approximately 25% of Swedish arable land was identified as potentially sensitive. Sensitive catchments were found in regions with sedimentary bedrock and showed higher concentrations of dissolved nutrient fractions even when the proportion of agricultural land was small, indicating higher background concentrations.

Highlights

Nitrogen (N) and phosphorus (P) cycles have been identified as important Earth system processes and exceeding their boundaries couldF
Sandström et al (2020) showed that the clay content and proportion of agricultural land were significantly and positively correlated with transport of suspended sediment (SS), which in turn led to higher losses of particulate P (PP), but such relationship was not found for dissolved P (DP)
The Principal component analysis (PCA) results (Fig. 3) showed that all water quality parameters were positively correlated with the proportion of arable land in the catchment and, to a smaller degree, the proportion of open land

Summary

Introduction

The soil texture of agricultural land influences nutrient losses. Soil nutrient status may influence nutrient losses, as shown in laboratory studies and at field plot level (Heckrath et al, 1995; Hooda et al, 2000; Djodjic and Mattsson, 2013). Another soil property that is important for P losses is P sorption capacity (PSC), often measured as the content of iron (Fe) and aluminum (Al) in the soil (Börling et al, 2004). Recent evaluation of long-term changes (1990–2015) in the atmospheric deposition and runoff water chemistry shows predominantly decreasing trends in NO3 concentrations in both deposition and runoff (Vuorenmaa et al, 2018)

Methods

Results

Discussion

Conclusion