The direct and indirect effects of watershed land use and soil type on stream water metal concentrations. Issue 10 (8th October 2016)

• Record Type: Journal Article
• Authors: Taka, M.; Aalto, J.; Virkanen, J.; Luoto, M.
• Is Part Of: Water resources research. Volume 52:Issue 10(2016:Oct.)
• Page Start: 7711
• Page End: 7725
• Publication Date: 2016-10-08
• Subjects: water quality -- metal concentration -- structural equation model -- spatial modeling -- watershed; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2016WR019226
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Identifying the factors controlling stream water pollutants is challenged by the diversity of potential sources, pathways, and processes. This study tests the effects of watershed characteristics on stream water metal concentrations across environmental gradients. By using an extensive data set of 83 watersheds in southern Finland and structural equation modeling (SEM), the direct and indirect effects of land use and soil type on metal concentrations were explored. Both land use and soil type resulted in statistically significant direct effects on metals; for example, land use was found to control dissolved metal concentrations, whereas soil type had the strongest links for total metal concentrations. The consideration of indirect correlation further strengthened the effects of soil type up to 50%, thus suggesting the dominant role of soil across land use intensities. Moreover, the results indicate that modified landscapes mediate the effect of natural soil processes in controlling stream metal concentrations. This work highlights the benefits of structural equation model framework, as the underlying paths for water quality are more likely to be identified, compared to traditional regression methods. Thus, the implementation of SEM on water quality studies is highly encouraged. Key Points: Direct and indirect effects of watershed characteristics on stream water quality were tested using structural equation model (SEM) Soil type and land use were strongly linked to metal concentrations across studied streams SEM revealed new insights into the complex network of water quality drivers and their underlying paths