water Article Response of Water Chemistry to Long-Term Human Activities in the Nested Catchments System of Subtropical Northeast India Paweł Prokop 1,* , Łukasz Wiejaczka 1, Hiambok Jones Syiemlieh 2 and Rafał Kozłowski 3 1 Department of Geoenvironmental Research, Institute of Geography and Spatial Organization, Polish Academy of Sciences, Jana 22, 31-018 Kraków, Poland;
[email protected] 2 Department of Geography, North-Eastern Hill University, Shillong, Meghalaya 793022, India;
[email protected] 3 Department of Environment Protection and Modelling, Jan Kochanowski University, Swi˛etokrzyska15,´ 25-406 Kielce, Poland;
[email protected] * Correspondence:
[email protected]; Tel.: +48-12-4224085 Received: 25 April 2019; Accepted: 8 May 2019; Published: 10 May 2019 Abstract: The subtropics within the monsoonal range are distinguished by intensive human activity, which affects stream water chemistry. This paper aims to determine spatio-temporal variations and flowpaths of stream water chemical elements in a long-term anthropogenically-modified landscape, as well as to verify whether the water chemistry of a subtropical elevated shield has distinct features compared to other headwater areas in the tropics. It was hypothesized that small catchments with homogenous environmental conditions could assist in investigating the changes in ions and trace metals in various populations and land uses. Numerous physico-chemical parameters were measured, including temperature, pH, electrical conductivity (EC), dissolved organic carbon (DOC), major ions, and trace metals. Chemical element concentrations were found to be low, with a total dissolved 1 load (TDS) below 52 mg L− . Statistical tests indicated an increase with significant differences in the chemical element concentration between sites and seasons along with increases of anthropogenic impact.