Distinguishing active and legacy source contributions to stream water quality: Comparative quantification for chloride and metals

Hydrochemical constituents in streams may originate from currently active sources at the surface and/or legacy earlier inputs, waste deposits and land contamination. Distinction quantification of these source contributions are needed for improved interpretation tracer data effective reduction waterborne environmental pollutants. This article develops a methodology that recognizes quantifies some general mechanistic differences stream concentration load behavior versus discharge between such contributions. The is applied to comparative analysis chloride (Cl−), copper (Cu), lead (Pb), zinc (Zn), corresponding water discharge, measured over period 1990–2018 multiple hydrological catchments (19 Cl−, 11 Cu Zn, 10 Pb) around major Lake Mälaren Sweden. For average fraction quantified be 19%, as 2.9 mg/L, respectively. metals, fractions outlets 1%–3% all 9%–14% relatively few with mixed metal sources. Average 0.14 3.2 μg/L Cu, 0.05 1.5 Pb, 1.4 12 multi-catchment thus indicates widespread prevalence sources, greater than both Cl− playing role metals. simple first-order developed study can used screen commonly available monitoring possible distinction any hydrochemical constituent across various catchment settings.