figure a

Torsten Ahl (squatting, bottom right) and Torbjörn Willén (upper left), two pioneers of the Swedish national freshwater monitoring on the investigation of Swedish great lakes. Unknown photographer

figure b

Christel Lindholm is one of the local inhabitants who each month takes a water sample and sends to the lab for analyses of water chemistry. Photo by Leif Lindholm

figure c

Gun Hölling who has worked with environmental monitoring since 1971 with the ion chromatograph, which replaced the old Macereth method for sulfate in 1984. Photo by Jens Fölster

figure d

Three generations of analytical techniques: Hand-made permanganate consumption made to ensure the consistency of the long-term time series (left), auto-analyser (upper right), and a high-throughput discrete analyser (lower right). Photo by Jenny Svennås-Gullner (left) and Jens Fölster (right)

figure e

Jonas Pålsson from the consulting company Al-control taking a sample in Helgeån. Photo by Lars Göran Karlsson

figure f

Helicopter sampling during the lake survey. Photo by Jens Fölster

figure g

Willem Goedkoop taking a kick sample for benthic invertebrates. Photo by Stefan Löfgren