Thanks to a new instrument, water pollutants can be measured automatically over a period of weeks – directly in the field, rather than in the laboratory. The mobile mass spectrometer is housed in a trailer and can be remotely controlled by smartphone.
Rain enables crops to grow, but it also causes the run-off of pesticides to rivers and streams. Concentrations of these substances in surface waters can be monitored by means of regular sampling. However, with the traditional approach – grab sampling and determination of mean values – it is rarely, if ever, possible to measure the peak concentrations associated with heavy rainfall.
To address this problem, a project was launched in 2017 by Christoph Ort of the Urban Water Management department and Heinz Singer of the Environmental Chemistry department: their aim is to use a highly sensitive instrument (mass spectrometer) mounted in a trailer to measure substances automatically, almost continuously and directly in surface waters or sewers, rather than performing measurements on samples in the lab. This explains the name of the project – “MS2field” (mass spectrometer to field).
Monitoring by mobile phone
Thanks to the mobile unit, water samples no longer need to be individually collected, transported and stored at the laboratory. Instead, using a hose, the water to be analysed is continuously pumped through the trailer. Here, every few minutes, samples (a few millilitres in each case) are automatically prepared for analysis in the mass spectrometer. The instrument can identify a broad spectrum of pollutants in the water sample. Christoph Ort is enthusiastic: “This means we can follow highly dynamic processes live – even on a smartphone!”
On an initial field test in February 2019, the team led by Ort and Singer studied wastewater from the treatment plant at Fehraltorf (canton of Zurich). Over a 4-week period, the unit analysed around 2000 raw wastewater samples, revealing previously unsuspected variations and diurnal patterns. As Ort points out, “With conventional sample collection and preparation, this would have taken several months.”