Monitoring 14C contamination in Chinese research vessels with swipe tests

Abstract Since 14 C-tracer is widely used in determining oceanic primary production, most research vessels have a history of using 14 C labeled sodium bicarbonate solutions for culture experiments. A contamination monitor test (swipe test) prior to each cruise can help to detect and prevent possible 14 C contamination before sampling for 14 C studies at natural abundance. Here we report 14 C measurements of more than 100 swipe samples collected onboard workplaces of seven Chinese research vessels over a four-year period (2012–2016). Five out of seven ships showed no obvious 14 C contamination with F 14 C values lower than 0.2. Two spots of R/V Dongfanghong 2 showed elevated 14 C contamination (F 14 C were as high as 0.831 and 0.573) during 2012–2014. However, the laboratory surface was cleaned by renovation before the next monitoring operation in May to June 2016. R/V Kexue Yihao was found to have elevated 14 C on swipe samples, with an F 14 C up to 0.331 from November to December 2012. During the same cruise, seawater samples for a natural-level DI 14 C study were also found to be contaminated. Our results highlight the need for stringent screening and protection procedures on research vessels regarding 14 C contamination if the cruise involves sampling for natural-level 14 C studies. We recommend the undertaking of swipe tests before and after each cruise.