Evaluate coastal seawater quality and propose sampling frequency for monitoring in the Northeast of Quang Ninh Province, Vietnam
Sampling frequency plays important role in water quality monitoring activity. A suitable sampling frequency could save time and cost of monitoring work. In this study, coastal seawater quality of the Northeast of Quang Ninh Province, Vietnam was evaluated by single indicator and statistical analysis of the monitored data from 2016–2019. Then the monitoring frequency was adjusted to match the current pollution status of the study area. The results showed that seawater of the area has good quality. Monitored parameters: pH, DO, TSS, Oil, and grease, Coliform were under the QCVN 10–MT:2015/BTNMT. The manager should pay more attention to NH4+ concentration in seawater by controlling the pollution source of NH4+. Seawater sampling frequency should be rearranged. More samples should be taken at potential pollution points, while reduced in low potential pollution points.