Two stations were visited in the western tropical Pacific Ocean: The South-East Asia Time-series Station (SEATS) in the northern South China Sea (SCS) and station F2 in the Philippine Sea, ~230 km to the northeast of the Luzon Strait. Water samples were taken aboard the R/V Dong-Fang-Hong 2 in July and August 2017 from 13 depths between 5 m and 3800 m at SEATS and 11 depths between 5 m and 3200 m at F2 using Niskin bottles mounted on a SeaBird 911 conductivity-temperature-depth (CTD) rosette sampler. A time-course irradiation with sampling time at 0, 1, 3, 5, 7, and 10 d was conducted for the bottommost samples from SEATS and F2. The value of different parameters was calculated as the ratio of the signal of property X at irradiation time t to that at time zero.