Data summary of 239,240Pu and 237Np in the marginal seas of China

The rapid global expansion of nuclear energy utilization coexists with the risks of nuclear accidents, making the migration and accumulation of artificial radionuclides in marine environments a research hotspot in the international environmental science field. As a key marginal sea in the Northwest Pacific, the China Seas face dual risks from external inputs of nuclear contaminants (such as the discharge of Fukushima nuclear wastewater from Japan) and the operation of domestic nuclear facilities, particularly against the backdrop of rapid coastal nuclear power development. There is an urgent need to systematically analyze the source-sink patterns and environmental behavior mechanisms of artificial radionuclides. Plutonium isotopes (239Pu, half-life 2.41 × 104 a; ²⁴⁰Pu, half-life 6.56 × 103 a) and neptunium-237 (237Np, half-life 2.14 × 106 a) serve as ideal tracers due to their long half-lives and distinct migration characteristics, collectively forming a complementary tracer system for studying the cycling of radioactive materials in the ocean.This dataset is derived from field sampling and previous literature. Field sampling covered three major sea areas—the Yellow Sea, East China Sea, and South China Sea—including Pu isotopes and 237Np data from 26 sediment cores and 17 surface sediment samples. Additionally, relevant data previously published for China's marginal seas were systematically integrated, focusing on 239,240Pu and spanning the region between 15°N–42°N and 105°E–132°E. The dataset comprises two categories: (1) sediment data, including 92 sediment cores and 494 surface sediment samples (thickness ≤5 cm); and (2) seawater data, containing 22 water column samples. All data underwent rigorous quality control and standardization to ensure comparability.The dataset is divided into three parts: (1) latitude and longitude coordinates and 240Pu/239Pu atom ratios of 528 surface sediment samples; (2) latitude and longitude coordinates, 239+240Pu inventories (Bq/m2), and 237Np inventories (mBq/m2) of 118 sediment cores; and (3) latitude and longitude coordinates and 239+240Pu inventories (Bq/m2) of 22 water column samples.