Administrative responsibility and land-sea synergistic regulating indicators for nutrient pollution: Linking terrigenous emission to water quality target in Laizhou Bay, China

•The bay polluted segments were identified by land-sea synchronous investigation.•The jurisdiction responsibility apportionment for polluted segments was quantified.•Land-based pollutant reduction indicators linked with the Bay’s water quality.•Differentiated nitrogen management scheme for each justification is efficient.