biogeochemistry
; biomass
; eutrophication
; food production
; human activity
; nutrient dynamics
; phosphorus
; population growth
; river basin
; river water
; surface water
; twentieth century
; Atlantic Ocean
; Chesapeake Bay
; China
; Europe
; Gulf of Mexico
; Maumee Basin
; South America
; Sub-Saharan Africa
; United States
; Yangtze Basin