Nitrate Dynamics in Shallow Groundwater and the Potential for Transport to Off-Site Water Bodies

摘要: Large quantities of the nitrate leaching below crop root-zone, particularly during wet season, in tropical Far North Queensland (FNQ) Australia, may be entering off and on-site water bodies. The objectives this study were to (i) provide quantitative information on NO3-N shallow fluctuating groundwater (GW) that develops rainy season (January through May) Johnstone River Catchment (JRC) FNQ (ii) determine whether is potentially transportable creeks/streams. concentration GW table heights monitored, at least weekly intervals, 6 piezometers, installed 8.5–12.0 m depth different soil types under fertilized sugarcane (Saccharum Officinarum-S) JRC 1999 season.Depending location piezometers landscape time sampling, fluctuated between from 1.5 11.5 abovethe piezometer bottom. also showed spatio-temporal dynamics it ranged 0.60 3.70 mg L-1. adsorbed anion exchanges sites, up 10 depth, 154 3956 kg ha-1, compared with 21 kgha-1 rainforest. In GW, increased increasing height exchange sites (R2 = 0.96). load 40 110 ha-1 concentration. estimated N-load was discharged into creeks/streams when receded 81 ha-1. results evidence a(i) a major proportion root-zone entered developed significant inthe transported receded.