Analysis of backscattering properties of petroleum polluted water: a case study at the Liaohe River and the Raoyang River in Laoning Province,China

Emulsificated oil and decomposed oil in water can be absorbed by suspended particles and influence the scattering properties of the particles.Backscattering coefficient is one of the important parameters on ocean color sensing and a key factor to the establishment of semianaly tical model,so as to the retrieval of petroleum pollution concentrations.The field data were collected in the rivers in Panjin City,Liaoning Province,China in May 2008,including absor ption coefficients of yellow subst ance,de-pig mented particles and phyt oplankt on pig ments.The backscattering data were measured by the in-situ spectral backscattering sensor,Hydro Scat-6.Water samples for chlorophyll and sediment concent rations as well as petroleum contamination were also collected.Based on the analysis of inherent optical properties,two models were established.One is the spectral model of water backscattering coefficient with petroleum pollution,and another is the relationship between the water backscattering coefficient and the inorganic particle concentration,including two types of water,with and without petroleum pollution.The results show that(1) the averaging exponent is 0.87 fo rall spectral backscattering models;(2) according to the correlative coefficients between the backscattering coefficient with phytoplankt on,inorganic particles,and petroleum pollution,the inorganic particles have a dominant effect on the water backscat tering,petroleum pollution is the next,and phy to plankt on almost has not any effect,since the sedimentload is higher than 100 mg/m³;and(3) in the waters without petroleum pollution,the relationship between sediment concentration and back-scattering coefficient is well formulated by logarithm function,however,in the waters with petroleum pollution,the linear relation is more suitable.