| Existing Dissolved Oxygen(DO)monitoring methods are all contact measurement,and it is difficult to simultaneously observe a large area.There are many ships in the sea area of Dalian Port,and there is a breeding area near the channel.It is not suitable to deploy buoys or other water quality monitoring equipment for a long time.Regular DO monitoring requires a lot of manpower and material resources.The large-scale simultaneous observation capability of water color remote sensing can make up for the lack of existing monitoring methods.The optical response of DO to the remote sensing image band is not obvious,so the method of inverting water quality parameters by looking for the optically sensitive band is not suitable for DO.The sea area of Dalian Port is a typical petroleum-substances-contaminated water body.DO has higher solubility in oily substances.Previous studies have shown that the concentration of petroleum substances in Dalian Port can be retrieved by optical satellite images.Therefore,the concentration of petroleum substances is used as an intermediate variable for DO The advantages of remote sensing estimation are obvious.Based on the analysis of the on-site measured data of Dalian Port in August 2018,the concentration of petroleum substances is a significant influence factor of the DO concentration in the sea area of Dalian Port.Taking petroleum substances as intermediate variables,the obtained DO estimation model is applied to Landsat-8 remote sensing images,and the remote sensing estimation results are evaluated.The main research results are as follows:1)When the concentration of petroleum substances is less than 1 mg/L,the concentration of petroleum substances is almost irrelevant to the DO concentration(?=-0.098,p=0.749,n=13,p is the Spearman correlation coefficient,p is the p value,n is the number of samples);when the concentration of petroleum substances in the sea area of Dalian Port is ?1 mg/L,the concentration of petroleum substances and DO show a very significant positive correlation(p=0.822,p=2.5897×10-16<<0.01,n=62),the correlation between the concentration of petroleum substances and DO is in the form of a power exponent:y=6.6224x0.1107(y is the DO concentration,x is the oil concentration,and the unit is mg/L).2)The DO estimation model based on the concentration of petroleum substances was applied to Landsat-8 remote sensing data,and the thematic map of DO concentration distribution in the Dalian Port sea area on August 25,2018 was drawn.The DO remote sensing estimation results of the thematic map are consistent with the measured data.The DO concentration estimation results in the sea area of Dalian Port are concentrated in the range of 6.61?7.91 mg/L.Compared with the measured value range of 6.84?7.47 mg/L on August 25,2018,the range of the inversion value is considered reasonable,and the average value of the inversion is 7.22,which is not much different from 7.10 mg/L,the average of DO concentration measured on site on August 25,2018.3)The results of the thematic map of DO concentration distribution show that the DO concentration along the coast of Dalian Bay,Dayao Bay,and Xiaoyao Bay is low.The reason is that it is mainly affected by land source input.There are more organic matter in the water body,and a large amount of oxygen is consumed when microorganisms are decomposed;The concentration of DO in the east of Sanshan Island is high,which may because the kelp culture in this area. |
PDF Full Text Request