Migration and changing law of PHC content under the action of ocean current
Authors: Yang Dongfang , Li Qing , Li Haixia , Lin Dong , Wang Qi 
Published: April 2021

According to the survey dataset of the waters of Jiaozhou Bay in May 1993, this paper studies the migration and changing process of PHC content caused by marine oil spill in the waters of Jiaozhou Bay. In May, take the center of eastern waters, H3107, as the source of marine oil spill, where PHC content is 51.00μg/L. Then a series of concentric circles with different gradients are formed with H3107 station as the center. The PHC content decreases from the high content of 51.00μg/L in the center to the surroundings along the gradient, to 4.16μg/L in the waters of bay mouth, 31.60μg/L in the central waters of the bay, 27.00μg/L in the northern waters, and 48.40μg/L in the northeast waters. According to the horizontal absolute loss rate model of material content, it can be calculated that the value of horizontal absolute loss rate of PHC content in the surface layer of the water body from the eastern center to the bay mouth in May is calculated to be 0.44 Yang Dongfang absolute number; to the central waters of the bay, 0.13 Yang Dongfang absolute number; to the northern waters of the bay, 0.33 Yang Dongfang absolute number; to the northeastern waters of the bay, 0.06 Yang Dongfang absolute number. According to the horizontal relative loss rate model of material content, it is calculated that in May, from the eastern central waters to the waters of bay mouth, the horizontal relative loss rate of PHC content in the surface layer of water body is 8.67 Yang Dongfang relative number; to the central waters of the bay, 2.72 Yang Dongfang relative number; to the northern waters of the bay, 6.47 Yang Dongfang relative number; to the northeastern waters of the bay, 1.33 Yang Dongfang relative number. Therefore, taking H3107, the central point in the eastern part of Jiaozhou Bay, as the source of marine oil spills, its PHC content decreases to the surroundings, whose horizontal absolute loss rate is within 0.06–0.44 Yang Dongfang absolute number and the horizontal relative loss rate is within 1.33–8.67 Yang Dongfang relative number. The order of the horizontal absolute (relative) loss rate of PHC content from low to high is: waters in the northeast of the bay < waters in the bay center < waters in the north of the bay < waters in the bay mouth. The Yang Dongfang horizontal loss rate model of material content reveals the migration and changing law of PHC content during the process of ocean current carrying PHC content: 1) In the downstream direction of the ocean current, the PHC content decreases at the slowest rate, and its loss is the smallest during the migration process. In the countercurrent direction of the ocean current, the PHC content declines the fastest, and the loss is greatest during the migration process. 2) In the downstream direction of the ocean current, as the migration distance continues to increase, the PHC content continues to decline and its loss is gradually increasing during the migration process. 3) In waters where the ocean current does not pass, the PHC content decreases slowly, and the PHC content reaches a relatively high value. During the migration process, its loss is relatively small. The PHC content reaches the waters where the ocean current does not pass, and the loss content is between the loss of the PHC content carried by the ocean current in the downstream direction and the upstream direction.