The Settlement of Pb Content Determined by Sources and Volume

Abstract

According to the investigation materials in the waters of Jiaozhou Bay in 1991, this paper studies the vertical distribution and seasonal changes of Pb content in the surface and bottom waters of Jiaozhou Bay from the center of bay to the north of bay mouth, and determines the seasonal distribution, range of variations and the trend of horizontal distribution. The results show that in May and August, the Pb content in waters ranges within 4.27-31.66ug/L from the north of bay mouth to the center of the bay, from the surface layer to the bottom, conforming to the 2nd, 3rd and 4th quality standards of sea waters and corresponding to slight, moderate and severe contamination respectively. In May and August, the waters from the north bay mouth to the center of the bay reveal the rule that the Pb content in the surface and bottom layers from May to August showed the changing of low to high. Therefore, the Pb content in the surface and bottom waters from low to high is spring and summer in sequence. In the waters of north of bay mouth and bay center, the Pb content is high in the bottom waters when it in the surface is high; the Pb content is low in the bottom waters when it in the surface is low. In May and August, the horizontal and vertical distribution of Pb content shows the same trend in the waters of north of bay mouth and bay center. Therefore, from May to August, the different supply volume from the same source determines the different seasonal changes of Pb content in the waters of north of bay mouth. In the same period, different supply volume from various sources determine the different seasonal changes of Pb content in the waters of bay center. Thus, in different waters and periods, different sources of water bring different Pb content. And seasonal changes are different as well. Based on the mentioned above, the author gets the conclusion that different sources of Pb content and various volume determine the various seasonal changes in waters. In addition, the results in the waters from north of bay mouth to the center of bay indicate that in the temporal and spacial scale, Pb content quickly and continuously settles to the seabed, resulting in the consistency in the waters between the north of bay mouth and the bay center. The horizontal distribution trends of Pb content are same in the surface and bottom waters in various sources of water and any time. This consistency is because of the gravity effect of Pb content. Human activities discharge Pb to the waters and land, settled to the seabed through water body effect, resulting in all the contamination of Pb content in the ocean.