Based on the investigation data of Plumbum (Pb) in surface waters in Jiaozhou Bay in April, August and November 1981, this paper analyzed the content, distribution and source of Pb. Results showed that Pb contents in April, August and November ranged from 0.20-2.65 μg. L-1, 0.79-3.34 μg. L-1 and 0.00-3.00 μg. L-1, respectively, all of which were lower than Grade II (5.00 μg.L-1) in according to National Standard of China for Seawater Quality (GB3097-1997). Agricultural non-point source and urban point source were the major pollution source of Pb in spring (growing season) and autumn (dry season), respectively; while both point and non-point sources were responsible in summer (wet season).

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Based on the investigation data of Hg in Jiaozhou Bay waters in April, July and October 1986, this paper tried to analysis the horizontal, vertical and seasonal distributions of Hg in Jiaozhou Bay, and to reveal the pollution sources and transfer processes of Hg. Results showed that Jiaozhou Bay had been heavily polluted by Hg, whatever in different seasons. Hg in Jiaozhou Bay was mainly from point sources such as industrial waste and sewage runoff. The horizonal and vertical distributions of Hg content showed the transfer processes as, from estuaries to their outside and the bay mouth, and form surface waters to bottom waters, respectively. The water environmental capacity of Hg in Jiaozhou Bay had been unable to carry the emission load of Hg, and therefore the reduction of emission as well as the improvement of cyclic utilization ratio were the primary processes for Hg pollution prevention and reduction.

Based on the investigation data of mercury (Hg) in waters in Jiaozhou bay during time peroids of 1979 to 1985 (absent of 1984), this paper tried to analysis the seasonal variations of Hg in Jiaozhou Bay, to reveal the transfer process of Hg, and to provide basis for decision-making of pollution control. Results showed that, there was indistint seasonal variations of Hg content, due to anthropogenic discharge was the major source of Hg, which was not static, but depended on industrial adjustment. The land transfer process of Hg could be divided into three major processes: 1) human discharges of Hg to soil, waters, and atmosphere, etc., 2) Hg is washouted and delivered into streams, and 3) Hg is transferred to ocean via river channel runoff. In order to reconcile economic growth with environmental protection, we should have to improve the use ratio of Hg, and to reduce the discharge load of Hg.

Field monitoring and incubation experiments were conducted to evaluate the litter yield and examine the decomposition of the litter of three representative mangrove species frequently used for mangrove re-vegetation in a subtropical mudflat on the South China coast. The results show that the litter yield of the investigated mangrove species varied significantly from season to season. The annual litter production was in the following decreasing order: Heritiera littoralis > Thespesia populnea > Kandelia obovata. Initially, rapid decomposition of easily degradable components of the litter materials resulted in a marked weight loss of the mangrove litter. There was a good linear relationship between the length of field incubation time and the litter decomposition rate for both the branch and the leaf portion of the three investigated mangrove species. Approximately 50% or more of the added mangrove litter could be decomposed within one year and the decomposed litter could be incorporated into the underlying soils and consequently affect the soil carbon dynamics. An annual soil carbon increase from 2.37 to 4.64 g/kg in the top 5 cm of the soil was recorded for the investigated mangrove species.