| With the development of society, the uses of heavy metals have become more popular. The result of these is the coming of the problems such as the shortage of the heavy metal resource and the pollution of heavy metals in nature water body. In the researches of aquatic environment pollution, heavy metals refer to the heavy element, such as lead, cadmium, chromium, mercury, that have biological toxicities. Mercury is regarded as the most toxic element, and then is the cadmium, lead and other elements. Due to their nonbiodegradable properties, bioaccumulation effects, and toxicities even at low concentrations, heavy metals have prompted great interests. The suspended particle matter in the nature water is pollution itself, and it can control the transport and recycling of the pollution in environment by reacting with them and becoming the carriers of them. Furthermore, pollution can release from the suspended particle matter, which can be harmful for aquatic ecosystem and the supply of drinking water. Natural surface coatings composed of microorganisms, oxide minerals and many other things are the composite solids existing widely in the natural aquatic environments, and they occur on all kinds of solid surfaces and affect the behaviors of heavy metals significantly. Due to the high surface reactivity and large surface areas, the most important role of surface coatings in the aquatic environments is the adsorption or enrichment of pollutants in the water. Besides, the adsorbed pollutants may be degraded or detoxified due to the bioactivity of microorganisms. Researches on heavy metals adsorption to suspended particle matter and the relationship with natural surface coatings in component will help to understand the behavior of heavy metals, the mechanism of their removal spontaneously in aquatic environments and the effect of suspended particle matter on the components and formatting process of surface coatings. Suspended particulate matter was obtained from Nanhu Lake by filtrating with filter membrane of 0.45μm. The kinetic and thermodynamic characteristics and affecting factors of Pb and Cd adsorption to suspended particulate matter were studied. Then the relation of components between natural surface coatings and suspended particle matter was investigated and discussed. The research work obtained the following conclusions: The adsorption of Pb to suspended particulate matter was faster than that of Cd which was estimated by double-constant rate equation. Adsorption of Cd and Pb to suspended particulate can be described by using Langmuir isotherms and the result indicated that the maximum adsorption of Pb was four times greater than that of Cd. The amount of Cd and Pb adsorption to suspended particulate matter increased linearly with the weight of suspended particulate matter. The amount of Cd adsorption to suspended particulate matter increased with the growth of pH, but the amount of Pb adsorption increased dramatically when pH was no more than 6.25, and then dropped quickly when pHwas above 6.25. The pH values of the Pb and Cd solutions increased remarkably during the initial adsorption period firstly which was mainly consisted of adsorption, subsequently to a stationary value gradually after 5h which was consist of both adsorption and deabsorption. The amount of Pb and Cd adsorption to surface coatings dropped dramatically with the increase of concentration of NaNO3 as supporting electrolyte(0~0.3mol/L), but when the concentration of NaNO3 was above 0.3mol/L, the amount of adsorption kept relatively steady. These proved the possible simultaneous existence of the electrostatic adsorption and specific adsorption in Pb and Cd adsorption to suspended particulate matter. It was also found that the amount of Cd adsorption to surface coatings was affected by Pb significantly, while the influence of Cd on Pb was almost negligible when Pb and Cd coexisted. The weight of surface coatings on the glass slide in different times changed greater than that of suspended particle matter obtained from 800mL water by filtrating, and in the same time the difference among the weight of surface coatings on every glass slide was bigger than that of suspended particle matter obtained from every 800mL water. The COD of surface coatings and suspended particle matter were rather steady in different times. The COD of surface coatings was twice as much as that of suspended particle matter, which was because the biomass and its organic products in the surface coatings was higher than that in the suspended particle matter. The major element contents of surface coatings and suspended particle matter were also steady.
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