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From April to July 2012, four species of univalves were selected and 60 samples were chosen from each species of univalves by random sampling in Dandong market. The heavy metal contents of Pb, Cd, Cr, Cu, Zn, total As and total Hg in the edible parts of the univalves were determined by using incomplete digestion - AAS method, and the assessment on the pollution situation of the four species of univalves was made by using the single factor index method. The results showed that bullacta exarata was slightly polluted by Zn, the pollution index was 0.65, and the edible value was threatened, which should be paid attention to. The heavy metal contents in the edible parts of the other univalves were far lower than the pollution limit of the national standard of food safety and the edible value was safe. The heavy metal accumulation ability in bullacta exarata is higher than in the other three species of univalves. Bullacta excta should be the biological indicator for the monitoring of heavy metal pollution.

From April to July 2012, four species of univalves were selected and 60 samples were chosen from each species of univalves by random sampling in Dandong market. The heavy metal contents of Pb, Cd, Cr, Cu, Zn, total As and total Hg in the edible parts of the univalves were determined by using incomplete digestion - AAS method, and the assessment on the pollution situation of the four species of univalves was made by using the single factor index method. The results showed that bullacta exarata was slightly polluted by Zn, the pollution index was 0.65, and the edible value was threatened, which should be paid attention to. The heavy metal contents in the edible parts of the other univalves were far lower than the pollution limit of the national standard of food safety and the edible value was safe. The heavy metal accumulation ability in bullacta exarata is higher than in the other three species of univalves. Bullacta excta should be the biological indicator for the monitoring of heavy metal pollution.

The application of Carboxylmethyl Cellulose Sulfate (CMC-S) in cement paste was studied. The effect of CMC-S on the setting time of cement paste was investigated. Hydration heat of specimens with different cured age was measured via the Hydration Heat Tester (HHT), and hydration process was recorded via Differential Scanning Calorimeter (DSC). The results indicated that CMC-S was a kind of set-retarding and water-reducing agent; its retarding properties appeared at early age, but after three days, the hydration process of cement paste was even improved.