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Abstract: Computers can not determine the exact size of the edge simply according to a bitmap image of the brick-carved to be processed, making it difficult to set up a three-dimensional digital model. To solve this problem, we proposed to process manual diagrams, the traditional processing materials of carved bricks, through adaptive median filtering, image sharpening, Canny edge operator, gray-scale image processing and other computer technologies. Simulation experiments of CNC engraving showed that three-dimensional model established by gray-scale image information could be effectively applied to CNC engraving. [Copyright &y& Elsevier]

Total mercury contents of cicadae bodies, wings and exuviaes were studied in Huludao City to discuss mercury distribution characteristics in cicadae and to reveal the environmental mercury accumulation effects in the long life-cycle insects through comparing cicadae with other insect species. The average mercury contents of cicadae bodies were 2. 64 mg x kg(-1) and much higher than those in the contrast sites (1.00 mg x kg(-1) on average) in Huludao City. Mercury contents were found in the order of cicadae bodies > wings (0.98 mg x kg(-1) on average) > exuviaes (0.50 mg x kg(-1) on average). Sex differences of mercury contents and body weights of cicadae were significantly great. The females had larger body weights (1.11 g on average) and lower mercury contents (1.34 mg x kg(-1) on average) than the males (body weight: 0.54 g on average; mercury contents: 3.38 mg x kg(-1) on average), respectively. Mercury contents of cicada's bodies varied greatly with sample sites, mercury contents of wings changed little. No significant correlation was found between mercury contents of soil and cicadae bodies. Mercury contents of cicadae were lower than those of dragonflies, higher than those of other insects with shorter life-cycle periods and it reflected the accumulation effects of environmental mercury in the long life-cycle insects such as cicadae.

14 insect species, which were classified to three groups: the herbivorous, the polyphagous and the carnivorous, and earthworms were collected from the grasslands in Huludao City, Liaoning Province, China. Mercury, cadmium and lead contents in biota were determined to discuss the heavy metal pollution in organisms. Mercury, cadmium and lead contents were 0.168, 9.19 and 12.58 mg x kg(-1) in the herbivorous insects, respectively; 0.375, 24.43 and 17.71 mg x kg(-1) in the polyphagous insects, respectively; 0.928, 29.78 and 18.39 mg x kg(-1) in the carnivorous insects, respectively. It showed that heavy metal pollution in biota in Huludao City was heavy. Bioaccumulation abilities to heavy metals significantly differed with insect species. Snails and dragonflies could accumulate more mercury than the other insects and spiders could accumulate the most cadmium and lead in all insect species. These three metals investigated in insects were all sorted as the herbivorous < the polyphagous < the carnivorous. Cadmium and lead contents between the polyphagous and the carnivorous varied slightly. Correlation analysis showed that cadmium and lead contents were significantly related, but mercury and cadmium or mercury and lead were not. It indicated that cadmium and lead in insects were from the same pollution sources while mercury was more complex.

Hg, Pb, Cd, Zn, and Cu concentrations in the soil, vegetables and crop of Huludao city were investigated. The Hg, Pb, Cd, Zn, and Cu concentrations in soils of the smelting areas are 1.422, 443.1, 60.94, 4084, and 247.8 mg x kg(-1), thus 6.092, 3195, 341.7, 35 157, and 1 557 mg x kg(-1) for the maximal concentrations, respectively. Spatial distribution maps of heavy metals concentrations in top soils in Huludao City were separately laid out by using Kriging. Heavy metals spatial distribution patterns in soils show that Ph, Cd, Zn, Cu emissions from Huludao Zinc Plant are the main pollution sources of heavy metals to the top soils in Huludao City, but Hg emission from Huludao Zinc Plant and chlor-alkali industry is the main pollution source of mercury to the top soils. Heavy metals concentrations in top soils decrease exponentially with distance from the zinc smelting area. Except Hg, the exponential equation could be better to fit the variety forother heavy metals. Heavy metals in vegetable and crop cultivated around Huludao Zinc Plant are higher than from markets, suggests that heavy metals affect the local soil and crops seriously.

The concentrations of methylmercury (MeHg) in water were investigated in both level period and flood period in the Second Songhua River. The results show that the MeHg concentrations in water of Hongshi, Shihaoxian and Ganshuigang sites are relatively higher than other sampling sites. The MeHg concentrations in the level period are higher than the flood season in most sampling sites beside Laozhou and Sifangtai sites. By comparing the MeHg concentrations in different years, the results reveal that the MeHg concentrations in 1981 decreased with the distances increasing from the sites to the pollution source. The MeHg concentrations in most sites greatly fell in 1983, when the pollution source had been ceased for one year. The concentrations approached the natural background level in most sites, however, they were over 0.35 ng x L(-1) from Zhaoyuan site to Sifangtai site. The MeHg concentrations in corresponding sites in 2006 were higher than that in 1983, but were lower than that in 1981. Moreover, the pollution level in water of the Second Songhua River was also discussed.

We researched mercury contents in plants and arthropods collected from the river banks in mercury polluted areas. The results show that total mercury (T-Hg) and methyl mercury (Me-Hg) in Locusta migratoria manilensis and Acrida chinensis are 0.032 - 0.402 mg x kg(-1), 0.023 - 0.362 mg x kg(-1) and 0.003 - 0.031 mg x kg(-1), 0.004 - 0.015 mg x kg(-1) while the proportion of Me-Hg to T-Hg are 3.5% - 49.7% and 2.0% - 44.4%. T-Hg in arthropods is higher than that a magnitude in non-polluted areas. As primary consumers, mercury contents in Locusta migratoria manilensis and Acrida chinensis are lower than plants they eat. That is not consistent with the non-polluted areas. Paratenodera sinensis is the second consumer and there is an obvious mercury accumulation in it. For Locusta migratoria manilensis, T-Hg decreased with the body length while for Acrida chinensis that increased following a decreasing. But Me-Hg in both increased with body length. Mercury contents in tissues of arthropods are significantly different. The order is abdomen > thorax > head. Mercury and methyl mercury contents in arthropods would lead wild birds, fowls and amphibians in the ecologic risk condition.

The transfer characteristics of Hg, Pb, Cd, Zn and Cu from soil to vegetables near zinc smelting plant in Huludao City, China were investigated, and the sources of heavy metals in the soil and vegetable were also analyzed. The results indicate that the Hg, Pb, Cd, Zn and Cu contents of vegetables are 0.013, 5.476, 2.852, 41.16 and 1.515 mg/kg (fresh weight), respectively, and the environment around Huludao Zinc Plant are contaminated seriously. The transfer factors (TF) of heavy metals decrease in the order of Cd > Zn > Cu > Pb > Hg. The transfer factors of heavy metals from soil to leaves are higher than from soil to other tissues. The heavy metals in soil derive from atmosphere, and the parts of Pb in the leaves of vegetable derive from atmosphere. Uptake of gaseous mercury is the predominant pathway by which mercury accumulates in the vegetable.

Temporal variation rule of mercury during 1973, 1976, 1983, 1991 and 2004 in surface sediments from the Second Songhua River was get. Mercury levels increased before 1976 and decreased on a certain extent in 1976-1982; mercury pollution source was halted in 1982, so mercury levels fell greatly; in the following years, mercury levels was in the slow purification time. Sediment samples taken this time were divided into three granularity scales. Based on sediments of 63 microm granularity, the horizontal variation rule was analyzed. Mercury levels reached the maximum at the pollution source site, increased from Shaokou Segment to Chaoyangqiao Segment, and fell largely from Chaoyangqiao Segment to Wujiazhan Segment, where mercury levels attained the minimum. And mercury levels slightly increased from Wujiazhan Segment to Ganshuigang Segment. In addition, the vertical variation rule of mercury levels in sediments of typical segments was shown.