Narrow Results

In this research, multivariate statistical analysis was employed for heavy metals sources identification of 89 samples of urban surface soil. Results indicated that concentrations of surface soil heavy metals were generally higher than environmental background values of soil elements. The concentration of Pb on surface soil in Guiyang city was lower than those in other cities for the short time usage of Pb gasoline. The concentrations of Cu, Ni and Zn on surface soil in Guiyang city were higher than those in more parts of cities for the size and production skill of steel plant, automobile emissions and external soil. The major sources of surface soil elements were the vehicle emissions, steel plant, geo-chemical genesis and external source. It was limited to identify heavy metals sources by using CA and PCA. We must analyze the spatial distribution characteristics of elements by the GIS technique and ambient environmental conditions.

The absorption and accumulation characteristics of 6 heavy metals of Cd, Cr, Cu, Mn, Pb and Zn by 8 indigenous weeds Miscanthus floridulu, Amaranthus spinosus, Conyza canadensis, Bidens pilosa, Opuntia stricta, Buddleja lindleyana, Mllrdannia triguetra, Gynura crepidioides, growing naturally in the wasteland of Mingshan Coalmine in Eastern Guangdong, were investigated. Results indicated that enrichment degree of heavy metals in plants varied with plant species, as well as heavy metals, and there were differences between the aerial part and underground part. Mn, Zn and Cu were the three highest-content metals in all the 8 weeds. Seven of the 8 plants except Amaranthus spinosus lad larger than 1 transfer factor for at least one heavy metal. Notably Conyza Canadensis had larger than 1 transfer factor for 4 heavy metal of Cd, Cr, Pb and Zn. The enrichment coefficients of the ground part and underground part of the 8 weeds were over 1 in most cases, especially in the roots. The 8 weeds were not typical hyper-accumulators, but all had certain enrichment ability. Conyza Canadensis, Bidens pilosa and Gynura crepidioides were assessed to be potent candidates for phytoremediation of heavy metals in waste coalmine.

In this paper, the design of the lower computer hardware circuit for the heavy metal detector based on electrochemical method is introduced. Firstly, the whole instrument is described according to the system structure, and then main parts are introduced from the principles and the specific circuits. After assembling the prototype, the performance of the system is tested. And the result shows that the system operates very well and could meet the needs of actual measurement. With the simple structure and high accuracy, the circuit design can be used as the basic structure for the expanding applications.