**1. Introduction**

On the issue of trace element contamination of environment, the trace elements refer to the elements with lower concentrations than the major elements, O, H, Si, Al, Fe, Ca, Mg, Na, K, Ti, which are usually take no more than 1% in rocks and minerals. The trace elements have attracting wide research attentions for their high potential on environmental contamination and health impact. In some articles, the phase heavy metals are frequently used to represent elements that have high density or is toxic or poisonous at low concentrations. From the view of environmental impact, the phases trace elements and heavy metals refer to similar research objects, which are used as group name for metals and metalloids that have been associated with contamination of water, river sediment, soil and air particles and potential toxicity and ecotoxicity. In this chapter, the phase trace elements (TEs) are used to present the elements that may cause contamination and health problems, and

address issue relating to the behavior and mechanism of them among environmental bodies.

The TEs are widely studies in the areas of water, rock, coal geochemistry, leaching and mobility potential, bioaccumulation and human health risk, survey technologies, and other related topics [1, 2]. The harm to human health of TEs are amount related. Some TEs are essential to human in a concentration scale, while become toxic along with the concentration elevation. Some toxic TEs may cause acute and chronic effect even in very low content. In light of the levels of toxicity, trace elements lead (Pb), zinc (Zn), copper (Cu), nickel (Ni), chromium (Cr), cadmium (Cd), arsenic (As), selenium (Se), mercury (Hg), are most investigated, studied and regulated. For example, small amounts of lead in the body can make it difficult for children to learn, pay attention and succeed in school. Lead accounts for most of the cases of pediatric heavy metal poisoning. Arsenic is the most common cause of acute heavy metal poisoning in adults and does not leave the body once it enters. Mercury exposure put newborns at risk of neurological deficits and increased cardiovascular risk in adults.

The TEs may be released from sources of lithogenic or anthropogenic [3, 4]. With the industrialization and urbanization process, TEs released from anthropogenic source are increasing, including discharge of industrial and municipal wastes, storms, run-offs, dry deposition, mine discharge, waste incineration, application of pesticides and fertilizers, sewage irrigation and transportation, and other diffused sources [1, 5–11]. The environmental medias, including water [10, 12–14], sediment, soil [3, 4, 15–23], air particles [15] can be contaminated.

In order to understand and control pollution of the trace element, source identification and quantification of TEs in water, sediment, soil, and particles are of great importance. The traditional techniques are mostly based on geochemical method. Statistical method based on univariate analysis are also used. However, the univariate analysis is cumbersome, and sometimes hard to explain. The multivariate analysis provides a new technique system for the TE source apportionment. Multivariate analysis, and related method, machine learning, data mining have been approved to be successful in a very wide aspects of human living and production. In the area of geochemistry, environmental engineering, applications of the method are also increasingly used.

In this chapter, two related topics are reviewed and discussed. First, the advances of multivariate analysis on the issue of source apportionment, especially several kinds of multivariate analytical method; second, understanding of the contaminating origin of TEs on important environmental media, ground and surface water, sediment in river and lake, soil, precipitate dust, suspended particle matters, PM 2.5 and PM 10.
