**Acknowledgements**

The concept of in-situ reactive walls involves the installation of impermeable barriers down‐ grading of the contaminated groundwater plume and hydraulic manipulation of impacted groundwater to be directed through porous reactive gates installed within the impermeable barrier. Treatment processes designed specifically to treat the target contaminants can be implemented in these reactive or treatment gates. Treated groundwater follows its natural course after exiting the treatment gates. The flow through the treatment gates is driven by natural groundwater gradients, and hence these systems are often referred to as passive treatment walls. If a groundwater plume is relatively narrow, a permeable reactive trench can be installed across the full width of the plume, and thus preclude the necessity for instal‐

In-situ reactive walls eliminate or at least minimize the need for mechanical systems, there‐ by reducing the long-term operation and maintenance costs that so often drive up the life cycle costs of many remediation projects. In addition, groundwater monitoring and system

Bioventing, also a modification of vapor extraction technology, is briefly contrasted with air sparging. With bioventing, extraction or injection of air into the vadose zone increases sub‐ surface oxygen concentration, promoting bioremediation of unsaturated soil contaminants. This technique is applicable to all biodegradable contaminants, but has been applied most frequently and reportedly most successfully to sites with petroleum hydrocarbon contami‐

The past 40 years, groundwater subjected to pollution, it cannot be ignored that there has a serious threat to human health and ecological security problems. The research on ground‐ water pollution risk assessment will help understand the relationship between the soil con‐ ditions and groundwater pollution, identify the high-risk regions of groundwater pollution, provide a powerful tools for the land use and groundwater resource management, and help the policy maker and managers to develop effective management strategies and protection

**1.** Continue to strengthen the research on the fate and transport in hydrogeological condi‐ tions. Hydrogeological conditions of the contaminated sites have a vital role in organic pollution of groundwater. We should pay attention to the impact that the thickness of the unsaturated zone, the aquifer lithology of unsaturated zone and groundwater, the groundwater runoff conditions on the organic pollution investigation and contaminated aquifer restoration. Unsaturated zone is the only avenue for the organic pollutant into the groundwater system. In the protection of groundwater quality, we should take im‐ pact of the physical, chemical, and biological characteristics of the unsaturated zone soil

on the transport and degradation of organic pollutants into consideration.

**2.** In the future research, the natural attenuation of typical organic contamination in groundwater should be reinforce research, especially the organic degradation mecha‐

measures on groundwater. So we can offer some suggestions as following:

compliance issues can be streamlined for even greater cost savings.

**8.2. The suggestions for groundwater pollutions**

lation of impermeable barriers.

106 Organic Pollutants - Monitoring, Risk and Treatment

nism of microbes.

nation

This study is granted by the Specific Research on Public Service of Environmental Protection in China (No. 201009009). The authors appreciate the tutor and classmates for help.
