Application of Big Data in the Remediation of Contaminated Sites

Jing WEI, Hui KONG, Wangtao FAN

Shaanxi Provincial Land Engineering Construction Group Co., Ltd.; Institute of Land Engineering and Technology, Shaanxi Provincial Land Engineering Construction Group Co., Ltd.; Key Laboratory of Degraded and Unused Land Consolidation Engineering, Ministry of Natural Resources; Shaanxi Provincial Land Consolidation Engineering Technology Research Center; Land Engineering Technology Innovation Center, Ministry of Natural Resources, Xi’an 710075, China

Abstract China has large population but little land. Such objective conditions determine that it is required to adhere to the policy path of "cherishing, rationally utilizing land and practically protecting cultivated land". Due to the relatively immature technology in the early stage of resource development in China, extensive utilization of resources leads to serious pollution, and the situation of the restoration of contaminated sites is severe. After nearly 20 years of a large number of pollution, land restoration there have been a lot of achievements in research and practice, but in the era of big data development, prevention and cure of soil pollution in China, there are a number of problems in the development of science and technology, this paper put forward the corresponding recommendations and opinions for the existing problems, in order to provide decision support for using big data to repair contaminated sites.

Key words Big data, Contaminated sites, Repair

1 Introduction

The definition of a contaminated site varies from country to country. Pollution sites in China is engaged in production, management, use, storage or handling of hazardous waste and other poisonous and harmful material, the content of toxic and harmful substances in site to achieve the cause of adverse effect of live and work and or harmful to surrounding ecological environment more than the site of the acceptable level of risk. The United States Environmental Protection Agency (USEPA) defines a contaminated site as "land contaminated with hazardous substances requiring cleanup or remediation. This includes contaminated objects (such as buildings, machinery and equipment) and land (such as soil, sediment, and plants)". In the opinion of the Government of Canada, a "contaminated site" is a land where the concentration of a substance above the background value has caused or is likely to cause immediate or long-term harm to human health and the environment, or where the concentration exceeds those specified in government regulations and policies. The British Environmental Pollution Committee (RCEP) believes that a contaminated site is a site that the local government determines has caused serious harm or has the possibility of causing such harm due to the pollution of hazardous substances and has caused or may cause water pollution of the land. The Australian and New Zealand Environmental Protection Commission (ANZECC) considers a contaminated site to be a site where the concentration of a hazardous substance is higher than the background value and where an environmental assessment has shown or is likely to cause immediate or long-term harm to human health or the environment. Although the concept and scope of contaminated sites are not completely consistent with each other among countries, they are generally defined as a specific space or region polluted by pollutants, and the pollution has a negative impact on the residents or natural environment within the specific space or region. Therefore, how to control and repair contaminated sites is a common issue all over the world.

2 Application in site survey

Site remediation project usually starts from the description of the site and site investigation. The project may need to do modeling, data collection,

etc

, with the accurate site description information carried out after the repair plan choice, and choose the appropriate repair plan cost assessment. After completion of repair, monitor whether the long-term repair results are as expected. Site survey is the key point for the power of big data. Only through site survey can we obtain a large amount of data and complete information. The selection and cost of subsequent restoration plan will depend on site description.

Some data should also be acquired in the repair construction to constantly correct possible deviations or strengthen the repair effect in the repair construction. Finally, in the process of monitoring and evaluation, it is necessary to determine whether the restored land will have the phenomenon of trailing and repeated, and whether the expected restoration purpose has been truly achieved in the long-term process.

In the case of the same investment, if we use the traditional survey method, there is no relevant data collection, we have to rely on laboratory instruments and a large number of human and financial input, so the corresponding cost is relatively high. If there are enough data points and convenient analysis, the efficiency can be improved. We can just analyze a small amount of pollutants to determine the pollution situation. Therefore, with the support of big data, better remediation effect is likely to be achieved.

3 Application in data acquisition

The acquisition process of traditional site survey data is basically drilling, sampling, laboratory analysis, data verification, modeling, data report and supplement,

etc.

If there is enough data support and a large enough database, in many cases, for a similar site, we can analyze the pollution characteristics through relevant data to determine which pollutants will appear in the chemical plant. After a quick investigation, we can analyze the conventional pollutants, and then do an in-depth analysis of pollutants.

4 Application in data modeling

After data forms information, we can build a model based on information. The more data we have, the more accurate the model will be. We can analyze and improve the model by combining human wisdom with the model, constantly supplement data, and finally make decisions through the demonstration of the model. For example, what kind of way should be adopted and what kind of site should be repaired. General polluted sites need climate data, such as temperature and precipitation. If a place is windy, it is necessary to consider whether the migration of pollutants will occur during the remediation process, and whether the impact will be caused if there are residential areas around. The second is data related to land use, the third is geological context, the fourth is geological conditions, and the fifth is hydrogeology, such as the flow velocity of groundwater and surface water. The more representative the samples are, the greater the density of the samples and the larger the number of samples, the more complex the model will be, and the less the uncertainty in the energy model will be, the more comprehensive the restoration project will be to cover the areas and locations that need to be invested, so as to reduce unnecessary engineering expenses and achieve the purpose of restoration more efficiently. How to balance the design of sampling points and how to balance the acquisition of data may need the support of the data platform at last.

5 Application in whole-process control

The whole process technology system of intelligent identification, traceable diagnosis, prediction and early warning, and risk control of site pollution driven by big data has been established. In terms of the big data system for site pollution identification and assessment, it is necessary to first detect the quality of multi-source heterogeneous data, compile the data resource catalog, build the hardware system of big data operation and maintenance, and realize the multi-dimensional cognitive representation of space and time, open sharing and multi-objective management. In pollution of the field of intelligent recognition, we need for selecting nonferrous metallic deposits, nonferrous metal smelting, oil exploitation, oil processing, chemical, coking, electroplating, leather and other different industries, using the Internet of Things (IOT), such as sensors, artificial intelligence technology, intelligent recognition method and mode, development of technology for the intelligent monitor and information acquisition, establish the intelligent identification information management system of site pollution. In terms of site pollutant traceability, aiming at the complexity of spatial and temporal process of regional site pollution, a large data set of characteristic pollutant source-sink was constructed to reveal the transport mode and law of pollutants in soil-groundwater system, and the spatiotemporal simulation and three-dimensional visualization were carried out to form the diagnostic technology of traceability of pollutant source-sink relationship. In terms of pollution risk prediction, using big data technology and mathematical models of pollution diffusion and solute transport, the coupling risk characteristics of soil and groundwater at the site were accurately identified, and the pollution assessment and risk prediction system of soil and groundwater at the site was established. In aspect of controlling pollution risk of the field, according to the risk source-way-receptor, in three stages: the field pollution big data and atmospheric diffusion model, model of water pollution, ecological dynamics model, such as organic combination, can be more scientific, accurate and efficient to develop site remediation engineering technology and management scheme, with a large number of detailed data and model as a support, establish the quantitative correlation between the repair plan and the repair target, and form the medium and long term control strategy.