China declared war on pollution in 2014 in response to a survey which deemed approximately 3.33 million hectares of farmland to be no longer arable due to polluted soils. Acknowledging previous poor management of its agricultural lands and, to offset public discontent, the Chinese Government vowed to address and respond to rising pollution levels resulting from three decades of economic growth in which little priority was given to the environmental consequences. China will attempt to clean up 90 per cent of its polluted agricultural farmland by 2020.
By any measure, restoring China’s polluted agricultural soil will be a large and costly project – quite possibly the largest of its type ever undertaken. A figure in excess of one trillion yuan (approximately $202.5 billion) has been cited as what will be required to clean up and remediate soils in a geographic area similar in size to Belgium. Remediation works will concentrate on large expanses of farmland lying along China’s eastern coast and in the country’s south-west region. Much of that land has been previously used for heavy industrial manufacturing where chemical spillages, consistent industrial use, sewage and waste refuse and other forms of pollution have resulted in a build-up of toxic heavy metals in the soil.
The project will first require a protracted programme of soil testing to determine the nature and extent of the pollution. That regime will consider differing soil types, landforms and geographical contexts to accurately identify and determine remediation options. To respond to these detailed investigations “pilot zones” will be test and determine appropriate treatment technologies to be applied. It will be necessary to accurately conduct research and development to plan remediation strategies. The significant costs associated with civil engineering and drainage operations as well as the logistics of purchasing and distributing soil additives and organic fertilisers will drive that planning. The pilot zones will also inform strategies for future soil pollution prevention.
Addressing large-scale soil pollution in China is likely involve the combination of bioremediation (using plants and micro-organisms to treat polluted soil) and mechanical programmes in strategies that are multi-faceted, but not overly complex. Planning and co-ordination to meet programme goals will be key. Cleaning operations will need to be followed by programmes to revitalise and increase soil nutrients, nitrogen and carbon levels that will, in turn, promote healthy plant growth. In some cases, the complete removal and disposal of affected soil may be necessary. Other options for managing and remediating in-situ soils polluted with heavy metals may include:
- Introducing organic matter such as peat, compost and manure. In combination with tillage to aerate compacted soils, watering and fertiliser application, this will lift soil nutrient levels, develop soil microbes and impart nitrogen and carbon into the soil.
- Adjusting soil acidity or alkalinity to near neutral levels.
- Improving drainage to increase water movement through the soil and inhibit surface run-off.
- Growing cleansing plants that will induce phytoremediation – certain plants (e.g. sunflowers, willow and Pelargonium) take up and store pollutants in their above-ground parts. These plants can be harvested and the materials used for other purposes, such as timber for building and construction or as biofuels.
Remediating and restoring soil to an arable condition takes periods of time normally measured in years and even decades. The scale of restoration of the estimated 3.33 million hectares of Chinese soil will be unprecedented. Measures will need to be planned and integrated to varying degrees, in localised and regional soil management plans. Furthermore, priority action needs to be taken and completed if China is to meet its ambitious timeframe to complete the bulk (90 per cent) of remediation by 2020. Critically important to successful outcomes will be communicating to the Chinese people that the government has heard their discontent and is working urgently to address the issues of soil pollution to secure food production to meet the future needs of the population.