Approximately 330 million tons of plastic were produced worldwide in 2015, and this figure continues to increase 1 . As a result, the contamination of our environment with plastics of all sizes is becoming one of the most widespread and long-lasting anthropogenic changes to the biosphere of our planet 2 . Microplastics (MPs) are generally defined as plastic particles in the size range of 100 nm to 5 mm, including submicrometre (100 nm to 1 μm) and micrometre (1 μm to 5 mm) plastics, and nanoplastics ranging from 1 nm to 100 nm (ref. 3 ). Furthermore, MPs are separated into primary MPs, which are originally manufactured in a particularly small size for specific applications, and secondary MPs, originating from the fragmentation of larger plastic debris by external forces 3 . Scientific research on MPs pollution is rapidly advancing. However, studies to date have focused almost exclusively on aquatic systems, especially the oceans 4-6 . The oceans represent the ultimate sink for most MPs, but the terrestrial environment is a major recipient of plastics of all sizes, owing to the large amounts of anthropogenic wastes derived from sewage sludges, organic fertilizers, plastic mulching, wastewater irrigation and other sources such as atmospheric particulate deposition [7][8][9] . On the basis of emissions data, it is estimated that 110,000 and 730,000 tons of MPs are added annually to farmlands in Europe and North America, respectively 10 . These figures exceed the estimated annual global burden of MPs in ocean surface waters of 93,000-236,000 tons 11 . Hence, there is a great need to understand and quantify the distribution, fate and transformation of MPs in the terrestrial compartment.Very little information exists on the accumulation and effects of MPs on soil biota 12,13 . Plants comprise a basic living component of terrestrial ecosystems and are an important source of human food.

Mathematical modelling study for water uptake of steadily growing plant root Science in China Series G-Physics, Mechanics & Astronomy 51, 184 (2008); The uptake diversity of soil nitrogen nutrients by main plant species in Kobresia humilis alpine meadow on the Qinghai-Tibet Plateau SCIENCE CHINA Earth Sciences 55, 1688 (2012); Alkali salts of heteropoly tungstates: Efficient catalysts for the synthesis of biodiesel from edible and non-edible oils

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