Critical Analysis Of The Article On The Amounts Of Microplastics And Mesoplastics In The Soil In Farmlands
The researchers of this article are M. Liu, S. Lu, Y. Song and L. Lei, all four of these researchers work at the the Schools Ecological and Environmental Sciences at East China Normal University in Shanghai, China. The corresponding author of this paper is D. He who also works at he Schools Ecological and Environmental Sciences at East China Normal University in Shanghai, China and the Shanghai Key Laboratory for Urban Ecological Processes and Eco-Restoration at East Ching Normal University in Shanghai, China.
The purpose of this study and what the researchers are trying to look into is the amounts of microplastics and mesoplastics that are found in the soil in farmlands. They are also interested in understanding the various ways in which these different types of plastic are distributed throughout the soil and what they characteristics of each type of plastic are. They are also interested in the idea of plastic mulching and if the has any direct effects on the quantity of plastic found in soil. To start this study, researchers gathers samples of soil from 20 vegetable farmlands in the suburbs of Shanghai, 2 sites in the Congming district, 1 site in songjian, 2 in Qingpu, 2 in Jiading, 1 in Minghan, 3 in Pudong and 5 in Fengxial.
In total six soil samples were taken from each location three being from the shallow layer and the other three from the deep layers, if there was any large materials found, they were taken out before being placed in aluminum boxes and shipped to be analyzed. Microplastics are categorized as pieces of plastic that are less than 5mm while mesoplastics are between 5mm-2cm. Samples were dried and stores at 70 degrees Celsius for 24 hours before a solution of NaCl was added, then stirred for 30 min to release any pieces of plastic to the surface, this process was done three times for each sample to ensure that any analogous plastics were removed from the soil.
Once the micro and meso plastics were removed from the samples researchers found that there were 9 types of micro plastics found: Polupropylene (PP), Polyethylene (PE), Polyamide (PA), Polethylene terephthalate (PET), Polyvinyl chloride (PVC), Polycarbonate (PC), Acrylonitrile butadiene styrene (ABS), Polymethyl methacrylate (PMMA) and Polystyrene (PS) (P. 256). The observation process of the different plastics lead to the micro and meso plastics to be looked at based on their shape, texture, colour and luster, amongst the microplastics they were classified as one of four shapes: fibers, fragments, films or pellets.
After the analysis of the multiple samples researchers found that there was evidence of micro and meso plastics in shallow an deep soil in all 20 locations. It is seen that there were more microplastics found in the samples compares to mesoplastics, the amounts found show that microplastics in shallow soil are 78. 00 +- 12. 91 items kg-1 and 62. 50 +- 12. 97 items kg-1 in deep soil. Since the samples were collected from 20 different locations it was seen that site 9 had the most micro(meso) plastics in shallow and deep soil while site 6 and 2 had some of the lowest amounts. Overall it is seen that there is a difference in the quantity of plastics found in soil 70% in shallow soil compares to 40% in deep soil while of those amounts 93. 3% were microplastics while 6. 7% were mesoplastics.
Overall amongst the samples PP(50. 51%), PE (43. 43%) and PES (6. 06%) were the three most commonly types of plastic polymers found in the samples. Some of the limitations brought to attention is the lack of innovative techniques that researchers are able to use to be able to tell how much plastic really is in soil, along with being able to to extract all types of polymers from the soil, from the 9 detected 7 were easily extracted while PET and PVC were harder to detect. One of the strengths of this study is that researchers were able to identify the different types of microplastics that are found in farmlands, and to the conclusion that plastic mulching is the main source of micro(meso) plastics being released into soil. I believe that this study does a good job of demonstrating the importance of looking into how micro and meso plastics are not only a problem when it comes to water pollution but how it affects the terrestrial ecosystems. By collecting multiple soil samples from the shallow and deep layer of the soil allows more tests to be conduced on the different types of plastic which can be found in the soil, in addition to taking samples from 20 different farmlands allows there to be a comparison and show the differences between the quantity of plastics and types which can be found in certain locations.
I think that by having multiple samples shows how plastics can be transferred to the different levels of the soil through plastic mulching and the other ways the plastic can come in contact with soil. I believe that this study and data provided is valid as it is related to the idea of how plastic moves around in the soil and having proper knowledge about the different types of plastic in the soil.
