Distribution Of Microplastics In Water Bodies Of Urban Ganzhou In Source Of Ganjiang River Basin

The birth of plastic has brought a lot of convenience to human life.However,microplastics（MPs）,which widely exists in water,has attracted much attention.Ganzhou City is the first prefecture-level city in Ganjiang source.The results of MPs pollutant can reflect the pollution level of MPs more accurately,due to the water body in this study area not affected by the pollution migration of other cities.Therefore,this study investigates the MPs pollution level of urban water body in Ganzhou for example.The MPs are collected,separated by a combination of sieving,H₂O₂ digestion,saturated sodium chloride solution flotation separation,vacuum filtration,etc.,and then the MPs in the samples are counted by microscopic examination,and finally identified by Fourier infrared spectroscopy.The abundances,morphological characteristics and polymer types of the MPs in the water body of the study area are studied.The main content and results are as follows:（1）Distribution of MPs in water section is studied.MPs abundance ranges from 0.25 to3.55 items/L.The MPs abundance decreases with the increase of sampling depth.Fiber accounts for 68–91%of the vertical water columns in the cross section,while the percentages of fragment,film and pellet range from 6–15%,1–17%and 0–7%,respectively.The cross-section particle size of MPs is mainly 0.125–3 mm,while the main particle sizes of surface water and bottom water MPs are 0.125–0.5mm and>0.5mm,respectively.Polyethylene and polypropylene occupy the largest proportion of main polymer types in water section,while polyethylene terephthalate in bottom water occupies the largest proportion.The polymer risk indexes and potential ecological risk index are 181.97 and 50.543 respectively.（2）MPs are collected in dry season（December 2020）and wet season（April and May2021）to study the spatial-temporal distribution of MPs.MPs abundance ranges from 1.93±0.25to 25.60±7.76 items/L.The average abundance in dry season was higher than that in wet season.Fiber is the dominating morphological characteristic of MPs in surface water,followed by fragment and film,while pellet at smallest amount.The particle sizes of MPs in surface water mainly in 0.125–0.5mm.There are no fixed distribution for color of MPs.The main polymer types of MPs in urban surface water are cellophane（36%）and polyethylene（29%）.The pollution load indices（PLI）in dry season（December 2020）and wet season（April and May2021）are 1.25,0.99 and 0.71,while the Nemero pollution index（P_z）are 2.13,2.86 and 0.70,respectively.（3）Combined with environmental factors such as precipitation,flow and urban functional area,the influencing factors of spatial-temporal distribution of MPs are explored.The MPs abundance fluctuated and decreased with the increase of precipitation duration,while a positive correlation between the variation of precipitation and microplastic abundance.The flow rate（Q）is linearly related to the MPs abundance（MP）（MP=0.0184Q,R²=0.991）.The average MPs abundance in industrial areas was the highest（4.78 items/L）,while that in natural areas was the lowest（2.36 items/L）.Industrial areas contribute the most to the abundance of fiber and fragment,the same as scenic area to film.The temporal distribution of MPs in urban Ganzhou of Ganjiang River Basin is greatly influenced by precipitation distribution pattern,while the spatial distribution of MPs is influenced by urban functional areas.