A new approach for concentration estimation of coastal organic substance was put forward through study on complex systems theory. Firstly, the COD monitoring data of Tianjin's coastal marine from the 20 monitoring points were prepared. Secondly, a typical multi-fractal method, which called the method of moments, was applied to compute the multi-fractal dimension spectrum function f(¿) of COD. The curve of ¿(a)-f(¿) was a continuous curve, which indicated that the spatial distribution mode of coastal organic substance was not a normal distribution or logarithm normal distribution, but a continuous multi-fractal distribution. Then, the MATLAB program of fractal surface interpolation algorithm was made to estimate the concentration of organic substance in coastal marine. Then, the COD concentration of organic substance in the whole area was gotten. The case analysis shows the method presented can identify the spatial pollution characteristics from the coastal organic substance monitoring data, which overcome the shortages of the precious method for the complexity of coastal marine water quality change.
With the worldwide regulation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), the alternatives (short chain analogues and emerging per- and polyfluoroalkyl substances, PFASs) have gradually attracted global attention. This study analysed the replacing of legacy PFASs in China using PFASs data from residential soils, which might be good environmental indicators of their present usage. The total concentrations of 21 PFASs ranged from 244 to 13564 pg/g, and PFOA was the dominant compound among the studied PFASs, with a concentration of 354 ± 439 pg/g. Serious PFASs pollution in residential soils mainly occurred in Eastern Coastal China as a result of locally developed industry and economies. Weak but significant correlations were found between PFASs and environmental and socioeconomic factors, suggesting that various factors determine PFASs contamination in residential soils. The concentration and detection frequency (DF) of short-chain analogues (C < 8) (375 ± 509 pg/g and 100%), and F-53B (216 ± 306 pg/g and 98.9%) were higher than those for PFOS (193 ± 502 pg/g and 85.4%), indicating that these compounds have been widely used as PFOS alternatives and their consumption has already exceeded that of PFOS in China. In addition, GenX (the PFOA alternative) had a concentration and DF of 19.1 ± 104 pg/g and 40.5%, respectively. These values were much lower than those for PFOA (354 ± 439 pg/g and 96.6%), indicating GenX consumption is still limited at the national scale of China, despite its use as a PFOA replacement. Moreover, the low concentration and DF of FC-98 (2.31 ± 11.1 pg/g and 27.0%) indicate that its consumption might be negligible. Our study demonstrated that short chain analogues and emerging alternatives have become the dominant PFAS pollutants in Chinese residential soils, and further studies need to be conducted to understand their toxicity and environmental risks.
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