eluted later. This study reveals isotopic heterogeneity as a function of SPE-DOC elution volume. These results show a partitioning of two distinct sources of SPE-DOC during elution, indicating a gradual transition from 'marine - like' DOC to 'terrestrial -lik e' DOC along a hydrophobicity continuum.

Li, C., Busquets, R., Campos, L.C., 2020. Assessment of microplastics in freshwater systems: A review. Science of The Total Environment 707, 135578.

http://www.sciencedirect.com/science/article/pii/S0048969719355731 The reliance on plastic for a vast number of consumer products, many of them single-use, results in their continuous entry into aquatic environments. Plastic waste can fragment into smaller debris, some with a diameter < 5 mm(microplastics). Microplastics are of growing concern especially since 2014, however to date research on microplastic pollution has mainly focused on marine environments, partly because it has been mistakenly thought that sewage treatment plants could remove all plastic debris. To understand the impact of microplastic pollution in freshwater environments, an assessment of research on the sources, distribution and effects of microplastics, and trends in their analysis and policy has been carried out. Main sources of microplastic found in freshwater environments include synthetic textiles, personal care products, industrial raw materials and the improper disposal of plastic waste. Microplastic pollution is a global issue that presents with a broad range of concentration: for example, 3.5 × 10^3 microplastic units·L-1 were reported in sediment of Lake Huron, in the US and as low as 1.2×10-4 units·L-1 in countries with sparse population such as Mongolia. The main polymer constituents of microplastics found in freshwaters have been identified as polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET), accounting for 70% of the total, each with a very similar frequency of occurrence. Despite microplastics being relatively inert, they are found to cause some effects in aquatic organisms. Future work should focus on monitoring microplastic pollution in regions from where there is currently scarce published data (e.g. South America, Africa and North Asia) and the study of their sources, stability, transport and effects to freshwater ecosystems. The establishment of standardized monitoring methods will allow for the comparison of data from different geographic areas. This information will inform measures to reduce the release and occurrence of microplastics in aquatic environments.

Li, D., Shi, Q., Mi, N., Xu, Y., Wang, X., Tao, W., 2020. The type, origin and preservation of organic matter of the fine-grain sediments in Triassic Yanhe Profile, Ordos Basin, and their relation to paleoenvironment condition. Journal of Petroleum Science and Engineering 188, 106875.

http://www.sciencedirect.com/science/article/pii/S0920410519312914 The Chang 7 oil layer in Yanhe Profile develops comprehensive fine-grained sediments, showing great significance to hydrocarbon exploration. Based on nineteen samples, organic elements, maceral identification, vitrinite reflectance (Ro), biomarkers and inorganic elements were tested. The results show that the fine-grain sediments have relatively high clay minerals and are mainly silicate and clay source rocks, showing good- excellent source rock quality at the bottom with the decreasing quality towards the top. The rock pyrolysis, maceral identification and Ro imply that the organic matter (OM) type is Type II with plankton and bacterials as the main organic origin, entering maturity stage. Biomarkers, major and trace elements manifest that the fine- grain sediments deposited in weak oxidizing-weak reducing environment with fresh water. The diagrams of OEP-CPI and C steraneββ(ββ+αα) - αααC sterane 20S(20R + 20S) also reflect the maturity stage of organic 29 29 matter. The Al/Si ratios are relatively big, implying the clay minerals content is high. This is in accordance with XRD analyses. Trace elements results demonstrate the high paleoproductivity, fresh water, and cold and dry weather. The increasing salinity, anoxic condition, and warm and humid climate are in favor of OMenrichment and preservation. This contribution provides systematic geologic foundation for hydrocarbon exploration and development of fine-grained sediments in Ordos Basin.

Li, F., Thevenon, A., Rosas-Hernández, A., Wang, Z., Li, Y., Gabardo, C.M., Ozden, A., Dinh, C.T., Li, J., Wang, Y., Edwards, J.P., Xu, Y., McCallum, C., Tao, L., Liang, Z.- Q., Luo, M., Wang, X., Li, H., O'Brien, C.P., Tan,