Enhanced desorption of persistent organic pollutants from microplastics under simulated physiological conditions.

Competitive sorption of persistent organic pollutants onto microplastics in the marine environment.

Microplastics represent an increasing source of anthropogenic contamination in aquatic environments, where they may also act as scavengers and transporters of persistent organic pollutants. As estuaries are amongst the most productive aquatic systems, it is important to understand sorption behaviour and transport of persistent organic pollutants (POPs) by microplastics along estuarine gradients. The effects of salinity sorption equilibrium kinetics on the distribution coefficients (Kd) of phenanthrene (Phe) and 4,4′-DDT, onto polyvinyl chloride (PVC) and onto polyethylene (PE) were therefore investigated. A salinity gradient representing freshwater, estuarine and marine conditions, with salinities corresponding to 0 (MilliQ water, 690 μS/cm), 8.8, 17.5, 26.3 and 35 was used. Salinity had no significant effect on the time required to reach equilibrium onto PVC or PE and neither did it affect desorption rates of contaminants from plastics. Although salinity had no effect on sorption capacity of Phe onto plastics, a slight decrease in sorption capacity was observed for DDT with salinity. Salinity had little effect on sorption behaviour and POP/plastic combination was shown to be a more important factor. Transport of Phe and DDT from riverine to brackish and marine waters by plastic is therefore likely to be much more dependent on the aqueous POP concentration than on salinity. The physical characteristics of the polymer and local environmental conditions (e.g. plastic density, particle residence time in estuaries) will affect the physical transport of contaminated plastics. A transport model of POPs by microplastics under estuarine conditions is proposed. Transport of Phe and DDT by PVC and PE from fresh and brackish water toward fully marine conditions was the most likely net direction for contaminant transport and followed the order: Phe-PE >> DDT-PVC = DDT-PE >> Phe-PVC.

/pdf/transport-of-persistent-organic-pollutants-by-microplastics-3pmk4vgjp7.pdf

Transport of persistent organic pollutants by microplastics in estuarine conditions

http://ir.yic.ac.cn/bitstream/133337/8647/1/Occurrence%20and%20spatial%20distribution%20of%20organophosphate%20ester%20flame%20retardants%20and%20plasticizers%20in%2040%20rivers%20draining%20into%20the%20Bohai%20Sea%2c%20north%20China.pdf

Occurrence and spatial distribution of organophosphate ester flame retardants and plasticizers in 40 rivers draining into the Bohai Sea, north China.

Distribution of patterns.

Distributions of polycyclic aromatic hydrocarbons in the Daliao River Estuary of Liaodong Bay, Bohai Sea (China).

The levels of 19 kinds of organochlorine pesticides (OCPs) in the aqueous phase, suspended particulate matter (SPM), pore water and sediments from Daliao River estuary of Liaodong Bay (Bohai Sea) in northeast China were investigated to evaluate their potential pollution risks. The total OCPs concentrations in the aqueous phase, SPM, pore water and sediments were 3.7–30.1 ng l −1 , 4.6–52.6 ng l −1 , 157–830 ng l −1 and 2.1–21.3 ng g −1 dry weight, respectively. The concentrations of OCPs, in the Daliao River estuary, are in the mid-range, as compared to those reported in other estuaries worldwide. The distribution of HCHs and DDTs were different indicating different contamination sources. Lindane is the main type of HCH and continuing use in northeast China of ‘pure’ HCH (lindane) rather than technical HCH accounts for the source. The ratios of (DDE + DDD)/DDT in the samples indicate no recent inputs of these chemicals to the estuary.

Distribution and sources of organochlorine pesticides in water and sediments from Daliao River estuary of Liaodong Bay, Bohai Sea (China)

Distributions of polychlorinated biphenyls in the Daliao River estuary of Liaodong Bay, Bohai Sea (China).

Understanding the land use and land cover (LULC) pattern of the Qinghai Tibet Plateau in China is crucial to support the structural and functional integrity of the ecological barrier of the plateau. This information has significant implications not only for the ecological environment and regional development of the plateau but also for the broader environmental impact at regional and global levels. It is critical to comprehend the spatial pattern and ascertain the underlying causes of land use and land cover in significant areas of the Qinghai Tibet Plateau. This can enable the formulation and implementation of context-specific policies and measures that can contribute to enhancing the ecological security barrier function of the plateau. This study focused on the core area of the Qinghai Tibet Plateau - the Qiangtang Plateau. Based on surface cover data from 2020 and ASTER GDEMV3 data, distribution indices and geographic detectors were used to explore the quantitative impact of land use/cover spatial patterns and terrain factors on land use/cover spatial distribution. The results showed the following: 1) The land use/cover space of the Qiangtang Plateau was dominated by grassland and bare land. Specifically, grassland had the greatest area, accounting for approximately 63.94% of the plateau area and covering an area of 449,983 km2. Grassland was widely distributed in most areas of the plateau. Bare land was the second-largest land cover type, with an area of 186,302 km2, accounting for 26.47% of the plateau area. Bare land was primarily located in the western and northern parts of the plateau. 2) The spatial differentiation of land use/cover in the Qiangtang Plateau was significant. Grasslands were primarily distributed in low mountainous areas characterized by high relief, gentle slopes, and low roughness. In contrast, bare land was mainly distributed in low mountainous areas with high relief, steep slopes, and low roughness. 3) The main drivers of the spatial distribution of land use/cover on the Qiangtang Plateau were elevation, roughness, and relief. Moreover, the interactions between these three terrain factors and other environmental variables significantly influenced the land use/cover pattern in the study area.

/pdf/spatial-pattern-of-land-use-along-the-terrain-gradient-of-25vshy8v.pdf

Spatial pattern of land use along the terrain gradient of Qinghai Tibet Plateau: a case study of Qiangtang Plateau, China

Paleoclimatic researches have revealed that the East Asian summer monsoon (EASM) strengthened and precipitation increased in north China during the early to middle Holocene. The lacustrine landform and sediment recorded approximately simultaneous Holocene high lake levels. However, relatively few studies have been reported involving the quantitative reconstruction of precipitation and lake areas in the Mu Us Desert (MUD), northwest edge area of the modern EASM. Based on the lacustrine landform, and by using the lake hydrologic model, this study quantitatively reconstructed precipitation and lake areas during the early to middle Holocene in the MUD. The results revealed the following: 1) A total of 127 paleolakes existed in the closed drainage area during the early to middle Holocene. The area of paleolakes was 896.1 km2, which is 2.96 times that of modern lakes. The relative height between the highstand and the modern lake surface is ∼5–9 m. 2) Precipitation during the early to middle Holocene decreased from 550 mm in the southeast to 350 mm in the northwest. The 400 mm isohyet moved 130–170 km to the northwest, roughly coincident with the modern 250 mm isohyet. 3) The relative increase in precipitation was ∼32–60%, and the increase in the west was significantly higher than in the east. The precipitation gradient in much of the MUD was lower than the present. The results show that the monsoon edge area and monsoon rain belt migrated to the northwest during the early to middle Holocene. The MUD was stably dominated by the EASM. Data also showed that the spatio-temporal pattern of the climate during the early to middle Holocene was relatively humid with a decreased precipitation gradient for millennia.

/pdf/quantitative-reconstruction-of-precipitation-and-lake-areas-1l64qqb6.pdf

Li Tan

Papers

Distributions of polycyclic aromatic hydrocarbons in the Daliao River Estuary of Liaodong Bay, Bohai Sea (China).

Distribution and sources of organochlorine pesticides in water and sediments from Daliao River estuary of Liaodong Bay, Bohai Sea (China)

Distributions of polychlorinated biphenyls in the Daliao River estuary of Liaodong Bay, Bohai Sea (China).

Spatial pattern of land use along the terrain gradient of Qinghai Tibet Plateau: a case study of Qiangtang Plateau, China

Quantitative Reconstruction of Precipitation and Lake Areas During Early to Middle Holocene in Mu Us Desert, North China