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Organophosphate esters (OPEs) are extensively applied in various materials as flame retardants and plasticizers, and have high biological toxicity. OPEs are detected worldwide, even in distant polar regions and the Tibetan Plateau (TP). However, few studies have been performed to evaluate the distribution patterns and origins of OPEs in different climate systems on the TP. This study investigated the distribution characteristics, possible sources, and ecological risks of OPEs in soils from the different climate systems on the TP and its surroundings. The total concentrations of OPEs in soil varied from 468 to 17,451 pg g−1 dry weight, with greater concentrations in southeast Tibet (monsoon zone), followed by Qinghai (transition zone) and, finally, southern Xingjiang (westerly zone). OPE composition profiles also differed among the three areas with tri-n-butyl phosphate dominant in the westerly zone and tris(2-butoxyethyl) phosphate dominant in the Indian monsoon zone. Correlations between different compounds and altitude, soil organic carbon, or longitude varied in different climate zones, indicating that OPE distribution originates from both long-range atmospheric transport and local emissions. Ecological risk assessment showed that tris(2-chloroethyl) phosphate and tri-phenyl phosphate exhibited medium risks in soil at several sites in southeast Tibet. Considering the sensitivity and vulnerability of TP ecosystems to anthropogenic pollutants, the ecological risks potentially caused by OPEs in this region should be further assessed. [Display omitted] • Occurrence and sources of OPEs in different climate zones on the Tibetan Plateau were identified. • Concentration of OPEs in soil were greater in the monsoon zone, followed by the transition and westerly zones. • Tri-n-butyl phosphate and tris (2-butoxyethyl) phosphate were dominant in the westerly and monsoon zones. • Tris (2-chloroethyl) phosphate and tri-phenyl phosphate in some Tibet soils showed medium risk. [ABSTRACT FROM AUTHOR]

The high HCO 3 − concentrations in the Yellow River (China) are generally believed to originate primarily from the carbonate-rich Loess Plateau as a result of carbonate weathering reactions that consume atmospheric CO 2 . We studied chemical weathering across the entire Yellow River basin in 2007 and 2009 and found that the amounts of CO 2 consumption by carbonate and silicate weathering were 87.61 × 10 9 mol/a and 10.70 × 10 9 mol/a, respectively. As the source of water for the Yellow River, although the Qinghai–Tibet Plateau accounts for only 30% of the area of the basin, it has a strong leaching effect and contributes a majority (61%) of the atmospheric CO 2 consumption of the entire basin and a majority of the riverine DIC flux (66%) to the ocean. As a result, the dissolved inorganic carbon (DIC) concentrations in this river are among the highest of the world's major rivers. In contrast, despite the abundant carbonate mineral content in the Loess Plateau, the high ratio of evaporation to precipitation (4.2) limits the weathering processes, and the low amount of runoff restricts the transport of weathering products, which results in a relatively low contribution (38%) to the basin-wide atmospheric CO 2 consumption, which is much lower than was previously thought. The Qinghai–Tibet Plateau is the origin of the high levels of HCO 3 − in and acts as the main DIC contributor to the Yellow River. [ABSTRACT FROM AUTHOR]