Persistent organic pollutants in mountain air of the southeastern Tibetan Plateau: Seasonal variations and implications for regional cycling

2014 ◽  
Vol 194 ◽  
pp. 210-216 ◽  
Author(s):  
Jiao Ren ◽  
Xiaoping Wang ◽  
Yonggang Xue ◽  
Ping Gong ◽  
Daniel R. Joswiak ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Seasonal Variations ◽  
Southeastern Tibetan Plateau

scholarly journals Atmospheric processes of persistent organic pollutants over a remote lake of the central Tibetan Plateau: Implications for regional cycling

2016 ◽  
Author(s):  
Jiao Ren ◽  
Xiaoping Wang ◽  
Chuanfei Wang ◽  
Ping Gong ◽  
Tandong Yao
Keyword(s):  
Tibetan Plateau ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Secondary Source ◽  
The Tibetan Plateau ◽  
Lake Area ◽  
Nam Co ◽  
Surface Exchange ◽  
Atmospheric Processes ◽  
Water Gas

Abstract. Atmospheric processes (air-surface exchange, and atmospheric deposition and degradation) are crucial for understanding the global cycling and fate of persistent organic pollutants (POPs). However, such assessment over the Tibetan Plateau (TP) remains uncertain. More than 50 % of the Chinese lakes are located on the TP, which exerts a remarkable influence on the regional water, energy, and chemical cycling. In this study, air and water samples were simultaneously collected in Nam Co, a large lake on the TP, to test whether the lake is a "secondary source" or "sink" of POPs. Lower concentrations of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were observed in the atmosphere and lake water of Nam Co, while the levels of polycyclic aromatic hydrocarbons (PAHs) were relatively higher. Results of fugacity ratios and chiral signatures both suggest that the lake acted as the net sink of atmospheric hexachlorocyclohexanes (HCHs), following their long-range transport driven by the Indian Monsoon. Different behaviors were observed in the PAHs, which primarily originated from local biomass burning. Acenaphthylene, acenaphthene, and fluorene showed volatilization from the lake to the atmosphere; while other PAHs were deposited into the lake due to the integrated deposition process (wet/dry and air-water gas deposition) and limited atmospheric degradation. As the dominant PAH compound, phenanthrene exhibited a seasonal reversal of air-water gas exchange, which was likely related to the melting of the lake ice in May. The annual input of HCHs from air to the entire lake area (2015 km2) was estimated as 1.9 kg year−1, while those estimated for PAHs can potentially reach up to 550 kg year−1. This study highlights the significance of PAH deposition on the regional carbon cycling in the oligotrophic lakes of the TP.

scholarly journals Spatial Distribution of the Persistent Organic Pollutants across the Tibetan Plateau and Its Linkage with the Climate Systems: Five Year Air Monitoring Study

2016 ◽  
Author(s):  
Xiaoping Wang ◽  
Jiao Ren ◽  
Ping Gong ◽  
Chuanfei Wang ◽  
Yonggang Xue ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Time Trends ◽  
Indian Monsoon ◽  
Temporal Trends ◽  
Sampling Period ◽  
The Tibetan Plateau ◽  
Transport Pathways ◽  
Air Masses

Abstract. The Tibetan Plateau (TP) has been contaminated by persistent organic pollutants (POPs), including legacy organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) through atmospheric transport. The exact source regions, transport pathways and time trends of POPs to the TP are not well understood. Here XAD-based passive air samplers (PAS) were deployed at 16 Tibetan background sites from 2007 to 2012 to gain further insight into spatial patterns and temporal trends of OCPs and PCBs. The southeastern TP was characterized by dichlorodiphenyltrichloroethane (DDT) -related chemicals delivered by Indian Monsoon air masses. The northern and northwestern TP displayed the greatest absolute concentration and relative abundance of hexachlorobenzene (HCB) in the atmosphere, caused by the westerly-driven European air masses. The interactions between the DDT polluted Indian monsoon air and the clean westerly winds formed a transition zone in central Tibet where both DDT and HCB were the dominant chemicals. Based on 5-year of continuous sampling, our data indicated declining concentrations of HCB and hexachlorocyclohexanes (HCHs) across the Tibetan region. Inter-annual trends of DDT class chemicals, however, showed less variation during this 5-year sampling period, which may be due to the on-going usage of DDT in India. This paper demonstrates the possibility of using POPs fingerprints to investigate the climate interactions and the validity of using PAS to derive inter-annual atmospheric POPs time trends.

Assessment of seasonal variations in persistent organic pollutants across the region of Tuscany using passive air samplers

2017 ◽  
Vol 222 ◽  
pp. 609-616 ◽  
Author(s):  
Victor H. Estellano ◽  
Karla Pozo ◽  
Petra Přibylová ◽  
Jana Klánová ◽  
Ondřej Audy ◽  
...  
Keyword(s):  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Seasonal Variations

Evidence for persistent organic pollutants released from melting glacier in the central Tibetan Plateau, China

2017 ◽  
Vol 220 ◽  
pp. 178-185 ◽  
Author(s):  
Jun Li ◽  
Guo-Li Yuan ◽  
Ming-Zhe Wu ◽  
Yong Sun ◽  
Peng Han ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Organic Pollutants ◽  
Persistent Organic Pollutants ◽  
Central Tibetan Plateau

scholarly journals Long-term energy and CO<sub>2</sub> flux observations over an agricultural field in southeastern Tibetan Plateau

2020 ◽  
Author(s):  
Anlun Xu ◽  
Jian Li
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Seasonal Variations ◽  
Carbon Sink ◽  
Dominant Role ◽  
Sensible Heat Flux ◽  
Vapour Pressure Deficit ◽  
Co2 Flux ◽  
Agricultural Field ◽  
Southeastern Tibetan Plateau

Abstract. Information on the exchange of energy, momentum and mass (H2O, CO2, CH4, etc.) over complex topography is critical for determining the development of the boundary layer, carbon and water cycles, weather and climate. This information can also improve the numerical modelling of physical atmosphere-land processes. Based on a 12-year (2007–2018) eddy covariance dataset over the Dali agricultural field in the southeastern Tibetan Plateau, we analysed the diurnal, seasonal and inter-annual changes in sensible heat flux (Hs), latent heat flux (LE) and CO2 flux (Fc) and their meteorological controls on multiple timescales (half-hourly, daily, monthly, and yearly). The results show that both Hs and LE have similar diurnal and seasonal variations, but the amplitude of LE is obviously larger than that of Hs throughout the year, which indicates that the LE plays a dominant role in surface heat exchange. The Fc has a noticeable diurnal cycle, reaching its minimum around noon, and clear seasonal variations, reaching its minimum in the summer. The annual average Hs increased from approximately 6 W m−2 during 2007–2012 to 19 W m−2 during 2013–2018, while the LE decreased from approximately 110 W m−2 during 2007–2013 to 79 W m−2 during 2014–2018. The Dali observational area is a carbon sink in all years, while the magnitude of net uptake decreases significantly from approximately 739 g C m−2 yr−1 during 2007–2013 to 218 g C m−2 yr−1 during 2014–2018. The results also show that wind speed (WS) is the major control of Hs, while the product of WS and vapour pressure deficit (VPD) is the main driver of LE on different timescales. The net radiation (Rn) and soil temperature (Ts) have the largest effects on Fc from the daily to monthly timescales, while the WS has the largest impact on annual total Fc.

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