Seasonal variation and sources of atmospheric polycyclic aromatic hydrocarbons in a background site on the Tibetan Plateau

The study of atmospheric polycyclic aromatic hydrocarbons(PAHs) in northeastern Tibetan Plateau with fragile ecological environment and complex atmospheric circulation system is blank. To understand the characteristics and sources of persistent organic pollutants in the atmosphere of the northeastern Tibetan Plateau, we monitored levels in the central Qilian Mountain. From 2016 to 2017, we collected 45-pair(particle + gas) samples using active air samplers to investigate the sources, transport paths, and their influencing factors.Sources of PAHs were analysed with a source diagnostic model, and atmospheric transport paths were calculated. The concentration range for Σ15PAHs was 439–4666 pg/m^(3), and the average was 2015 pg/m^(3). The PAHs in central Qilian Mountain are mainly low molecular weight(LMW) PAHs. Winter concentrations of PAHs were higher than those in summer. The transport of PAHs is mainly affected by westerlies, and there are seasonal differences. Source analysis showed that PAHs mainly came from coal and biomass combustion and vehicle emissions, with seasonal differences. This study clarifies the concentration and seasonal variation of PAHs in the northern Tibetan Plateau, which is conducive to understanding the atmospheric transport process and fate of pollutants. The background site of Qilian Mountains located in the Silk Road economic belt has the value and significance of longterm observation of pollutants.

Organophosphate Esters in Air and Seawater of the South China Sea:Spatial Distribution,Transport,and Air−Sea Exchange

Organophosphate esters(OPEs)have become one group of chemicals with emerging concern in the marine environment.In this work,we investigated OPEs in the air and seawater of the South China Sea in summer 2019.The concentrations of∑_(10)OPEs in the atmosphere ranged from 66 to 550 pg/m^(3),with TCIPP,TNBP,TPhP,and TEP predominating in the air.The total dissolved OPE concentrations(∑_(10)OPEs without TEP)measured in high-volume water samples ranged from 300 to 3600 pg/L,with a mean concentration of 1180±910 pg/L.TEP was measured with liquid−liquid extraction(LLE),and it showed the highest concentration(average 2000±1450 pg/L)among the selected OPEs.Total suspended matter associated OPEs accounted for less than 4.7%of the sum of OPE concentrations in seawater.Fugacity fractions and air−sea exchange fluxes showed that TCEP,TCIPP,TIBP,TEHP,TPhP,and EHDPP were favored to volatilize,TEP dominated the deposition,while TPrP and TNBP varied between volatilization and deposition.Atmospheric particle deposition fluxes ranged from 5 to 71 ng/m^(2)/day with an average of 17±15 ng/m^(2)/day.The input of∑OPEs to the entire South China Sea via atmospheric particle deposition was estimated to be 22±19 tons/year,while the net air−sea exchange fluxes of OPEs were volatilization from seawater to air with an average of 44±33 tons/year.This work suggests that air−sea exchange and atmospheric particle deposition are significant processes interfering with the transport of OPEs in the marine environment.

Bioaccumulation and changes of trace metals over the last two decades in marine organisms from Guangdong coastal regions, South China

Trace metal(Cr, Ni, Cu, Zn, Cd and Pb) exposures, distribution and bioaccumulation were investigated in marine organisms from Guangdong coastal regions, South China. The results showed that all of the selected metals were observed in marine organisms with a predomination of Cu and Zn. The metal exposure levels exhibited obvious variations between species with the decreasing order of crab > shellfish > shrimp > fish. The higher metals enrichment seen in shellfish and crab species primarily attributed to their living habits and the higher sediment background values of trace metals. Endpoint bioaccumulation factor(BAFfd) was used to characterize the bioaccumulation potentials of marine organisms to trace metals, of which Cu and Zn were the most accumulated elements. The exposure of trace metals in the cultured organisms was far lower than those in wild marine organisms, which is probably due to the effect of growth dilution. Comparisons with previous studies demonstrated that the concentration profiles of most trace metals declined over the last one to two decades, except Cu, that increased indistinctively.

Polycyclic aromatic hydrocarbons in benthos of the northern Bering Sea Shelf and Chukchi Sea Shelf

Eighteen polycyclic aromatic hydrocarbons(PAHs)were detected in benthos collected onboard the‘Snow Dragon’in the Northern Bering Sea Shelf and Chukchi Sea Shelf during the 6 th Chinese National Arctic Research Expedition(CHINARE 2014).18 PAHs for all biota samples ranged from 34.2 to 128.1 ng/g dry weight(dw),with the highest concentration observed in fish muscle(Boreogadus saida)samples close to St.Lawrence Island.The PAH composition pattern was dominated by the presence of lighter 3 ring(57%)and 2 ring(28%)PAHs,indicating oil-related or petrogenic sources as important origins of PAH contamination.Concentrations of alkyl-PAHs(1-methylnaphthalene and 2-methylnaphthalene)were lower than their parent PAH(naphthalene)in all biological tissue,and their percentage also decreased significantly(p<0.05)compared with those in the corresponding sediment.There were no significant relationships between PAH concentrations and trophic levels,which is possibly due to the combined results of the complex benthic foodweb in the subarctic/Arctic shelf region,as well as a low assimilation/effective metabolism for PAHs.According to toxic potency evaluation results from TCDD toxic equivalents(TEQs)and Ba P-equivalent(Ba PE)values,whelk(Neptunea heros)and starfish(Ctenodiscus crispatus)are two macroinvertebrate species showing relatively higher dioxin-like toxicity and carcinogenic risk.