Anthropogenic ^(129)I in seawaters along the north-central part of the English Channel:Levels and tracer applications

The English Channel(the Channel)represents a major sink and transport pathway of anthropogenic radioactive ^(129)I.Despite this important role,data concerning the distribution of ^(129)I in seawater of the Channel are scarce,and most of existing data are restricted to the eastern part of the Channel.The advection and dispersion of ^(129)I from the French coast toward the central and further the English coast,especially in the Channel west of Cap de La Hague,are not fully investigated.We present results of iodine isotopes( ^(127)I and ^(129)I)analyses of surface water samples collected along the central English Channel in October,2010.The data show high ^(129)I concentrations between Dover Strait and La Hague,followed by a dramatic drop towards the Celtic Sea and reveal the dispersal of ^(129)I towards central and northern part of the Channel.Our observation also implies that the entire British coast is contaminated by ^(129)I. ^(129)I levels in the westernmost English Channel,close to the English coast,may reflect combined influences from La Hague and Sellafield.Evolution of ^(129)I between 2005 and 2010 suggests a strong link to temporal marine discharges from La Hague plant.The discharges from the nuclear reprocessing facility have continued since 2010 and thus an ecological evaluation of ^(129)I radioactive hazards in the environment of the Channel may be needed.

Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries,especially in big cities,like Beijing.However,the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear,and the processes driving evolution and degradation of heavy haze events are not well understood.Iodine isotopes(127Ⅰand129Ⅰ)as tracers were analyzed in time series aerosol samples collected from Beijing.It was observed that the127Ⅰconcentrations in aerosols peaked during the heavy haze events.The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles,which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events.Anthropogenic ^(129)Ⅰconcentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer.^(129)Ⅰoriginated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon.Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of ^(127)Ⅰand ^(129)Ⅰ,i.e.,iodine oxides intermediated secondary air particles,dust storm and mixed mode by both secondary air particles and dust storm induced processes.

Evaluation of 124I-JS001 for hPD1 immuno-PET imaging using sarcoma cell homografts in humanized mice

JS001(toripalimab)is a humanized IgG monoclonal antibody which strongly inhibits programmed cell death protein 1(PD1).In this study,we used a different iodine isotype(nat/124/125I)to label JS001 probes to target the human PD1(hPD1)antigen.In vitro,the half maximal effective concentration(EC50)value of natI-JS001 did not significantly differ from that of JS001.The uptake of 125I-JS001 by activated T cells was 5.63 times higher than that by nonactivated T cells after 2 h of incubation.The binding affinity of 125I-JS001 to T cells of different lineages after phytohemagglutinin(PHA)stimulation reached 4.26 nmol/L.Humanized PD1 C57 BL/6 mice bearing mouse sarcoma S180 cell tumors were validated for immuno-positron emission tomography(immuno-PET)imaging.Pathological staining was used to assess the expression of PD1 in tumor tissues.The homologous 124I-human IgG(124I-hIgG)group or blocking group was used as a control group.Immuno-PET imaging showed that the uptake in the tumor area of the 124I-JS001 group at different time points was significantly higher than that of the blocking group or the 124I-hIgG group in the humanized PD1 mouse model.Taken together,these results suggest that this radiotracer has potential for noninvasive monitoring and directing tumor-specific personalized immunotherapy in PD1-positive tumors.