“…Indeed, our 240 Pu/ 239 Pu atom ratios (0.187 ± 0.012, n = 6) were also comparable to the previous observations made elsewhere in the Chinese surface soils (0.183 ± 0.018, n = 71; Fig. 1), namely, Northwest China (0.178 ± 0.013, n = 21) 24–26,32 , Southwest China (0.187 ± 0.005, n = 6) 29,33–35 , South China (0.181 ± 0.008, n = 10) 9,36 , Central China (0.190 ± 0.025, n = 2) 37 , East China (0.177 ± 0.012, n = 5) 35,38 and Northeast China (0.187 ± 0.023, n = 27) 39,40 . As shown in Fig.…”
Section: Resultssupporting
confidence: 90%
“…Blue dashed lines represent the average 240 Pu/ 239 Pu atom ratio (0.180 ± 0.014) of global fallout 12 . Pu data of surface soils/sediments are cited from previous studies (Northwest China 24–26,29,32 ; Southwest China 29,33–35 ; South China 9,36 ; Central China 37 ; East China 35,38 ; Northeast China 39,40 ).Figure 2Frequency distributions of 240 Pu/ 239 Pu atom ratios ( a ) and 239+240 Pu activities ( b ) in Chinese surface soils. Pu data sourced as same as Fig.…”
Section: Resultsmentioning
confidence: 99%
“…1.Figure 4Distributions of ( a ) 240 Pu/ 239 Pu atom ratio and ( b ) 239+240 Pu activity of the surface soil in China. Pu data of surface soils/sediments are cited from the previous studies (Northwest China 24–26,29,32 ; Southwest China 29,33–35 ; South China 9,36 ; Central China 37 ; East China 35,38 ; Northeast China 39,40 ). This map was prepared with surfer 10.0 software.…”
The
239+240
Pu activities and
240
Pu/
239
Pu atom ratios in the frozen soils of the Yellow River Source Area (YRSA) were determined to examine the Pu source and evaluate its environmental risk. The
239+240
Pu activities of surface frozen soils in the YRSA, ranging from 0.053 to 0.836 mBq g
−1
, are comparable to those observed in China elsewhere (0.005–1.990 mBq g
−1
). The
240
Pu/
239
Pu atom ratios of surface soils in the YRSA are in the range of 0.168–0.201 (average = 0.187 ± 0.012, n = 6), comparable to the global fallout of 0.180 ± 0.014. Based on the latitudinal and spatial distribution of Pu isotopic composition, I clarified that the Pu source is mainly from global fallout at present. The activity levels of Pu in the YRSA do far not cause a Pu toxicity to the downstream drinking water even the frozen soil begins to melt and release Pu to the Yellow River. However, since close-in fallout from Lop Nor where the Chinese nuclear tests were carried out during 1964–1980, high deposition and accumulation of Pu was observed in the Chinese soil cores through synthesizing an expanded Pu dataset, which alerts us it is necessary to further monitor the Pu activity levels in the YRSA soil cores to ensure the safety of downstream drinking water. Finally, I point out that information on Pu isotopes would help in establishing a baseline for future environmental risk assessment.
“…Indeed, our 240 Pu/ 239 Pu atom ratios (0.187 ± 0.012, n = 6) were also comparable to the previous observations made elsewhere in the Chinese surface soils (0.183 ± 0.018, n = 71; Fig. 1), namely, Northwest China (0.178 ± 0.013, n = 21) 24–26,32 , Southwest China (0.187 ± 0.005, n = 6) 29,33–35 , South China (0.181 ± 0.008, n = 10) 9,36 , Central China (0.190 ± 0.025, n = 2) 37 , East China (0.177 ± 0.012, n = 5) 35,38 and Northeast China (0.187 ± 0.023, n = 27) 39,40 . As shown in Fig.…”
Section: Resultssupporting
confidence: 90%
“…Blue dashed lines represent the average 240 Pu/ 239 Pu atom ratio (0.180 ± 0.014) of global fallout 12 . Pu data of surface soils/sediments are cited from previous studies (Northwest China 24–26,29,32 ; Southwest China 29,33–35 ; South China 9,36 ; Central China 37 ; East China 35,38 ; Northeast China 39,40 ).Figure 2Frequency distributions of 240 Pu/ 239 Pu atom ratios ( a ) and 239+240 Pu activities ( b ) in Chinese surface soils. Pu data sourced as same as Fig.…”
Section: Resultsmentioning
confidence: 99%
“…1.Figure 4Distributions of ( a ) 240 Pu/ 239 Pu atom ratio and ( b ) 239+240 Pu activity of the surface soil in China. Pu data of surface soils/sediments are cited from the previous studies (Northwest China 24–26,29,32 ; Southwest China 29,33–35 ; South China 9,36 ; Central China 37 ; East China 35,38 ; Northeast China 39,40 ). This map was prepared with surfer 10.0 software.…”
The
239+240
Pu activities and
240
Pu/
239
Pu atom ratios in the frozen soils of the Yellow River Source Area (YRSA) were determined to examine the Pu source and evaluate its environmental risk. The
239+240
Pu activities of surface frozen soils in the YRSA, ranging from 0.053 to 0.836 mBq g
−1
, are comparable to those observed in China elsewhere (0.005–1.990 mBq g
−1
). The
240
Pu/
239
Pu atom ratios of surface soils in the YRSA are in the range of 0.168–0.201 (average = 0.187 ± 0.012, n = 6), comparable to the global fallout of 0.180 ± 0.014. Based on the latitudinal and spatial distribution of Pu isotopic composition, I clarified that the Pu source is mainly from global fallout at present. The activity levels of Pu in the YRSA do far not cause a Pu toxicity to the downstream drinking water even the frozen soil begins to melt and release Pu to the Yellow River. However, since close-in fallout from Lop Nor where the Chinese nuclear tests were carried out during 1964–1980, high deposition and accumulation of Pu was observed in the Chinese soil cores through synthesizing an expanded Pu dataset, which alerts us it is necessary to further monitor the Pu activity levels in the YRSA soil cores to ensure the safety of downstream drinking water. Finally, I point out that information on Pu isotopes would help in establishing a baseline for future environmental risk assessment.
“…Procedure blanks were prepared and analyzed using the same method as the samples, the analytical results (Table 4) 239 Pu and 240 Pu in the surface soil ranging from 0.07 to 0.13 mBq/g for 239 Pu and 0.048-0.087 mBq/g for 240 Pu, corresponding to a range of 0.12-0.22 mBq/g for 239,240 Pu, which fall into the reported range of 239,240 Pu concentrations in the surface soil in the background areas in China (0.07-0.85 mBq/g for 239,240 Pu) 35,36 . The concentrations of 239 Pu and 240 Pu in the deep soil are more than 50 times lower than that determined in the surface soil in the same site.…”
Section: Verification Of the Developed Methods For Determination Of Lomentioning
ICP-MS is becoming a competitive technique for the measurement of plutonium isotopes. However, the abundance sensitivity (tailing of 238 U to m/z=239 and 240), isobaric and polyatomic ions interferences (e.g. U H +) are the most critical challenges for determination of low-level plutonium in high uranium samples. This work presents a new method to solve this problem using ICP-MS with two tandem quadrupole separators and dynamic collision/reaction cell combined with chemical separation. The interference of uranium hydrides (238 U 1 H + and 238 U 1 H2 +) was effectively eliminated using CO2 as reaction gas by converting hydrides to oxides of uranium ions (UO + /UO2 +), but still keep the intensity of Pu + signal. The tailing interference of 238 U + (abundance sensitivity) was intensively eliminated by significantly suppressing the 238 U + signal using CO2 as reaction gas and using two tandem quadrupole mass separators in the ICP-MS/MS. With these approaches, the overall interference of uranium was reduced to <110-8 , which is 3 orders of magnitude better than the conventional ICP-MS. Combined with chemical separation with a decontamination factor of 10 5 for uranium, an overall factor of 10 12 for elimination of uranium interference was achieved. The developed method was demonstrated to enable accurate determination of <10-15 g/g level plutonium isotopes in environmental samples even in uranium debris sample with a U/Pu atomic ratio up to 10 12. The developed method was validated by the analysis of spiked solution and certified reference materials of soil.
“…Procedure blanks were prepared and analyzed using the same method as the samples, the analytical results (Table 4) 239 Pu and 240 Pu in the surface soil ranging from 0.07 to 0.13 mBq/g for 239 Pu and 0.048-0.087 mBq/g for 240 Pu, corresponding to a range of 0.12-0.22 mBq/g for 239,240 Pu, which fall into the reported range of 239,240 Pu concentrations in the surface soil in the background areas in China (0.07-0.85 mBq/g for 239,240 Pu) 35,36 . The concentrations of 239 Pu and Pu in the deep soil are more than 50 times lower than that determined in the surface soil in the same site.…”
Section: Verification Of the Developed Methods For Determination Of Lomentioning
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