Geochemical Distribution and Environmental Risks of Radionuclides in Soils and Sediments Runoff of a Uranium Mining Area in South China.

Uranium mining activities have contributed to the distribution and uptake of radionuclides, which have increased the active concentrations of natural radionuclides in environmental media, causing elevated human health risks. The present study aims to assess the spatial distribution characteristics of natural radionuclides in the surface soils and river sediments of the typical granite uranium mining area in South China, as well as investigate the geochemical features of natural radionuclides in the soil and sediments to understand their migration processes. The activity concentrations for 238U, 226Ra, 232Th, and 40K ranged from 17-3925 Bq/kg, 50-1180 Bq/kg, 29-459 Bq/kg, and 240-1890 Bq/kg, respectively. The open-pit mining areas and tailings pond locations exhibited the highest concentrations of activity for all these radionuclides. This distribution points to an elevated potential health risk due to radiological exposure in these specific areas. Additionally, the values of radium equivalent activity (Raeq) and annual gonadal dose equivalent (AGDE) in those areas were higher than the limits recommended by ICRP (2021). 238U and 226Ra have a significant correlation (0.724), and the cluster analysis was showing a statistically meaningful cluster below 5 indicated that they have similar behavior during parent rock weathering and watershed erosion, and the distribution of 232Th and 40K were influenced by the addition of rock types. The activity ratios of 226Ra/238U, 226Ra/232Th, 238U/40K, and 226Ra/40K variation indicated that 40K more mobile than 226Ra and 238U, U(VI) was reduced to U(IV) by organic matter in the downstream area and re-entered into the sediment during the sediment surface runoff in the small watershed of the uranium ore open-pit mining area. Therefore, it is necessary to further seal up and repair the tailings landfill area.

Geochemical distributions of natural radionuclides in surface soils and sediments impacted by lead-zinc mining activity.

This study investigated the distribution features of uranium-238 (238U), radium-226 (226Ra), thorium-232 (232Th), and potassium-40 (40K) and evaluated the associated environmental radiological hazards of the topsoil and river sediments in the Jinding lead-zinc (Pb-Zn) mine catchment from Southwest China. The activity concentrations of 238U, 226Ra, 232Th, and 40K ranged from 24.0 ± 2.29-60.3 ± 5.26 Bq.kg-1, from 32.5 ± 3.95-69.8 ± 3.39 Bq.kg-1, from 15.3 ± 2.24-58.3 ± 4.92 Bq.kg-1, and from 203 ± 10.2-1140 ± 27.4 Bq.kg-1, respectively. The highest activity concentrations for all these radionuclides were primarily found in the mining areas and decreased with increasing distance from the mining sites. The radiological hazard indices, including radium equivalent activity, absorbed gamma dose rate in the air, outdoor annual effective dose equivalent, annual gonadal dose equivalent, and excess lifetime cancer, revealed that the highest values were observed in the mining area and downstream, specifically in the vicinity of the ore body. These elevated values exceeded the global mean value but remained below the threshold value, suggesting that routine protection measures for Pb-Zn miners during production activities are sufficient. The correlation analysis and cluster analysis revealed strong associations between radionuclides such as 238U, 226Ra, and 232Th, indicating a common source of these radionuclides. The activity ratios of 226Ra/238U, 226Ra/232Th, and 238U/40K varied with distance, suggesting the influence of geological processes and lithological composition on their transport and accumulation. In the mining catchment areas, the variations in these activity ratios increased indicated the impact of limestone material dilution on the levels of 232Th, 40K, and 238U in the upstream region. Moreover, the presence of sulfide minerals in the mining soils contributed to the enrichment of 226Ra and the removal of 238U caused those activity ratios decreased in the mining areas. Therefore, in the Jinding PbZn deposit, the patterns of mining activities and surface runoff processes in the catchment area favored the accumulation of 232Th and 226Ra over 40K and 238U. This study provides the first case study on the geochemical distributions of natural radionuclides in a typical Mississippi Valley-type PbZn mining area and offers fundamental information on radionuclide migration and baseline radiometric data for PbZn deposits worldwide.

Study of Ra desorption processes in an estuary system with high-turbidity at the Southeast China.

Radium (Ra) isotopes are extensively used as geochemical tracers for studying water mass mixing and submarine groundwater discharge in marginal and coastal seas. However, river-borne particles and seafloor sediments are an important source of Ra in marine systems due to Ra desorption. Therefore, it is necessary to study the desorption behaviors of Ra isotopes in river sediment or suspended particles. Here, the desorption behaviors of four Ra isotopes (223Ra, 224Ra, 226Ra, and 228Ra) in the Zhangjiang River sediments were investigated by a series of designed variable-controlling experiments in the laboratory. Within the designed salinity range, desorption amounts of Ra isotopes increased with increasing salinity, and when the salinity was greater than 15 ppt, Ra desorption reached an equilibrium state. Overall, desorption of Ra isotopes increased with the decrease of particle grain size, however, the desorption fractions of 224Ra and 228Ra decreased with decreasing particle size due to the increase of original Ra activities in smaller sediment particles. In the experiments, we found that two sediment samples with similar mean grain size (3.8 µm and 3.3 µm) and similar grain size distributions had significantly different Ra desorption under the same conditions. The results of mineral composition analysis based on X-ray diffraction showed that these two samples had different percentages of kaolinite, quartz, and plagioclase, which indicated that the mineral composition of particles had an important effect on Ra isotope desorption. In conclusion, salinity, particle grain size, and mineral composition all had significant effects on Ra desorption behaviors of sediment particles. Based on the above desorption experiments, the desorbed fluxes of four Ra isotopes from river-borne sediments to the Dongshan Bay were estimated to be (5.95 ± 1.47) × 107 Bq yr-1 for 223Ra, (1.95 ± 0.27) × 109 Bq yr-1 for 224Ra, (2.73 ± 0.47) × 108 Bq yr-1 for 226Ra, and (1.26 ± 0.20) × 109 Bq yr-1 for 228Ra, respectively.

Trace elements accumulation over a century in sediment cores from a tectonic lake on the Qinghai-Tibet plateau: Source identification and risk assessment.

A record of trace elements in lake sediment can help in assessing the impact of anthropogenic activities on aquatic environments. In the present work, the trace elements profiles (Cu, Cr, Pb, Zn, As, and Cd) were determined in four sediment cores (QH01, QH02, QH07, and Z04) collected in 2012 and 2014 from Lake Qinghai to reconstruct the history of anthropogenic activity in the watershed and to evaluate the pollution status and eco-environmental risks of a typical Third Pole lake environment over the past century. The concentrations of Cu, Cr, Pb, Zn, As, and Cd in these studies ranged between 19.4 and 34.2 µg g-1, 35.6-53.6 µg g-1, 3.10-26.8 µg g-1, 56.4-93.5 µg g-1, 6.20-15.3 µg g-1, and 0.086-0.572 µg g-1, respectively. Statistical analyses indicated that the Pb, Zn, and Cd contents combination of coal, gasoline burning, and agricultural activities in the Lake Qinghai catchment and larger-scale atmospheric inputs during the past 60 years. The enrichment factors for Pb, Zn, and Cd in the sediments of Lake Qinghai are considered to be related to the region of the Qinghai-Tibet Plateau and national socioeconomic development. Enrich factor of Cd values was higher than 3.5 and maximum values of the geo-accumulation index of Pb and Cd were observed in the top layer of the sediment (0-2 cm), indicating moderate contamination. The RI values suggest that the risks to the ecological environment of Lake Qinghai are increasing since the 1950s. The results of this study illustrate that Lake Qinghai is still experiencing high trace elements pollution pressure due to the rapid environmental changes caused by anthropogenic activities on the remote and isolated Qinghai-Tibet Plateau.

Potential Sources, Pollution, and Ecological Risk Assessment of Potentially Toxic Elements in Surface Soils on the North-Eastern Margin of the Tibetan Plateau.

Due to increased levels of human activity, various pollutants are frequently detected on the Tibetan Plateau, where the environment is extremely fragile and sensitive. Therefore, this study investigated the sources, pollution, and ecological risks of soil potentially toxic elements (PTEs) in different landscape areas within the Qaidam Basin in the northeastern part of the Qinghai−Tibet Plateau. The contents of seven PTEs (Cd, Cu, Pb, Zn, As, Cr, and Ni) in 32 topsoil samples (0−2 cm) were analyzed in different regions of the Qaidam Basin. The concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn were 10.4−29.9 mg/kg, 0.08−4.45 mg/kg, 19−66 mg/kg, 8.2−40 mg/kg, 11.7−30.8 mg/kg, 11.1−31.2 mg/kg, and 32−213 mg/kg, respectively. The correlation between Pb and Cd in unpopulated areas was 0.896 (p < 0.01). The correlations among Pb, Cd, and Zn in agricultural areas, among As, Cd, Cr, and Zn in saline lake areas, and among As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were all greater than 0.65 (p < 0.05). The principal component analysis results showed that Pb and Cd in unpopulated areas, Pb, Cd, and Zn in agricultural areas, As, Cd, Cr, Zn, and Pb in saline lake areas, and As, Cd, Cr, Cu, Ni, Pb, and Zn in residential areas were affected by human activities (significant factor >0.70). Based on the geological accumulation index and single-factor pollution index results, the maximum Cd values were found to be 4.93 and 45.88, respectively; Cd was thus the most serious PTE pollutant. The comprehensive pollution index of Nemero showed that moderately and severely polluted areas accounted for 18.89% and 18.46% of the total area, respectively. The results of the potential risk index showed that very strong and strong ecological risk points together accounted for 18.8% of the total points. The spatial variations in PTE pollution and the potential ecological risk index had similar patterns; both increased from the unpopulated areas in the northeastern Qaidam Basin to Golmud city in the south-western Qaidam Basin. These results indicate that human activities negatively impacted the soil ecological environment in the Qaidam Basin during the rapid development of the economy and urbanization and that these negative impacts tended to spread to unpopulated areas. Therefore, it is necessary to emphasize the significant impacts of human activities on environmental quality and formulate preventive measures to reduce PTE pollution in the Qinghai−Tibet Plateau.

Effects of salinity and particle size on radium desorption from river sediments in the Qinghai-Tibet Plateau.

Natural radium isotopes have been widely used to study groundwater discharge in different systems. Therefore, it is of great significance to understand the desorption behavior of radium isotopes on sediments to trace water-land exchange processes. However, there is very limited studies observing the desorption Ra isotopes to lake water of the brine lake. 224Ra desorption experiments with different salinities and particle sizes were carried out by collecting samples of brackish water from Qinghai Lake, brine from Dabuxun Lake and river sediments entering the lakes. The results show that the desorption activity of 224Ra from the river sediments to lake water of Qinghai Lake is 0.2 dpm/g when the salinity is 10.07‰. The maximum desorption activity of 224Ra from river sediments to lake water of Dabuxun Lake is 0.195 dpm/g at a salinity of 40.81‰. A salinity of 41.81‰ and particle size of 16.28 µm are the threshold points affecting the desorption behavior of Ra. When the salinity is less than 40.81‰, the desorption activity of Ra increases linearly with increasing salinity. When the salinity is greater than 40.81‰, the desorption activity of Ra decreases nonlinearly with increasing salinity and tends toward a stable low value. When the particle size is larger than 16.28 µm, the small particle size promotes desorption. The smaller the particle size is, the greater the desorption activity is. When the particle size is less than 16.28 µm, the small particle size inhibits desorption. The smaller the particle size is, the smaller the desorption activity. The co-precipitation of Ra2+ with supersaturated Ca2+, SO42- and other ions may be the main reason for the threshold point of salinity and particle size in Ra desorption process in salt lake system.

A systematic review and meta-analysis of video-assisted thoracoscopic surgery treating spontaneous pneumothorax.

BACKGROUND: With the adoption of high-tech thoracoscopic surgical instruments, video-assisted thoracoscopic surgery (VATS) has gradually replaced traditional thoracotomy and is used in the clinical treatment of spontaneous pneumothorax. METHODS: The composite logic retrieval and Boolean logic retrieval methods were adopted for this meta-analysis. Databases such as PubMed, Medline, Cochrane Library, CNKI, Wanfang, VIP, and Google Scholar were searched using the combination of search terms "Video-assisted thoracoscopic surgery", "spontaneous pneumothorax", and "thoracotomy". Literatures which used video-assisted thoracoscopic surgery for spontaneous pneumothorax as the experimental group were screened. The software RevMan 5.3 provided by the Cochrane system was employed for meta-analysis. RESULTS: A total of 12 studies were included. After the meta-analysis, heterogeneity testing of the operation time in 8 studies showed that Tau2 =29.99, Chi2 =16.99, degrees of freedom (df) =7, I2=59%>50%, and the operation time of participants in the experimental group was considerably inferior to that of control group. The mean difference (MD) was -31.02, 95% confidence interval (95% CI: -36.07 to -25.97), Z=12.03, P<0.0001. The heterogeneity test of the length of hospital stay in 9 studies showed that Tau2 =4.41, Chi2 =122.58, df =8, I2=59%>50%, P<0.01, and the length of hospital stay of participants in the experimental group was remarkably shorter than that of the control group. The MD was -7.29, 95% CI: (-8.76 to -5.82), Z=9.74, and P<0.01. The heterogeneity test of the bleeding volume in 6 studies showed that Tau2 =191.74, Chi2 =27.65, df =5, I2=82%>50%, P<0.01, and the bleeding volume of participants in the experimental group was remarkably lower in contrast to that of the control group. The MD was -65.48, 95% CI: (-77.84 to -53.13), Z=10.39, and P<0.01. The heterogeneity test of the chest tube removal time in 7 studies showed that Tau2 =0.29, Chi2 =28.27, df =6, I2=79%>50%, P<0.05, and the chest tube removal time of participants in the experimental group was substantially lower in contrast to that of the control group. The MD was -3.10, 95% CI: (-3.56 to -2.64), Z=13.30, P<0.01. DISCUSSION: This meta-analysis confirmed that VATS for spontaneous pneumothorax is better than other surgical methods.

Effectiveness and safety of ivabradine in the treatment of acute myocardial infarction: a systematic review and meta-analysis.

BACKGROUND: Cardiovascular diseases have become a prominent threat to public health and quality of life. In recent years, some studies have reported that ivabradine can improve the cardiac function and prognosis of patients with acute myocardial infarction (AMI). METHODS: We searched China National Knowledge Infrastructure (CNKI), Wanfang database, Chinese Biomedical Literature (CBM), Chongqing Weipu Chinese Sci-tech Journal Database (VIP), PubMed, Cochrane Library, and EMBASE for randomized controlled trials (RCTs) of ivabradine in the treatment of AMI from January 1980 until December 2020. Each RCT was systematically reviewed. RESULTS: A total of 7 RCTs with 658 patients were included. Compared with the control group, the heart rate [mean deviation (MD) =-9.20, 95% confidence interval (CI): -13.03 to -5.38, P<0.00001] and brain natriuretic peptide (BNP) (MD =-112.73, 95% CI: -186.12 to -39.35, P=0.003) of patients who received ivabradine combined with conventional standard treatment were significantly lower and left ventricular ejection fraction (LVEF) (MD =3.17, 95% CI: 2.12 to 4.23, P<0.00001) was significantly better. The difference in adverse events was not statistically significant [odds ratio (OR) =2.45, 95% CI: 0.92 to 6.55, P=0.07]. DISCUSSION: Ivabradine combined with ß-blockers can reduce the resting heart rate and improve heart function in patients with AMI while not increasing adverse events. However, due to limitations in the number and quality of studies included, our conclusions need to be further confirmed by analyzing more studies.

222Rn, 210Pb and 210Po in coastal zone groundwater: Activities, geochemical behaviors, consideration of seawater intrusion effect, and the potential radiation human-health risk.

Groundwater quality in human-influenced coastal landscapes is receiving novel attention. Radionuclides have been recognized as another important monitoring indicator in many developed countries due to the discovery of extremely high level of natural 210Po (up to 10,000 Bq/m3) and radium and radon isotopes. This study aims to evaluate the groundwater quality in the Beibu Bulf-Guangxi coast from radiological point of view. 210Po, 210Pb and 222Rn activities in 20 wells ranged from 0.24 ± 0.05 to 6.96 ± 1.62 Bq/m3, 2.17 ± 0.12 to 13.08 ± 0.74 Bq/m3 and 1500 ± 200 to 31,800 ± 900 Bq/m3, respectively. Compared with research data of other countries, groundwaters in this area have 210Po, 210Pb and 222Rn activity within low levels. The large deficiencies of 210Po and 210Pb relative to 222Rn in groundwaters implied that 210Po and 210Pb are strong particle-reactive radionuclides and they might be controlled by similar scavenging processes in groundwaters due to a good positive correlation between 210Pb and 210Po (R2 = 0.67, p < 0.01). The concentrations of 210Po and 210Pb decreased with increasing pH values and salinity, which indicated that geochemical behaviors of 210Po and 210Pb in groundwater were influenced by seawater intrusion and pH changing. Groundwater 222Rn activity concentrations decreased with increasing salinity in coastal zone, which may be caused by dilution due to seawater intrusion or intensified 222Rn escaping from well-developed pores in coastal zone. The estimated annual ingestion doses for infants, children and adults were well below the recommended reference dose level (RDL) of 0.2-0.8 mSv/a, suggesting that consumption of analyzed groundwaters is safe from radiological point of view.

Accumulation of natural and anthropogenic radionuclides in body profiles of Bryidae, a subgroup of mosses.

Mosses can be used as biomonitors to monitor radionuclide deposition and heavy metal pollution in cities, forests, and grasslands. The aims of this work were to determine the activity concentrations of natural (210Po, 210Pb or 210Pbex (excess 210Pb is defined as the activity of 210Pb minus the activity of 226Ra), 7Be, 40K, 226Ra, 238U, and 232Th) and anthropogenic radionuclides (137Cs) in moss body profiles and in situ underlying soils of moss samples and to assess/determine the distribution features and accumulation of these radionuclides. Activity concentrations of radionuclides in the samples were measured using a low-background gamma spectrometer and a low-background alpha spectrometer. Consistent with their source, the studied radionuclides in the moss samples and underlying soils were divided according to the principal component analysis (PCA) results into an airborne group (210Po, 210Pb (210Pbex), 7Be, and 137Cs) and a terrestrial group (40K, 238U, 226Ra, and 232Th). The activity concentrations of 210Po and 210Pbex in moss body profiles were mainly concentrated in the stems-rhizoid parts, in which we measured some of the highest 210Po and 210Pbex levels compared to the results in the literature. 7Be mainly accumulated in the leaves-stem parts. Different positive correlations were observed between 210Po and 210Pb and between 7Be and 210Pb, which indicated that the uptake mechanisms of 210Po, 210Pb, and 7Be by moss plants were different, to some extent. 137Cs was detected only in some moss samples, and the fraction of 137Cs in the underlying soils was much lower than that in the moss, suggesting that mosses were protecting the underlying soils from further pollution. Except for 40K, the terrestrial radionuclide (238U, 226Ra, and 232Th) content in mosses was predominantly at low levels, which indicated not only the inability of mosses to use those elements for metabolic purposes but also the rather poor capability of mosses to directly mobilize, absorb, and transport elements (U, Ra, or Th) not dissolved in water.

Historical changes in the major and trace elements in the sedimentary records of Lake Qinghai, Qinghai-Tibet Plateau: implications for anthropogenic activities.

Sediment sequences in Lake Qinghai spanning the past 100 years were explored to assess the effects of changes in local land desertification, dust input and agriculture on sediment deposition in different parts of Lake Qinghai. Three short sediment cores (QH01, QH02, QH07) were collected from the main lake and one sediment core (Z04) from a sublake (Lake Gahai) of Lake Qinghai, China, during 2012 and 2013. The concentrations of Fe, Mn, Al, Rb, Ti, Ca, and Sr were analysed to determine the effects of historical and regional anthropogenic activities in the Lake Qinghai catchment from 1910 to 2010. The elemental concentrations in the sediment cores ranged from 1.85 to 2.79% for Fe, 397 to 608 µg/g for Mn, 3.04 to 5.64% for Al, 13.5 to 19.7 µg/g for Rb, 0.171 to 0.268% for Ti, 9.43 to 13.9% for Ca, 652 to 1020 µg/g for Sr, and 0.049 to 0.075% for P. Good correlations were found between the concentrations of Fe, Mn, Al, and Rb, and the Ti/Al ratios in the sediments suggest that these elements share a similar source. The enrichment factors (EFs) of Ti [EF(Ti)] and P [EF(P)] in each core were utilized to reflect variations in anthropogenic activities from 1950 to 2010. EF(Ti) ranged from 1 to 1.17 in QH01 and QH02, reflecting the variation of land desertification areas in the Buha River catchment from 1950 to 2010. The EF(Ti) showed positive linear correlations with the variation in cropland area in Gangcha County, suggesting that agricultural activity in the Quanji River and Shaliu River catchments was enhanced from 1950 to 2010. The sediment records showed similar biogeochemical changes in most lakes and bays in China, indicating that the intensity of changes in anthropogenic activities was caused by national policy enforcement from the 1950s to 2010. EF(Ti) can serve as a tracer for anthropogenic activities in Lake Qinghai, with the anthropogenic activities in different parts of the Lake Qinghai catchment represented in the homologous sediments from parts of Lake Qinghai over the past 100 years. The variation of EF(P) increased from 1 to 1.55 from deep layer to upper layer in all sediment cores, reflecting the increased fertilizer input and tourism activity from 1980 to 2010, a period during which the lake was evolved into a eutrophic lake.

Regional environmental change and human activity over the past hundred years recorded in the sedimentary record of Lake Qinghai, China.

Environmental change and human activity can be recorded in sediment cores in aquatic systems such as lakes. Information from such records may be useful for environmental governance in the future. Six sediment cores were collected from Lake Qinghai, China and its sublakes during 2012 and 2013. Measurements of sediment grain-size fractions indicate that sedimentation in the north and southwest of Lake Qinghai is dominated by river input, whereas that in Lake Gahai and Lake Erhai is dominated by dunes. The sedimentation rates in Lake Qinghai were calculated to be 0.101-0.159 cm/y, similar to the rates in other lakes on the Qinghai-Tibetan Plateau. Using these data and sedimentation rates from the literature, we compiled the spatial distribution of sedimentation rates. Higher values were obtained in the three main areas of Lake Qinghai: two in river estuaries and one close to sand dunes. Lower values were measured in the center and south of the lake. Measurements of total organic carbon (TOC), total nitrogen (TN), phosphorus concentrations, and TOC/TN ratios in three cores (QH01, QH02, and Z04) revealed four horizons corresponding to times of increased human activity. These anthropogenic events were (1) the development of large areas of cropland in the Lake Qinghai watershed in 1960, (2) the beginning of nationwide fertilizer use and increases in cropland area in the lake watershed after 1970, (3) the implementation of the national program "Grain to Green," and (4) the rapid increase in the tourism industry from 2000. Profiles of Rb, Sr concentrations, the Rb/Sr ratio, and grain-size fraction in core Z04 indicate that the climate has become drier over the past 100 years. Therefore, we suggest that lake sediments such as those in Lake Qinghai are useful media for high-resolution studies of regional environmental change and human activity.