Over-standard Rate Research Articles

Investigation on the current situation of occupational disease hazards in stone processing enterprises in Weihai City

Objective: To analyze the occupational disease hazards in stone processing enterprises in Weihai City to provide scientific basis for occupational disease prevention. Methods: From January 2021 to December 2022, 107 stone processing enterprises in Weihai City were selected to collect the detection status of occupational hazard factors in the workplace through on-site investigation and on-site monitoring of occupational hazard factors. The diagnostic reports on occupational diseases and suspected occupational diseases of 780 workers were collected through the Occupational Diseases and Hazard Factors Monitoring Information System of the Chinese Center for Disease Control and Prevention, the occupational health monitoring files of the occupational health examination institutions and the information data of the occupational disease diagnosis institutions. The differences between the measurement data were analyzed by Chi-square test or Fisher exact probability method. Results: 107 stone processing enterprises were mainly focused on granite processing, and the average free silica content in granite was 32.92% (12.78%-47.84%). The over-standard rate of silica dust was 0.31% (6/1920), and the over-standard rate of noise was 86.20% (1324/1536). Among them, the noise intensity of cutting position was the highest[120.5 dB (A) ]. The over-standard rates of noise in cutting, water grinding, dry grinding (polishing) and material preparation (forklift transportation) were 98.05%, 89.55%, 70.00% and 42.62%, respectively, and the differences were statistically significant (P<0.05). Among 780 workers, 31 cases (3.97%) of suspected silicosis were detected, and 13 cases (1.67%) were diagnosed with silicosis. 51 cases (6.54%) of suspected occupational noise deafness were detected, and 11 cases (1.41%) were diagnosed with occupational noise deafness. Conclusion: Silicon dust and noise in some positions of stone processing enterprises in Weihai City exceed the standard, and supervision should be strengthened, prevention and control measures should be implemented to protect the occupational health of workers.

Spatial Differentiation Characteristics and Influencing Factors of Surface Soil Cd in Karst Plateau Area of Guiyang City

In order to explore the spatial differentiation characteristics and variation law of soil Cd content in a high geological background area, 14 421 topsoil samples were collected from topsoil in the karst area of Guiyang City. Global Moran's I index, cold hot spot analysis, semi-variance function, and Kriging interpolation were used to reveal the spatial structure and distribution law of soil Cd content. The influence of environmental factors on soil Cd content and its main controlling factors were analyzed through analysis of variance and geographic detector. The results showed that： ① The Cd content of karst surface soil in Guiyang varied from 0.03 to 1.36 mg·kg-1, with an average of 0.440 mg·kg-1, which was 1.77 times and 5.95 times the Guizhou soil Cd background value and Chinese soil Cd background value, respectively. The over-standard rate of soil Cd was 30%, which was 4.29 times that of 7% of soil Cd in China. ② There was a significant spatial positive correlation of soil Cd content, showing an aggregation trend in the global space, whereas in the local region, the northeast and southwest were hot spots, and the north was a cold spot. The nugget coefficient of soil Cd content was 10.37%, indicating that soil Cd was mainly affected by structural factors. ③ In terms of spatial distribution, soil Cd showed different accumulation trends. In some massive soils, such as Xifeng County, Xiuwen County, Qingzhen City, Huaxi District, and Nanming District, the soil ω（Cd）was less than 0.3 mg·kg-1. The soil ω（Cd）was between 0.3 and 0.6 mg·kg-1,and soil Cd in Baiyun District, Wudang District, Guanshan Lake area, and Yunyan area as a whole lied within this range. The soil ω（Cd）between 0.6 and 0.9 mg·kg-1 was concentrated in the southwest of Qingzhen City, the south of Huaxi District, and the north of Kaiyang County, whereas soil ω（Cd） between 0.9 and 1.2 mg·kg-1 was mainly concentrated in the southwest of Qingzhen City. The extreme value of soil Cd content （ &gt; 1.2 mg·kg-1） was mostly distributed in Kaiyang County, Xiuwen County, Qingzhen City, and Huaxi District. ④ The results of analysis of variance and geo-detector showed that different environmental factors had significant effects on the spatial differentiation of soil Cd, but their explanatory power on soil Cd content varied： stratum （0.176 5） &gt; soil type （0.026 0） &gt; organic matter （0.025 1） &gt; altitude （0.010 5） &gt; parent rock （0.007 3） &gt; land use （0.006 4） &gt; pH （0.001 3）, and the interaction between stratum and arbitrary environmental factors was the greatest. Therefore, stratum was the main factor affecting the spatial differentiation of soil Cd content.

Occurrence and health risk of pesticide residues in Chinese herbal medicines from Shandong Province, China.

Pesticide residue was one of the stress factors affecting quality and safety of Chinese herbal medicines (CHMs). The present study was designed to investigate the occurrence and dietary exposure of 70 pesticide residues in 307 samples of CHMs, including 104 American ginseng, 100 Ganoderma lucidum (G. lucidum), and 103 Dendrobium officinale (D. officinale) in Shandong Province, China. The study revealed that a total of 29 pesticides were detected in the majority (92.5%) of samples, and the pesticide residues of 85 (27.7%) samples exceeded the maximum residue levels (MRLs). Particularly, the maximum concentration of chlorpyrifos was 23.8mgkg-1, almost 50 times of the MRLs in food in GB 2763-2021, while there's no standard restrictions specified in CHMs in China. The chronic, acute, and cumulative risk assessment results indicated that risk exposure of the three types of CHMs were unlikely to pose a health risk to consumers. However, more attention should be paid to the multiple residues with the presence of four or more pesticides in one sample and high over-standard rate of pesticides. The pesticide users and the government should pay more attention to the pesticides used in CHMs and regularly monitor the presence of these compounds. The study recommended the MRLs of these pesticides in CHMs should be established and perfected by the relevant departments in China.

The study on biological exposure index of occupational exposure to arsenic and its inorganic compounds

Objective: To establish biological exposure index (BEI) of occupational exposure to arsenic and its inorganic compounds through occupational epidemiology and the regression analysis of internal and external exposure of workers. Methods: In November 2021, 125 workers with occupational exposure to arsenic and its inorganic compounds and 49 office administrators in a non-ferrous metal smelter in Yunnan Province were selected as the exposure group and control group, respectively. Air samples from the workplace of the study subjects on weekdays were collected and arsenic concentrations were determined. Urine samples were collected in end-of-work weekend and high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) was used to detect the levels of trivalent inorganic arsenic (iAs(3+)) , pentavalent inorganic arsenic (iAs(5+)) , monomethyl arsenic (MMA) and dimethyl arsenic (DMA) in urine. The correlations between arsenic concentration in the workplace air and arsenic species in urine of workers were analyzed. Arsenic exposure concentration and the level of urinary arsenic (ΣiAs+MMA+DMA) of workers was analyzed by linear regression and the BEI of arsenic and its inorganic compounds in the workplace was proposed based on the results of micronucleus test. Results: The median of time-weighted average concentration (C(TWA)) of arsenic in the workplace air of the exposure group was 0.0116 mg/m(3), and the over-standard rate was 71.2% (89/125) . The concentrations of iAs(3+), iAs(5+), inorganic arsenic (iAs=ΣiAs(3+)+iAs(5+)) 、MMA、DMA and urinary arsenic in the exposure group were higher than those in the control group at the end of shift, and the differences were statistically significant (P<0.05) . The concentration of arsenic in the workplace air had the strongest correlation with the concentration of urinary arsenic at the end of the shift (r(s)=0.909, P<0.001) . The regression equation was lg (y) =7.662+2.968lg (x) (r=0.821, P<0.05) . According to the occupational exposure limit (OEL) of arsenic in China, the concentration of urinary arsenic in the end-of-work weekend was calculated to be 53.2 μg/L. Combined with the results of micronucleus test, the BEI of occupational exposure to arsenic and its inorganic compounds in the workplace was proposed to be 50 μg/L. Conclusion: The urinary arsenic in the end-of-work weekend can be used as a biomarker of occupational exposure to arsenic, and its BEI is recommended to be 50 μg/L.

Hydrochemical Characteristics and Genesis Mechanism of Groundwater in the Dry Period in the Zhangjiakou Area

In order to better support the construction of the capital water conservation functional area and ecological environment support area， research on the chemical characteristics of groundwater and its formation mechanism in the dry period in the Zhangjiakou area can provide a great reference for the rational development and utilization of groundwater resources. A total of 41 groups of groundwater samples were collected， and the hydrochemical types， composition characteristics， and control factors of groundwater in the study area were analyzed by using the combined method of descriptive statistical analysis， Piper triplot， correlation analysis， Gibbs plot， and ion ratio. The results showed that the groundwater in the study area was weakly alkaline， with the total hardness and ρ（TDS） ranging from 105.00 mg·L-1 to 1 433.00 mg·L-1 and 137.00 mg·L-1 to 2 286.00 mg·L-1， respectively. The total hardness and TDS mass concentrations of groundwater in the Bashang area were higher than those in the Baxia area. HCO3- and Na+ were the main dominant anions and cations in the groundwater in the study area. The highest overstandard rate of the main components in groundwater was that of total hardness （36.59%）. The overstandard rate and maximum excess multiple of each component in groundwater in the Bashang area were greater than those in the Baxia area. HCO3-Ca·Mg·Na was the main type of groundwater hydrochemistry in the study area， and there was little difference between the Bashang area and the Baxia area. SO42-， Cl-， HCO3-， Na+， and Mg2+ contributed the most to TDS. The chemical characteristics of groundwater were affected by weathering and filtration of rock minerals such as salt rock， albite， and dolomite； cation exchange； and human activities. Evaporative crystallization and atmospheric precipitation contributed to a small part of the main ion source of groundwater in the area. The effect of human activities on groundwater in the Bashang area was greater than that in the Baxia area， and NO3- mainly originated from agricultural activities.

Water quality and microecosystem of water tanks in karst mountainous area, Southwest China.

Karst mountainous areas in Southwest China, the world's largest bare karst area, are faced with growing water shortages. Rainwater harvesting plays an important role in alleviating water shortage. However, there remains a substantial gap in the research regarding the water quality of tanks. Water samples were seasonally collected from ten tanks to investigate the physicochemical properties, microbial communities, and their key influencing factors. The result showed that pH, turbidity, chroma, DOC, and CODMn exceeded drinking water guidelines. The alkaline pH value and the deterioration of sensory properties was the main feature of tank water, from which the over-standard rate of the uncleaned water tanks was higher. Moreover, principal component analyses suggested that tank water quality was influenced by human activities, catchment areas, and material cycling processes within the tanks, of which in-tank microbial activities were the most important driving factors in water quality variation. Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Verrucomicrobia were the predominant bacterial phyla in water tanks. Acinetobacter, Cyanobium-PCC-6307, CL500-29-marine-group, Candidatus-Aquiluna, and Exiguobacterium were the most abundant genera. The bacterial communities were significantly affected by the management practices. Higher relative abundance of Cyanobacteria and lower relative abundance of Proteobacteria was detected in the uncleaned tanks, which was a sign of tank water quality deterioration. The microbial community structure was closely related to the environmental factors. There was evidence that the water quality was affected by the existence of a microecosystem dominated by photosynthetic microorganisms in the water tanks. In addition, Acinetobacter, Enterobacter, Pseudomonas, and Legionella identified as the potential opportunistic pathogenic genera were frequently detected but the relative abundances except Acinetobacter were low in the tanks. Overall, our findings indicated that management style influences water quality and bacterial communities of tank water.

Multiresidue analysis and health risk assessment of sulfonamides and quinolones from edible Batrachia and other aquatic products

Tailless amphibians belonging to the order Batrachia are a significant component of human consumption. However, there is limited literature on the consumption of these amphibians by humans. Therefore, the present work aimed to examine the presence of drug residues in edible Batrachia, and compare them with other aquatic products. We assessed 22 veterinary drug residues, including 12 sulfonamides (SAs) and ten quinolones (QNs), in various aquatic products, including edible Batrachia. To provide a comparative analysis, we referenced literature from China between 2005 and 2020 regarding SAs and QNs detected in aquatic products. Additionally, we calculated the food safety index (IFS) of antibiotics, and conducted a health risk assessment. The findings revealed that the detection rate, average residual amount, and over-standard rate of antibiotics in edible Batrachia were higher than most other aquatic products. Furthermore, the systematic cluster analysis demonstrated that edible Batrachia could serve as a potential sentinel animal, distinguishing them from several other aquatic products. The total IFS of all residues obtained from different aquatic products in the present work was less than 1, thus indicating their safety in terms of public health. Nevertheless, it is essential to conduct detailed investigations into the maximum residues of certain antibiotics in specific aquatic products that exceed the safety limits to understand their impact on human health.

Determination of priority influencing factors for risk assessment of carcinogenic toxic elements in resuspendable surface dust of urban communities

Urban communities are important places for residents' daily life and activities. This study determined the contamination, eco-health hazards, and influencing factors of certain carcinogenic toxic elements (CTEs) in resuspendable surface dust (RSD) of urban communities in Xi'an. The results indicated that the mean contents of As (12.7 mg kg−1), Cr (132.9 mg kg−1), Ni (33.5 mg kg−1), and Pb (112.6 mg kg−1) in the study areas were higher than their background values. The contamination level and eco-health risk were quantified based on the enrichment factor, Nemerow integrated enrichment factor, modified Nemerow integrated ecological risk index, and health risk estimation method, combined with Monte Carlo simulation. The overall pollution and ecological risk of CTEs in the RSD were moderate and low, respectively. CTEs in RSD have a high cancer risk to all residents (over-standard rate > 80%) and non-cancer risk to children (over-standard rate = 26.9%) in Xi'an. The major factors affecting the environmental risks of CTEs were traffic and residential activities. Vegetation distribution in the city reduced the environmental risks of CTEs in the RSD. Therefore, future management strategies should focus more on protecting children's health, increasing green spaces and public transportation, and maintaining the hygiene of urban communities.

Investigation of serum surface active protein D and clara cell protein levels in workers exposed to silica dust in ferrous metal foundry

Objective: To investigate the levels of serum surface active protein D (SP-D) and clara cell protein (CCl6) in workers exposed to black silica dust, and analyze its influencing factors. Methods: From July to September 2021, 174 workers in 37 positions exposed to silica dust in 5 ferrous metal foundry were investigated by cross-sectional research method. The exposure concentration of silica dust workers was obtained through occupational health field investigation and detection, and the general situation of the study subjects was obtained through questionnaire survey and peripheral blood was collected. Double antigen sandwich enzyme-linked immunosorbent assay (ELISA) was used to detect the concentrations of SP-D and CC16 in serum of workers. The mean values were compared by one-way ANOVA, and the influencing factors of SP-D and CC16 concentrations in serum were analyzed by ordered multiple logistic regression. Results: The time-weighted average concentration (C-TWA) of 174 workers exposed to silica dust (respirable dust) ranged from 0.09 mg/m(3)~3.58 mg/m(3), and the C-TWA overstandard rate of dust exposed workers was 32.18% (56/174) , with differences among workers in different positions (χ(2)=28.85, P<0.001) . The highest concentration of silica dust was (0.82±0.11) mg/m(3). Using C-TWA<50% OEL occupational exposure limit (OEL) as reference, serum SP-D concentration in workers with ≥50% OEL was increased (OR=4.95, 95%CI: 1.86~13.17, P=0.001) , while CC16 concentration was decreased (OR=0.15, 95%CI: 0.05~0.40, P<0.001) ; Serum CC16 concentration decreased in workers exposed to silica dust C-TWA≥OEL (OR=0.46, 95%CI: 0.28~0.98, P=0.043) . Compared with those with low occupational health literacy, the serum SP-D concentration of workers with high occupational health literacy decreased (OR=0.48, 95%CI: 0.25~0.92, P=0.027) and CC16 concentration increased (OR=2.09, 95%CI: 1.10-3.97, P=0.024) . Conclusion: When no abnormality was found in the physical examination of workers, the serum SP-D and CC16 concentration levels changed, and the change was related to the concentration of workers exposed to silica dust.

Health Risk Assessment and Environmental Benchmark of Cadmium in Farmland Soils around the Gangue Heap of Coal Mine, Chongqing

To analyze the health risk assessment and environmental benchmark of cadmium in farmland soils surrounding the gangue heap of a coal mine in Chongqing, Hakanson, the ecological risk index and health risk assessment were used. Meanwhile, the soil environmental reference value of the regional cultivated land was inverted based on the species sensitive distribution model (SSD). The results showed that the dryland soil was polluted by Cd, with an over-standard rate of 55.8%, and the paddy field soil was polluted by Cd, with an over-standard rate of 31.6%. The corn was polluted by Cd, with an over-standard rate of 4.4%, and the rice was not polluted by Cd. The Hakanson ecological risk index showed that Cd was mainly characterized in soils by high ecological risk and considerable ecological risk. The health risk assessment indicated that Cd presented low non-carcinogenic risk by corn and rice; however, it showed acceptable carcinogenic risk by corn and unacceptable carcinogenic risk by rice in this study. The sensitivity analysis of health risks showed that the content of Cd was the most sensitive. The SSD inversion showed that the reference values for Cd in dryland soil of pH ≤ 5.5, 5.5<pH ≤ 6.5, 6.5<pH ≤ 7.5, and pH>7.5 had HC5 values of 0.491, 0.382, 0.376, and 0.588 mg·kg-1, respectively, and that for Cd in paddy soil had an HC5 value of 0.807 mg·kg-1. The reverse analysis showed that the HC5 of Cd in dryland soil (pH ≤ 7.5) and paddy soil was relatively relaxed and was higher than the soil risk screening values, which showed that the current standard was relatively loose. However, the HC5 of Cd in dryland soil (pH>7.5) was lower than the soil risk screening values, which showed that the current standard was relatively strict. It is suggested that the current soil standard could be adjusted in this area.

Health Risk Assessment and Environmental Benchmark of Heavy Metals in Cultivated Land in Wanjiang Economic Zone

Focusing on the cultivated land in Wanjiang Economic Zone, 338 sets of soil samples of rice, wheat, and their roots were collected; the concentrations of five heavy metals (As, Cd, Cr, Hg, and Pb) were determined; the soil-crop pollution characteristics were evaluated using the method of geo-accumulation index and comprehensive evaluation; the human health risk of ingesting heavy metals from crops was assessed; and the soil environmental reference value of the regional cultivated land was inverted based on the species sensitive distribution model (SSD). The results showed that in the study area, the soil of rice and wheat was polluted by heavy metals (As, Cd, Cr, Hg, and Pb) in varying degrees, among which Cd was the primary pollution factor of rice, with the over-standard rate of 13.33%, and Cr was the main over-standard factor of wheat, with the over-standard rate of 11.32%. The cumulative index showed that the percentage of Cd pollution in rice was 80.7%, and that in wheat was 35.85%. Contrary to the high pollution level of soil heavy metals, only 17.19% and 7.55% of Cd in rice and wheat exceeded the national food safety limit, and the accumulation capacity of the heavy metal Cd was rice>wheat. The health risk assessment indicated that heavy metals had high non-carcinogenic risk and unacceptable carcinogenic risk to adults and children in this study. The carcinogenic risk of rice intake was higher than that of wheat, and the health risk of children was higher than that of adults. SSD inversion showed that the reference values of As, Cd, Cr, Hg, and Pb in paddy soil in the study area were an HC5 of 6.24, 0.13, 258.27, 0.12, and 53.61 mg·kg-1 and an HC95 of 68.81, 5.71, 1068.92, 0.80, and 174.22 mg·kg-1, respectively. The reference values of As, Cd, Cr, Hg, and Pb in wheat soil HC5 were 32.99, 0.04, 271.14, 0.09, and 47.53 mg·kg-1, and the values of HC95 were 225.28, 0.71, 998.58, 1.43, and 241.99 mg·kg-1, respectively. The reverse analysis showed that the HC5 of heavy metals in rice and wheat were lower than the soil risk screening values in the current standard to varying degrees. The current soil standard had loosened for the evaluation results of this region.

Mercury Pollution in Dryland Soil and Evaluation of Maize Safety Production in Guizhou Province

Guizhou Province is the province with the largest Hg production and reserves in China, and maize is the second largest grain crop in Guizhou Province. It is necessary to identify the status of soil Hg content in Guizhou Province and evaluate the safety of maize production. A total of 990 soil-maize samples and 270 single soil samples were collected in the main maize-producing areas to determine soil pH, cation exchange capacity (CEC), and organic matter content (SOM), as well as Hg content in soil and maize. The results showed that the pH of dryland soil in Guizhou Province ranged from 3.93 to 9.82, the geometric mean of ω(SOM) was 27.5 g·kg-1, and the geometric mean of CEC was 11.7 cmol·kg-1. Soil ω(Hg) ranged from 0.005 to 686 mg·kg-1, the geometric mean was 0.632 mg·kg-1, and the over-standard rate was 7.22%. Among them, the soil Hg pollution in Tongren was the most prominent, with the exceedance rate of 21.3%. At the county level, Danzhai County, Qiandongnan Miao and Dong Autonomous Prefecture, and Tongren City Wanshan District and Bijiang District had high exceedance rates of Hg. According to the Limit of Pollutants in Food according to National Standards for Food Safety (GB 2762-2017), the exceedance rate of Hg content in maize grains was 1.11%, and the exceedance points were mainly distributed around industrial and mining activity areas such as Wanshan District in Tongren City and Xixiu District in Anshun City. According to the results, there was serious soil Hg pollution in Guizhou Province. On the whole, maize can be safely planted, but it is necessary to pay close attention to the Hg content in grains and the Hg exposure risk of residents around industrial and mining areas.

Spatiotemporal characteristics of groundwater quality and health risk assessment in Jinghe River Basin, Chinese Loess Plateau

Groundwater is a very important natural resource for humanity, however, the degradation of groundwater quality caused by anthropogenic activities may pose a serious hazard to human health and ecosystem. In this study, 143 groundwater samples were analyzed to investigate the spatiotemporal variations of hydrochemistry, groundwater quality and potential human health risk of groundwater in Jinghe River Basin, Chinese Loess Plateau. Based on the mean concentrations value (MCV) and over-standard rate (OSR), the groundwater in Jinghe River Basin were divided into three groups: Group Ⅰ (high MCV: greater than standard values and high OSR: ≥ 10 %) contains TDS (total dissolved solids), TH (total harness), SO42-, F- and Fe; Group Ⅱ (low MCV and high OSR) contains pH, Cl-, NO3-, Cr6+ and As, Group Ⅲ (low MCV and low OSR) contains NO2-, NH4+, Zn, Mn, Pb, I- and Cd. The results of set pair assessment indicated that the unsuitable and doubtful class of comprehensive groundwater quality are mainly distributed in the northern part of study area, accounting for 29 % and 13.6 % of the area in 2004 and 2015, respectively. Human health risk assessment based on the triangular fuzzy number suggested that the variation of risk levels in different age groups is Children > Adult Men > Adult Women. Average carcinogenic risks of As in groundwater for the three groups exceed the acceptable level, and non-carcinogenic risk of NO3- for Children is higher than the acceptable threshold. The findings of this study provide valuable insight into the spatiotemporal characteristics of groundwater quality and potential health risks of polluted groundwater by anthropogenic activities.

Pollution Characteristics and Health Risk Assessment of Heavy Metals in Agricultural Soils over the Past Five Years in Zhejiang, Southeast China.

Heavy metal contamination in agricultural soils has attracted increasing attention in recent years. In this study, 1999 agricultural soil samples were collected from 11 cities in Zhejiang Province from 2016 to 2020, and the spatial and temporal variation characteristics of 3 of the most important heavy metals, i.e., lead (Pb), cadmium (Cd), and chromium (Cr) were analyzed. The results showed that Cd had a slightly higher sample over-standard rate of 12.06%. Spatial distribution and temporal trends showed that the Pb concentrations overall increased from 2016 to 2020 and mainly accumulated in southern Zhejiang. In addition, multiple exposure routes were evaluated for human health risks. Children are more susceptible to the adverse effects of heavy metals in agricultural soils, and oral ingestion was the major exposure route. Cr poses higher human health risks to humans than Pb and Cd in agricultural soils. Therefore, more rigid environmental monitoring and related soil remediation counter-measures for some sites with high concentrations of heavy metals are necessary to limit the potential threat to human health.

Cumulative Risk Assessment of Soil-Crop Potentially Toxic Elements Accumulation under Two Distinct Pollution Systems

High geological background and human activities are the two major pollution sources for soil potentially toxic elements (PTEs) accumulation around the world. Mining is the prime human activity that poses a serious threat to the farmland’s ecosystem safety. This study assesses the farmland safety in the typical high geological background area and the superimposed area of high background-mining activity in eastern Yunnan in China by systematic analysis of the accumulation and risk characteristics of seven PTEs such as arsenic (As), mercury (Hg), copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), and chromium (Cr). Furthermore, we used Cd as the characteristic element to establish a relationship model between crop PTEs accumulation and the physical and chemical characteristics of the soil. We find that in the farmland soil from the superimposed area, the accumulation point over-standard rate of seven PTEs is higher than in the typical high geological background area. The accumulation of Pb, Cd, Cu, and Zn is related to frequent man-made mining activities. The bioavailability relationship model, using Cd as the soil-crop characteristic element, reveals that only in the crops (cereals, vegetables) of the high geological background area; the Cd bio-concentration factor significantly correlate with the physical and chemical properties of the soil. This suggests that the PTEs contaminated farmland in high geological background areas can be concomitantly restored during usage by adjusting the soil’s physical and chemical properties, while in the superimposed area, the farmland area needs prior restoration by removing man-made mining activities.

Source Apportionment and Health Risk Assessment of Heavy Metals in Endemic Tree Species in Southern China: A Case Study of Cinnamomum camphora (L.) Presl.

As a developed economic region in China, the problem of heavy metals (HMs) pollution in the Yangtze River Delta has become increasingly prominent. As an important evergreen broad-leaved tree species in southern China, the camphor tree cannot only be used as a street tree but also its various tissues and organs can be used as raw materials for Chinese herbal medicine. In order to explore whether heavy metal contamination in the region threatens the safety of camphor trees as pharmaceutical raw materials, we collected the bark and leaves of the tree most commonly used for pharmaceuticals in Yixing City. Based on the determination of HMs content, the health risks after human intake are evaluated, the sources and contributions of HMs are analyzed, and then the health risks of pollution sources are spatially visualized. The results showed that under the influence of human activities, the camphor trees in the study area had obvious enrichment of HMs, and the over-standard rate of Pb in the bark was as high as 90%. The non-carcinogenic risks of bark and leaves are acceptable, but the carcinogenic risks are not acceptable. The bark had the highest average carcinogenic risk, approaching six times the threshold. The results of Pb isotope ratio analysis showed that the average contribution rate of industrial activities to HMs in camphor trees in the study area was the highest, reaching 49.70%, followed by fossil fuel burning (37.14%) and the contribution of natural sources was the smallest, only 13.16%. The locations of the high-risk areas caused by the three pollution sources in the study area are basically similar, mainly concentrated in the northwest, northeast, and southeast, which are consistent with the distribution of industries and resources in the study area. This study can provide a reference for the precise prevention of HMs pollution of camphor and the safe selection of its pharmaceutical materials.

Effects of soil properties on heavy metal bioavailability and accumulation in crop grains under different farmland use patterns

Mining activities have increased the accumulation of heavy metals in farmland soil and in food crops. To identify the key soil properties influencing heavy metal bioavailability and accumulation in food crops, 81 crop samples and 81 corresponding agricultural soil samples were collected from rape, wheat, and paddy fields. Heavy metal (copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), iron (Fe), and manganese (Mn)) concentrations in soils and rape, wheat, rice grains were determined using inductively coupled plasma atomic emission spectroscopy, and soil physicochemical properties (pH, organic matter, total nitrogen, total phosphorus, available phosphorus, and available potassium (AK)) were analyzed. Soil extractable metals were extracted using various single extractants (DTPA, EDTA, NH4OAc, NH4NO3, and HCl). The average concentrations of Cu, Zn, Pb, Cd, and Mn in the soil samples all exceeded the local geochemical background value (background values of Cu, Zn, Pb, Cd, and Mn are 43.0, 81.0, 28.5, 0.196, and 616 mg/kg, respectively), and Cd over-standard rate was the highest, at 98%. Furthermore, soil total Cd concentrations (0.1–24.8 mg/kg) of more than 86% of the samples exceeded the soil pollution risk screening value (GB 15618-2018). The sources of Cu, Zn, Pb, Cd, and Mn in soils were mainly associated with mining activities. The key factors influencing heavy metal bioavailability were associated with the types of extractants (complexing agents or neutral salt extractants) and the metals. Cd and Pb concentrations in most wheat and rice grain samples exceeded the maximum allowable Cd and Pb levels in food, respectively, and Cd concentrations in approximately 10% of the rice grain samples exceeded 1.0 mg/kg. Furthermore, rice and wheat grains exhibited higher Cd accumulation capacity than rape grains, and despite the high soil Cd concentrations in the rape fields, the rape grains were safe for consumption. High soil pH and AK restricted Cd and Cu accumulation in wheat grains, respectively. Soil properties seemed to influence heavy metal accumulation in rice grains the most.

Investigation and health risk assessment of veterinary drug residues in chickens and eggs sold in Ningxia from 2016 to 2020

To understand the monitoring status of veterinary drug residues in chickens and eggs sold in Ningxia from 2016 to 2020, and to evaluate the health risks of human intake. A total of 303 chicken and 237 eggs were collected from 2016 to 2020, and the veterinary drug residues in chickens and eggs sold in Ningxia were detected and analyzed by high performance liquid chromatography-tandem mass spectrometry. The food safety index method was used to assess the health risks in combination with the dietary intake of residents. The detection rate of veterinary drug residues in chicken was 38.0%(115/303), and the over-standard rate was 7.6%(23/303). The detection rate of veterinary drug residues in eggs was 26.6%(63/237), and the over-standard rate was 19.8%(47/237). The food safety index of doxycycline in chicken was 4.59, and the food safety indexes of doxycycline, flumequine and flufenicol in eggs were 7.09, 26.5 and 2.33, respectively, all of which were much higher than 1, suggesting that there were health risks. The food safety indexes of other substances were all less than 1, and the food safety indexes were all acceptable. Veterinary drugs were widely detected in chicken and eggs in Ningxia from 2016 to 2020. Some veterinary drugs had hidden health risks.

Characteristics and Source Analysis of VOCs Pollution During the Period of Ozone Exceeding the Standard in Zibo City

In recent years, ozone pollution has been growing increasingly serious in the urban areas of China. Volatile organic compounds (VOCs) are important precursors of O3 formation, which is of great significance to studying the main characteristics and sources of VOCs for controlling O3 pollution. In this study, we conducted online VOCs observation in Zibo City from May to September in 2019, monitoring 56 species in total. During the observation, the over-standard rate of ozone was up to 67.8%, the average of ρ(VOCs) was 140.71 μg·m-3, and the concentration of VOCs in the ozone over standard days was 1.04 times that on the non-standard days. The rank of VOC classes was aromatic hydrocarbons>alkanes>alkenes>alkynes. Among them, 1,3,5-tritoluene, o-ethyltoluene, 1-butene, and n-hexane achieved high emission in the exceeding O3 and non-exceeding days. Aromatic hydrocarbon and alkenes contributed more to the potential of ozone formation. According to the PMF source analysis results, VOCs sources in the urban area mainly included motor vehicle sources, fixed combustion sources, solvent sources, process sources, and natural plant sources, among which motor vehicle sources were the most important source of VOCs in the urban area. In addition, motor vehicle sources accounted for 32.3%, and fixed combustion sources accounted for 24.2% on days when ozone exceeded the standard, which increased by 3.3% and 6.9%, respectively, compared with those on days when ozone did not exceed the standard. However, the proportion of solvent sources and process sources decreased by 5.1% when ozone exceeded the standard compared with that on a non-standard day.

Main Control Factors of Cadmium Content in Rice in Carbonate Rock Region of Guangxi Based on the DGT Technique

In order to explore the main controlling factors of Cd enrichment in rice under a geological high background in the Guangxi carbonate rock area, this study was based on rice grain-root soil samples from the carbonate rock areas in the southwest and north of Guangxi. Combined with diffusive gradients in thin films technology (DGT), the relationship between soil pH, organic matter, cation exchange capacity (CEC), DGT-Cd, and ω(rice-Cd)-BCF value in rice grains was analyzed and discussed. The main factors were determined by principal component analysis, and a quantitative model was established. The results showed that the average value of ω(soil-Cd) was 0.975 mg·kg-1, and the over-standard rate was 33.33%; the average value of ω(rice-Cd) was 0.020 mg·kg-1, and the average BCF value was 0.038, and the over-standard rate of Cd content in rice grains was 4.2%. The content of Cd in paddy soil was high, but bioavailability was low in the study area. The BCF value of rice grains in the study area was significantly negatively correlated with soil pH and cation exchange capacity at the level of 0.01, positively correlated with DGT-CD at the level of 0.01, and negatively correlated with organic matter at the level of 0.05. The results of principal component analysis showed that the total amount of Cd in the soil, pH, and DGT-Cd were the main factors affecting the accumulation of Cd in rice in the Guangxi carbonate rock area. Taking the total amount of Cd in the soil, pH, and DGT-Cd as variables, the fitting equation of BCF value of rice grains in the Guangxi carbonate rock region was established, and the determination coefficient of the model was 0.717, which could better predict the content of Cd in rice grains in this region.