Characteristics of heavy metal accumulation and risk assessment in understory Panax notoginseng planting system.

Yunnan Province is the main planting area of the precious Chinese herbal medicines (CHM) Panax notoginseng; however, it locates the geological area with high soil heavy metals in China. The frequent land replacement due to continuous cropping obstacles and excessive application of chemicals makes P. notoginseng prone to be contaminated by heavy metals under the farmland P. notoginseng (FPn) planting. To overcome farmland shortage, understory P. notoginseng (UPn) was developed as a new ecological planting model featured by no chemicals input. However, this newly developed planting system requires urgently the soil-plant heavy metal characteristics and risk assessment. This study aimed to evaluate the pollution status of eight heavy metals in the tillage layer (0-20 cm), subsoil layer (20-40 cm) and the plants of UPn in Lancang County, Yunnan Province. Pollution index (Pi) showed that the contamination degree of heavy metals in the tillage layer and subsoil layer was Cd > Pb > Ni > Cu > Zn > Cr > Hg > As and Pb > Cd > Cu > Ni > Cr > Hg > Zn > As, respectively. Potential ecological risk index (PERI) for the tillage layer and subsoil layer was slight and middle, respectively. The exceeding standard rate of Cd, As, Pb, Hg, Cu in the UPn roots was 5.33%, 5.33%, 13.33%, 26.67% and 1.33%, respectively, while only Cd and Hg in the UPn leaves exceeded the standard 10% and 14%, respectively. The enrichment abilities of Cd and Hg in the roots and leaves of UPn were the strongest, while that of Pb was the weakest. The Hazard index (HI) and target hazard quotient (THQ) of eight heavy metals in the roots and leaves of UPn were less than 1.Therefore, our results prove that Upn has no human health risk and provide a scientific basis for the safety evaluation and extension of UPn.

The improved entropy weighting model in water quality evaluation based on the compound function.

Entropy weight model (EWM) is widely used in water quality evaluation. In the conventional EWM, the weight is a monotone increasing function of the dispersion degree. However, this weighting principle often neglects the heavily polluted indicators. To solve this problem, an improved EWM is designed, in which the weight of the indicator is a compound function of its dispersion degree and pollution degree. In the clean domain, the weight increases with the dispersion degree, while in the polluted domain, the weight decreases with the dispersion degree. And for the same dispersion degree, the larger the pollution degree is, the higher the weight is, and vice versa. Subsequently, the improved EWM is applied to the water quality evaluation of Wucheng Wetland in Poyang Lake, China. Results are as follows: (i) For TP, CODMn, and NH3-N, their dispersion degrees are 0.001, 0.158, and 0.084; and their pollution degrees are 0.971, 0.277, and 0.281, respectively. (ii) According to the improved EWM, the weights of TP, CODMn, and NH3-N are 0.613, 0.197, and 0.190, respectively. (iii) The comprehensive water quality indices of estuary region, wetland region, and the central lake area are 32.5, 30.9, and 35.6, respectively, all of which belong to a "bad" grade. The water environment of Wucheng Wetland suffered serious damage of phosphorus, and the ecosystem faced a high threat. (iv) Compared with the conventional EWM, the improved EWM highlights the importance of polluted indicators, which makes the comprehensive evaluation results more rigorous and reasonable.

Construction of the comprehensive evaluation system of waterbody pollution degree and the response of sedimentary microbial community.

This study proposed and established a comprehensive evaluation system for the pollution degree of the waterbody by taking overlying water and sediment as a whole. By dividing different sampling points into three gradients according to the pollution degree, the changes in sedimentary microbes under various pollution gradients were compared. The results showed that microbial diversity, abundance and specific OTUs decreased significantly with the increase in pollution degree. Meanwhile, Firmicutes, Bacteroidota and Caldiseriota increased in the severely polluted group, while Chloroflexi and Acidobacteriota decreased. Spearman correlation analysis and co-occurrence network revealed that COD, pH in overlying water, and Mn, Fe in sediments were the most significant pollution degree evaluation indicators affecting sedimentary microorganisms, which drove the sedimentary microbial communities dominated by Proteobacteria and Firmicutes. FAPROTAX functional prediction indicated that increased pollution levels led to the weakening of functional genes related to nitrogen metabolism and sulfur metabolism and the increase of functional genes related to carbon metabolism in sediment microorganisms. This study not only provided new insights into waterbody pollution evaluation but also verified the feasibility of this evaluation method by the response of sedimentary microbial communities to different pollution degrees.

Pollution characteristics and health risks of heavy metals in road dust in Ma'anshan, China.

Road dust contains various heavy metals, which are re-suspension in the air under the action of wind and other external forces, threatening people's health all the time. Road dust was collected in the industrial heavy traffic area (IHT), non-industrial heavy traffic area (HT), urban area (UA), and study recreation area (SR) of Ma'anshan. The pollution degree of heavy metals in the four areas was calculated and demonstrated IHT > HT > UA > SR. In addition to the Ni (24.24 mg kg-1)metals, the metals concentrations of Cr (74.14 mg kg-1), Cu (91.8 mg kg-1), Zn (393.03 mg kg-1), Cd (9.93 mg kg-1), and Pb (72.85 mg kg-1) were all higher than the local soil background values. Cu comes from traffic emissions, Pb, Cd, and Zn mainly come from industrial emissions, as well as traffic emissions. While Cr and Ni mainly come from industrial emissions and local soil re-suspension. The non-carcinogenic risk of each heavy metal to children is 10 times higher than that of adults. Among them, the non-carcinogenic risk of Cr, Cd, and Pb to children is close to 1, so great attention should be paid to it. According to the study of enrichment factor (EF) and geo-accumulation index (Igeo), Cd is extremely polluted and it is imperative to reduce Cd pollution.

Foliar dust particle retention and metal accumulation of five garden tree species in Hangzhou: Seasonal changes.

As particulate matter and heavy metals in the atmosphere affect the atmospheric quality, they pose a threat to human health through the respiratory system. Vegetation can remove airborne particles and purify the atmosphere. Plant leaves are capable of effectively absorbing heavy metals contained by particulates. To evaluate the effects of different garden plants on the particulate matter retention and heavy metal accumulation, the seasonal changes of dust retention of five typical garden plants were compared in the industrial and non-industrial zones in Hangzhou. Results revealed that these species differed in dust retention with the descending order of Loropetalum chinense > Osmanthus fragrans > Pittosporum tobira > Photinia × fraseri > Cinnamomum camphora, which were related to the microstructure feature of the leaf. These species also showed seasonal variation in dust retention, with the highest in summer, followed by winter, autumn, and spring, respectively. The total suspended particle per unit leaf area was higher in the industrial site (80.54 g m-2) than in the non-industrial site (19.77 g m-2). Leaf particles in different size fractions differed among species, while coarse particles (d > ten µm) predominated in most cases. The L. chinense and C. camphora plants accumulated the greatest Pb and Ni compared to other plants. Overall, L. chinense was the best suitable plant species to improve the air quality.

[Pollution Properties and Ecological Risk Assessment of Heavy Metals in Farmland Soils and Crops Around a Typical Manganese Mining Area].

In order to assess the ecological risks of heavy metals and explore the pattern of heavy metal migration between farmland and corresponding crops in a typical and closed manganese mining area in Hunan province, farmland soils and crops surrounding the mining area (pollution area) and away from the mining area (control area) were collected, and then the contents of Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb were analyzed. The sources and distribution of heavy metals in farmland soils were analyzed using Kriging spatial interpolation and principal component analysis, and the ecological risk was evaluated using the single factor index, comprehensive pollution index, and potential ecological risk index. The results showed that the surrounding farmland soils in the closed Manganese mining area presented serious pollution of Cd, Zn, As, and Mn, in which the average contents of the above heavy metals in the dry land soil in the polluted area were 6.22, 612.28, 37.72, and 1506.2 mg·kg-1, respectively. Compared with the soil risk screening value of agricultural land, the over-standard rates of Cd, Zn, and As were 88.41%, 94.20%, and 84.06%, respectively, and the average content of Mn in the farmland soil was three times that of the background value in the Hunan soil; however, the heavy metal pollution in the paddy field was relatively light. The principal component analysis showed that the sources of Cd, Mn, and Zn in the farmland soil were related to the manganese ore mining, whereas the source of As in the farmland soil might originate from agricultural activities. The pollution area was at a heavy pollution level, and the main pollution factors were Cd, Mn, and Zn. The Cd in the farmland soil could pose a strong potential ecological risk, but the rest of the heavy metals presented only a slight potential ecological risk. The content of Cr, Pb, and Cd in the crops in the study area exceeded the standard, and the exceeding standard rate was between 1.1% and 37.3%, where the average content of over-standard heavy metals in corn was higher than that in rice, and the average content of heavy metals in leafy vegetables was higher than that in root vegetables. The soil pollution degree of heavy metals could affect the accumulation ability of crops, and different crops had different accumulation abilities. For instance, leafy vegetables and root vegetables easily accumulated Cd and Zn; however, rice and corn separately enriched Cd and Cr, as well as Zn and Cu. The contents of heavy metals in dryland soils had a positive correlation with the content of heavy metals in corresponding crops. The contents of Cd and As in the paddy field and rice presented a positive correlation, but the remaining six heavy metal contents in rice (i.e., Cr, Mn, Ni, Cu, Zn, and Pb) did not correlate with the content of the paddy fields.

Impact of Industrially Affected Soil on Humans: A Soil-Human and Soil-Plant-Human Exposure Assessment.

Heavy metal (HM) contaminated soil can affect human health via ingestion of foodstuffs, inhalation of soil dust, and skin contact of soil. This study estimates the level of some heavy metals in soils of industrial areas, and their exposures to human body via dietary intake of vegetables and other pathways. Mean concentrations of Cr, Fe, Cu, Zn, As and Pb in the studied soil were found to be 61.27, 27,274, 42.36, 9.77, 28.08 and 13.69 mg/kg, respectively, while in vegetables the respective values were 0.53, 119.59, 9.76, 7.14, 1.34 and 2.69 mg/kg. Multivariate statistical analysis revealed that Fe, Cu, Zn, and Pb originated from lithogenic sources, while Cr and As are derived from anthropogenic sources. A moderate enrichment was noted by Cr, As, and Pb in the entire sampling site, indicating a progressive depletion of soil quality. The bioaccumulation factor (BCF) value for all the vegetables was recorded as BCF < 1; however, the metal pollution index (MPI) stipulates moderately high value of heavy metal accumulation in the vegetable samples. Hazard Index (HI) of >0.1 was estimated for adults but >1 for children by direct soil exposure, whereas HI < 1 for both children and adults via dietary intake of vegetables. Estimated Total carcinogenic risk (TCR) value due to soil exposure showed safe for adults but unsafe for children, while both the population groups were found to be safe via food consumption. Children are found more vulnerable receptors than adults, and health risks (carcinogenic and non-carcinogenic) via direct soil exposure proved unsafe. Overall, this study can be used as a reference for similar types of studies to evaluate heavy metal contaminated soil impact on the population of Bangladesh and other countries as well.

[PM2.5 adsorption capacity of Osmanthus fragrans and Cinnamomum camphora leaf surface and influencing factors under different pollution levels in Changsha, China]. / 长沙市不同污染程度区域桂花和香樟叶表面PM2.5å¸é™„é‡åŠå ¶å½±å“å› ç´ .

To understand the PM2.5 adsorption mechanisms of plants under different pollution levels and analyze pollutant sources, the PM2.5 adsorption amount of the leaves of two garden plant species (Cinnamomum camphora and Osmanthus fragrans) in different polluted level area (traffic area, culture and education area, cleaning area) of Changsha was measured using an aerosol generator. AFM scanning was used to obtain leaf surface micromorphological characteristics. Ion chromatography was used to measure the water-soluble ion content. Results showed that amount of PM2.5 adsorbed by leaves was positively correlated with pollution levels. The annual mean value of PM2.5adsorbed per leaf area of different plants was traffic area (0.56±0.04 µg·cm-2) > culture and education are (0.48±0.06 µg·cm-2) > clearing area (0.33±0.02 µg·cm-2). The season with amount of PM2.5adsorbed in leaves from the highest to lowest was winter (0.70±0.10 µg·cm-2) > spring (0.43±0.14 µg·cm-2) > autumn (0.39±0.12 µg·cm-2) > summer (0.31±0.09 µg·cm-2). Osmanthus fragrans had higher capacity to absorb PM2.5 than Cinnamomum camphora. Leaves of plants grown in low pollution areas were relatively smooth, whereas those in high pollution areas were rough. The order of leaf roughness in both species from high to low was traffic area (195.45±16.09 nm) > culture and education area (176.99±8.45 nm) > cleaning area (131.88±12.98 nm). The PM2.5 ionic content was the highest in winter, intermediated in spring and autumn, and the lowest in summer. The PM2.5 ions mainly included Na+, NH4+, Cl- and Br- in three pollution areas. PM2.5 pollution was due to removable source pollution at different pollution levels.

[Impacts of Land Use and Landscape Patterns on Heavy Metal Accumulation in Soil].

Land use cover change (LUCC) is one of the most important human activities that drive the evolution of the environment. It has great effect on the accumulation, distribution, and migration of heavy metals in the environment. Vegetation can absorb heavy metals directly, and it can also change the physical, chemical, and biological properties of soil and then control the mobility and activity of heavy metals in soil, which will eventually cause pollution of heavy metals in soil. In addition, the migration of heavy metals in soil is also affected by changes of landscape element composition and landscape pattern at sample points, plots, watersheds, and regional scales. Based on the soil sampling data and land use data of Ningbo city in 2003 and 2013, the decision tree classification method based on classification and regression tree algorithm was used to classify the land use and cover type. Single-factor pollution index and Nemero composite pollution index were used to evaluate the soil heavy metal pollution status. The landscape pattern indexes were used to explore the change of landscape patterns under different degrees of heavy metal accumulation. Finally, redundancy analysis and partial redundancy analysis were used to identify those landscape pattern factors that had the most significant impacts on the soil heavy metal accumulation in the study area. The results showed that:①The eight soil heavy metal elements including As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn presented different degree of accumulation from 2003 to 2013 in the study area, of which Hg, Ni, and Cr had the highest degree of accumulation. Most of the study area has been polluted by heavy metals, and the pollution degree in the heavily polluted areas is still increasing. ②Higher accumulation degrees of heavy metals was not distributed entirely in areas where land use types have always been construction land, or in areas where other types of land use had been converted to construction land. A considerable proportion of heavy metals accumulated in areas where land use types have always been cultivated land or converted from other types to cultivated land. ③Heavy metal polluted areas have fragmented, complex, and aggregated landscape pattern, and the correlation between this kind of landscape pattern characteristics and soil heavy metal accumulation in arable land, residential land, and industrial land was the highest. ④The higher the aggregation degree of construction land patch, the higher the accumulation degree of most heavy metals. The accumulation degree of Cu, Hg, Pb, and Cd increased significantly with the increase of landscape diversity and shape complexity of agricultural land. The closer the distance to the mining site, the more obvious the effect on the increase of Cd content.

Spatial Distribution and Contamination Assessment of Surface Heavy Metals off the Western Guangdong Province and Northeastern Hainan Island.

Surface sediments collected from the continental shelf off the western Guangdong Province and northeastern Hainan Island are analyzed for selected heavy metals contents including Cd, Cr, Cu, Pb, Zn, and As to determine spatial distribution, potential ecological risks, and sources. In addition, some of the controlling factors of heavy metals distribution are also discussed. The average heavy metals contents decrease in the order of Zn > Cr > Pb > Cu > As > Cd. The averaged pollution degree, as shown by the index of geo-accumulation (Igeo), decreases in the order of Zn > Cu > Pb > Cr > Cd > As. Due to the barrier of islands, the Igeo values of Zn, Pb, Cr, Cu, and Cd near the Hailing and Xiachuan Islands are larger than those in other areas. Meanwhile, the Igeo value of As near the coastal area off the estuary of Wanquan River is clearly larger than that in other areas. Based on the results of potential ecological risk index, Cd, Cu, and As should be paid more attention for the contamination risk in future. The results of Pearson correlation analysis and principal component analysis indicate that Zn, Cr, Pb, Cu, and Cd are mainly from the Pearl River and surrounding small rivers, whereas As originates from the Hainan Island. The grain size is one of the main controlling factors for heavy metals distribution, and the anthropogenic activity also plays an important role.

Spatial distribution and transport characteristics of heavy metals around an antimony mine area in central China.

The spatial distribution and transport characteristics of heavy metals in an antimony mine area (Xikuangshan, China) were systematically studied using a field survey and geostatistical analytical methods. In the study area, 52 soil and sediment samples were collected from bare land, grassland, woodland and river sediments covering a surface area of 20 km2. The soil properties and heavy metal concentrations were measured by wavelength dispersive X-ray fluorescence spectrometry and inductively coupled plasma-mass spectrometry, respectively. Correlation analysis and principal component analysis suggest that Cu, Zn, Cd, As, Pb and Sb can be attributed to anthropogenic inputs, whereas Cr, Mn and Ni are of natural origin. Distribution maps of heavy metals were generated using the Kriging interpolation method to identify their distribution trends. The results show the influence of wind, river, distance and vegetation on the spatial distribution. The results also revealed that windborne transport may play a significant role in the spreading of contaminants. In addition, the environmental risk of heavy metal pollution was evaluated using their geoaccumulation indexes in the whole region. All of the results indicate that the heavy metal distributions in the soils were consistent with the local prevailing wind direction. In addition, the environmental quality could be seriously threatened by heavy metal contaminants from the smelter and tailings.

Research in relationship between storage method and pollution degree for medical devices after cleaning / 中国实用护理杂志

Objective The study aimed to explore the relationship between storage methods and pollution degrees of two different storage methods for medical devices which can not be packed promptly after cleaning.Methods 300 pieces of surgical devices were randomly divided into the experimental group and the control group according to random digit table,150 pieces in each group.Each group was washed with two cleaning machines of the same brand and model number using the same cleaning protocol,and after cleaning,the experimental group was stored in the cleaning machine,while the control group was exposed in the packaging area.Ten hours later,each surgical instrument was detected using ATP biological fluorescence detector.Results The percent of pass in the experimental group was higher than that of the control group [98％ (147/150) vs.86％ (129/150)],x2=12.7,P＜ 0.05.Conclusions Medical devices should better be stored in the washing machine than exposure to the air after cleaning if they could not be packaged and sterilized immediately.