Xigu District Research Articles

Hybrid Deep Learning Model for Traffic Flow and Speed Forecasting at Urban Junction

The hybrid deep learning model H-CNN-LSTM (Hybrid Convolution Neural Network and Long Short-Term Memory) is introduced in this paper. The model combines CNN to extract traffic flow and speed features, LSTM networks to model temporal dependencies, and employs a combined matrix and a rolling forward input method during data input, enhancing the coarse-grained extraction of traffic data and further refining the utilization of adjacent data. Our research focuses on the complex dynamic traffic conditions of Fuli East Road in Xigu District, Lanzhou City of China. Using detailed traffic video data collected during one month of evening rush hours, we predict future traffic using the H-CNN-LSTM model. By comparing it with other prediction methods, we validate the effectiveness of our approach in predicting traffic flow and speed in real-world traffic scenarios

Impact of fine particulate matter 2.5 on hospitalization for upper respiratory tract infections in Lanzhou urban industrial area, China.

Abundant evidence has shown that an increase in the concentration of fine particulate matter 2.5 (PM2.5) leads to a simultaneous increase in the incidence of respiratory diseases. Xigu District is the main industrial district of Lanzhou, located in Lanzhou City in northwest China and central Gansu Province. Because of limited research and data in the region, the impact of PM2.5 on human health has not been systematically recognized. The aim of the study was to investigate the relationship between PM2.5 pollution and upper respiratory tract infections in urban industrial areas of Lanzhou City. Data on outpatient visits, air pollutants, and meteorological indices were collected in the Xigu District of Lanzhou City from 1 January 2013 - 31 December 2019. A generalized additive model was used to evaluate the association between PM2.5 and outpatient visits for upper respiratory tract infections. The results show that PM2.5 had the greatest impact on outpatient visits for upper respiratory tract infections on 7 cumulative lag days. At cumulative lag days 1, 3, and 5, the effects gradually increased. In the subgroup analysis, the effect of PM2.5 on visits for upper respiratory tract infections was significantly influenced by gender. Men were more susceptible to PM2.5 pollution. An increase in atmospheric PM2.5 concentration was associated with an increase in visits for upper respiratory tract infections with the lag effect. The obtained results can provide a reference for the development of prevention strategies to protect the population from the adverse effects of PM2.5 pollution.

Land Subsidence Monitoring and Building Risk Assessment Using InSAR and Machine Learning in a Loess Plateau City—A Case Study of Lanzhou, China

As a representative city located in the Loess Plateau region of China, Lanzhou is affected by various environmental and engineering factors, such as precipitation, earthquake subsidence, and building construction, which all lead to frequent geological disasters. Obtaining information on land subsidence over a long time series helps us grasp the patterns of change in various types of ground hazard. In this paper, we present the results of using Interferometric Synthetic Aperture Radar (InSAR) to monitor land subsidence in the main urban area of Lanzhou from 26 October 2014 to 12 December 2021. The main influential factors leading to subsidence were analyzed and combined via machine learning simulation to assess the land subsidence risk grade distribution of a building unit. The results show that the annual average deformation rate in Lanzhou ranged from −18.74 to 12.78 mm/yr. Linear subsidence dominated most subsidence areas in Lanzhou during the monitoring period. The subsidence areas were mainly distributed along the Yellow River, the railway, and villages and towns on the edges of urban areas. The main areas where subsidence occurred were the eastern part of Chengguan District, the railway line in Anning District, and the southern parts of Xigu District and Qilihe urban area, accounting for 38.8, 43.5, 32.5, and 51.8% of the area of their respective administrative districts, respectively. The random forest model analysis results show that the factors influencing surface subsidence in Lanzhou were, in order of importance, precipitation, the distribution of faults, the lithology of strata, high-rise buildings, and the distance to the river and railway. Lanzhou experienced excessive groundwater drainage in some areas from 2015 to 2017, with a 1 m drop in groundwater and 14.61 mm surface subsidence in the most critical areas. At the same time, extensive subsidence occurred in areas with highly compressible loess ground and most railway sections, reaching a maximum of −11.68 mm/yr. More than half of the super-tall building areas also showed settlement funnels. The area at a very high risk of future subsidence in Lanzhou covers 22.02 km2, while the high-subsidence-risk area covers 54.47 km2. The areas at greatest risk of future subsidence are Chengguan District and Qilihe District. The city contains a total of 51,163 buildings in the very high-risk area, including about 44.57% of brick-and-timber houses, 51.36% of old housing, and 52.78% of super-tall buildings, which are at especially high risk of subsidence, threatening the lives and properties of the population. The deformation results reveal poor building safety in Lanzhou, providing an essential basis for future urban development and construction.

Ecological technology of green building in the initial stage of design based on BIM technology

At present, the whole world is faced with a common topic, that is, the contradiction between energy consumption, serious fog, the continuous rise of PM2.5, plastic waste, white pollution and other environmental pollution and the worldwide energy shortage. In this paper, aiming at the international new town construction project in Xigu District, Lanzhou, Revit software is used to establish a physical model for data integration and integrated management of the geometric information of building space, functional information of building space, building materials and other related data information of the project, and an analysis model for the scheme design of the residential building of the project is obtained, and ecological and technical factors such as energy consumption analysis, lighting analysis, indoor lighting analysis, solar radiation analysis, shading and thermal comfort analysis of the project location are analyzed. The research shows that the thermal performance, energy consumption simulation analysis and hourly heat gain/loss analysis of the envelope in the coldest weather in the local area show that the heat conduction of the envelope is small under the three conditions of structural design (case A), standard limit (case B) and hypothetical construction (case C), which indicates that the solar radiant heat is mainly related to the material performance of the external window when the heat transfer coefficient of the roof is close, and the heat gain and loss between regions has little change.

Risk Assessment and Attribution Analysis of "Five Toxic" Heavy Metals in Cultivated Land in Lanzhou

Heavy metals in cultivated soil may migrate and transform through the food chain to harm the ecological environment and human health. At present, the ecological environment and human health risks of heavy metals in cultivated soil in Lanzhou city remain unclear, which impacts the effective management and control of heavy metals. The potential ecological risk hazard index was used to evaluate the ecological environmental risks of As, Cd, Cr, Hg, and Pb in the surface soil of cultivated land in Lanzhou, and the health risk model proposed by USEPA and the recommended standard were used to evaluate their human health risk. The main factors influencing the spatial differentiation of human health risk were explored by using geographic detectors. The risk of heavy metals to the ecological environment of the cultivated land surface soil in the study area was mainly medium (65.25%), and small portions were low (13.80%) and high (20.95%). The low-risk areas were mainly located in the southeast of Yongdeng County, the middle and north of Yuzhong County, and the southwest of Gaolan County. Moderate risk areas were distributed in three counties and five districts. The high-risk areas were located in the north and southeast of Yongdeng County, the south of Chengguan District, the northeast of Qilihe, the east of Xigu District, and the middle of Yuzhong County. The non-carcinogenic and carcinogenic risks of five types of heavy metal exposure pathways were as follows:oral ingestion>skin contact>respiratory ingestion; generally speaking, children were at higher risk than adults. The non-carcinogenic risk in children was higher than that in adults; however, there was no such risk for local residents, as they were all less than 1. At the same time, the carcinogenic risk of As was greater than 1×10-5 (children 2.04×10-5) and less than 1×10-4 (adults 1.91×10-5), respectively. This indicated an acceptable medium risk to the local residents, and the risk to children was again greater than that to adults. Geographical detector analysis showed that average precipitation during the sampling season had the greatest impact on the spatial differentiation of human health risks of As and Cd, GDP had the greatest impact on the spatial differentiation of human health risks of Cr, and distance from the railway had the greatest impact on the spatial differentiation of human health risks of Hg and Pb. Interaction detection showed that all factors were enhanced by double factors. In addition to leading factors, other factors such as pH, slope, and altitude also enhanced the influence of leading factors on the spatial differentiation of heavy metal risk in cultivated soil.

The Influence of Environment Factors on Chronic Non-Communicable Diseases in a Heavy Industry City—A Case of Xigu District of Lanzhou City

Taking Xigu District of Lanzhou City as an example, this paper systematically analyzes the spatio-temporal distribution characteristics of patients with chronic non-communicable diseases (NCD) and compares the differences between heating period and non-heating period. Furthermore, the impact paths of natural environmental factors and built-up environmental factors on NCD are probed with the help of the geographic detector. The results are as follows: In time, the incidence of NCD in Xigu district fluctuated from 2012 to 2019. In space, there was an overall declining trend in high incidence rate from the central area to the surrounding areas, among which Xigucheng street was the high-risk area. The incidence of NCD in heating period was higher than that of in non-heating period, and the number of H-H cluster areas was witnessed an obviously increasing growth in Sijiqing Street. There are significant differences in the explanatory power of different factors (if any) for NCD. The explanatory power of each index in Xigu District is as follows: Facility > SO2 > NO2 > PM2.5 > food > Beverage Service > Green Facilities > Traffic Regulations > medical facilities. The interaction between plant facilities and SO2 has the strongest effect on NCD. Except for the negative correlation between greening and medical facilities and the incidence of NCD, all the influencing factors were positively correlated with NCD.

The characteristics and change trends of air pollutants in Lanzhou City from 2014 to 2020

To study the distribution characteristics of atmospheric pollutants and their correlation with meteorological factors. The PM_(2.5), PM_(10), NO_2, SO_2, O_(3-1 h), O_(3-8 h) and CO daily average concentration data from 2014 to 2020 were obtained from Lanzhou Environmental Protection Bureau. The interannual changes of pollutants, monthly changes, seasonal changes and trend of spatial distribution were analysed. Spearman correlation analysis was performed on the relationship among pollutants. The main pollutants exceeding the standard in Lanzhou from 2014 to 2020 were PM_(10), PM_(2.5) and NO_2, average annual concentration of PM_(10), PM_(2.5), NO_2 and CO were decreasing year by year, and O_3 was increasing year by year. The monthly average concentration of PM_(10) was the highest in December, January, March and November were the second highest, and it was higher in February, April and May. The monthly change trends of PM_(2.5), NO_2, SO_2 and CO concentrations were the same, and the monthly change trends of the 1 hour average and daily maximum 8-hour average concentrations of O_3 were the same. The seasonal variation of atmospheric pollutant concentration was obvious, the concentrations of PM_(10), PM_(2.5), SO_2, NO_(2 )and CO were the highest in winter and the lowest in summer. O_3 concentration was the highest in summer and lowest in winter. Average annual concentration of 6 pollutants in different regions had statistically significant differences(H=750.40, 1112.99, 1410.05, 352.04, 360.17, 619.20, 729.52; P<0.001). Among them, the average annual concentration of PM_(10), PM_(2.5), SO_(2 )and O_(3-1 h) in Xigu District were the highest. PM_(10), PM_(2.5), NO_2, SO_2, CO average annual concentration were negatively correlated with temperature and wind speed(r_s=-0.423, -0.561, -0.395, -0.660, -0.569, -0.043, -0.094, -0.130, -0.172, -0.135), the concentration of PM_(10), PM_(2.5), O_3, SO_2 concentration were negatively correlated with humidity(r_s=-0.238, -0.121, -0.110, -0.094), only O_3 was positively correlated with temperature(r_s=0.486). The primary pollutants in Lanzhou from 2014 to 2020 were PM_(10), PM_(2.5) and NO_2.O_3 had an obvious upward trend year by year. The 6 pollutants had obvious seasonal changes and regional distribution characteristics. Some pollutants had the same homology, and meteorological factors affected each pollution. The concentration of the substance had an important influence. Relevant air pollution control measures should be formulated based on the main excessive pollutants, the monthly change trend of air pollution and the seasonal pollution characteristics, the same emission sources and geographical distribution characteristics should be considered, and the meteorological factors should be combined.

A coupled study of ecological security and land use change based on GIS and entropy method-a typical region in Northwest China, Lanzhou.

Due to rapid population growth, industrialization, and urbanization, it is particularly important to address the increasingly serious ecological security issues in the process of urbanization, while it is important to grasp the impact of changes in land use structure on ecological security for scientific planning and to aid decision-making. As a typical valley basin industrialized city in northwest China, Lanzhou has complex geomorphology and climate with distinct regional characteristics, and the relationship between land use and ecological security is complex. In order to understand the current status and influencing factors of ecological security in various regions of Lanzhou, and to explore the intrinsic connection between ecological security and land use, this study constructed an ecological security evaluation index system based on the pressure-state-response (PSR) model with 14 secondary factors including natural, social, and economic factors. Based on the entropy method, GIS was used to analyze the trend of ecological security in each district and to clarify the coupling relationship between ecological security and land use change in Lanzhou City. The results show that the ecological security index (ESI) of Xigu District, a typical heavy industrial area, increased from 0.26 to 0.35, and the ESI of Yuzhong County, an agricultural development area, increased from 0.51 to 0.55 from 2000 to 2017. Low ESI was mainly distributed in areas with developed heavy industry, while high ESI was mainly found in areas with favorable natural conditions and mainly agricultural development. Economic factors were the leading factors affecting the ecological security of Lanzhou. In general, changes in land use structure and ecological security were inextricably linked, and the two influence and interact with each other. These results could provide some reference for the study of ecological security development and land use change in typical river valley cities and also provide a new path for other cities to study ecological security and the conservation of the ecological environment.

Trend of atmosphreic PM_(2. 5) and their components in two districts of Lanzhou City from 2015 to 2019

To analyse the variation of the fine particulate matter(PM_(2. 5)) concentration and its chemical composition in two districts of Lanzhou City from 2015 to 2019. From January 2015 to December 2019, two sampling points, namely residential district(Chengguan District) and industrial district(Xigu District) were selected in Lanzhou City, to collect PM_(2. 5) samples, and the mass concentrations, metals and metalloid elements, water-soluble ions and polycyclic aromatic hydrocarbons(PAHs) contents were determined. A total of 838 samples were collected in Chengguan District and Xigu District in Lanzhou City during 2015-2019, the average annual mass concentration and the daily average concentration of the PM_(2. 5) were decreasing year by year(P<0. 05). The higher metal content in PM_(2. 5) were Al, Pb, Mn and As during 2015-2019. Sb, Al, As, Cd, Cr, Pb, Mn and Tl element content were higher in 2015 and 2016 than in other years(P<0. 05), the average annual concentration of As were 7. 92 and 8. 63 ng/m~3 respectively, which exceeded the reference concentration limit of the ambient air quality standard. The average annual mass concentration of Cr from 2015 to 2019 was much higher than the annual average reference concentration limit of the ambient air quality standard. From 2015 to 2019, except for 2018, the highest average concentration of PAHs in atmospheric PM_(2. 5) in the two districts of Lanzhou City was Ant, B(b)F and I(cd)P mass concentration were highest in 2015, N(a)P, FI, Ace, Phe, Ant, Flu, Pyr, B(k)F and B(a)P mass concentration were highest in 2017, Acy, Chr and B(ghi)P mass concentration were highest in 2018(P<0. 05). From 2017 to 2018, the average annual content of B(a)P in the two districts of Lanzhou City were 1. 16 and 1. 11 ng/m~3, respectively, which exceeded the annual average concentration limit of the ambient air quality standard. The concentration of Cl~- in PM_(2. 5) in the two districts of Lanzhou City was decreasing year by year, the annual average concentrations of SO~2-_4, NO~-_3 and NH~+_4 from 2017 to 2019 showed a downward trend year by year. SO~2-_4, Cl~- of both districts were the highest in 2015, and NO~-_3, NH~+_4 were the highest in 2017(P<0. 05). The air quality of Lanzhou City has been improved obviously, but the pollution problem is still serious.

Concentration changes of ten metal and metalloid elements in atmospheric PM_(2. 5) in two districts of Lanzhou City from 2015 to 2018

To detect the concentrations of ten metals and metalloid elements in the atmospheric PM_(2. 5) in Chengguan district and Xigu district of Lanzhou City from 2015 to 2018, and analyze the pollutant concentration and its change trend. From 2015 to 2018, 662 samples of PM_(2. 5) were collected from Chengguan district and Xigu district of Lanzhou City. The concentrations of 10 kinds of metals and metalloid elements such as lead(Pb), arsenic(As), mercury(Hg), cadmium(Cd), chromium(Cr), antimony(Sb), manganese(Mn), nickel(Ni), selenium(Se), beryllium(Be) were detected, and the change trends of different monitoring points, years, seasons and months were analyzed. There was a significant difference in lead content between Chengguan District and Xigu District(χ~2=4. 80, P<0. 05), the median of Pb content in Chengguan and Xigu District was 45. 30 and 37. 20 ng/m~3, which was higher than that in Xigu District; the difference of Mn content in the two districts was statistically significant(χ~2=21. 28, P<0. 05), the median in two District was 32. 04 and 23. 37 ng/m~3, which was higher than that in Xigu District; the median of Be content in the two districts was statistically significant(χ~2=11. 57, P<0. 05), and the median of Be content in two districts was 0. 05 and 0. 07 ng/m~3, Xigu Distric was higher than Chengguan, there was no significant difference in other seven elements(P>0. 05). From 2015 to 2018, the element content of PM_(2. 5) in Chengguan District decreased by 47. 66% compared with 2015; Xigu District in 2018 decreased by 43. 79% compared with 2015; the higher element Pb, Mn and As in Chengguan District decreased by 52. 93%, 47. 00% and 49. 37% compared with 2015; in Xigu District, the content in 2018 decreased by 46. 87%, 47. 49% and 41. 98%compared with 2015, the contents of the remaining seven elements decreased in 2018 compared with those in 2015. There was no statistical significance(P>0. 05) in different seasons except for the difference of Ni content(P<0. 05), and the content of other elements showed a significant seasonal change: winter>spring>autumn> summer. The trend of monthly concentration change in the two regions was basically the same, the concentrations of Sb, As, Pb, Mn, Cd, Ni, Se, Hg and Cr were higher in November and February of next year. In Chengguan District and Xigu District, Ni content was higher in July and August, respectively;and Hg in Xigu District was higher in June, and Be was higher in less months, especially in February, October and December. From 2015 to 2018, the levels of 10 metals and metalloids element pollutants in PM_(2. 5) samples from Chengguan District and Xigu District of Lanzhou City showed a decreasing trend year by year, and had obvious seasonal changes.

Distribution characteristics and health risk assessment of volatile organic compounds in the groundwater of Lanzhou City, China.

Volatile organic compounds (VOCs) typically exist in the aqueous environment due to global anthropogenic activities. The distribution and contaminated profile (or characteristics) of VOCs in the groundwater of Lanzhou, China, were investigated in this study. Groundwater samples were collected from 30 sampling points in December 2015, and a total of 17 VOCs were analyzed by purge and trap gas chromatography-mass spectrometry. Thirteen types of VOCs were detected at 29 sampling points in the study area. Of these, dichloromethane and toluene, which were found at 22 sampling points, had the highest detection frequency (73.3%), followed by benzene (66.7%), 1,2-dichloroethane (50%), and xylenes (50%). The highest average concentration among the detected VOCs was found for chloroform (5151.5μg/L). The spatial distribution of VOC contamination in four major urban areas of Lanzhou and the variation in VOC concentration caused by land use transitions were also analyzed. The results showed that Xigu district was the most polluted area in Lanzhou, mainly due to land use for industrial proposes. On the contrary, the samples for Anning district showed lower VOC concentrations because of better groundwater quality, which is associated with the absence of manufacturing industries in this region. The health risk assessment model developed by the United States Environmental Protection Agency was employed in this study to evaluate safety for drinking water use. This study found that despite considering the volatilization of VOCs from water due to heating, six sampling points (G05 in Qilihe district; G07 and G09 in Xigu district; G16, G17, and G15 in Chengguan district) showed non-carcinogenic risks, ranging from 1.63 to 14.2, while three points (G16 in Chengguan district, and G10 and G07 in Xigu district) exhibited high carcinogenic risks for human health, ranging from 2.94 × 10-4 to 6.85 × 10-4. Trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene were identified as the dominant VOCs, presenting high non-carcinogenic risk. 1,2-dichloroethane and vinyl chloride were the primary factors for high carcinogenic risk. The high-risk areas were concentrated in Xigu and Chengguan districts, suggesting the need to alert the relevant local government departments.

Refined Assessment of Exposure and Health Risks of Heavy Metals in Water for the Children in Xigu District, Lanzhou

Water is an important pathway for human exposure to heavy metals. Accurate assessment of the health risks that are related to exposure to heavy metals in drinking and household water are required for the preparation of targeted health risk prevention measures. This study explores and identifies the health risks related to exposure to heavy metals via drinking and household water pathways in Xigu District, Lanzhou, northwestern China, using household water samples and survey data obtained during July-September 2015 (wet season) and December 2015-January 2016 (dry season). During each period, drinking water and household water that were available for use by children aged 0-5 and 6-17 years were sampled and a questionnaire on water-related behavior patterns was completed for each household. Cd, Cr, Pb, and As concentrations were analyzed in all water samples, and were used along with water-related exposure factors from the questionnaires to estimate exposure doses and associated health risks using models recommended by the United States Environmental Protection Agency (US EPA). The results showed that the concentrations of Cd, Cr, Pb, and As in both drinking and household water samples did not exceed the relative thresholds defined in China's national water quality standards. The concentrations of heavy metals in household water were more affected by seasonal factors than of those of drinking water. The non-cancer and cancer risks were in the ranges of 2.82×10-8-2.43×10-2 and 7.55×10-9-3.62×10-5, respectively, which are within acceptable levels, although the non-cancer and cancer risks from drinking water were both higher than of those determined for household water. Furthermore, the non-cancer and cancer risks from household water for children aged 0-5 years were lower than of those for children aged 6-17 years in each period. However, the cancer risk from drinking water for children aged 0-5 years was lower than of that for children aged 6-17 years, whereas the reverse was found for non-cancer risks. This study indicates that Cd, Cr, Pb, and As in drinking and household water did not pose significant detrimental effects to human health, and that the refined exposure assessment used could reduce uncertainties in health risk assessments.

Ecological Change Analysis of Lanzhou City Based on Remote Sensing Ecological Index

Abstract. Lanzhou City is the capital of Gansu Province and located in the semi-arid of northwest China. The Yellow River passing through the inner city from west to east, which has formed a special ecological environment. In recent years, the economic level of Lanzhou City has continued to develop, and the degree of urbanization has been continuously improved, which has had a certain impact on the ecological environment of the city. This paper used the Remote Sensing Ecology Index (RSEI) model (Xu, H.Q.,2013) to assess the ecological changes of the four major urban areas Chengguan District, Qilihe District, Anning District and Xigu District of Lanzhou from 2013 to 2017, and evaluate the current ecological environment of the city to provide a basis for the sustainable development of the city.

Formation Potential of Ozone and Secondary Organic Aerosol of VOCs from Fossil Fuel Combustion in Lanzhou City

With the rapid development of China's industry and the acceleration of urbanization, the massive use of fossil fuels has increased the concentration of air pollutants such as sulfur dioxide, particulate matter, and volatile organic compounds (VOCs) in the cities. However, there is little research on the environmental impact of volatile organic compounds from fossil fuel combustion emissions. In this paper, ozone formation potential(OFP)and secondary organic aerosol formation potential (SOAFP) of VOCs from fossil fuel combustion in Lanzhou city were calculated. The OFP and SOAFP of the cement industry were the largest, representing 45.3% and 50.9%, respectively, followed by brick and tile industries. However, when the calculations were based on tons of standard coal equivalent, the largest contributors to OFP and SOAFP of VOCs emitted from combustion were the brick and tile industries, and the smallest was the natural gas industry. VOCs from fossil fuel combustion of power plants and industry enterprises in the Xigu District are the main contributors to the OFP and SOAFP in the urban district of Lanzhou city. The contribution rates of the aromatic hydrocarbons from fossil fuel to OFP and SOAFP account for 40.0% and 67.2%, respectively. Aromatic hydrocarbons are also the main component in the top 10 species that contribute to OFP and SOAFP. The mass ratio of OFP and SOAFP per VOCs from fossil fuel combustion (2.58 t·t-1, 3.16 kg·t-1) is larger than those from biomass combustion (2.22 t·t-1, 1.38 kg·t-1).

The levels of polycyclic aromatic hydrocarbons (PAHs) in human milk and exposure risk to breastfed infants in petrochemical industrialized Lanzhou Valley, Northwest China

We investigated in this paper the presence of PAHs in human milk from lactating women residing in Lanzhou, a petrochemical industrialized valley city in Northwest China. The PAH concentration levels in human milk samples from 98 healthy women were determined by gas chromatography/mass spectrometry (GC/MS). The associations between the lifestyle factors and the PAHs levels of human milk were analyzed. Moreover, we applied principal component analysis (PCA) method to gain a better insight into the similarities or dissimilarities of the human milk PAH loads and different pathways of source exposure. In addition, the exposure risks of breastfed infants due to PAH ingestion via breast milk were assessed and the relative breast-feeding risk to the total intake dose of infants was addressed. The results showed that the average fat-normalized human milk ∑15PAHs concentrations for the lactating women residing in four districts of Lanzhou, namely, Xigu, Anning, Qilihe, and Chengguan were 320.40, 270.36, 374.04, and 259.84ng/g of fat, respectively. The ∑15PAHs of human milk from the lactating women of Qilihe District exhibited the highest concentration level, while the concentration level for women from Xigu District is the second highest for the observed human milk ∑15PAHs. And the corresponding BaPeq concentrations for women in Xigu, Anning, Qilihe, and Chengguan districts were 58.29, 47.95, 65.13, and 45.60ng/g of fat, respectively. A significant correlation was only found between human milk and living district environment (p < 0.05). Although the Spearman correlation analysis showed that there were no significant correlation existing between other lifestyle and human milk PAHs, we confirmed that consuming barbecue food could elevate PAHs levels in human milk: the barbecue intake frequency caused 10% fluctuation of ∑15PAHs concentration between high frequency and low frequency group in our study. Furthermore, the exposure to second-hand smoke can also increase the ∑15PAHs levels in human milk by 4 to 11% here. Ingestion doses of PAHs by infants (19.37-77.75ngkg-1day-1) were much higher than the inhalation doses (2.83-16.48ngkg-1day-1), which indicated that the ingestion is the main exposure risk pathway for infants. Since there are limited guidelines and standards for PAHs ingestion dose in human milk by infant, we compared the ingestion dose of BaP with the upper bound estimates of BaP dietary exposure of 108ngkg-1day-1 for toddlers of ages between 1.5 and 2.5years of age in the UK reported by Committee on Toxicity of Chemicals in Food (COT) and the data we obtained were lower than this upper bound. However, the estimated margin of exposure (MOE) values of BaP-MOE, PAH2-MOE, PAH4-MOE, and PAH8-MOE were smaller than 10,000 which indicated that there are potential hazard for breastfed infants consuming these human milk samples.

Spatial distribution of atmospheric PAHs and their genotoxicity in petrochemical industrialized Lanzhou valley, northwest China.

The present study investigated the spatial and seasonal variations and sources of 16 priority polycyclic aromatic hydrocarbons (PAHs) in Lanzhou, a petrochemical industrialized and the capital city of Gansu province, northwest China. The human health risks to these PAHs were assessed using an in vitro genotoxic bioassay technique. Associations among direct genotoxic potency, atmospheric PAH concentrations, and potential carcinogen risks were examined. Due to high PAH emissions from fossil fuel combustion and petrochemical industries, considerable higher PAH levels in the atmosphere were observed in Xigu district, a suburb featured by heavy petrochemical industry, compared with those collected at downtown and rural sampling sites. Ambient PAH levels at all sampling sites during the wintertime were higher than that in the summertime due to the winter domestic heating. BaP equivalent (BaPeq) concentrations in winter (41ng/m3) and summer (28ng/m3) exceeded the China's new national daily BaPeq standard. The average excess inhalation cancer risks (ECR) due to human exposure to PAHs during winter and summer sampling periods were 45-3540 cancer cases and 31-2451 cases per million people, respectively. The average ECR in the industrial area of Lanzhou valley was 1.97 (winter) and 1.88 times (summer) higher than that in other sampling areas. The higher ECR in the industrial area was resulted primarily by industrial activities and insufficient emission control measures. Extracts from passive air samples in genotoxicity SOS/umu test demonstrated that the genotoxic effect of atmospheric PAHs in Lanzhou was seasonal dependent. PAH air samples collected in winter showed more statistically significant genotoxicity, as manifested by a strong correlation between in vitro genotoxicity and atmospheric PAH concentrations. This indicates that the local residents were under higher potential cancer risk through the inhalation of ambient PAH air concentrations in Lanzhou valley during the wintertime.

Chemical composition and source apportionment of PM10 and PM2.5 in different functional areas of Lanzhou, China

To elucidate the air pollution characteristics of northern China, airborne PM10 (atmospheric dynamic equivalent diameter≤10μm) and PM2.5 (atmospheric dynamic equivalent diameter≤2.5μm) were sampled in three different functional areas (Yuzhong County, Xigu District and Chengguan District) of Lanzhou, and their chemical composition (elements, ions, carbonaceous species) was analyzed. The results demonstrated that the highest seasonal mean concentrations of PM10 (369.48μg/m3) and PM2.5 (295.42μg/m3) were detected in Xigu District in the winter, the lowest concentration of PM2.5 (53.15μg/m3) was observed in Yuzhong District in the fall and PM10 (89.60μg/m3) in Xigu District in the fall. The overall average OC/EC (organic carbon/elemental carbon) value was close to the representative OC/EC ratio for coal consumption, implying that the pollution of Lanzhou could be attributed to the burning of coal. The content of SNA (the sum of sulfate, nitrate, ammonium, SNA) in PM2.5 in Yuzhong County was generally lower than that at other sites in all seasons. The content of SNA in PM2.5 and PM10 in Yuzhong County was generally lower than that at other sites in all seasons (0.24–0.38), indicating that the conversion ratios from precursors to secondary aerosols in the low concentration area was slower than in the area with high and intense pollutants. Six primary particulate matter sources were chosen based on positive matrix factorization (PMF) analysis, and emissions from dust, secondary aerosols, and coal burning were identified to be the primary sources responsible for the particle pollution in Lanzhou.

A toxicological study of inhalable particulates in an industrial region of Lanzhou City, northwestern China: Results from plasmid scission assay

The city of Lanzhou in northwestern China experiences serious air pollution episodes in the form of PM10 that is characterized by having high levels of heavy metals. The Xigu District represents the industrial core area of Lanzhou City and is denoted by having the largest petrochemical bases in western China. This study investigates heavy metal compositions and oxidative potential of airborne PM10 (particulate matter with aerodynamic diameter of 10 μm or less) collected in Xigu District in the summer and winter of 2010. An in vitro plasmid scission assay (PSA) was employed to study the oxidative potential of airborne PM10 and inductively coupled plasma-mass spectrometry (ICP-MS) was used to examine heavy metal compositions. Transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (TEM/EDX) was used to investigate elemental compositions and mixing states of PM10. The average mass concentrations of PM10 collected in Xigu District were generally higher than the national standard for daily PM10 (150 μg/m3). Cr, Zn, Pb and Mn were the most abundant metals in the intact whole particles of PM10. Zn, Mn and As was the most abundant metal in the water-soluble fraction, while Cr, Pb, and V existed primarily in insoluble forms. TD20 values (i.e. toxic dosage of PM10 causing 20% of plasmid DNA damage) varied considerably in both winter and summer (from 19 μg/mL to >1000 μg/mL) but were typically higher in summer, suggesting that the winter PM10 exhibited greater bioreactivity. In addition, the PM10 collected during a dust storm episode had a highest TD20 value and thus the least oxidative damage to supercoiled plasmid DNA, while the particles collected on a hazy day had a lowest TD20 value and thus the highest oxidative damage to supercoiled plasmid DNA. The particles collected on the first day after snow fall and on a day of cold air intrusion exhibited minor oxidative potential (i.e. caused limited DNA damage). The water-soluble Zn, Mn, As, and Cu displayed a significant negative correlation with TD20 values, suggesting that these heavy metals were responsible for the increase of oxidative potential. The high mass concentration of PM10 and resulting high oxidative potential in Xigu District may be due to the constant low wind speed and high relative humidity, particularly in winter. Finally, TEM analysis suggested that the oxidative potential of PM10 may be associated with its degree of internal mixing, whereby the heterogeneous assortment of soot, mineral and metals created a highly reactive moiety.

Magnetic records of heavy metal pollution in urban topsoil in Lanzhou, China

This study is a systematic analysis of the magnetic characteristics and heavy metal elements in soil samples collected from Lanzhou City, China. The 117 surface soil samples were measured to study the feasibility and effectiveness of environmental magnetism for evaluating heavy metal pollution in urban soils. Results of the study indicate that low-coercivity magnetite dominates the magnetic properties in the samples. The high values of the soil magnetic mineral concentration parameters and low values of magnetic particle size parameters are distributed throughout the northern area of Xigu District, the industrial zones of the eastern section of Chengguan District and the districts of the narrow sections connecting Chengguan District and the other three districts; these parameters are fundamentally consistent with the distribution of the high values of the Pollution Load Index and Nemerow Pollution Index. Semi-quantitative studies which use the environmental magnetic method to monitor pollution of heavy metals (such as As, Cr, Cu, Ni, Pb, Zn, and Fe) have shown that when χlf⩽35×10−8 m3 kg−1, it is unpolluted; when 35 ⩽ χlf<150×10−8 m3 kg−1, it is moderately polluted to unpolluted; when 150 ⩽ χlf<365×10−8 m3 kg−1, it is moderately polluted; when 365 ⩽ χlf<750×10−8 m3 kg−1, χfd%<2.7 and χARM/SIRM<0.2×10−3 m A−1, it is moderately to highly polluted; when χlf⩾750×10−8 m3 kg−1, χfd%<2.7 and χARM/SIRM<0.2×10−3 m A−1, it is highly polluted. The region of moderately to highly polluted distribution is caused by industry and vehicles, showing that the change of pollution in Lanzhou City bears the trend of “vehicle emission + industrial”.

Short-term effects of air pollution on lower respiratory diseases and forecasting by the group method of data handling

Abstract Risk of lower respiratory diseases was significantly correlated with levels of monthly average concentration of SO 2 ; NO 2 and association rules have high lifts. In view of Lanzhou’s special geographical location, taking into account the impact of different seasons, especially for the winter, the relations between air pollutants and the respiratory disease deserve further study. In this study the monthly average concentration of SO 2 , NO 2 , PM 10 and the monthly number of people who in hospital because of lower respiratory disease from January 2001 to December 2005 are grouped equidistant and considered as the terms of transactions. Then based on the relational algebraic theory we employed the optimization relation association rule to mine the association rules of the transactions. Based on the association rules revealing the effects of air pollutants on the lower respiratory disease, we forecast the number of person who suffered from lower respiratory disease by the group method of data handling (GMDH) to reveal the risk and give a consultation to the hospital in Xigu District, the most seriously polluted district in Lanzhou. The data and analysis indicate that individuals may be susceptible to the short-term effects of pollution and thus suffer from lower respiratory diseases and this effect presents seasonal.