The rhamnogalacturonan-II dimer decreases intestinal absorption and tissue accumulation of lead in rats

The rhamnogalacturonan-II dimer (dRG-II) forms strong complexes in vitro with lead (Pb) and other selected cations. We examined the in vivo bioavailability of Pb complexed with dRG-II and the effect of unleaded dRG-II on the intestinal absorption and tissue retention of Pb in rats. Forty male Wistar rats were divided into four groups. Each group consumed a purified control diet for 3 wk or the same diet supplemented with: i) 3 mg of Pb/kg, ii) 0.5 g of leaded dRG-II/kg, or iii) 0.5 g of leaded dRG-II/kg and 4.5 g of unleaded dRG-II/kg. The leaded dRG-II provided approximately 3 mg of Pb/kg of diet. A chemical balance study was conducted during the last 5 d of the 3-wk study, and blood and organs were sampled for Pb and mineral analyses. The apparent intestinal absorptions of Pb were 62.3, 15.2, 11.8 and -0.1%, and Pb balances were 1.9, 9.6, 5.6 and -0.2 microg/d for the control and the three experimental groups, respectively. The Pb complexed with dRG-II was less available than Pb acetate, as reflected by significantly lower blood and tissue Pb levels. The addition of unleaded dRG-II decreased the intestinal absorption and the tissue retention of Pb significantly. We further found that the apparent absorption and status of magnesium, zinc and iron were unaffected by Pb treatment or dRG-II addition. We conclude that dRG-II may be useful in decreasing toxicity related to chronic Pb exposure. Human studies will be necessary however, to further evaluate the clinical utility of this beneficial effect.     

积累指数法对公路旁土壤中重金属污染的评价

目的评价公路旁土壤中重金属污染.方法以319国道龙岩市新罗区路段为例,应用积累指数法对公路环境土壤介质中重金属(Cu、Zn、Cd、Pb、As、Cr、Ni、Fe、Mn)污染叠加进行评价. 结果研究区土壤中Cd、Pb、Cr和Cu元素含量高于福建省土壤背景值,其平均含量分别是福建省土壤背景值的23.6倍、4.6倍、1.7倍和1.5倍.已形成强污染的元素为Cd,中等污染的元素为Pb,轻污染的元素为Cr.土壤对重金属元素的吸附及污染程度Cd＞Pb＞Cr＞Cu＞As＞Zn＞Ni＞Mn＞Fe.结论公路旁土壤中Cd、Pb污染严重,重金属污染物质主要来源于机动车辆燃料和轮胎中所含微量重金属成分.     

Comparative toxicity of tetra ethyl lead and lead oxide to earthworms,Eisenia fetida (Savigny)

Leaded gasoline contains tetra ethyl lead (TEL) as an antiknocking agent, which produces major amounts of lead oxide in automobile exhaust along with traces of TEL. To minimize the lead contamination, methyl tertiary butyl ether (MTBE) is used as a substitute for producing unleaded gasoline. It has become increasingly apparent that young children are highly susceptible to the harmful effects of lead. Hence, a study was carried out to monitor lead toxicity in soil, using adult earthworms (Eisenia fetida, Savigny). Leaded gasoline (TEL) and lead oxide are 383- and 211-fold more toxic than unleaded gasoline (MTBE) in 7 days of exposure and 627- and 290-fold more toxic in 14 days, respectively. Results indicate that the presence of TEL in leaded gasoline and lead oxide has a significant effect on behavior, morphology, and histopathology of earthworms. Absorption of TEL into the tissues is comparatively less than that of lead oxide but toxic effects were severe. Rupture of the cuticle, extrusion of coelomic fluid and inflexible metameric segmentation were observed, causing desensitization of the posterior region leading to fragmentation in earthworms.     

Heavy Metal Sources,Contamination and Risk Assessment in Legacy Pb/Zn Mining Tailings Area: Field Soil and Simulated Rainfall

This study investigated heavy metal(HM) soil pollution and evaluated the risk and sources at a legacy tailings pond’s area in Meizhou, China. Result shows that HM accumulation in soil, particularly Cd, Pb, and Zn, were serious. Zn and Cd in tailing soil and all studied elements in field soil had a significant release potential. Four HM sources were identified by positive matrix factorization (PMF) model: cinder and vehicle emissions (11.3%), natural sources (16.3%), tailings pond and human activities (32.8%), tailings pond (39.7%). The soil was severely polluted with Cd, Pb, and Zn, which posed a high potential environmental risk near surrounding area. Column leaching tests showed that large quantities of HMs were released from the tailings soil during simulated rainfall with different pH. This study indicates that the study area has been severely polluted and continues to have a great risk of HM pollution under natural conditions.

     

Impact of a Long Term Fire Retardant (Fire Trol 931) on the Leaching of Na,Al, Fe,Mn, Cu and Si from a Mediterranean Forest Soil: A Short-Term,Lab-Scale Study

Long term fire retardant (LTR) application for forest fire prevention purposes as well as wildland fires can result in chemical leaching from forest soils. Large quantities of sodium (Na), aluminium (Al), iron (Fe), manganese (Mn), copper (Cu) and silicon (Si) in leachates, mainly due to ammonium (one of the major LTR components) soil deposition, could affect the groundwater quality. The leaching of Na, Al, Fe, Mn, Cu and Si due to nitrogen based LTR application (Fire Trol 931) was studied at laboratory scale. The concentrations of Na⁺, Al³⁺, Fe³⁺/Fe²⁺, Mn²⁺, Cu²⁺ and Si⁴⁺ were measured in the resulting leachates from pots with forest soil and pine trees alone and in combination with fire. The leaching of Na, Fe and Si from treated pots was significantly greater than that from control pots. The leaching of Al, Mn and Cu was extremely low.     

Iron plaque formation on roots of different rice cultivars and the relation with lead uptake

The relationships between lead (Pb) uptake and iron/manganese plaque formation on rice roots were investigated with three cultivars. The results showed that the rice cultivars with indica consanguinity were more sensitive to soil Pb stress than the cultivar with japonica consanguinity. Pb concentrations and distribution ratios in root tissues were in the order: Shanyou 63>Yangdao 6>Wuyunjing 7, but Pb and Fe concentrations and distribution ratios in the plaques showed a reverse order. Mn concentrations and distribution ratios in the plaques of Wuyunjing 7 were significantly higher (P<0.01 or 0.05) than those of Shanyou 63 and Yangdao 6. The results indicate that iron/manganese plaque on rice root can provide a barrier to soil Pb stress. The plaque will increase sequestration of Pb on rice root surface and in the rhizosphere, providing a means of external exclusion of soil Pb to some extent.     

Multiple metal contamination from house paints: consequences of power sanding and paint scraping in New Orleans.

Power sanding exterior paint is a common practice during repainting of old houses in New Orleans, Louisiana, that triggers lead poisoning and releases more than Pb. In this study we quantified the Pb, zinc, cadmium, manganese, nickel, copper, cobalt, chromium, and vanadium in exterior paint samples collected from New Orleans homes (n = 31). We used interior dust wipes to compare two exterior house-painting projects. House 1 was measured in response to the plight of a family after a paint contractor power sanded all exterior paint from the weatherboards. The Pb content (approximately 130,000 microg Pb/g) was first realized when the family pet died; the children were hospitalized, the family was displaced, and cleanup costs were high. To determine the quantity of dust generated by power sanding and the benefits of reducing Pb-contaminated dust, we tested a case study house (house 2) for Pb (approximately 90,000 microg/g) before the project was started; the house was then dry scraped and the paint chips were collected. Although the hazards of Pb-based paints are well known, there are other problems as well, because other toxic metals exist in old paints. If house 2 had been power sanded to bare wood like house 1, the repainting project would have released as dust about 7.4 kg Pb, 3.5 kg Zn, 9.7 g Cd, 14.8 g Cu, 8.8 g Mn, 1.5 g Ni, 5.4 g Co, 2.4 g Cr, and 0.3 g V. The total tolerable daily intake (TTDI) for a child under 6 years of age is 6 microg Pb from all sources. Converting 7.4 kg Pb to this scale is vexing--more than 1 billion (10(9)) times the TTDI. Also for perspective, the one-time release of 7.4 x 10(9) microg of Pb dust from sanding compares to 50 x 10(9) microg of Pb dust emitted annually per 0.1 mile (0.16 km) from street traffic during the peak use of leaded gasoline. In this paper, we broaden the discussion to include an array of metals in paint and underscore the need and possibilities for curtailing the release of metal dust.     

Metal sources and exposures in the homes of young children living near a mining-impacted Superfund site

Children living near hazardous waste sites may be exposed to environmental contaminants, yet few studies have conducted multi-media exposure assessments, including residential environments where children spend most of their time. We sampled yard soil, house dust, and particulate matter with aerodynamic diameter <2.5 in 59 homes of young children near an abandoned mining area and analyzed samples for lead (Pb), zinc (Zn), cadmium (Cd), arsenic (As), and manganese (Mn). In over half of the homes, dust concentrations of Pb, Zn, Cd, and As were higher than those in soil. Proximity to mine waste (chat) piles and the presence of chat in the driveway significantly predicted dust metals levels. Homes with both chat sources had Pb, Zn, Cd, and As dust levels two to three times higher than homes with no known chat sources after controlling for other sources. In contrast, Mn concentrations in dust were consistently lower than in soil and were not associated with chat sources. Mn dust concentrations were predicted by soil concentrations and occupant density. These findings suggest that nearby outdoor sources of metal contaminants from mine waste may migrate indoors. Populations farther away from the mining site may also be exposed if secondary uses of chat are in close proximity to the home.     

厨房空气中烹调油烟有害成分的测定和分析

目的研究3种类型民用燃料燃烧的烹调油烟中气态污染物（SO2、NO2、CO、CO2）及颗粒物（PM2.5、PM10）的污染状况,并分析PM2.5、PM10中8种金属元素（铅、铬、铜、镉、锰、锌、铁、汞）和两种多环芳烃（菲、苯并[a]芘）的含量。方法采用气体检测仪检测SO2、NO2、CO、CO2值;采用称重法分析PM25和PM10的质量浓度,石墨炉原子吸收分光光度法定量检测PM25和PM10中铅、铬、铜、镉,火焰原子吸收分光光度法定量检测PM2.5和PM10中锰、锌、铁,冷原子吸收法定量检测PM2,和PM10中汞,高效液相色谱法定量检测PM2,和PM10中菲、苯并[a]芘浓度。结果SO2、NO2、CO、CO2及PM2.5、PM10的浓度均超过室内空气质量标准规定的浓度限值,其中超标倍数较大的分别是天然气的CO2（5．2）,液化石油气的NO2（11．1）,蜂窝煤的SO2（12．4）、CO（16．5）;天然气的PM2.5、PM10超标倍数分别是117．0、145．5。PM2.5、PM10的金属成分分析结果显示锰、锌、铁含量较高,铅、铜次之,铬、镉、汞含量最低;PM2.5、PM10的多环芳烃类有机成分菲、苯并[a]芘含量均较高。结论3种类型燃料燃烧产生的烹调油烟中气态污染物及颗粒物污染严重,不同类型燃料产生的污染物污染状况不同,PM2.5、PM10中金属元素及多环芳烃类有机成分污染水平较高,烹调油烟可能是居室内空气污染主要来源,且污染程度严重。     

公路旁土壤中重金属和类金属污染评价

目的 评价公路旁土训重金属和类金属污染。方法 选择３１９国道龙岩市新罗区路段进行土壤４ 采样,用原子吸收光谱法和分光光度法分析封保重金属和类金属（Ｃｄ、Ｐｂ、Ｃｕ、Ｚｎ、Ｎｉ、Ｃｒ、Ａｓ）的含量。结果 土壤综合污染指数为１．６３,ｄ、ｂ,轻度污染的元素为Ｃｕ、Ｃｒ,污染晕带自公路起向其两侧扩散范围约为２５０ｍ,土壤对重金属元素的吸附及污染程度：Ｃｄ〉Ｐｂ〉Ｃｕ〉Ｃｒ〉Ｚｎ〉Ｎｉ〉Ａｓ。结论 公路旁     

Changes in Metal Availability and Improvements in Microbial Properties After Phytoextraction of a Cd,Zn and Pb Contaminated Soil

Assessing the effects of phytoextraction on soil properties is important for successful implementation of this method. This study was conducted to evaluate the effects of phytoextraction by Sedum alfredii Hance on the availability of metals and improvement of the microbial community (biomass and structure) of a Cd, Zn and Pb contaminated soil. Phytoextraction significantly decreased the acid extractable, Mn/Fe oxide and organic matter bound fractions of Cd and Zn as well as the acid extractable Pb in the rhizosphere soil. Soil microbial biomass, total, bacterial, actinomycete, fungal, AM fungal, and protozoa phospholipid fatty acids (PLFAs) were significantly enhanced. The ratio of fungal to bacterial and gram-positive to gram-negative bacterial PLFAs were significantly changed. Redundancy analysis showed that microbial biomass and specific groups of PLFAs were negatively correlated with available metals while positively correlated with dissolved organic carbon/organic acids. In conclusion, phytoextraction by S. alfredii reduced available metal concentrations and improved soil microbial properties.     

电焊作业工人血中几种生物指标变化的探讨

目的　探讨电焊作业工人血中 5种微量元素、过氧化物歧化酶 (SOD)和脂质过氧化代谢产物———丙二醛 (LPO -MDA)及铁代谢蛋白的变化。方法　分别测定电焊作业工人 (锰暴露人群 )和对照人群全血SOD和血清LPO -MDA、铁、锰、铅、铜、锌及血清铁蛋白、转铁蛋白、转铁蛋白受体的浓度。结果　暴露组的SOD活性下降 ,LPO-MDA升高 ,与对照组比较有显著性差异 (P <0 0 5) ;暴露组血清转铁蛋白量比对照组高 1 19倍 ;转铁蛋白受体水平低于对照组 1 3 4倍。暴露组与对照组血清中 5种微量元素含量测定结果表明 ,暴露组锰和铁的含量均明显高于对照组 (P <0 0 1) ,而锌和铅的含量则明显低于对照组 (P <0 0 1)。结论　锰暴露导致作业工人血中的脂质过氧化(LPO -MDA)水平明显升高 ,参与铁代谢蛋白合成的血清转铁蛋白含量、转铁蛋白受体发生了变化 ,同时引起体内部分微量元素的失衡     

Lead, cadmium, manganese, cobalt, zinc and copper levels in whole blood of urban teenagers with non-toxic diffuse goiter

The amount of lead (Pb), cadmium (Cd), manganese (Mn), cobalt (Co), zinc (Zn), and copper (Cu) present in whole blood of 118 teenagers were determined by atomic absorption spectrometry. The blood samples of 23 healthy teenagers were compared with the blood samples of 95 adolescents who were diagnosed with non-toxic diffuse goiter (NTDG). The study was aimed at examining whether in addition to mild iodine deficiency other trace elements could contribute to the development of non-toxic diffuse goiter. The results indicated that the levels of Pb, Cd and Mn in the blood samples of teenagers diagnosed with NTDG were higher than that in healthy children. Also, the results indicated that higher levels of metals were present in the blood samples with NTDG in adolescent patients who lived in areas with a higher amount of pollution.     

典型燃煤污染型氟中毒病区氟斑牙流行程度与饮用水源化学元素组成的空间关联性

目的探讨燃煤污染型氟中毒病区氟斑牙流行程度与饮用水源化学元素组成的空间分布特征及其关联性。方法 2022年基于贵州省CDC氟斑牙流行程度的调查资料, 在典型燃煤污染型氟中毒区域采集274份原有地表饮用水源, 测定水中氟、钙、镁、铝、钛、铬、锰、铁、镍、铜、锌、砷、硒、钼、镉、钡、铅17种元素的含量;应用Moran’’sI指数、Getis-OrdGi*热点分析饮用水中化学元素的全局空间自相关性以及各元素在局部区域上聚集程度, 并与该区域氟斑牙流行程度进行关联分析。结果除铜、锌、镉元素全局空间自相关Moran’’sI指数为负值外, 其他元素均为正值;氟、钙、铝、钛、砷、钼、镉、铜元素在东南部低海拔地区呈高值聚集;镁、钡、铅、铬、锰、铁元素主要在中部海拔地势过渡区聚集, 锌、硒元素则主要聚集在西南部高海拔地区;水源中锌、硒元素与氟斑牙流行程度呈显著正相关(P<0.05), 而氟、镁、铝、钛、砷、钼、镉、钡、铅元素与之呈显著负相关(P<0.05)。氟、钙、铝、钛、砷、钼元素在东南部地区及锰、铁、钡元素在中部地区呈高-高聚集, 为疾病高发的热点聚集区, 而氟、铝、锰、钼、镉、钡元素在...     

Potential Risk by Disposal of Bottom Ash from Thermal Power Plants and Minimization by Addition of NaHCO<Subscript>3</Subscript>

In the present study, the leachability of traced elements from the bottom ash of three different Indian power plants was investigated. Environmental impact of bottom ash was studied by varying the liquid-to-solid (L/S) ratio from 20:1 to 60:1. Leaching results show the presence of a major proportion of elements Mn, Mg, Cr, Zn and Cu and a minor proportion of Pb, Fe, Co, and Mo. The effect of the addition of sodium bicarbonate (NaHCO₃) on leaching characteristics of bottom ash was also studied. Leaching concentration of bottom ash samples reduces with addition of additive from 0.2% to 0.6% and found to be optimum with 0.4% the addition of additive. This aspect of the investigation helps to design the ash disposal system for higher solid concentrations to minimize the environmental pollution.     

Heavy Metals in the Surface Sediments in Lanzhou Reach of Yellow River,China

The heavy metal pollution and their fractionations in the surface sediments of Yellow River in Lanzhou Reach was monitored for arsenic (As), lead (Pb), Zinc (Zn), chromium (Cr), copper (Cu) and manganese (Mn) with Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). The mean sediment concentrations (in μg/g dry weight) ranged from 13.68–48.11 (As), 26.39–77.66 (Pb), 89.80–201.88 (Zn), 41.49–128.30 (Cr), 29.72–102.22 (Cu), and 773.23–1459.69 (Mn). Spatial distribution showed that each heavy metal concentration remained almost constant in this reach. Correlation coefficients indicated that metals were not strongly associated with sediment sand content or organic carbon content (f_oc). Labile fractions (exchangeable + carbonate + Fe–Mn oxide) had no significant correlations with sand content or f_oc, either. Results from the present study are useful for understanding heavy metal distributions in a torrential river sediment environment.     

Pollution Characteristics,Sources, and Health Risk Assessments of Potentially Toxic Elements in Community Garden Soil of Lin’an,Zhejiang, China

The characteristics, sources and risk assessment of heavy metal pollution in community garden soil of Lin’an District were evaluated. The 28 soil samples from community garden were collected for determination of 7 heavy metal elements. The Geostatistical analysis, Spearman correlation coefficient, Principal component analysis and PMF model have explored sources of heavy metal pollution. The health risk assessment model has assessed ecological risk of heavy metals. The results revealed that average concentration of As, Cd, Cr, Cu, Ni, Pb and Zn were 16.0, 0.158, 76.1, 34.6, 45.8, 20.9 and 166 mg kg^-1, respectively. Whereas As, Cd, Cr, Cu, Ni and Zn were higher than background values. The spatial distribution of heavy metal pollution in the southwest of the study area was higher than northeast. The pollution sources of Cd, Cu, Ni and Zn in the study area were due to agricultural activities (42.9%), Cr and Pb were from traffic sources (36.2%), and As was domestic pollution (20.9%) according to Spearman correlation coefficient, Principal component analysis and PMF model. The non-carcinogenic risks of As (5.39), Cr (3.53) and Ni (2.07) have a value of 1, which indicated significant risk. The potentially toxic elements have not exceeded maximum threshold of USEPA, with regard to carcinogenic risk, while As (3.37E?05) and Cr (5.74E?05) have exceeded the safety range. It is concluded that soils of community gardens are facing pollution problem due to potentially toxic elements which require environmental monitoring of the soil to reduce risk of human health.

     

Changes in manganese and lead in the environment and young children associated with the introduction of methylcyclopentadienyl manganese tricarbonyl in gasoline--preliminary results

A 4-year longitudinal study is being conducted to evaluate potential changes to the environment and exposure of young children associated with the introduction of methylcyclopentadienyl manganese tricarbonyl (MMT) into Australia in 2001. The cohort consists of 57 females and 56 males, with an age range of 0.29-3.9 years. Samples are collected every 6 months from children in residences located at varying distances from major traffic thoroughfares in Sydney. Environmental samples include air, house, and daycare center dustfall, soil, dust sweepings, and gasoline; samples from the children include blood, urine, handwipes prior to and after playing outdoors, and a 6-day duplicate diet. All samples are analyzed for a suite of 20 elements using inductively coupled plasma methods. Results are presented for the first three 6-month sampling periods for lead (Pb) and manganese (Mn). For dustfall accumulation, expressed as metal concentration/m2/30 days, there was no significant difference between homes and daycare centers for either Pb or Mn, no significant change over the three sampling periods (time) for Pb or Mn, and a positive relationship between "traffic exposure" (traffic volume and proximity to the road) and Pb but not Mn. Lead concentrations in soil was a significant predictor for Pb in the house dustfall. For handwipes, the concentrations of Pb and Mn in wipes taken from children after playing outdoors was usually significantly greater than those for wipes taken prior to playing. There was no significant association between the concentrations of either Pb or Mn in handwipes and traffic exposure, and there was no significant association between Pb concentrations in the handwipes and gender, although the latter showed a marginally significant association for Mn (P = 0.053). Age was related to Pb level in the handwipes, with older subjects having higher Pb levels, and there were significant decreases in Pb and Mn concentrations over time. Dustfall accumulation was a significant predictor for Pb in the handwipes, and dust sweepings were a significant predictor of Mn in handwipes. Blood lead (PbB) concentrations ranged from 0.6 to 19 microg/dL (GM 2.6) (n = 269), and manganese in blood (MnB) ranged from 1.8 to 45 microg/L (GM 11.6) (n = 254). There was no significant difference between females and males for either mean PbB or MnB; over time there was a significant decline in PbB but no significant change in MnB. The only significant predictor for PbB was dustfall accumulation, although dietary intake may also be important, and the only significant predictor for MnB was Mn in handwipes prior to playing. At this early stage of the investigation we have not been able to detect any increases in Mn in these environmental samples or blood samples potentially associated with the use of MMT; in fact the Mn levels in handwipes declined over time.     

Heavy-Metal Levels in Feathers of Cattle Egret and Their Surrounding Environment: A Case of the Punjab Province, Pakistan

Levels of 10 heavy metals in cattle egret chick feathers, prey, and surrounding soils from three heronries in Punjab Province, Pakistan, were assessed by atomic absorption spectrophotometry. Mean levels of cadmium (Cd), iron (Fe), chromium (Cr), and lithium (Li) in feathers, manganese (Mn), cobalt (Co), and nickel (Ni) in prey, and lead (Pb), iron (Fe), chromium (Cr), zinc (Zn), cobalt (Co), and lithium (Li) in soils were significantly different among Trimun Headworks, Shorkot, and Mailsi heroneries. Mean levels of Pb (43.10 μg/g), Cr (35.77 μg/g), Co (18.34 μg/g), Cu (0.20 μg/g), and Ni (0.22 μg/g) in feathers were significantly greater at Mailsi, and Mn (3.07 μg/g), Zn (18.83 μg/g), and Li (1.5 μg/g) levels were significantly greater at Shorkot. Multivariate analysis identified that some metals, such as Fe, Zn, and Li, in feathers were either associated with natural sources or with human-related activities, whereas Ni, Cr, Pb, Cd, Cu, Co, and Mn were correlated mainly with anthropogenic processes. Alarming levels were recorded for Cr, Pb, and Cd in feathers that were above threshold levels that may affect cattle egret flighting capacity and reproduction, thus leading to their population decline in Punjab Province. The results of this study provide evidence for the potential of feathers of cattle egret to be used as a biomonitor for the local heavy-metal contamination.     

银川市大气PM2.5中12种元素污染特征及变化趋势分析

目的 分析银川市大气PM2.5中12种元素(锑、铝、砷、铍、镉、铬、汞、铅、锰、镍、硒、铊)的污染特征及变化趋势,为大气污染进一步治理提供科学依据。方法 2015年1月至2018年2月每月定期在银川市采集大气PM2.5,采用称重法和电感耦合等离子质谱法(ICP-MS)分别测定大气PM2.5及其元素的质量浓度,分析其污染特征及污染趋势。结果 2017年银川市大气PM2.5年均质量浓度较2015年、2016年明显降低,P＜0.05;2015年、2016年呈现明显的季节变化,冬春高、夏秋低,2017年四季变化趋势不明显。银川市大气PM2.5中金属元素Al、Pb、Mn含量较高,其它元素含量相对较低;从2015年到2017年元素Al、Pb、Mn、Sb、Be、Cd、Ni、Tl的质量浓度呈递降趋势。结论 从2015年至2017年,银川市空气质量明显好转,但空气污染的治理仍需要加强。