Heavy metals in bark of <Emphasis Type="Italic">Pinus massoniana</Emphasis> (Lamb.) as an indicator of atmospheric deposition near a smeltery at Qujiang,China

Goal, Scope and Background Rapid urbanization and the expansion of industrial activities in the past several decades have led to large increases in emissions of pollutants in the Pearl River Delta of south China. Recent reports have suggested that industrial emission is a major factor contributing to the damages in current natural ecosystem in the Delta area. Tree barks have been used successfully to monitor the levels of atmospheric metal deposition in many areas, but rarely in China. This study aimed at determining whether atmospheric heavy metal deposition from a Pb-Zn smeltery at Qujiang, Guangdong province, could be accurately reflected both in the inner bark and the outer bark of Masson pine (Pinus massoniana L.). The impact of the emission from smeltery on the soils beneath the trees and the relationships of the concentrations between the soils and the barks were also analyzed. Methods Barks around the bole of Pinus massoniana from a pine forest near a Pb-Zn smeltery at Qujiang and a reference forest at Dinghushan natural reserve were sampled with a stainless knife at an average height of 1.5 m above the ground. Mosses and lichens on the surface barks were cleaned prior to sampling. The samples were carefully divided into the inner bark (living part) and the outer bark (dead part) in the laboratory, and dried and ground, respectively. After being dry-ashed, the powder of the barks was dissolved in HNO₃. The solutions were analyzed for iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni) and cobalt (Co) by inductively coupled plasmas emission spectrometry (ICP, PS-1000AT, USA) and Cadmium (Cd) and lead (Pb) by graphite furnace atomic absorption spectrometry (GFAAS, ZEENIT 60, Germany). Surface soils (0–10 cm) beneath the sample trees were also collected and analyzed for the selected metals. Results and Discussion Concentrations of the selected metals in soils at Qujiang were far above their environmental background values in the area, except for Fe and Mn, whilst at Dinghushan, they were far below their background values, except for Cd and Co. Levels of the metals, in particular Pb and Zn, in the soils beneath the sample trees at Qujiang were higher than those at Dinghushan with statistical significance. The result suggested that the pine forest soils at Qujiang had a great input of heavy metals from wet and dry atmospheric deposition, with the Pb-Zn smeltery most probably being the source. Levels of Cu, Fe, Mn, Zn, Ni and Pb at Qujiang, both in the inner and the outer bark, were statistically higher than those at Dinghushan. Higher concentrations of Pb, Fe, Zn and Cu may come from the stem-flow of elements leached from the canopy, soil splash on the 1.5 m height and sorption of metals in the mosses and lichens growing on the bark, which were direct or indirect results from the atmospheric deposition. Levels of heavy metals in the outer barks were associated well with the metal concentrations in the soil, reflecting the close relationships between the metal atmospheric deposition and their accumulation in the outer bark of Masson pine. The significant (p<0.01) correlations of Fe-Cu, Fe-Cr, Fe-Pb, Fe-Ni, Pb-Ni, and Pb-Zn in the outer barks at Qujiang again suggested a common source for the metals. The correlation only occurred between Pb and Ni, Cd and Co in the outer barks at Dinghushan, which suggested that those metals must possibly have other uncommon sources. Conclusions Atmospheric deposition of the selected metals was great at Qujiang, based on the levels in the bark of Pinus massoniana and on the concentrations in the soils beneath the trees compared with that at Dinghushan. Bark of Pinus massoniana, especially the outer bark, was an indicator of metal loading at least at the time of sampling. Recommendations and Perspectives The results from this study and the techniques employed constituted a new contribution to the development of biogeochemical methods for environmental monitoring particularly in areas with high frequency of pollution in China. The method would be of value for follow up studies aimed at the assessment of industrial pollution in other areas similar with the Pearl River Delta.     

长三角城市群污染输送相互影响的敏感性试验

利用WRF-Chem模式,对2013年11月29日至12月11日长江三角洲地区的严重空气污染事件进行数值模拟,研究长三角核心区不同污染物本地源和外来输送所占比重。分析长三角核心区排放源对本地不同污染物浓度的污染贡献。结果表明,在2013年12月的这一次污染事件中,颗粒物平均本地贡献与外来输送基本比重相当;而SO_2、CO、NH_3、NO_x这4种气体污染物则以本地贡献为主,本地贡献的差异与气体的化学反应活性有关,活性越强本地贡献比重越大。污染过程中12月7日至12月9日00:00为污染最严重的时段,污染物的本地贡献有明显上升。区域间输送的方向和强度与地面风向、风速有紧密的联系。在边界层高度范围内,大部分污染物越往高空本地排放源的贡献越弱,外来输送主导作用增强,而硝酸盐在地面、1 km和1.5 km的本地贡献差异远小于其他污染物。     

长三角典型城市公交车实际道路细颗粒物排放测试

为研究长三角典型城市公交车细颗粒物排放特征,采用便携式排放测试系统（PEMS）,对上海、杭州和苏州三大城市的8辆典型城市公交车开展实际道路细颗粒物排放实验。研究结果表明：长三角典型城市车辆的实际道路平均车速为22.7 km/h,怠速比例为20.4%,加减速比例为54.5%;在稳态行驶工况下,随车速增大,公交车颗粒物质量及数量排放呈逐渐增大趋势;在20 km/h车速范围内,上海国III、国IV和苏州国III公交车颗粒数浓度呈双峰粒径分布,其他公交车均为单峰分布;随比功率的增大,公交车颗粒质量呈逐渐增大的趋势,国IV公交车颗粒数量呈先下降再增大趋势,国III公交车颗粒数量呈上升趋势;公交车颗粒质量综合排放因子为0.8~189 mg/km,颗粒数量综合排放因子为6.2×10¹²~9.6×10¹⁴#/km。     

长三角经济能源约束下的大气污染问题及对区域协作的启示

长三角地区大气污染治理取得一定成效,然而空气质量改善逐渐进入瓶颈期和攻坚期,大气污染治理战略需要从宏观层面系统谋划。本文系统分析了近10年来长三角区域经济、能源、产业、交通的发展状况和趋势,结合区域大气污染物浓度水平的演变,分析了大气污染与经济社会发展的耦合关系。结合当前区域空气污染的空间分布差异以及经济能源交通结构的内在差别,识别了大气污染的区内差异特征及关键制约因素。在此基础上,从能源结构和产业结构调整、交通结构优化、分区施策、深化治理等角度,为深化区域大气污染联防联控,持续改善大气污染问题提出了政策建议。     

珠江三角洲4种淡水养殖鱼类重金属的残留及食用风险评价

为全面了解珠江三角洲淡水水产品中重金属污染现状,评估其生态风险与食用安全,于2014年8月至2015年8月采集罗非鱼、草鱼、乌鳢及鳜鱼主要养殖鱼类样品共计57份,采用原子荧光光谱仪(AFS),电感耦合等离子体质谱(ICP-MS)仪进行分析测定,并采用单因子污染指数(Pi)、重金属污染指数(MPI)、每周可耐受摄入量(PTWI)以及食入健康风险指标(Ri总)分别评估其污染程度、食用安全性与健康风险。结果表明,样品中Cr、Ni、Cu、Zn、As、Cd、Hg、Pb的含量范围分别为0.020~3.240,0.020~0.800,0.110~1.100,0.190~19.970,0.030~1.480,nd~0.606,0.003~0.118,0.040~0.803 mg·kg-1(湿重),Cr、As、Cd、Pb在水产品中超标率大小依次为As(7.0%),Pb(7.0%),Cd(5.3%),Cr(1.8%)。Pi结果表明,目前珠江三角洲养殖水域水产品中Cu与Zn残留处于正常范围内,Cr和Hg有少量样品为轻度污染,Pb、Cd与As存在重度污染样品,所占比例为2.86%、6.02%和5.74%。MPI结果显示不同水产品污染程度为乌鳢>鳜鱼>罗非鱼>草鱼,总体上各种水产品MPI依然处于较低的水平;食用安全性结果显示,目前成人每周摄入水产品是安全的,但乌鳢Cr,罗非鱼As含量较高分别达到PTWI的37.76%和19.51%,表明水产品中Cr、As残留可能存在一定的食用安全隐患。健康风险模型结果显示,所有样品均未超过国际辐射防护委员会(ICRP)的推荐的最大可接受水平(5×10-6a-1)。综合分析珠江三角洲淡水养殖主要水产品可知,其尚未出现明显的污染安全问题,但As与Cr等元素的潜在风险值得进一步关注。     

长三角城市群“空间流”网络结构特征——基于公路运输、火车客运及百度指数的综合分析

信息技术的应用与社会信息技术的传输,使大量的要素(人流、物流、信息流)在城市群空间内集聚与扩散,加密城市群空间内城市联系。在基于公路运输、普通列车、高速列车以及百度指数4个要素的综合分析基础上,对长三角城市群"空间流"网络结构特征进行探析。研究结果表明:(1)长三角城市群区域内城市联系虽具备了网络化规模,但城市间的联系不均衡,以上海、南京、杭州等城市为多中心的协调网络发展格局特征明显;(2)长三角城市群16个核心城市"空间流"特征呈现三角形网络结构,其三角形的顶角分别由上海(沪)、南京(宁)与杭州(杭)3个核心节点城市构成。在空间结构内部,形成若干次级城市网络连线;在空间分布上,北翼网络化程度较高于南翼线性联系程度,区域联系强度以"沪—宁"、"沪—杭"沿线向两侧递减;(3)上海、南京、杭州、苏州、无锡5个核心城市排名处于网络中心的前列,扬州、南通、泰州、舟山等周边城市相对靠后,这与区域经济发展过程的"吸虹效应"有关,随着区域经济一体化程度的加深,中心城市会向周边地区提供服务与经济辐射,完善整个长三角城市群网络体系。     

长江三角洲生产性服务业的空间分布特征分析

在国家层面,生产性服务业向大都市地区聚集的趋势十分明显;在地区层面,生产性服务业在都市核心区集群化发展日益凸显。长三角地区生产性服务业发展不平衡,总体上初步形成了以上海生产性服务业与其他城市现代制造业相互促进的发展局面,产业之间的联系更加紧密,横向联系日益加强,推动着长三角地区产业竞争力和区域竞争力的提升。     

Occurrence, sources, and inventory of hexabromocyclododecanes (HBCDs) in soils from Chongming Island, the Yangtze River Delta (YRD)

Hexabromocyclododecanes (HBCDs) is a concern due to their large usage combining with physico-chemical properties and toxicity to wildlife and human. However, very limited data were reported on HBCDs in soils, especially from rural area. In this study, 22 soil samples were collected from Chongming Island at estuary of the Yangtze River Delta, to investigate the level, diasteroisomer profile, potential sources, and mass inventory of HBCDs. The total concentrations ranged from not detected to 93.8 pg g⁻¹ dry weight (dw) with a mean of 23.3 pg g⁻¹ dw, which was at the low end of the global levels. The wide distribution of HBCDs in soils suggested that the local emissions of HBCD-containing materials and/or the inputs via atmospheric transport from other regions were two possible sources. Variation of HBCDs levels was observed in different types of soils. Woodland, tideland and road soils contained slightly higher HBCDs than those of farmland and grassland. Overall, γ-HBCD was the dominant diasteroisomer in soils, followed by α-HBCD and β-HBCD. Significant but weak correlations were only found between α-HBCD and β-HBCD versus TOC content in soils. Currently, the mass inventory of HBCDs in soils of Chongming Island was 5.3 kg. Based on these data, we gave perspective on human intake of HBCDs via soil ingestion by age. Local resident’s intakes ranged from 15.5 to 97.8 fg kg body weight⁻¹ d⁻¹, in which children are exposed more than adults.     

长三角地区台风危险性定量分析

台风灾害是影响我国最主要的自然灾害之一。由于地处西北太平洋西侧,长三角地区每年都会受到台风的侵袭。根据中国气象局公布的1949-2010年西北太平洋台风最佳路径数据,首先提取了影响长三角16个城市的台风最大风速数据,分别从台风影响频次、强度和最大风速极值分布的角度定量地分析了各个城市的台风灾害危险性,并通过对比分析得出了台风灾害危险性在长三角地区的分布状况。结果显示,台风影响频次和强度都呈现从东南向西北递减的趋势,综合台风影响频次、强度和极端台风重现水平,这16个城市可以划分为3个危险等级:"高危险"城市,包括台州、绍兴、宁波和舟山;"中危险"城市,包括杭州、上海、嘉兴、湖州、无锡和苏州;"低危险"城市,包括南通、常州、镇江、南京、泰州和扬州。致灾因子危险性定量评估是灾害风险评估中重要的一环,研究结果可供制定长三角地区台风灾害防灾规划参考。     

高速铁路影响下的长三角城市群可达性空间格局演变

交通网络体系对城市群空间结构的优化有重要作用,随着“高铁时代”的到来,长三角城市群区域空间结构也将发生深远的变化。引入可达性的概念,以现状2010年与规划2020年的长三角综合交通设施网络为基础,选取长三角各城市之间加权平均最短旅行时间为度量指标,分析了高速铁路系统的发展对长三角区域空间格局未来演化的影响,揭示了高速铁路将全面提升长三角区域可达性水平,大大缩短城市之间的时空距离,推动长三角一体化发展,并通过都市圈、经济轴带的形成与发展,促进区域均衡化空间结构的形成。另一方面,虽然高速铁路将推动多中心空间结构的形成,但对城市可达性水平的影响具有明显的区域差异,城市在新的高铁格局下应探析符合自身特点的发展战略