ABSTRACT
Samples of PM2.5 were collected from 5 sites in Quanzhou in March, April and July, 2014. The concentrations of lanthanoid and other trace metals in the PM2.5 were determined by Inductively Coupled Plasma Mass Spectrometry(ICP-MS). The total lanthanoid concentration (ΣLoid), the ratio of light-lanthanoid(L Loid, including, La, Ce, Pr, Nd, Sm and Eu) to heavy-lanthanoid(H Loid, including Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) in PM2.5 were 2.490-5.708 ng·m-3(65.682-126.529 µg·g-1) and 12.086-14.319, respectively. The distribution pattern of Loid in PM2.5 was also evaluated in this study. All PM2.5 samples showed similar distribution pattern with local topsoil. And positive Ce and negative Eu anomalies were observed in PM2.5. La-Ce-V plots and chemical mass balance(CMB) model were used for source identification and apportionment of PM2.5in Quanzhou. The CMB model was used to identify four main sources:urban fugitive dust, coal combustion, vehicle exhaust and waste incineration emission which had a contribution of 18.9%, 10.9%, 30.6% and 30.2%, respectively.
ABSTRACT
In this study, the seasonal characteristics of water-soluble ions (WSIs) present in fine particulate matter (PM2.5) in Quanzhou City were investigated. PM2.5 samples were collected at five different sites in the city from March 2014 to January 2015 and the concentrations of Na+, NH4+, K+, Ca2+, Mg2+, F-, Cl-, NO3-, and SO42- were determined by ion-exchange chromatography. In order to identify the sources of these WSIs, the positive matrix factorization (PMF) analysis was applied. The seasonal variations in total WSI concentrations were found to decrease in the order of spring > winter > summer > autumn. The ions SO42-, NO3-, and NH4+ were the major WSIs found in PM2.5, accounting for 90.3%±3.3%, 68.8%±11.7%, 78.9%±7.1%, and 74.0%±18.4% of the total amount of ions found in spring, summer, autumn, and winter, respectively. These results suggested that the level of secondary ions was relatively high in the spring season. The anion-to-cation ratio in each of the four seasons was less than one, which indicated that PM2.5 in Quanzhou City was slightly alkaline. Furthermore, NH4+ ions in PM2.5 mostly existed in the form of (NH4)2SO4, NH4HSO4, and NH4NO3 during spring and winter, while they were primarily found as NH4HSO4 and NH4NO3 in the summer and autumn seasons. PMF analysis revealed that marine salt, secondary sources, fugitive dust from construction, municipal incineration, and biomass burning were the main potential sources of the ionic components of PM2.5.
ABSTRACT
Concentrations of 23 metal elements in the dustfall collected from different functional areas of Quanzhou City, China, were determined. Several methods were applied to assess the enrichment degree, pollution level and potential ecological risk of the above elements. The sources of the above elements were analyzed based on the multivariate statistical analysis combining Pb and Sr isotopic tracing technology. The results showed that the concentrations of metals in the dustfall presented significant spatial difference. The results of enrichment factor and geo-accumulation index indicated that Cd, Hg, Zn, Ca, Pb, Cu, Ni and Sr showed relatively higher enrichment degree and pollution level. The results of ecological risk index showed that the comprehensive ecological risk of heavy metals was very high in the dustfall of all functional areas with the sequence of industrial area>heavy traffic area >commercial area >residential area >scenic area >agricultural area. Cd and Hg showed extremely high potential ecological risk, and they contributed 95.56% to the comprehensive potential ecological risk index. The multivariate statistical analysis demonstrated that the elements of V, Fe, Ba, Bi, Ni, Sr, Pb, Cs, Sc, Zn, Cd were mainly from industrial and vehicle emissions; Th, U, Rb, Y, Ti were mainly derived from soil dust; Li, Mn, Cu, Hg, Cr, Co, Ca were mainly from coal combustion. The contribution ranges of parent soil, coal combustion and vehicle emission to the Pb in the dustfall were 29.41%-64.00%, 22.53%-60.48% and 3.13%-13.47%, respectively, as calculated by a ternary hybrid model; The plots of 87Sr/86Sr vs 1/Sr showed that Sr in the dustfall was dominated by coal combustion and vehicle emission.
ABSTRACT
Rare earth elements (REE) have certain properties as tracing elements which result in their special geochemical characteristics. In order to study the geochemical characteristics of REE in the dustfall and their sources, 34 dustfall samples were collected in five functional areas and potential source areas of Quanzhou City, then REE compositions, distribution patterns and characteristic parameters were analyzed together with ternary diagrams and characteristic parameter diagrams, for investigating the main provenance. The results showed that ∑REE in the dustfall presented significant spatial difference with the sequence of industrial area>heavy traffic area > commercial area > residential area > agricultural area. The lower coefficient variation of ∑REE in residential, heavy traffic, commercial areas indicated homogeneous sources of REE. The chondrite-normalized REE patterns were all of the rightward inclined type with the enrichment of LREE relative to HREE and showed obvious negative Eu anomalies which indicated that the dustfall in study area had obvious terrigenous property. Some REE characteristic parameters in each functional area were close to the average in potential source areas, failed to reveal the causes for spatial differences. The results of LaCeV diagram demonstrated that REE in the dustfall of residential area, heavy traffic area and commercial area were mainly derived from traffic source and soil dust, followed by coal combustion, δEu vs. ∑REEs diagram and HREEN/MREEN vs. LaN diagram further explained that vehicle emission was the main anthropogenic source of REE in the dustfall of heavy traffic area and commercial area. The REE in the dustfall of Quanzhou City was less affected by steelworks emissions and cement plant dust and there were additional REE sources in the dustfall of industrial and agricultural area different from other functional areas.
