Sea to air transport of trace gases in the coastal zone: a literature review

Exchange of trace gases between the oceans and the atmosphere affects the atmospheric content and cycling of a range of chemical species which are related to climate change, ozone layer depletion, acid deposition, eutrophication, atmospheric particle formation, photo-oxidants, trace metals and persistent organic pollutants (POPs). The effects and impacts of air–sea exchange of these gases can be local, regional and global. Until now, most of the research has concentrated on the sea–air exchange of trace gases in the open ocean. The flux rates of the trace gases from the coastal waters to the air are much higher than the rates for the open ocean and the contribution of the coastal areas to the total oceanic emissions of these trace gases can be significant on a global scale. This contribution can be as high as 50% and more for nitrous oxide and COS. Concerning the contribution of the trace gas production in the coastal areas to the total global production of these gases, it can be concluded that this contribution seems to be below 2% except for nitrous oxide. However, it should be pointed out that on the local and even regional scale the emissions in the coastal areas can be very important, contributing substantially to the total emission of these gases in a studied area. Thus, there is a need to carry out studies in the future with the aim to provide more accurate understanding of the production and sea–air exchange processes for these gases around the world. Electronic Publication     

Metal Contamination in the Republic of Armenia

/ Air, soil, and water samples were collected throughout the Republic of Armenia both before and after its independence from the Soviet Union in 1991. Reported analyses of those samples indicated that levels of several trace metal concentrations (Ag, Cd, Cr, Cu, Mo, Ni, Pb, Ti, and Zn) exceeded the maximum allowable concentrations established by the former Soviet Union (FSU) and subsequently adopted by Armenia. Although industrial production has declined by more than 80% since the 1980s, the economy is improving and there is potential for a significant increase in the generation of industrial metal emissions. These include automobile emissions, which are now considered to be the primary source of atmospheric lead. Historically, the Soviet Union did not strictly enforce environmental standards, and Armenia is now faced with the resulting environmental problems and the associated risks to public health. Since some trace metal concentrations may be at or near potentially toxic levels, there is a need to accurately assess the extent of metal contamination in order to devise cleanup plans and develop long-term environmental protection and public health strategies in Armenia.     

Assessment of the nitrogen and carbon budget of two managed temperate grassland fields

Greenhouse gas budgets as well as the productivity of grassland systems are closely related to the carbon (C) and nitrogen (N) cycles. Within the framework of the CarboEurope and NitroEurope projects we have measured C and N exchange on the field scale at the grassland site Oensingen previously converted from arable rotation. The site is located on the Swiss Central Plateau and consists of two parallel fields of equal size. One field was subjected to intensive management with average nitrogen input of 230 kg-N ha⁻¹ year⁻¹ and 4–5 cuts per year, and the other to an extensive management with no fertilisation and less frequent cutting. The total C budget of the fields was assessed by measuring the CO₂ exchange by eddy covariance and analysing the carbon import by manure application and export by harvest. The N budget of the managed grassland is more complex. Besides the management related import and export, it includes gaseous exchange in many different forms (NO, NO₂, HNO₃, N₂O, NH₃, N₂) needing different analytical techniques, as well as input by rain and leaching of N-compounds with the soil water. The main (“level-3”) field sites in the NitroEurope project are supposed to measure 95% of the N fluxes at the field scale. For several of the N fluxes specific measurements have been performed for 1 year or longer at the site. Some of the remaining N budget components (dry and wet deposition) could be estimated from results of a national deposition network, while other components (NH₃ and N₂ emission) were estimated based on literature parameterisations. However, we found indications that the (systematic) uncertainties of these estimated N-fluxes are large and that it is important to make site-specific measurement for all relevant budget components. The suitability of corresponding experimental methods is discussed.Analysis of the C budget over a 6-year period (2002–2007) showed a significant mean difference between the two newly established grassland fields with a likely net carbon loss for the extensive management and a net sequestration for the intensive management. Since the C/N ratio of the soil organic matter of the grassland is constrained in a rather narrow range around 9.3, the change in the soil carbon pool is supposed to be accompanied by a corresponding change in the N storage. This approach provided an alternative method to check the N budget of the two grassland fields derived from the individual N fluxes.     

Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W and Pb in bottom ashes from fluidized-bed coal combustion power station

This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu,Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed（for all four combustion tests） for S, As, Cl and Br（R = 0.917-0.999）. Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds（e.g., to aluminosilicates, organic matter, etc.）. Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically ＂not significant＂, i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of5% of the finest ash particles brings about a decrease in As concentration down to 77%-80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization.     

Synchrotron micro-scale measurement of metal distributions in Phragmites australis and Typha latifolia root tissue from an urban brownfield site

Liberty State Park in New Jersey,USA,is a "brownfield" site containing various levels of contaminants.To investigate metal uptake and distributions in plants on the brownfield site,Phragmites australis and Typha latifolia were collected in Liberty State Park during the growing season(May–September)in 2011 at two sites with the high and low metal loads,respectively.The objective of this study was to understand the metal(Fe,Mn,Cu,Pb and Zn)concentration and spatial distributions in P.australis and T.latifolia root systems with micro-meter scale resolution using synchrotron X-ray microfluorescence(μXRF)and synchrotron X-ray computed microtomography(μCMT)techniques.The root structure measurement by synchrotron μCMT showed that high X-ray attenuation substance appeared in the epidermis.Synchrotron μXRF measurement showed that metal concentrations and distributions in the root cross-section between epidermis and vascular tissue were statistically different.Significant correlations were found between metals(Cu,Mn,Pb and Zn)and Fe in the epidermis,implying that metals were scavenged by Fe oxides.The results from this study suggest that the expression of metal transport and accumulation within the root systems may be element specific.The information derived from this study can improve our current knowledge of the wetland plant ecological function in brownfield remediation.     

Concentrations and modes of occurrence of trace elements in the Late Permian coals from the Puan Coalfield, southwestern Guizhou, China

The concentration, mode of occurrence, and origin of trace elements in the Late Permian coals from the Puan Coalfield, southwestern Guizhou, China, were examined using inductively coupled plasma-mass spectrometry (ICP-MS), X-ray fluorescence (XRF), cold-vapor atomic absorption spectrometry (CV-AAS), ion-selective electrode method (ISE), sequential chemical extraction procedure (SCEP), scanning electron microscopy equipped with energy-dispersive X-ray (SEM-EDX), and optical microscope. Results show that minerals in the No. 2 Coal from the Puan Coalfield were mainly made up of epigenetic pyrite of low-temperature hydrothermal fluid origin and kaolinite of detrital terrigenous origin. Elements including As (36.9 μg/g), Cd (10.2 μg/g), Cr (167.3 μg/g), Cu (365.4 μg/g), Hg (2.82 μg/g), Mo (92.6 μg/g), Ni (82.6 μg/g), Pb (184.6 μg/g), Se (6.23 μg/g), Zn (242.3 μg/g), and U (132.7 μg/g) are significantly enriched in the No. 2 Coal from the Puan Coalfield. However, concentrations of trace elements in the other four coals, the No. 1, No. 8, No. 11, and No. 18 Coals, were close to the usual ranges found for Guizhou of China, China, and USA. Results of SEM-EDX and SCEP showed that As, Cd, Hg, Mo, Ni, Pb, and Zn occur mainly in veined pyrite, while Cr, Cu, and U distribute mainly in kaolinite, indicating that the low-temperature hydrothermal fluid and detrital materials of terrigenous origin are the main contributors to the enrichment of these trace elements in the No. 2 Coal.     

Assessing Potential Removal of Low-Head Dams in Urban Settings: An Example from the Ottawa River,NW Ohio

This is a study of the scientific component of an effort to restore an urban river by removing a low-head dam. The Secor Dam is owned by a local government entity near Toledo, Ohio. The proposed removal of the last structure impeding flow on the Ottawa River has broad appeal, but the owner is concerned about liability issues, particularly potential changes to the flood regime, the presence of contaminated sediments behind the dam, and possible downstream transport of reservoir sediments. Assessing sediment contamination involved sediment sampling and analysis of trace metals and organic contaminants. Forecasting sediment transport involved field methods to determine the volume and textural properties of reservoir and upstream sediment and calculations to determine the fate of reservoir sediments. Forecasting changes in the flood regime involved HEC-RAS hydrological models to determine before and after dam removal flood scenarios using LiDAR data imported into an ArcGIS database. The resulting assessment found potential sediment contamination to be minor, and modeling showed that the removal of the dam would have minimal impacts on sediment transport and flood hazards. Based on the assessment, the removal of the dam has been approved by its owners.     

Combined effects of elevated temperature and CO2 concentration on Cd and Zn accumulation dynamics in Triticum aestivum L.

A simulated climate warming experiment was conducted to evaluate the combined effects of elevated temperature and CO_2 concentration on the bioaccumulation,translocation and subcellular distributions of Cd and Zn in wheat seedlings(Triticum aestivum L.cv.Xihan 1.) at Dingxi,Gansu Province,China.The objective was to find evidence that global climate change is affecting the bioaccumulation of Cd and Zn in T.aestivum L.cv.Xihan 1.The results showed that compared to control A,elevated temperature and CO_2 increased Cd bioaccumulation in the shoots by 1.4–2.5 times,and increased that in the roots by 1.2–1.5times,but decreased Zn levels in wheat shoots by 1.4–2.0 times,while decreased that in the roots by 1.6–1.9 times.Moreover,temperature and CO_2 concentration increase also led to increased Cd concentration,and decreased Zn concentration in subcellular compartments of wheat seedlings.The largest Cd concentration increase(174.4%) was observed in the cell wall and debris fractions of shoots after they were subjected to the highest CO_2 and temperature treatment(TC3).The largest Zn concentration decrease(53.1%) was observed in the soluble(F3) fractions of shoots after they were subjected to the medium CO_2 and temperature treatment(TC2).The temperature and CO_2 increase had no significant effect on the proportional distribution of Cd and Zn in the subcellular fractions.The root-to-shoot translocation of Cd increased with the increasing temperature and CO_2 concentration.However,the Zn distributions only fluctuated within a small range.     

Active moss biomonitoring of trace elements with Sphagnum girgensohnii moss bags in relation to atmospheric bulk deposition in Belgrade, Serbia

Active biomonitoring with wet and dry moss bags was used to examine trace element atmospheric deposition in the urban area of Belgrade. The element accumulation capability of Sphagnum girgensohnii Russow was tested in relation to atmospheric bulk deposition. Moss bags were mounted for five 3-month periods (July 2005-October 2006) at three representative urban sites. For the same period monthly bulk atmospheric deposition samples were collected. The concentrations of Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, and Pb were determined by instrumental neutron activation analyses and atomic absorption spectrometry. Significant accumulation of most elements occurred in the exposed moss bags compared with the initial moss content. High correlations between the elements in moss and bulk deposits were found for V, Cu, As, and Ni. The enrichment factors of the elements for both types of monitor followed the same pattern at the corresponding sites.     

平顶山市大气PM10、PM2.5污染调查

于2003年12月-2004年11月对平顶山市城区大气PM10、PM2.5污染进行了调查.结果表明,2004年大气PM10、PM2.5质量浓度分别为0.031 mg/m3～0.862 mg/m3、0.019 mg/m3～0.438 mg/m3;年均值分别为0.174 mg/m3、0.114 mg/m3,超标0.74倍、6.60倍.PM10、PM2.5污染的季节变化趋势是以冬季、春季高,秋季次之,夏季最低,细颗粒(PM2.5)约占PM10 65%;As、Pb、Cd、S、Zn、Cu、Mn、Ca等元素是颗粒物中主要污染元素,易在PM2.5中富集.平顶山市大气颗粒物污染的主要来源有煤炭燃烧、汽车尾气、城市基础建设和有色金属冶炼行业.