Arsenic Speciation in Transplanted Lichens and Tree Bark in the Framework of a Biomonitoring Scenario

Arsenic and its chemical species were determined in transplanted lichens (Parmelia caperata) and tree bark (Platanus hybrida), in order to get a better understanding of their atmospheric cycling and the suitability of these materials for biomonitoring purposes. Various strategies were used (discontinuous and cumulative exposure of transplants) to biomonitor two locations in Portugal, viz. the northern Lisbon area and Sines, both highly industrialised areas.Analytical techniques comprised instrumental nuclear activation analysis (INAA), inductively coupled plasma-mass spectrometry (ICP-MS) and high performance liquid chromatography-hydride generation atomic fluorescence spectrometry (HPLC-HGAFS) for determination of total arsenic in solid materials, total arsenic in extracts of solid materials and arsenic species in extracts of solid materials, respectively.Only a fraction (up to 50%) of the extracted arsenic species could be identified and quantified in the transplanted lichens, being mainly inorganic arsenic and some methylated arsenic species. Since in a previous study these methylated arsenic species were not found in aerosols collected in the same area, it is probable that the lichen transplants studied (Parmelia caperata) do not behave as genuine passive biomonitors but are able to actively methylate inorganic arsenic to methylated arsenic species. Furthermore, this lichen-induced methylation occurs with some delay, possibly as a reaction to the transplantation of the lichen itself, and therefore transplanted lichens are only suitable for long-term biomonitoring studies. For tree bark only total arsenic concentration data could be generated since speciation analysis failed due to too low an initial total arsenic concentrations.     

Diversity of Epiphytic Lichens and Hg Contents of Xanthoria parietina Thalli as Monitors of Geothermal Air Pollution in the Mt. Amiata Area (Central Italy)

The diversity of epiphytic lichens and mercury concentrations in lichen samples were measured to monitor the release of airborne pollutants from the industrial exploitation of geothermal resources in the Mt. Amiata area (Italy). The lichen biodiversity showed a general condition of moderate environmental alteration around the geothermal power plants, contrasting with the low environmental alteration of the remaining sites investigated. According to the accumulated Hg in lichen thalli, it was possible to estimate mean Hg and H₂S concentrations in the air, which resulted in very good agreement with values measured instrumentally. Based on these data and the correlation between lichen diversity values and Hg concentrations in lichens, it was possible to calculate the threshold of 8 μg/m³ H₂S as responsible for the worsening from low to moderate environmental alteration according to the biodiversity of epiphytic lichens, and to infer that around geothermal power plants, although not toxic to humans, H₂S concentrations are such to alter the nasal quality of the air. Based on the growth rate of X. parietina, it was possible to convert Hg concentrations into estimates of average Hg deposition rates, which showed fluxes of the order of 65–100 mg/ha/y, indicating a dispersions factor of about 10⁴ for the Hg emitted from the geothermal power plants.     

Atmospheric Dioxin and Furan Deposition in Relation to Land-Use and Other Pollutants: A Survey with Lichens

Polychlorodibenzeno-dioxins and polychlorodibenzeno-furans (PCDD/Fs) are considered among the most toxic compounds on earth. The aim of the present study was to evaluate atmospheric PCDD/F deposition and identify the areas with greater deposition of these compounds in an important industrialized and urbanized region of Portugal, using lichens as biomonitors. For this purpose, samples of the lichen Xanthoria parietina were collected at 60 sampling sites, covering urban, industrial, forestry and agriculture areas, and analyzed for PCDD/Fs, sulfur, nitrogen, zinc, iron, chromium, lead, cobalt, nickel, copper, calcium, manganese, magnesium and potassium. The concentrations of PCDD/Fs in lichens were compared with the other elements and related to land-use and population density. The results obtained through the geostatistical interpolations and after principal component analysis have shown that PCDD/F deposition estimated by lichens is greater near industrial and highly populated urban areas. We found that lichens are suitable biomonitors of PCDD/F atmospheric deposition and can contribute to a better knowledge of air quality in a region, enabling identification of critical pollutant deposition areas.     

Lichens as bioindicators of atmospheric heavy metal deposition in Valencia, Spain

The lichens due to their symbiotic nature have unique characteristics that confer them a key role as bioindicators of the environmental contamination. Many investigations have been done using epiphytic lichens as bioindicators, but only a few of these studies have used epilithic-crustose lichens. Three different epilithic-crustose lichens species: Candelariella sp., Lecanora sp. and Caloplaca sp. were studied as bioindicators of V, Cr, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Ba, Pb, Bi and U trace elements. Inductively Coupled Plasma Mass Spectrometry routine procedure is used to determining these element concentrations. Two sites were selected for lichens sampling according to environmental contamination. The lichens were collected on the facade of the Santos Juanes church in an urban area of Valencia; and on the rural area of Albarracin. The main aim of this work is showing the efficacy of the epilithic-crustose lichens as bioindicators of the air pollution. This study shows that the city of Valencia, compared with the rural area has high levels of Cu and Pb as detected using lichens as bioindicators. Therefore on the basis of these results, it can be hypothesized that Candelariella sp., Lecanora sp. and Caloplaca sp. are good accumulators of air borne heavy metals.     

Interactive Effects of UV-B Radiation and Chemical Contamination on Physiological Parameters in the Lichen Ramalina lacera

To assess the impact of ultraviolet B (UV-B) radiation under laboratory conditions on lichens from different biomonitoring sites, thalli of the lichen Ramalina lacera were transplanted from a clean air site to nine different polluted sites in Israel. Our objective was to determine the probability of synergistic/antagonistic effects on physiological parameters by considering two stressors: chemical contamination and UV-B. Exposure to both airborne pollutants in the field and subsequent UV-B radiation in the laboratory which led to a severe disintegration of cell membranes, followed by electrolyte leakage, indicate the probability of a synergistic effect. The impairment of the potential quantum yield of electron transfer through photosystem II (PSII) of photosynthesis indicated by a significant decrease of the ratio F_v/F_m, further demonstrated the synergistic effect of both chemical contamination and UV-B radiation. Besides enlarged amounts of stress-ethylene in lichens at contaminated sites, the reduced levels of ethylene production upon UV-B radiation in the present study suggest the likelihood of an antagonistic effect of xenobiotic elements and UV-B radiation as a result of an impaired ethylene-producing system.     

Monitoring of Short-Term Heavy Metal Deposition by Accumulation in Epiphytic Lichens (Hypogymnia Physodes (L.) Nyl.)

Many lichens are very sensitive to air pollution due to their symbiotic nature. However, they are generally less sensitive to toxic effects of trace elements; therefore they can be used as accumulator organisms for estimating concentrations of these elements in the environment. Heavy metal accumulation in lichens is a commonly used bioindication method for assessing heavy metal ambient levels. An active biomonitoring method was used for the determination of short-term accumulation of zinc, lead, arsenic and cadmium by epiphytic lichens transplanted at different localities in Slovenia polluted by heavy metals. The atomic absorption spectrophotometry method was used for the determination of heavy metal content in lichen thalli. The content of heavy metals in lichens collected in the background area with clean air (Rogla, Pohorje Mountains) was used as the reference value. Lichens were transplanted from Rogla using the branch transplantation technique for a period of 6 months in the surroundings of Slovenian thermal power plants (Velenje, otanj, Zavodnje, Veliki Vrh, Vnajnarje, and Dobovec) and close to the lead and zinc ore smelter at erjav. The monthly accumulation of heavy metals was comparable within years at selected locations. Heavy metal pollution was the highest at erjav despite of remediation of lead and zinc ore smelter. The monthly accumulation of all four heavy metals was statistically significantly higher in lichens exposed at erjav than at other localities.     

Lichen as quantitative biomonitors of atmospheric heavy metals deposition in Central India

Three different growth forms of lichens belonging to six species; Phaeophyscia hispidula, Parmotrema praesorediosum (foliose); Caloplaca subsoluta, Diploschistes candidissmus (crustose) and Peltula euploca, Phylliscum indicum (squamulose) were studied comparatively for the biomonitoring of Al, Cd, Cr, Cu, Fe, Ni and Zn in Mandav city in central India. Based on the anthropogenic activities three sites were selected for lichen collection. To identify the sources of heavy metal pollution, their concentration was analyzed in thallus as well as in their respective substrates. The thallus of studied lichens showed higher concentration of metals such as Cd, Cr, Ni and Zn, while most of the metals were absent or present in negligible amount in substrates (Fe, Al, Cu), which proves that the accumulated metals were air borne. The foliose lichens (P. hispidula and P. praesorediosum) found highly significant in metal accumulation at each sites followed by crustose and squamulose forms. Lichen samples collected from site 2, adjacent to road side accumulated maximum quantities of Zn, Ni, Cd and Cr whereas the city centre (Site 1) had maximum concentrations of Fe, Cu and Al. The site 3 situated away from the city had lowest amount of all the metals. The analysis of variance and LSD indicated that the metal concentrations among lichen species as well as between substratum is significant at p < 0.05% and P < 0.01% level respectively.     

Applicability of In Situ or Transplanted Lichens for Assessment of Atmospheric Pollution in Patagonia, Argentina

This study is part of a project, in which the ultimate aim is to evaluate the applicability of lichens to assess atmospheric pollution in urban and in agricultural areas in northern Patagonia (Argentina). Two cities with different characteristics were selected for the evaluation: San Carlos de Bariloche, a touristic city, and Villa Regina, a city surrounded by agricultural areas, both located in Río Negro Province. Different methods were considered, with comparative purposes, and aiming to detect the most suitable to evaluate atmospheric pollution in the area of relevance for the present project. The Index of Atmospheric Purity (IAP) was calculated; IAP values were mapped and lines of iso-contamination were drawn for both cities. Furthermore, they were compared with data of multi-elemental composition of lichen thalli analyzed by instrumental neutron activation analysis (INAA). The results indicate that the IAP is an accurate method to detect and evaluate atmospheric pollution in Bariloche, a result that can be extended to other cities with similar characteristics within the lake area of Patagonia. Instead, the index showed to be not appropriate for use in fruticulture areas, even when bio-accumulation of pesticides in transplanted thalli was detected, in the preliminary tests that have been done. As an alternative method, detection of algal layer vital signs, by red neutral staining of algae of in situ lichens and by electrical conductivity were also evaluated in preliminary tests; the results obtained could be related with the fumigation intensities.     

Photosynthetic performance of lichen transplants as early indicator of climatic stress along an altitudinal gradient in the arid Mediterranean area

A climatic change was simulated transplanting samples of the lichens Evernia prunastri (L.) Ach. and Pseudevernia furfuracea (L.) Zopf v. furfuracea along a 1,400 m altitudinal gradient in the northern side of the island of Crete (Greece). The working hypothesis was that the photosynthetic performance (i.e. pigment content, chlorophyll degradation and photosynthetic efficiency) of transplanted lichens varies along the altitudinal gradient. The overall effect observed was a general depression of the photosynthetic performance along the gradient. Concentrations of chlorophyll a, chlorophyll b and carotenoids decreased with decreasing elevation and along with the hottest and driest months of the year, with chlorophyll b being the most sensitive parameter to dry conditions. Chlorophyll degradation decreased with increasing elevation. The exposure period was the main factor affecting photosynthetic efficiency, with lower values during summer months. We argued that the water content of lichen thalli is the most important factor determining differences in photosynthesis under the experimental conditions. This allowed to suggest that the lichen photosynthetic performance deserves further investigation as early biological indicator of atmospheric stress induced by dry conditions and, to a greater extent, for the assessment of the desertification risk in the arid Mediterranean environment.     

Lichens as Biomonitors of Depleted Uranium in Kosovo

This paper reports the results of a study using lichens as biomonitors to investigate the environmental distribution of depleted uranium (DU) at selected Kosovo sites as a consequence of the use of DU ordnance during the conflict of 1999. The results suggested that the use of DU ammunitions did not cause a diffuse environmental contamination in such a way to have caused a detectable U enrichment in lichens. Also isotopic ²³⁵U/²³⁸U measurements did not indicate the presence of DU particles in lichens, except for some samples at a heavily shelled site, which resulted contaminated by DU.     

A microscale model for air pollutant dispersion simulation in urban areas: Presentation of the model and performance over a single building

A microscale air pollutant dispersion model system is developed for emergency response purposes. The model includes a diagnostic wind field model to simulate the wind field and a random-walk air pollutant dispersion model to simulate the pollutant concentration through consideration of the influence of urban buildings. Numerical experiments are designed to evaluate the model's performance, using CEDVAL(Compilation of Experimental Data for Validation of Microscale Dispersion Models) wind tunnel experiment data, including wind fields and air pollutant dispersion around a single building. The results show that the wind model can reproduce the vortexes triggered by urban buildings and the dispersion model simulates the pollutant concentration around buildings well. Typically, the simulation errors come from the determination of the key zones around a building or building cluster. This model has the potential for multiple applications; for example, the prediction of air pollutant dispersion and the evaluation of environmental impacts in emergency situations; urban planning scenarios;and the assessment of microscale air quality in urban areas.     

A Kriging-based Estimate of the Survey Quality in Biomonitoring of Trace Element Air Pollution

The present paper addresses Kriging-based approaches to estimate survey quality, thereby using data on biomonitoring surveys of trace element air pollution. Data were used of a 1995 moss monitoring study in The Netherlands, thereby taking sodium (Na), arsenic (As) and bromium (Br) to illustrate the points made. Survey quality was expressed as the survey signal-to-noise ratio (SSNR), with the survey variance as the signal and the local variance as the noise. The Kriging approaches were regarded in parallel to direct approaches where local variances are determined from multi-fold local sampling.The paper addresses the uncertainties in SSNR associated to the uncertainties in local values and variances if based on pooled samples and a limited 5-fold sub-sampling in a restricted number of sampling sites. It further introduces a Kriging approach to SSNR_K (_K for Kriging), by Kriging-assisted recalculation of local values and variances, in turn based on fitted experimental variograms. The outcomes suggest that the Kriging approach may yield reliable SSNR_K values; the approach implies that SSNR_K depends on survey set-up, site density and sampling grid characteristics. The discussion of the paper addresses the points made and further suggests the use of large sample analytical facilities to permit a change in survey approach from mixing and milling of pooled sub-samples to bulk analyses of all sampled material in higher site-density surveys.     

Problems Related to Lichen Transplants to Monitor Trace Element Deposition in Repeated Surveys: A Case Study from Central Italy

The results of a transplant experiment with the fruticose lichen Evernia prunastri aimed at monitoring the trends of trace elements deposition in a repeated biomonitoring study are reported. Data comparability between the two surveys and interpretation of the results were addressed in this study. The ratio between the concentration of each element after the exposure and in control samples prior to exposure (exposed-to-control ratio, EC ratio), as well as an appropriate interpretative scale, were adopted as a means of determining the temporal trends of element accumulation by lichen transplants. The results showed that the method adopted is indeed a reliable tool, pinpointing a Zn smelting plant and an oil refinery as principal pollution sources in the area, which indicate that elements associated with the former were similarly accumulated in both 2002 and 2003, while elements associated with the latter tended to decrease in 2003.     

Uranium Isotopes, Metals and Other Elements in Lichens and Tree Barks Collected in Bosnia–Herzegovina

The United Nations Environment Programme (UNEP) performed field surveys at 15 sites in Bosnia–Herzegovina where depleted uranium (DU) ammunition was used by the North Atlantic Treaty Organization (NATO) during the Balkans conflict (1994–1995). During the field missions, the Italian Environmental Protection Agency (APAT) evaluated airborne contamination due to DU dusts or aerosol particles, generated at the time of the conflict by the impact of DU ammunition on hard targets, using lichens and tree barks as biomonitors. Each sample was analyzed by alpha-spectrometry for DU determination. The ²³⁴U/²³⁸U activity concentration ratios were used to distinguish natural from anthropogenic uranium. This paper reports the data obtained by the UNEP investigation, including (non-radioactive) metal and other element concentrations in lichen and tree bark samples measured by instrumental neutron activation analysis (INAA). The results indicated: (i) lichens and tree barks are sensitive bio-accumulators of past airborne contamination by depleted uranium dusts; (ii) 8 years after the conflict, environmental DU contamination is still present at some of the target sites; and (iii) the highest concentrations of most non-radioactive elements were found at sites used for ammunition destruction.     

PM2.5 and ozone pollution-related health challenges in Japan with regards to climate change

The degradation of air quality, an environmental consequence of anthropogenic activities, poses a challenge to human health. However, the corresponding control measures incur additional costs. This study presents an analysis of the health and socioeconomic benefits of air quality control measures and climate change mitigation. Multidisciplinary modelling was used for PM_2.5 and ozone distribution to analyze the co-benefits of end-of-pipe measures and electrification as well as their period-specific impacts on human health and the economy. The results indicated that the long-term impacts of end-of-pipe technologies and electrification in Japan's residential, building, and transportation sectors could reduce premature deaths, caused by PM_2.5 and ozone pollution, by 65,500 annually from 2010 to 2050. These technologies could save a per capita work hour loss of 3.64 h and avoid an economic loss of 5.43 billion USD by 2050. This study predicted climate actions would enable western Japan to benefit from PM_2.5 control measures, whereas the entire country would benefit from ozone pollution reduction.     

Important meteorological variables for statistical long-term air quality prediction in eastern China

Weather is an important factor for air quality. While there have been increasing attentions to long-term (monthly and seasonal) air pollution such as regional hazes from land-clearing fires during El Niño, the weather-air quality relationships are much less understood at long-term than short-term (daily and weekly) scales. This study is aimed to fill this gap through analyzing correlations between meteorological variables and air quality at various timescales. A regional correlation scale was defined to measure the longest time with significant correlations at a substantial large number of sites. The air quality index (API) and five meteorological variables during 2001–2012 at 40 eastern China sites were used. The results indicate that the API is correlated to precipitation negatively and air temperature positively across eastern China, and to wind, relative humidity and air pressure with spatially varied signs. The major areas with significant correlations vary with meteorological variables. The correlations are significant not only at short-term but also at long-term scales, and the important variables are different between the two types of scales. The concurrent regional correlation scales reach seasonal at p < 0.05 and monthly at p < 0.001 for wind speed and monthly at p < 0.01 for air temperature and relative humidity. Precipitation, which was found to be the most important variable for short-term air quality conditions, and air pressure are not important for long-term air quality. The lagged correlations are much smaller in magnitude than the concurrent correlations and their regional correction scales are at long term only for wind speed and relative humidity. It is concluded that wind speed should be considered as a primary predictor for statistical prediction of long-term air quality in a large region over eastern China. Relative humidity and temperature are also useful predictors but at less significant levels.     

往返式探空观测资料的质量控制及不确定性分析

为了推动新型探测资料在数值预报模式中的应用,本文进行了往返式探空资料同化应用前重要的基础性研究工作。基于国内首次往返式探空观测资料,首先建立了面向业务化应用的往返式探空资料质量控制方案,通过对比和分析质量控制前后观测样本的统计特征,论证了质量控制方案的合理性,质量控制后探测要素抽样分布更为合理,要素间一致性得到提高。进而以数值天气预报高时间分辨率的模式预报场和同站址业务常规探空观测资料为参考,分析质量控制后资料的不确定性,结果表明往返探空探测精度达到了世界气象组织WMO（World Meteorological Center）规定的突破目标,部分探测要素甚至实现了理想目标,探测资料具有可用性。最后结合数值模式背景场探讨往返探空资料的可同化性,研究表明往返探空的风场观测和夜间温度观测满足变分同化系统的高斯、无偏假定,可直接同化;气压、湿度和日间温度观测在资料同化前需要开展偏差订正工作,从而更有效的发挥资料价值。本文的研究工作为今后往返探空资料在模式中的同化应用奠定了基础。     

Arsenic Speciation in Lichens and in Coarse and Fine Airborne Particulate Matter by HPLC–UV–HG–AFS

A three-step sequential extraction procedure with Milli-Q, CaCl₂ and H₃PO₄ was applied for extraction of arsenic species in lichen transplants and airborne particulate matter (fine and coarse fractions). The samples used in this work were collected in 1994–1995 near coal-fired power plants. Both transplant lichens and airborne particulate matter were submitted to the same environment simultaneously. Arsenic species identification and quantification was performed by HPLC–UV–HG–AFS. Inorganic forms of arsenic (arsenite and arsenate) were present in significant amounts in most of the samples. Only in lichens also organic forms of arsenic (monomethyl arsonic acid and dimethyl arsinic acid) were identified which may indicate biotransformation of inorganic arsenic.     

大气污染物非线性回归模型构建

本文基于重庆主城区（沙坪坝站）2014—2018年逐日同期同步观测的气象要素和环境空气质量监测数据进行分析。首先通过对不同大气污染物与各种气象要素进行相关性分析，剔除影响预报模型共性的气象因子，明确显著影响空气质量的气象要素；然后结合污染物排放、大气扩散过程和湿沉降作用机理；最后构建乘幂与线性叠加的混合模式的空气质量预报方程。结果表明：构建的非线性回归方程能较为真实地反映主要大气污染物与气象要素的相互影响关系，回归模型预报检验准确率高（预报评分达87.6）。     

无人直升机搭载大气颗粒物采样装置的前期地面评估

与搭载气溶胶观测和分析仪器测量相比,利用无人直升机搭载气囊采集高空大气颗粒物是一种经济、便捷和安全的采集方式。为了解无人直升机采样装置的采样效果,选择2014年10月至2015年3月的4次重污染天气过程,由无人直升机搭载气囊采集大气颗粒物,然后利用气溶胶采样器采集气囊内的大气颗粒物样品并计算采样时间,再利用气溶胶采样器采集相同时间段内的地面大气颗粒物(气囊外),并将两者进行对比。结果表明:在稳定的污染天气条件下,采集气囊内的大气颗粒物,与相同时间段内利用气溶胶采样器直接采集气囊外的大气颗粒物相比,两种方式采集到的大气颗粒物质量最大差值29%,最小差值11%,平均为21%;利用无人直升机的大气采样装置采集大气颗粒物对碳气溶胶组分影响很小,气囊内与气囊外OC/TC最大相差2.0%,最小相差0.5%。上述结果表明,无人直升机的大气采样装置有比较好的采集效率,利用气囊这种经济、便捷、安全的方式,搭载在无人机平台上,采集高空大气是一种获取气溶胶垂直廓线的有效方法,有望在未来的气溶胶气候和环境研究中提供宝贵数据。