Human activities have introduced high amounts of microplastics (MPs) into the atmosphere that can be transported long distances and be later deposited in terrestrial and aquatic ecosystems with ...precipitation (rain or snow). In this work, it has been assessed the presence of MPs in the snow of El Teide National Park (Tenerife, Canary Islands, Spain, 2150–3200 m above sea level) after two storm episodes (January–February 2021). The data set (63 samples) was divided into three groups: i) samples from “accessible areas” (after the first storm episode and in places with a strong previous/recent anthropogenic activity); ii) “pristine areas” (after the second storm episode, in places with no previous anthropogenic activity), and iii) “climbing areas” (after the second storm episode, in places with a soft recent anthropogenic activity). Similar pattern profiles were observed among sampling sites in terms of morphology, colour and size (predominance of blue and black microfibers of 250–750 μm length), as well as in composition (predominance of cellulosic -either natural or semisynthetic-, with a 62.7 %, polyester, 20.9 %, and acrylic, 6.3 %, microfibers); however, significant differences in MPs concentrations were found between samples collected in pristine areas (average concentration of 51 ± 72 items/L) and those obtained in places with a previous anthropogenic activity (average concentration of 167 ± 104 and 188 ± 164 items/L in “accessible areas” and “climbing areas”, respectively). This study shows, for the first time, the presence of MPs in snow samples from a high altitude protected area on an insular territory and suggests that the sources of these contaminants could be atmospheric transport and local human outdoor activities.
Display omitted
•Microplastics have been detected in snow from a high mountain National Park.•Similar morphology, colour, size and composition was observed after two storm events.•Predominance of cellulosic, polyester and acrylic microfibers was observed.•Human activities in isolated areas increased microplastics pollution.
The use of pesticides in agriculture to protect crops against pests and diseases generates environmental contamination. The atmospheric compartment contributes to their dispersion at different ...distances from the application areas and to the exposure of organisms in untreated areas through dry and wet deposition. A multiresidue analytical method using the same TD–GC‐MS analytical pipeline to quantify pesticide concentrations in both the atmosphere and rainwater was developed and tested in natura. A Box-Behnken experimental design was used to identify the best compromise in extraction conditions for all 27 of the targeted molecules in rainwater. Extraction yields were above 80% except for the pyrethroid family, for which the recovery yields were around 40–59%. TD–GC–MS proved to be a good analytical solution to detect and quantify pesticides in both target matrices with low limits of quantification. Twelve pesticides (six fungicides, five herbicides and one insecticide) were quantified in rainwater at concentrations ranging from 0.5 ng·L−1 to 170 ng·L−1 with a seasonal effect, and a correlation was found between the concentrations in rainwater and air. The calculated cumulative wet deposition rates are discussed regarding pesticide concentrations in the topsoil in untreated areas for some of the studied compounds.
Display omitted
•A reliable method to quantify pesticides in rainwater and air was tested in natura.•27 pesticides were monitored in rainwater during an agricultural season in France.•Collections were done by tenax tubes for air and stir bar sorption for rain.•Fungicides, herbicides, and insecticides were detected in both air and rainwater.•The contribution of wet deposition to the exposure of untreated areas was evaluated.
Current estimates of agricultural ammonia (NH3) emissions in China differ by more than a factor of 2, hindering our understanding of their environmental consequences. Here we apply both bottom-up ...statistical and top-down inversion methods to quantify NH3 emissions from agriculture in China for the year 2008. We first assimilate satellite observations of NH3 column concentration from the Tropospheric Emission Spectrometer (TES) using the GEOS-Chem adjoint model to optimize Chinese anthropogenic NH3 emissions at the 1∕2° × 2∕3° horizontal resolution for March–October 2008. Optimized emissions show a strong summer peak, with emissions about 50 % higher in summer than spring and fall, which is underestimated in current bottom-up NH3 emission estimates. To reconcile the latter with the top-down results, we revisit the processes of agricultural NH3 emissions and develop an improved bottom-up inventory of Chinese NH3 emissions from fertilizer application and livestock waste at the 1∕2° × 2∕3° resolution. Our bottom-up emission inventory includes more detailed information on crop-specific fertilizer application practices and better accounts for meteorological modulation of NH3 emission factors in China. We find that annual anthropogenic NH3 emissions are 11.7 Tg for 2008, with 5.05 Tg from fertilizer application and 5.31 Tg from livestock waste. The two sources together account for 88 % of total anthropogenic NH3 emissions in China. Our bottom-up emission estimates also show a distinct seasonality peaking in summer, consistent with top-down results from the satellite-based inversion. Further evaluations using surface network measurements show that the model driven by our bottom-up emissions reproduces the observed spatial and seasonal variations of NH3 gas concentrations and ammonium (NH4+) wet deposition fluxes over China well, providing additional credibility to the improvements we have made to our agricultural NH3 emission inventory.
This study analyzed the rainwater collected in Central Taiwan during the near typhoon period. Mercury (Hg) was analyzed and the Hg volume weighted mean concentrations (VWM) and wet depositions were ...calculated during the near typhoon period. In addition, the Hg wet depositions, VWM and precipitation values obtained were compared with Plum rain and regular precipitation periods. The relationship between wet Hg depositions, VWM and precipitations were also discussed. Wet Hg depositions, VWM and precipitations were also compared with the precipitation collected from other parts of the world during 2009 to 2021. The results indicated that the precipitations, VWM and wet Hg depositions in the near typhoon period were 152.5 mm, 0.82 ng/L, and 0.29 μg/m2, respectively. The Hg precipitation ratio values of this study to the plum rain and regular precipitation periods were 3.70 and 6.63, respectively. The Hg VWM ratios values of this study to the plum rain and regular precipitation periods were 12,852.56 and 1.56, respectively. Moreover, the wet Hg deposition ratios values of this study to the plum rain and regular precipitation periods (near typhoon period) were 105.97 and 9.90, respectively. The results further indicated that the Hg VWM and wet depositions obtained in the near typhoon period showed the lowest values when compared with plum rain and regular precipitations periods. Compared with Hg(p) VWM and Fw values obtained from plum season, regular precipitation, this study (typhoon period) demonstrated it has the average lowest VWM and Fw values among these three sampling periods. The correlation coefficient of precipitation and the mercury wet deposition was 0.72051 which was significant in this study. The correlation coefficient for the VWM of mercury was 0.0826 which displayed insignificant relationship in this study. Finally, when comparing the Hg VWM, wet deposition and precipitation values from various studies, the results further indicated that the near typhoon period has the lowest average Hg VWM, wet deposition and precipitation values.
•13 dust samples possess different levels of light transmittance disturbance.•Some dust particles degrade photovoltaic performance by as much as 98%.•Acrylic plastic appears to accumulate more dust ...when compared to low iron glass.•Wet deposition retains more particles on surfaces compared to dry deposition.
Photovoltaic technology penetration is experiencing noticeable progress. However, its performance is significantly affected by soiling, which is influenced by several factors such as site characteristics, weather, tilt angle and surface orientation, surface material and dust properties. This indoor study investigates the effect of soiling on photovoltaic modules, focusing on dust properties and PV surface materials as influencing factors. A Solar simulator, spectrometer and SEM/ EDX were used to characterise and investigate the effect of accumulation of 13 different samples (ash, bird droppings, carpet dust, cement, charcoal, clay, coarse sand, laterite, loam soil, salt, sandy soil, stone dust and wood dust) on PV performance. The findings develop upon previous studies on the effects of dust particle accumulation on PV performance by using more dust samples and applying more rigorous techniques. The results show that charcoal appears to have the worst degradation effect on PV performance with about 98% reduction in short circuit current while salt seems to have the least impact with about 7%. The influence of 2 PV surface materials (acrylic plastic and low iron glass) on dust accumulation were examined, and results show that the acrylic plastic accumulates more dust when compared to low iron glass. Results also show that dry deposition has a reduced adhesion to the coupons compared to wet deposition. The findings could be used in selecting PV farm sites by avoiding areas with high pollution, and it could stimulate further research on selecting an appropriate mitigation technique. The ramifications caused because of soiling cannot be overlooked or overemphasis; as such there is a need to identify appropriate and cost-effective mitigation techniques that can continue to promote the global penetration of PV technologies and sustain its performance.
We review recent progress in our understanding of the global cycling of mercury (Hg), including best estimates of Hg concentrations and pool sizes in major environmental compartments and exchange ...processes within and between these reservoirs. Recent advances include the availability of new global datasets covering areas of the world where environmental Hg data were previously lacking; integration of these data into global and regional models is continually improving estimates of global Hg cycling. New analytical techniques, such as Hg stable isotope characterization, provide novel constraints of sources and transformation processes. The major global Hg reservoirs that are, and continue to be, affected by anthropogenic activities include the atmosphere (4.4–5.3 Gt), terrestrial environments (particularly soils: 250–1000 Gg), and aquatic ecosystems (e.g., oceans: 270–450 Gg). Declines in anthropogenic Hg emissions between 1990 and 2010 have led to declines in atmospheric Hg
0
concentrations and Hg
II
wet deposition in Europe and the US (− 1.5 to − 2.2% per year). Smaller atmospheric Hg
0
declines (− 0.2% per year) have been reported in high northern latitudes, but not in the southern hemisphere, while increasing atmospheric Hg loads are still reported in East Asia. New observations and updated models now suggest high concentrations of oxidized Hg
II
in the tropical and subtropical free troposphere where deep convection can scavenge these Hg
II
reservoirs. As a result, up to 50% of total global wet Hg
II
deposition has been predicted to occur to tropical oceans. Ocean Hg
0
evasion is a large source of present-day atmospheric Hg (approximately 2900 Mg/year; range 1900–4200 Mg/year). Enhanced seawater Hg
0
levels suggest enhanced Hg
0
ocean evasion in the intertropical convergence zone, which may be linked to high Hg
II
deposition. Estimates of gaseous Hg
0
emissions to the atmosphere over land, long considered a critical Hg source, have been revised downward, and most terrestrial environments now are considered net sinks of atmospheric Hg due to substantial Hg uptake by plants. Litterfall deposition by plants is now estimated at 1020–1230 Mg/year globally. Stable isotope analysis and direct flux measurements provide evidence that in many ecosystems Hg
0
deposition via plant inputs dominates, accounting for 57–94% of Hg in soils. Of global aquatic Hg releases, around 50% are estimated to occur in China and India, where Hg drains into the West Pacific and North Indian Oceans. A first inventory of global freshwater Hg suggests that inland freshwater Hg releases may be dominated by artisanal and small-scale gold mining (ASGM; approximately 880 Mg/year), industrial and wastewater releases (220 Mg/year), and terrestrial mobilization (170–300 Mg/year). For pelagic ocean regions, the dominant source of Hg is atmospheric deposition; an exception is the Arctic Ocean, where riverine and coastal erosion is likely the dominant source. Ocean water Hg concentrations in the North Atlantic appear to have declined during the last several decades but have increased since the mid-1980s in the Pacific due to enhanced atmospheric deposition from the Asian continent. Finally, we provide examples of ongoing and anticipated changes in Hg cycling due to emission, climate, and land use changes. It is anticipated that future emissions changes will be strongly dependent on ASGM, as well as energy use scenarios and technology requirements implemented under the Minamata Convention. We predict that land use and climate change impacts on Hg cycling will be large and inherently linked to changes in ecosystem function and global atmospheric and ocean circulations. Our ability to predict multiple and simultaneous changes in future Hg global cycling and human exposure is rapidly developing but requires further enhancement.
Purpose. The study is purposed at identifying both the features of seasonal and interannual variability of the aerosol wet deposition velocity and the factors that determine this variability on the ...time scales under study. Methods and Results. The deposition velocity in 2012–2020 was estimated using the field data on temporal variability of the 7Be concentration on atmospheric aerosols and the 7Be “wet” deposition fluxes. The correlation analysis permitted to assess quantitatively the influence of the precipitation amount and frequency upon the seasonal and interannual variability of the deposition velocity. The multiple regression analysis was applied for constructing the regression models. Conclusions. The deposition velocity varies from 0.21 to 1.40 cm·s–1 and averages 0.62 ± 0.29 cm·s–1. It has been established that its seasonal variability is conditioned by the amount and frequency of precipitation, whereas its interannual variability – only by the precipitation amount. Based on the obtained results, two regression models were been proposed. The first model describes seasonal variability of the deposition velocity, while the second one – the interannual variability of this parameter. The corresponding time series of precipitation variability data are used in both models as predictors. The validation results indicate that the errors in the obtained estimates constitute 21.1 and 12.9% for the seasonal and annual values of wet deposition velocity, respectively.
Atmospheric wet deposition is an important process for the occurrence of perfluoroalkyl substances (PFASs) in polar/remote mountain regions; however, there are limited data on PFASs in precipitation ...from the Tibetan Plateau (TP). Precipitation (rain from May to October 2017) was therefore collected across the TP to investigate the concentrations, composition profiles, sources, and fluxes of perfluoroalkyl acids (PFAAs). The average ∑PFAA concentrations ranged from 212.3 pg L−1 to 547.7 pg L−1, and perfluoroalkyl carboxylic acids (PFCAs) accounted for 87% of the measured PFAAs (mean value). Significant positive associations (p < 0.05) were found for most PFCAs in the southeast TP, indicating that they may come from similar sources. The monthly PFAA deposition flux ranged from 12.6 to 68.9 ng m−2 month−1, decreasing from east to west. As climate of the eastern TP is controlled mainly by the Indian monsoon, indicating that the Indian monsoon plays an important role in delivering PFAAs to the TP. PCA (principal component analysis) combined with back-trajectory analysis was used to estimate the atmospheric transport pathways, and the PSCF (potential source contribution function) model was applied to define the potential source regions of individual PFAAs. The results suggested that northeast India, Bangladesh, and southern Nepal are the potential sources of C4–C7 PFCAs; C8–C10 PFCAs are more influenced by emissions from southern Nepal and Bhutan; while the source regions of long-chain PFCAs (C11–C12) can be attributed to northern India and Pakistan. Specifically, PFOS (perfluorooctane sulfonic acid) has a local contribution from the central TP.
•The mean PFAA concentrations are higher in the eastern Tibetan Plateau (TP).•The ∑PFAAs flux (12.6–68.9 ng m−2 month−1), decreasing from east to west of the TP.•South Asia offers the important sources of PFAAs on the TP, especially for PFCAs.•The Indian monsoon plays an important role in delivering PFAAs to the TP in summer.
The studies on global pollutant mercury (Hg), which is of public concern due to its high toxicity and capacity to long-range transport via atmospheric circulation, is poorly characterized in wet ...deposition over the Nepal-Himalayas region. Therefore, in order to understand the concentration levels, spatial distribution and seasonal variation of total Hg, 333 precipitation samples were collected from south to north: Kathmandu (1314 m a.s.l.), Dhunche (2065 m a.s.l.), Dimsa (3078 m a.s.l.) and Gosainkunda (4417 m a.s.l.) characterized as urban, rural, remote forest and remote alpine sites, respectively, for over one-year period. The highest Hg concentration was found in Kathmandu comparable to the urban sites worldwide, and significantly lower concentrations at other three sites demonstrated similar levels as in rural and remote alpine sites worldwide. Higher wet deposition fluxes of 34.91 and 15.89 μg m−2 year−1 were found in Kathmandu and Dhunche respectively, due to higher precipitation amount. Clear and distinct seasonal differences were observed with higher concentrations in non-monsoon and lower values in monsoon periods due to less scavenging and high pollutant concentration loadings during the dry period. The positive correlation of Hg flux and precipitation amount with Hg concentration suggested that both precipitation amount and Hg concentration plays a vital role in Hg deposition in the central Himalayan region. Enrichment factor (EFHg) indicated that the anthropogenic emission sources play a significant role for Hg enrichment and a high ratio of EFmonsoon to EFnon-monsoon (>2.18) suggested that the anthropogenic atmospheric mercury could likely be long-range transported from south Asian regions to the Himalayas during the monsoon season. In addition, our results showed that the major ionic compositions (e.g., SO42−, NO3−, NH4+, K+, Ca2+) could influence Hg concentration in wet precipitation. The anthropogenic sources of Hg such as biomass and fossil fuel combustion, crustal aerosols may contribute to the Hg concentration in wet precipitation over the central Himalayas.
Display omitted
•Over 1-year spatial data-set of total mercury in wet precipitation is presented.•Higher Hg concentration appeared in urban site and lower similar levels in rural to remote sites.•All four sites experienced high Hg concentrations during non-monsoon period.•Local and regional emission sources impact on Hg enrichment in the central Himalayas.
Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NO(x) triple bond NO + NO2) and biogenic isoprene. Model estimates of ...surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC(exp 4)RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25 deg x 0.3125 deg horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NO(x) from the US Environmental Protection Agency (EPA) is too high. This finding is based on SEAC(exp 4)RS observations of NO(x) and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NO(x) emissions from mobile and industrial sources must be reduced by 30-60%, dependent on the assumption of the contribution by soil NO(x) emissions. Upper-tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NO(x) emissions. We find that only half of isoprene oxidation proceeds by the high-NO(x) pathway to produce ozone; this fraction is only moderately sensitive to changes in NO(x) emissions because isoprene and NO(x) emissions are spatially segregated. GEOS-Chem with reduced NO(x) emissions provides an unbiased simulation of ozone observations from the aircraft and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NO(x) oxidation products. However, the model is still biased high by 6 plus or minus 14 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to the surface that GEOS-Chem does not capture. This bias may reflect a combination of excessive vertical mixing and net ozone production in the model boundary layer.
PDF
