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[en] Hydrochemical changes between 1991 and 2001 were assessed based on two synoptic stream surveys from the 820-km2 region of the Slavkov Forest and surrounding area, western Czech Republic. Marked declines of sulfate, nitrate, chloride, calcium and magnesium in surface waters were compared with other areas of Europe and North America recovering from acidification. Declines of sulfate concentration in the Slavkov Forest (-30 μeq L-1 yr-1) were more dramatic than declines reported from other sites. However, these dramatic declines of strong acid anions did not generate a widespread increase of stream water pH in the Slavkov Forest. Only the most acidic streams experienced a slight increase of pH by 0.5 unit. An unexpected decline of stream water pH occurred in slightly alkaline streams. - Acidified streams experienced unprecedented recovery from sulfate and nitrate pollution but pH and ANC decreased in alkaline streams
[en] The occurrence of POPs in remote areas, such as Antarctica, is the result of their ability to udergo Long Range Transport (LRT) in the atmosphere, precipitation and cold condensation. In this study, both recent levels of various POPs in Trematomus bernacchii and their changes in roughly three decades were determined in order to evaluate trends of POPs in Antarctic benthic seawaters. In fact, Trematomus bernacchii is considered a good sentinel bio-indicator for monitoring not only the extent of contamination by POPs in the Antarctic aquatic ecosystem, but also changes in Antarctic ecosystem quality and trends. A slight decreasing PCB trend was detected during 30-years time span (from early 1980's to 2010) in the circumantarctic seawaters. Two higher peaks of concentrations were reported in 2001 and 2005 in the Ross Sea and they may reflect the ice melting of icebergs. Because fire risk is very high in Antarctica due to the very dry air, a large use of flame retardants in buildings and furniture of stations is highly probable; moreover, many stations were built when there were no restrictions on flame retardants use. The PBDE levels in the T. bernacchii from 2001 to 2011 ranged 0.05–0.35 pg/g and were of the same order of magnitude in 2001/2011 and in 2002/2005, with a maximum value in 2005 (0.35 pg/g). Comparable concentrations of HCB, HCHs PCDDs and PCDFs are available only for few seasons: all these compounds showed a decreasing temporal trends and their concentrations were one or more order of magnitude lower in 2000s–2010s. - Trematomus bernacchii was used to evaluate the POP temporal trend in Antarctic benthic seawaters: some POPs showed a decreasing trend and for others the tendencies are uncertain.
[en] The Ordos region of Inner Mongolia is rapidly developing and suffers from poor air quality and unhealthy levels of fine particulate matter. PM2.5 concentrations in the Ordos region were found to exceed 75 μg/m3 on average, annually, with peak pollution days in excess of 350 μg/m3, but local air pollution emissions from surrounding sources are not sufficient to drive pollution levels to these concentrations. The current study was designed to quantify sources of PM2.5 and assess the local source contributions and effects of regional transport on local pollution. The results show that the Ordos region is primarily impacted by regional long-range transport of pollutants from anthropogenic sources located outside of the Inner Mongolia in Shanxi province areas but is also largely affected by regional dust transported from the deserts located in western Inner Mongolia. The analysis proved that approximately 77% of PM2.5 mass is transported long-range from the sites exterior to the study area and contributes 59.32 μg/m3 on average, annually, while the local sources contribute 17.41 μg/m3 (23%) on annual average to the PM2.5 mass in the study area. High spatial correlation coefficients (R2 > 0.6) were observed for most of the factors pointing to the transport of external emissions into the area. Spatial correlation analysis, bivariate polar plots and hybrid trajectory models for industrial and secondary inorganic factors provide evidence for the impact of long-range transport from Shanxi province areas. In addition, the deserts in western Inner Mongolia were found to be the source regions for dust. Finally, our analysis shows that the source of oil combustion and mobile factors are impacted by local sources in the Ordos region; however, some regional impacts from other regions were also observed for mobile source in the area. - Dominance of the regional long-range transport of PM2.5 sources in the Ordos region. Around 77% of PM2.5 mass is transported long-range from the sites exterior to the Inner Mongolia.
[en] Antibiotic resistance is a worsening global concern, and the environmental behaviors and migration patterns of antibiotic resistance genes (ARGs) have attracted considerable interest. Understanding the long-range transport of ARG pollution is crucial. In this study, we characterized the dynamics of ARG changes after their release into aquatic environments and demonstrated the importance of traditional chemical contaminants in the transmission mechanisms of ARGs. We hypothesized that the main route of ARG proliferation switches from active transmission to passive transmission. This antibiotic-dominated switch is motivated and affected by non-corresponding contaminants. The effect of anthropogenic activities gradually weakens from inland aquatic environments to ocean environments; however, the effect of changes in environmental conditions is enhanced along this gradient. The insights discussed in this study will help to improve the understanding of the distribution and migration of ARG pollution in various aquatic environments, and provide a modern perspective to reveal the effect of corresponding contaminants and non-corresponding contaminants in the process of antibiotic resistance proliferation. - Highlights: • Process of ARGs flow through WWTPs, rivers, estuaries and ocean to implement global proliferation and commutation. • The diversity and concentrations of ARGs progressively decrease during dynamic long-range migration processes. • The main route of ARG proliferation switches from active transmission to passive transmission from inland to ocean. - The diversity and concentrations of antibiotic resistance genes progressively decrease during dynamic long-range migration processes.
[en] Organochlorine pesticides (OCPs) with different usage states, such as currently, historically or never used, may show different behaviors and potential risks in the environment. It is essential to identify their distribution patterns and fates and to assess their associated health risks to humans. In this study, based on a nationwide sampling campaign across China, we determined the concentrations of currently (endosulfan), historically (chlordane and heptachlor) and never-used (aldrin, dieldrin and endrin) OCPs in agricultural soils. The total residue inventories of ∑Endosulfans, ∑Chlordanes, heptachlor and ∑Drins in soils were 260, 64.3, 54.2 and 88.6 t, respectively. The residues of endosulfan were influenced by current usage, showing a latitude transect trend. Drins were mainly from long-range transport, but the illegal usage in China still affected their residues. This finding indicates that endosulfan and drins in Chinese agricultural soils mainly follow the primary and secondary distribution pattern, respectively. Both primary and secondary distribution have a great impact on the distribution pattern of chlordane, which had been banned for only 4 years at the time we sampled. The health risks of these OCPs were estimated based on their concentrations. There were 0.813% and 1.63% of samples that exceeded the target values for chlordane and endrin according to the Netherlands guideline for unpolluted soil. Their residues in most of the samples posed no or few non-carcinogenic and carcinogenic risks to human beings. The results from this study will provide powerful support for pollution control and management. - Highlights: • Currently, historically and never-usedOCPs were analyzedin arable soils across China. • Endosulfan and drinsfollowedthe primary and secondary distributionpattern, respectively. • Both primary and secondary distribution influencedthe distribution of chlordane. • The health risks of these OCPs in Chinese arablesoils were within acceptable levels. - Geographic distributions, factors influencing the residue characteristics and human health risks of currently, historically and never-used OCPs in agricultural soils across China.
[en] Epiphytic lichens were useful as an early warning system for changes in forest ecosystems. - The results of a study using epiphytic lichens (Parmelia caperata) as sentinels for heavy metal deposition at six selected forest ecosystems of central Italy are reported. The woods investigated are characterized by holm oak (Quercus ilex), turkey oak (Quercus cerris) and beech (Fagus sylvatica) and represent the typical forest ecosystems of central Italy at low, medium and high elevations, respectively. The results showed that levels of heavy metals in lichens were relatively low and consequently no risk of heavy metal air pollution is expected for the six forest ecosystems investigated. However, for two of them there are indications of a potential risk: the beech forest of Vallombrosa showed signs of contamination by Pb as a consequence of vehicle traffic due to the rather high touristic pressure in the area, and the holm oak forest of Cala Violina showed transboundary pollution by Mn, Cr and Ni originating from the steel industry in Piombino. Epiphytic lichens proved to be very effective as an early warning system to detect signs of a changing environment at forest ecosystems
[en] The role of marine plastic debris and microplastics as a carrier of hazardous chemicals in the marine environment is an emerging issue. This study investigated expanded polystyrene (EPS, commonly known as styrofoam) debris, which is a common marine debris item worldwide, and its additive chemical, hexabromocyclododecane (HBCD). To obtain a better understanding of chemical dispersion via EPS pollution in the marine environment, intensive monitoring of HBCD levels in EPS debris and microplastics was conducted in South Korea, where EPS is the predominant marine debris originate mainly from fishing and aquaculture buoys. At the same time, EPS debris were collected from 12 other countries in the Asia-Pacific region, and HBCD concentrations were measured. HBCD was detected extensively in EPS buoy debris and EPS microplastics stranded along the Korean coasts, which might be related to the detection of a quantity of HBCD in non-flame-retardant EPS bead (raw material). The wide detection of the flame retardant in sea-floating buoys, and the recycling of high-HBCD-containing EPS waste inside large buoys highlight the need for proper guidelines for the production and use of EPS raw materials, and the recycling of EPS waste. HBCD was also abundantly detected in EPS debris collected from the Asia-Pacific coastal region, indicating that HBCD contamination via EPS debris is a common environmental issue worldwide. Suspected tsunami debris from Alaskan beaches indicated that EPS debris has the potential for long-range transport in the ocean, accompanying the movement of hazardous chemicals. The results of this study indicate that EPS debris can be a source of HBCD in marine environments and marine food web. - Highlights: • A brominated flame retardant, HBCD, was assessed in EPS debris and microplastics. • HBCD was widely detected in EPS debris from the Asia-Pacific coastal region. • Additive HBCD are dispersed via EPS pollution in marine environments. • EPS debris can be a source of HBCD in the marine environment. - A brominated flame retardant, hexaboromocycledodecane, was widely detected in EPS marine debris and microplastics from the Asia-Pacific coastal region.
[en] East Asia is one of the world's largest sources of dust and anthropogenic pollution. Dust particles originating from East Asia have been recognized to travel across the Pacific to North America and beyond, thereby affecting the radiation incident on the surface as well as clouds aloft in the atmosphere. In this study, integrated analyses are performed focusing on one trans-Pacific dust episode during 12–22 March 2015, based on space-borne, ground-based observations, reanalysis data combined with Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT), and the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem). From the perspective of synoptic patterns, the location and strength of Aleutian low pressure system largely determined the eastward transport of dust plumes towards western North America. Multi-sensor satellite observations reveal that dust aerosols in this episode originated from the Taklimakan and Gobi Deserts. Moreover, the satellite observations suggest that the dust particles can be transformed to polluted particles over the East Asian regions after encountering high concentration of anthropogenic pollutants. In terms of the vertical distribution of polluted dust particles, at the very beginning, they were mainly located in the altitudes ranging from 1 km to 7 km over the source region, then ascended to 2 km–9 km over the Pacific Ocean. The simulations confirm that these elevated dust particles in the lower free troposphere were largely transported along the prevailing westerly jet stream. Overall, observations and modeling demonstrate how a typical springtime dust episode develops and how the dust particles travel over the North Pacific Ocean all the way to North America. - Highlights: • One trans-Pacific transport episode of dust was systematically examined from multiple observations and WRF-Chem modeling. • The westerly jet stream along with Aleutian cyclonic circulation facilitate the trans-Pacific transport of dust. • Physical mechanisms underlying the long-range transport of dust episode were investigated. - One trans-Pacific transport episode of dust was examined from multiple observations and WRF-Chem modeling, and the underlying physical mechanism has been investigated.
[en] Wuhan as a megacity of Central China was suffering from severe particulate matter pollution according to previous observation studies, however, the mechanism behind the pollution formation especially the impact of regional chemical transport is still unclear. This study, carried out on the Nested Air Quality Prediction Modeling System (NAQPMS) coupled with an on-line source-tagging module, explores different roles regional transport had in two strong haze episodes over Wuhan in October 2014 and quantitatively assesses the contributions from local and regional sources to PM2.5 concentration. Validation of predictions based on observations shows modeling system good skills in reproducing key meteorological and chemical features. The first short-time haze episode occurred on 12 October under strong northerly winds, with a hourly PM2.5 peak of 180 μg m−3, and was found to be caused primarily by the long-range transport from the northern regions, which contributed 60.6% of the episode's PM2.5 concentration (versus a total of 32.7% from sources in and near Wuhan). The second episode lasted from the 15–20 October under stable regional large-scale synoptic conditions and weak winds, and had an hourly PM2.5 peak of 231.0 μg m−3. In this episode, both the long-distance transport from far regions and short-range transport from the Wuhan-cluster were the primary causes of the haze episode and account for 24.8% and 29.2% of the PM2.5 concentration respectively. Therefore, regional transport acts as a crucial driver of haze pollution over Wuhan through not only long-range transfer of pollutants, but also short-range aerosol movement under specific meteorological conditions. The present findings highlight the important role of regional transport in urban haze formation and indicate that the joint control of multi city-clusters are needed to reduce the particulate pollution level in Wuhan. - Highlights: • Regional transport impacts studied on two haze episodes in Wuhan. • Chemical transport model and on-line source-tagging method employed. • Different types of regional transport found in formation of haze. • Long-range transport caused first short-time episode. • Long- and short-range transport responsible for second long-term episode. - Different types of the regional transport were found to play key roles in formation of the two haze episodes over the Wuhan Megacity in Central China.
[en] Observations and modeling results were used to examine spatial scales and transport patterns of ozone pollution in the Ontario-New York region. - We investigated the effects of transboundary pollution between Ontario and New York using both observations and modeling results. Analysis of the spatial scales associated with ozone pollution revealed the regional and international character of this pollutant. A back-trajectory-clustering methodology was used to evaluate the potential for transboundary pollution trading and to identify potential pollution source regions for two sites: CN tower in Toronto and the World Trade Center in New York City. Transboundary pollution transport was evident at both locations. The major pollution source areas for the period examined were the Ohio River Valley and Midwest. Finally, we examined the transboundary impact of emission reductions through photochemical models. We found that emissions from both New York and Ontario were transported across the border and that reductions in predicted O3 levels can be substantial when emissions on both sides of the border are reduced