Induced Air Pollution Research Articles

Polluted air evokes nostalgic reverie: A preliminary investigation in China.

Air pollution is related to a variety of psychological distresses (e.g., insecurity), and such distresses may in turn evoke nostalgia as a coping response. Three studies with complementary methodologies were conducted to examine the potential relationship between air pollution and nostalgia in China. Drawing on panel data from 2011 to 2018 covering 31 provincial regions, Study 1 indicated that air pollution positively predicted nostalgia. Study 2 found that air-polluted days were correlated with elevated nostalgia during the 212-day study period. Study 3 further demonstrated that compared with the control condition, participants in the experimentally induced air pollution condition reported more nostalgia, and insecurity mediated this effect. Collectively, our findings provide preliminary evidence that air pollution is positively associated with nostalgia. The implications and limitations of this work were discussed.

Evaluation of Outdoor Environment PM10 Concentration in an Organized Industrial Zone Using Geographical Information System

Air pollution adversely affects human health, visibility distance, materials, plants and animal health. Air pollution’s impact on human health arises from inhaling high amounts of harmful substances in the atmosphere. Notably, our understanding of the damage caused by PM10 pollutants is improving daily. This study aims to measure and analyze PM10 pollution in the Konya Organized Industrial Zone at certain times and places. Measurements were taken at twenty-four locations in the morning, noon and evening hours. The results were compared with the Turkish Air Quality Assessment and Management Regulation, and pollution maps of the regions were created with Surfer Software and ArcGIS 10.1 programs. With the measurements, it was observed that the times at which the limit was exceeded were mainly the evening hours. While no limit exceedance was recorded in the morning hours, the average concentration value was observed once in those hours, and around noon the maximum value was observed five times. In this study, we correlated the measurement results, the values of the measurement points located in the city center and the average number of vehicles passing through the region. It was observed that the PM10 -induced air pollution in the Konya Organized Industrial Zone was caused by dense traffic during evening hours. To prevent traffic-related pollution in the region, it is recommended to increase the number of entrance and exit gates in the industrial zone and to plant trees in appropriate sections.

Perception of Risks from Wood Combustion and Traffic Induced Air Pollution: Evidence from Northern Europe

The health effects of particulate matter, increasing emissions from transportation and requisites for making use of biofuels brings up the need to understand how individuals interpret air-pollution-related risks from wood burning and traffic. We aim to clarify the extent to which perceived risks from road-traffic and wood-smoke can be explained by the individual psychological, social status-related and socio-institutional factors in the case of two Northern European countries, Finland and Estonia. This approach elucidates which of the closely intertwined factors shape the perception of risks from air pollution in different socio-institutional contexts and for different air pollution sources. The study uses data from cross-sectional population surveys conducted among 1112 Finnish and 1000 Estonian residents about environmental health risk perception and coping. Binary logistic regression analysis demonstrated that in both countries’ cases, the perceived personal and general risk from traffic exhaust and wood-smoke can be explained by the perception of exposure to pollution and, also, by the level of knowledge of, the worry about and the possible symptoms from environmental health factors. The perceived vulnerability due to poor health further sensitises individuals towards risks from air pollution. Higher trust towards state institutions in guaranteeing a healthy living environment and greater perceived openness about the risks may attenuate the feelings of vulnerability to air pollution risks in Finland compared to Estonia. The ingrained appeal for wood burning may explain the higher acceptance of exhausts from wood-burning compared to traffic. This may lead to scant support for measures to reduce emissions from wood combustion.

Field study of visitors' behavior in incense burning and its induced air pollution assessment and treatment.

This study conducted a field investigation in the behavior of visitors in the pagoda and burning incense as well as its air pollution situation in Vietnam, and revealed that 92% of people used stick form for offering incense and mainly burning either 1 or 3 sticks/time. Incense smoke exposure caused aroma, comfortable, eye irritation, or hard to breathe. There were 70% of people being aware of the hazard of incense smoke. VOCs, PM2.5, PM10, and CO2 concentrations from burning incense in the Great hall were 1.6-2.5 times higher than those in outside areas. Pollutants' concentrations on the first of the month, full moon day, and Lunar New Year were from 1.5 to 2.0 times higher than those of normal days. A model was designed to collect incense smoke emitted by burning 1 and 3 sticks of seven types of incense on an open area. Except for CO found at low concentrations, VOCs, HCHO, PM2.5, PM10, and CO2 appeared in the smoke with the maximum concentrations higher 2.5-13.5 times than their allowable values. A photocatalytic device using titania nanotubes (TNTs) impregnated with various metals (Cd, Zn, Al, Cu, and Fe) was installed for incense smoke treatment. Effect of type and amount of photocatalyst, as well as initial VOC concentration, were tested. The results show that using 2.0g of Zn/TNT photocatalysts under UV irradiation provided the highest VOC removal efficiency of 73%, suggesting the potential of application for burning incense in open areas.

Forest Fire Induced Air Pollution over Eastern India during March 2021

Being a significant contributor to atmospheric CO2, forest fires are considered a threat to the terrestrial ecosystems that influence climate change. This study integrates in-situ and earth observation platforms to investigate an episodic forest fire event at the Similipal National Park and the adjacent areas in eastern India and its effect on the ambient atmosphere of the nearby areas in 2021 March. The analysis brings out a substantial rise in the Aerosol Optical Depth (AOD) during this period with apparent anomalies in carbon monoxide (CO) and ozone (O3). The pronounced increase in the surface concentration of PM2.5 was increased about 12 µg m–3. Furthermore, the AOD exhibited a spike of about 56.21% during the fire episode. The pollutants' intensity (except NO2) was directly proportional to the fire counts, translated across the northern part of the region. The study also employed an emission index to calculate the amount of CO2 emitted and was pressed against changes in atmospheric XCO2 concentrations retrieved from OCO-2 during the fire episode.

COVID-19 lockdown induced air pollution reduction over India: A lesson for future air pollution mitigation strategies

Air pollution is one of the biggest problems worldwide and needs to be addressed potentially with the implementation of updated stringent policies and legislative laws. The nationwide lockdown imposed to prevent the COVID-19 outbreak, has given us a unique opportunity to understand the contribution of anthropogenic emissions to the total atmospheric pollutant burden on a global as well as regional scale. Thus, in the present study, we try to investigate the impact of COVID-19 induced lockdown on common ambient air pollutants (i.e., PM2.5, NO2, and SO2) concentration over 22 cities in India using in-situ measurement under a network of Centre Pollution and Control Board (CPCB). A significant reduction in the mean mass concentration of all the studied air pollutants (i.e., PM2.5, NO2, and SO2) (nearly 10–70%) is found during different phases of lockdown which reached within the National Ambient Air Quality Standard (i.e., NAAQS). The reduction in studied air pollutants is more prominent during the first phase of lockdown (mainly NO2) which could be due to the complete shutdown of industrial activities. The outcome of the present study will be helpful for policymakers to design cost-effective and accurate air pollution mitigation strategies for the development of a sustainable environment. The study also suggests that well-planned short-term and periodical lockdown could be an alternative effective tool of air pollution mitigation.

Comparative Analysis of Predictive Models for Fine Particulate Matter in Daejeon, South Korea

Air pollution is a critical problem that is of major concern worldwide. South Korea is one of the countries most affected by air pollution. Rapid urbanization and industrialization in South Korea have induced air pollution in multiple forms, such as smoke from factories and exhaust from vehicles. In this paper, we perform a comparative analysis of predictive models for fine particulate matter in Daejeon, the fifth largest city in South Korea. This study is conducted for three purposes. The first purpose is to determine the factors that may cause air pollution. Two main factors are considered: meteorological and traffic. The second purpose is to find an optimal predictive model for air pollutant concentration. We apply machine learning and deep learning models to the collected dataset to predict hourly air pollutant concentrations. The accuracy of the deep learning models is better than that of the machine learning models. The third purpose is to analyze the influence of road conditions on predicting air pollutant concentration. Experimental results demonstrate that considering wind direction and wind speed could significantly decrease the error rate of the predictive models.

Measuring Traffic Induced Air Pollution in Onne Port’s Environment

Maritime shipping has been a major facilitator of economic prosperity throughout the world and it is likely to grow to meet continued and growing transport needs in both developed and developing countries. However, global emissions from maritime shipping have increased considerably, causing depletion of the ozone layer and most importantly posing threat to lives and coastal environment through air pollution. This study investigated the constituents of ambient air in Onne port’s environment in Rivers State of Nigeria. Six air pollutants (O3 CO, NO2, PM2.5, PM10, and SO2) were critically monitored with hand-held mobile Aeroqual gas monitors, series 500, at strategic locations within the port’s environment and Eleme Junction (the control). We found that mean concentrations (μg·m3) of the following pollutants: O3 (71.776 ± 0.726), CO, (19.145 ± 0.275) NO2 (28.145 ± 0.965) and SO2 (36.913 ± 0.378) were significantly high. The particulates (PM10, PM2.5) also showed higher mean concentrations of 48.400 ± 0.197 and 29.676 ± 0.352 respectively. The observed values were found to be significantly higher than those observed in the control group and also exceeded the safe permissible limits for gaseous pollutants when compared to the World Health Organization’s (WHO) standards. This exceedance raises questions on Nigeria’s commitments to implementations of (Annex VI) International Maritime Organization’s (IMO) Convention for the Prevention of Marine Pollution (MARPOL 73/78) from Ships. Again, the findings portend ecological hazards to residents, flora and fauna as elevated levels of these gaseous pollutants have been associated with chronic respiratory diseases. The policy implications of the findings were discussed.

Environmental impacts of fireworks on aerosol characteristics and radiative properties over a mega city, India

The study focusses to investigate the variations in aerosol characteristics, concentrations and radiative properties due to the burning of firecrackers during Diwali festival event followed with New year festival celebrations over a representative urban environment. A six day's long intensive in situ measurements of Black Carbon, Particulate Matter and Aerosol Optical Depth were collected to capture pre to post-Diwali and New Year festival celebrations marked with massive fireworks. We observed an increase of 286%, 89.5%, and 60.5%, in BC, PM10, and PM2.5 concentrations, respectively on festival night as compared to pre-event days. An increase in in situ measured AOD is comparable with concurrent satellite derived AOD. Angstrom exponent, α > 1.0 along with high turbidity coefficient; β estimated for the festival period clearly implies the abundance of fine-mode particles, probably the smoke aerosols loading from fireworks. The Mie-scattered return signals received by the ground based Raman LiDAR at 532 nm showed an increased concentration of ‘anthropogenic aerosols’, attributed to the increased crackers activity. Space based CALIPSO LiDAR observations also validate the presence of ‘polluted dust’ and ‘smoke’ types aerosols at the near surface to 5 km altitude over the study area. A sharp increase in gaseous air pollutants like SO2 and NOx concentrations exceeding the National Ambient Air Quality Standards is also observed. The COART model run simulations in SWIR region showed an increased ‘cooling’ at the surface (−125 Wm−2 to −185 Wm−2) as compared to ‘warming’ in the atmosphere during the event period. A maximum heating rate (1.9 Kday−1) due to total aerosol radiative forcing is also estimated. These investigations provide useful insights into the impact of burning firecrackers on urban air quality besides radiative impacts at a regional scale. Such celebration induced air pollution events may lead to severe health impacts; particularly respiratory and cardiovascular ailments in the resident population.

Mapping spatial distribution of traffic induced criteria pollutants and associated health risks using kriging interpolation tool in Delhi

The present study undertakes to understand the spatial influence of traffic-induced criteria air pollutants and associated health risks assessment at major transport corridors in Delhi. The study includes the classification of vehicular pollutants parameters into five different distribution categories, i.e., low, moderately low, moderate, moderately high, and high. Spatial distribution maps were developed using Geographic Information System (GIS) environment for eleven districts covering 36 transport corridors of the city. The study demonstrated the concentration of three out of the five ambient air pollutants, namely, NOx, PM10 and PM2.5, with highest values in the range of 294.10–362.57, 203.99–422.42 and 333.71–541.72 μg/m3, respectively. Corresponding National Ambient Air Quality Standards (NAAQS) values were found to be grossly violated as reflected by NOx, PM2.5 and PM10 concentrations with 2–5 times higher values. Remaining two (CO and SOx) were found to be under permissible limits, and most of them exhibited low levels of observed concentrations. The ambient air quality in south, central, east, and New Delhi areas were found to be in high and moderately high categories and necessitating adequate control measures. The study reported a total of 281107, 20791, 31636 expected cases of human exposure to respiratory mortality, cardiovascular mortality and total mortality, respectively whereas, 281107 and 71608 number of cases were reported in relation to respiratory morbidity in terms of COPD hospital admission and cardiovascular morbidity along the transport corridors. The outcome of the study may provide a basis for decision makers to formulate the policy as per the scale of impact of traffic induced air pollution in critical areas around the major transport corridors.

A review of aerosol chemistry in Asia: insights from aerosol mass spectrometer measurements.

Anthropogenic emissions in Asia have significantly increased during the last two decades; as a result, the induced air pollution and its influences on radiative forcing and public health are becoming increasingly prominent. The Aerodyne Aerosol Mass Spectrometer (AMS) has been widely deployed in Asia for real-time characterization of aerosol chemistry. In this paper, we review the AMS measurements in Asia, mainly in China, Korea, Japan, and India since 2001 and summarize the key results and findings. The mass concentrations of non-refractory submicron aerosol species (NR-PM1) showed large spatial distributions with high mass loadings occurring in India and north and northwest China (60.2-81.3 μg m-3), whereas much lower values were observed in Korea, Japan, Singapore and regional background sites (7.5-15.1 μg m-3). Aerosol composition varied largely in different regions, but was overall dominated by organic aerosols (OA, 32-75%), especially in south and southeast Asia due to the impact of biomass burning. While sulfate and nitrate showed comparable contributions in urban and suburban regions in north China, sulfate dominated inorganic aerosols in south China, Japan and regional background sites. Positive matrix factorization analysis identified multiple OA factors from different sources and processes in different atmospheric environments, e.g., biomass burning OA in south and southeast Asia and agricultural seasons in China, cooking OA in urban areas, and coal combustion in north China. However, secondary OA (SOA) was a ubiquitous and dominant aerosol component in all regions, accounting for 43-78% of OA. The formation of different SOA subtypes associated with photochemical production or aqueous-phase/fog processing was widely investigated. The roles of primary emissions, secondary production, regional transport, and meteorology on severe haze episodes, and different chemical responses of primary and secondary aerosol species to source emission changes and meteorology were also demonstrated. Finally, future prospects of AMS studies on long-term and aircraft measurements, water-soluble OA, the link of OA volatility, oxidation levels, and phase state were discussed.

Polymer/MOF-derived multilayer fibrous membranes for moisture-wicking and efficient capturing both fine and ultrafine airborne particles

Particulate matter (PM)-induced air pollution has become a serious threat to public health in many regions. There is, therefore, a need for development of advanced respirator materials that can efficiently capture PM and also exhibit both low breathing resistance and good moisture wicking properties to ensure physiological comfort of the wearers. Herein, we report a new type of multilayer membranes that exhibit excellent filtration efficiencies for PM of various sizes, low air resistance and good directional moisture transport properties. We incorporated a type of metal-organic framework, ZIF-8, into polyacrylonitrile (PAN) to prepare microfibers with high surface roughness, and alternatingly stacked layers of rough microfibers with layers of PAN nanofibers via electrospinning, resulting in multi-level structured membranes. Moreover, subsequent acid and base treatments could not only tailor the hydrophilicity of fiber surfaces, but also induce multiscale surface roughness, facilitating both moisture wicking and PM adsorption. This allowed us to construct a unique multilayer membrane composed of a super-hydrophilic outer layer made of PAN fibers with multiscale surface roughness, a hydrophilic composite intermediate layer consisting of porous PAN-ZIF-8 microfibers and PAN nanofibers, and a hydrophobic polystyrene fibrous inner layer, which could offer excellent directional moisture transport performance and a high water vapor transmission rate of 10.56 kg m−2 d−1 due to strong capillary force and push-pull effect. More importantly, benefiting from the large specific surface area, rough fiber surface, and hierarchical pore structure, the membrane exhibits high removal efficiencies of 99.973% for 0.3-μm particles and ≧99.99% for particles of other sizes, including the more harmful ultrafine particles, at a low pressure drop of 80.1 Pa. Moreover, the multilayer composite filter still maintains a high removal efficiency of 99.951% after continuous air purification for 48 h in a high PM2.5 concentration (>300 μg m−3) environment. These make such membranes promising high-performance filtration media for respirator applications.

Health effects of brick kiln operations: A study on largest brick kiln cluster in Bangladesh

Brick manufacturing industry is considered as one of the fastest-growing industrial sectors posing serious health hazards in most South East Asian countries like Bangladesh. A major portion of brick kilns in Bangladesh are located in and around the Dhaka, one of the world’s most densely populated cities, where the health effects of these brick kilns are obvious but yet not completely known. The study was thus performed based on a structured questionnaire survey to assess the health effects of brick kiln operations on kiln workers and local inhabitants at Baghiya of Konabari union in Gazipur near Dhaka of Bangladesh. A total of 100 randomly selected respondents (70 brick kiln workers and 30 local inhabitants) were surveyed. The results of the survey revealed that wood and coal are mostly used fuel for brick production in the study area. The respondents were suffering from skin disease (28%), headache (20%), eye irritation (10%), lung disease (8%), and respiratory diseases such as, asthma (20%), bronchitis (10%) and others (6%) problems, while skin diseases, asthma and other lung diseases were prevalent in workers, and eye irritation, headache and bronchitis were in inhabitants. Inhabitants (36%) who were living in surrounding areas of brick kilns for more than 20 years and workers (40%) who were residing for less than 5 years were suffering most from various diseases. Health education or awareness programs need to be organized since 77.1% and 63.3% of the workers and inhabitants, respectively, were never participated in any health education or awareness programs, and eco-friendly brick kilns should be installed maintaining the existing rules and regulations for minimizing the impacts of brick kiln operation induced air pollution in this respect.
 South East Asia Journal of Public Health Vol.8(1) 2018: 32-36

Traffic induced air pollution modeling: scenario analysis for air quality management in street canyon

Mathematical models are intensively used in environmental science for various reasons – status quo assessment, statistical modeling, forecasting, and planning, scenario analysis. Traffic flow and related atmospheric pollution modeling is one of the most complex challenges because of various aspects, - wide versa of affecting factors, daily, diurnal, weekly, monthly and yearly variability and non-stability of them. In the present study atmospheric model OSPM (Operational Street Pollution Model) is used to calculate NOx and PM10 concentration levels in the historical center (street canyon) of the city of Riga (Latvia) in order to make further assumptions (e.g., for the traffic load) for minimizing traffic induced air pollution in street canyons. In total five different scenarios were analyzed involving prioritizations of public transport, restrictions for old private cars or flow limitations in traffic jam situations during working days.

Impact of Automobile Induced Air Pollution on roadside vegetation: A Review

Impact of Automobile Induced Air Pollution on roadside vegetation: A Review

Air pumping for alleviation of heavy smog in Beijing

Beijing often suffers under heavy smog. During such events which occur mostly in autumn and winter, people are desperate for fresh air. The formation of heavy smog is due to foremost human induced air pollution, but geographic and meteorological conditions, especially below a surface inversion, play an important role. We propose to destroy the inversion by pumping air from above the inversion layer to the surface layer to alleviate the severity of the smog. While long-term air quality improvement depends on the reduction of air pollution emission, air pumping may provide relief in the interim for the Beijing citizens. We estimate that an air pumping at a rate 2×107 m3 s–1 can lead to significantly improved air quality in Beijing, due to (1) direct clean air input; (2) increased instability and vertical mixing and (3) a positive radiation-mixing feedback. The pumping requires an energy input of 10 GW, comparable with the energy consumption in Beijing for air conditioning in summer. We propose to use wind energy from Inner Mongolia for the pumping, which has currently an installed wind energy capacity of 70 GW.

PHYTOMONITORING OF BRICK KILN INDUCED AIR POLLUTION AT KONABARI OF BANGLADESH

The study was conducted to assess the effects of brick kiln induced air pollution on the surrounding vegetation as a function of distance at Baghiya of Konabari union in Gazipur district of Bangladesh. Four samples of two indigenous (Mangifera indica and Artocarpus heterophyllus) and two exotic (Eucalyptus camaldulensis and Acacia auriculacformis) plant species, mostly common in the study area, were collected from three sampling stations (southwest of brick kilns following the prevailing wind) which were 200m away from each other to analyze total chlorophyll, Na+, K+, K+/Na+ ratio, total sugar and proline contents. The study observed that a reduction in total chlorophyll, Na+ and total sugar contents in the leaf samples of all sampled plant species at SS-1 (near source station) when compared to the samples at SS-3 (distant station). The study found that indigenous plant species were more sensitive in case of the total chlorophyll content, whereas exotic plant species were more sensitive in case of total sugar content. At SS-1, the lower value of K+ content and higher value of K+/Na+ ratio were found in all plant species than at SS-3 except E. camaldulensis and A. auriculacformis, respectively. The lower level of proline content was observed in M. indica (240.00 µg/g) and A. heterophyllus (249.05 µg/g) at SS-1, whereas the higher level of proline content was found in E. camaldulensis (388.00 µg/g) and A. auriculacformis (354.09 µg/g) at SS-1 when compared to SS-3 which indicated that the more sensitivity of indigenous plant species to air pollution than exotic plant species. Monitoring of existing kilns and strictly following of brick kiln related rules and regulations in installing new kilns is, thus, necessary for minimizing the impacts of air pollution in the study area. Keywords: Phytomonitoring, brick kiln, air pollution, indigenous and exotic species.

A fuzzy logic urea dosage controller design for two-cell selective catalytic reduction systems

Diesel engines have dominated in the heavy-duty vehicular and marine power source. However, the induced air pollution is a big problem. As people's awareness of environmental protection increasing, the emission regulations of diesel-engine are becoming more stringent. In order to achieve the emission regulations, the after-treatment system is a necessary choice. Specifically, the selective catalytic reduction (SCR) system has been widely applied to reduce the NOX emissions of diesel engine. Different from single-cell SCR systems, the two-cell systems have various benefits from the modeling and control perspective. In this paper, the urea dosage controller design for two-cell SCR systems was investigated. Firstly, the two-cell SCR modeling was introduced. Based on the developed model, the design procedure for the fuzzy logic urea dosage controller was well addressed. Secondly, simulations and comparisons were employed via an experimental verification of the whole vehicle simulator. And the results showed that the designed controller simultaneously achieved high NOX reduction rate and low tail-pipe ammonia slip.

Integrated Monitoring of Induced Air Pollution in Mining Regions

The authors propose to assess air pollution in mining regions using the integrated instrumental monitoring, calculation and remote sensing. The algorithms for experimental data processing for the calculation and remote monitoring of snow cover pollution as a universal indicator of the pollution distribution in air are substantiated. The article presents the integrated monitoring data on the induced load in the air in the large mining industry cluster in Kuzbass.

Advances in understanding Hg dynamics in mercury contaminated paddy soils under straw amendment

It is well-known that interactions between Hg and organic matter could greatly affect biogeochemistry of Hg in soils, and its subsequent uptake by plants. Crop straw is mainly composed of organic matter, and its incorporation into soils may have impacts on Hg dynamics in soil-plant systems. Straw return is being widely encouraged, in order to mitigate straw-burning induced air pollution, as well as to promote plant growth by increasing soil fertility and improving the soil. Meanwhile, potential impacts of straw return on the ecological risk of metals in agricultural soils warrant investigation. While much progresses have been made in understanding the reduced metal bioavailability (e.g., for Cu, Cd and Zn) under straw amendment, little is known about the potential effects of straw return on Hg dynamics in soils and the associated ecological risks. Here, we summarize recent advances in understanding Hg dynamics in soil-rice systems under straw amendment. Recent studies revealed evidently enhanced ecological risk of Hg in paddy soils under straw amendment. Especially, straw return was found to have positive effects on methylmercury (MeHg) concentrations in soils, as well as those in crops. The underlying mechanisms may include: (1) Straw amendment has evident effects on the geochemical fractionation of Hg in soils, by facilitating transformation of Hg from the refractory fractions (e.g., residual fractions, including HgS) to more mobile fractions (e.g., organic-complexed fraction), which may increase availability of inorganic Hg to microbial methylators. (2) Transformation of inorganic Hg to MeHg was facilitated under straw amendment, which could be mainly attributed to the increased availability of inorganic Hg as well as enhanced activities of microbial methylators (e.g., sulfate reducing bacteria). (3) Straw return was found to have positive effects on Hg accumulation in grains of crops. The observed effects could be explained by the increased soil MeHg levels, enhanced mobility of MeHg in the presence of dissolved straw-derived organic matter, as well as changes in plant physiology, e.g., increased uptake of MeHg by root and MeHg transformation from other tissues to grains. Information summarized in this manuscript would improve mechanistic understanding about dynamics and risk of Hg in soil-plant systems and ensure appropriate straw management in Hg-contaminated areas. Particularly, more attentions should be paid to the interactions between ‘fresh’ organic matter (e.g., those from crop straw), which may have great impacts on Hg speciation, methylation, mobility, and bioavailability in soils. Furthermore, results gained in those pioneering studies highlight the importance to re-consider the policy of straw return in farming soils, especially in Hg-contaminated areas.