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Based on cloud-probe data and airborne Ka-band cloud radar data collected in Baoding on 5 August 2018, the microphysical structural characteristics of cumulus (Cu) cloud at the precipitation stage were investigated. The cloud droplets in the Cu cloud were found to be significantly larger than those in stratiform (STF) cloud. In the Cu cloud, most cloud particles were between 7 and 10 μm in diameter, while in the STF cloud the majority of cloud particles grew no larger than 2 μm. The sensitivity of cloud properties to aerosols varied with height. The cloud droplet effective radius showed a negative relationship with the aerosol number concentration (Na) in the cloud planetary boundary layer (PBL) and upper layer above the PBL. However, the cloud droplet concentration (Nc) varied little with decreased Na in the high liquid water content region above 1500m. High Na values of between 300 and 1853 cm−3 were found in the PBL, and the maximum Na was sampled near the surface in August in the Hebei region, which was lower than that in autumn and winter. High radar reflectivity corresponded to large FCDP (fast cloud droplet probe) particle concentrations and small aerosol particle concentrations, and vice versa for low radar reflectivity. Strong updrafts in the Cu cloud increased the peak radius and Nc, and broadened cloud droplet spectrum; lower air temperature was favorable for particle condensational growth and produced larger droplets.

Detailed airborne measurements were carried out to explore aerosol-cloud interactions and cloud microphysical properties in a drizzling marine stratocumulus cloud deck over eastern China. Results show that the collision-coalescence of cloud droplets, the condensation of small droplets, and the collision-induced break-up of drizzle were the dominant microphysical processes in the sampled water cloud parcel. The region in the vicinity of the cloud's lateral boundary was spatially divided into sub-regions to better understand aerosol and droplet interactions. Relationships between the relative dispersion (e) and the cloud’'s microphysical and dynamical characteristics were also examined. A negative relation was found between e and the cloud droplet number concentration, with e showing a close relationship with the liquid water content (LWC) and updraft velocity. When LWC was greater than ~0.75 g kg−1, the range of e values narrowed, and updrafts dominated. By introducing e in the cloud droplet effect radius (Re) parameterization, we find that e can further affect indirect forcing by changing the Re distribution for the cloud examined in this study. The dispersion effect (DE) was estimated using the effective radius ratio and the specific cloud water content. An in-depth analysis indicates that DE may offset the Twomey effect by ~12%. Two different methods of estimating the indirect effect (IE) yielded close values (0.084 and 0.077), suggesting that introducing DE into the estimation had a small influence on the IE calculation in the drizzling marine stratocumulus cloud of this study. Note that the estimated IE has a large uncertainty, given the large biases in the cloud properties measured.

The atmospheric volatile organic compounds (VOCs) are the key participators in the formation of secondary organic aerosol and other atmospheric photochemical processes. However, it is still far from clear understanding of the VOCs in Northern China. In this study, VOCs were measured using a proton transfer reaction-time of flight-mass spectrometer (PTR-TOF-MS) in the downtown area of Beijing during a winter haze period in December 2016. The average mixing ratios of VOCs on the haze days were (ppb): methanol (51.75), formaldehyde (41.65), acetaldehyde (15.81), acetone (7.92), C8-aromatics (7.35), toluene (6.11), benzene (4.30), MEK (2.53), acetonitrile (2.05), C9-aromatics (1.54), benzaldehyde (1.12), isoprene (1.00), styrene (0.62). These concentrations represented the largest values among the cities around the world. VOC concentrations varied dramatically, with the largest value mainly appeared on days having the weakest diffusion condition. Due to the different solar radiation in this period, the photochemical reactivity of the VOCs showed the minimum and maximum values on haze and clear days, respectively. The primary anthropogenic emissions contributed more than half of the mixing ratios of most VOCs. However, formaldehyde received 56.6% contribution from the secondary or biogenic sources, and this contribution mainly increased at the noon hours when sunlight was stronger.

This paper proposes a novel approach for target scale and rotation adaptive estimation based on template matching, which is robust to undergo brightness, contrast invariance, and noise corruption. Improved features based on ring projection transform are extracted, which can not only improve the matching ability of some special scenes by taking into account changes of pixel intensity and structure information, but also automatically recommend the sampling rings involved in the angle estimation. Moreover, treating image features from the perspective of signal time series, we have designed a hierarchical adaptive estimation strategy to solve the problem of scale invariance while reconstructing the transformation of brightness and contrast. Eliminating the limitations of the pre-prepared fixed-scale vertex template, the proposed approach implements an adaptive estimation of the scale. Additionally, rotation angle calculation based on the normalization cross-correlation can be used as the secondary verification of the candidate solution to further improve the matching accuracy. Numerical evaluation shows that the method enjoys attractive results.

Using in-situ aircraft observations from six flights over Zhejiang on Sep. 1 and Sep. 4, 2016, this study investigates differences in aerosol and cloud properties between daytime and nighttime. The samples were divided into marine type and continental type based on the backward air mass trajectories and aerosol characteristics. The results show that the aerosol number concentration (Na) near the ground during daytime is higher than that at nighttime. During daytime, Na has a significant decreasing trend near the top of the planetary boundary layer (PBL), which is not obvious during nighttime. There may be still a relative high concentration of aerosols remaining in the transition zone between the PBL and the free troposphere. Under similar liquid water content (LWC) conditions, the cloud droplet number concentration (Nc) at night is lower, and the cloud droplet effective diameter (cloud ED) is larger. The total Na of marine type aerosols is generally lower than that of continental type aerosols, but for aerosols with particle diameters greater than 1 μm, the marine type aerosols are higher. The study shows a strong negative Na-cloud ED relationship for marine type aerosols, but no obvious Na-cloud ED relationship for continental type aerosols. The number of cloud condensation nuclei (CCN) is higher under high-Na conditions; the ratio of CCN to Na reveals that the activation efficiency of marine type aerosols is higher than that of continental type aerosols. There is no obvious difference in activation efficiency between day and night.

Particles emitted from five typical types of vehicles (including light-duty gasoline vehicles, LDG; heavy-duty gasoline vehicles, HDG; diesel buses, BUS; light-duty diesel vehicles, LDD and heavy-duty diesel vehicles, HDD) were collected with a dilution sampling system and an electrical low-pressure impactor (ELPI+, with particle sizes covering fourteen stages from 6 nm to 10 μm) on dynamometer benches. The mass concentrations and emission factors (EF) for organic carbon (OC) and elemental carbon (EC) were obtained with a DRI Model 2001 thermal/optical carbon analyzer. A respiratory deposition model was used to calculate the deposition fluxes of size-segregated carbonaceous aerosols in human respiratory system. Results indicated that the OC produced from LDG mainly existed in the size range of 2.5–10 μm, while EC from HDG enriched in 0.94–2.5 μm. For diesel vehicles, both OC and EC concentrations peaked at 0.094–0.25 μm. The OC/EC ratios for PM2.5 varied from different types of vehicles, from 0.61 to 8.35. The primary emissions from LDD and HDD exhibited high OC/EC ratios (>3), suggesting that using OC/EC higher than 2 to indicate the formation of secondary organic aerosol (SOA) was not universal. The emission factors for OC and EC of LDG (HDG) in PM10 were 1.78 (3.14) mg km−1 and 0.88 (4.32) mg km−1, respectively. The OC2 and OC3 were the main section (over 60%) of OC emitted from all the five types of vehicles. EC1 was the most abundant EC fraction of LDG (76.9%), while EC2 dominated for other types of vehicles (more than 62%). About 60% of the OC in ultrafine particles could be deposited in the alveoli. Diesel EC mainly could be deposited in the alveolar region. It is necessary to control the emission of ultrafine particles and diesel EC.

Background: The association between handgrip strength (HGS) and pulmonary function is still controversial, and this relationship has not yet been established among the healthy Chinese Han population.Methods: Data from 1519 healthy Han community dwellers in Beijing were analysed. Subjects were divided into two groups by age: the younger group (

Characterizing vertical profiles of aerosol optical properties is important because only replying on the surface or column-integrated measurements is unable to unambiguously constrain the radiative impacts of aerosol. This study presents series of vertical profiles of in-situ measured multi-wavelength optical properties of aerosols during three pollution events in Nov. to Dec. 2016 over Beijing region. For all pollution events, clean periods (CP) before pollution initialization showed higher scattering Ångström exponent and smaller asymmetry parameter (g), and relatively uniform vertical structures. The heavy pollution (HP) periods showed increased particle size, causing these parameters to vary in the opposite way. During the transition periods (TP), regional transport of aged aerosols at upper level was found. The AERONET aerosol optical depth (AOD) matched the in-situ measurements within 10 %, however the AERONET absorption optical depth (AAOD) was 10–20 % higher than in-situ measurements, and this positive discrepancy increased to 30 % at shorter wavelength. The absorption of brown carbon (BrC) was identified by increased absorption Ångström exponent (AAE), and the heating rate of black carbon (BC) and BrC was calculated by computing the wavelength-dependent absorption coefficient and actinic flux by the radiative transfer model. BC and BrC had heating rate up to 0.18 K/h and 0.05 K/h in the planetary boundary layer (PBL) respectively during the pollution period. The fraction of BrC absorption increased from 12 % to 40 % in the PBL from CP to HP period. Notably, higher contribution of BrC heating was found above the PBL under polluted condition. This study gives a full picture of shortwave heating impacts of carbonaceous aerosols during different stages of pollution event, and highlights the increased contribution of BrC absorption especially at higher level during pollution.

Petrochemical industry (PI) is an important emission sector of anthropogenic volatile organic compounds (VOCs). The health impacts of VOCs from PI have caused a wide attention by both scientists and publics. In this study, compositions, sources and health risks of VOCs at a typical petrochemical industrial park along the middle reach of Yangtze River were studied. The total VOC concentrations were in the range of 5.59 to 541 ppbv with a mean value of 54.8 ppbv. Alkanes (41.4 ± 15.7%) were the predominant group, followed by alkenes (19.9 ± 18.3%), OVOCs (14.7 ± 9.26%), halo hydrocarbon (11.2 ± 6.42%), aromatics (8.17 ± 5.08%), and acetylene (4.54 ± 2.80%). Compound-specific health risk results showed that acrolein and 1,3-butadiene had the highest non-carcinogenic risk (expressed by hazard ratio, HR: 22.8) and carcinogenic risk (expressed by lifetime cancer risk, LCR: 6.7 × 10−3), respectively. Positive matrix factorization (PMF) model identified four VOC sources including fuel evaporation, industrial sources, ethylene industry and regional background with the average contributions of 35.6%, 12.0%, 26.5% and 25.9%, respectively. The receptor-originated approach combining the PMF model and conventional methods (HR and LCR) was used to assess the source-specific health risks. The non-cancer risks of four VOC sources were above safe level with regional background contributing most (38.3% or 4.91) to HR. The cancer risks of the four sources were below the tolerable level (

Black carbon aerosol plays an important role on absorbing shortwave solar radiation. The absorption of BC in urban environment with intensive anthropogenic emissions may modify the atmospheric thermodynamics by heating the planetary boundary layer (PBL), however the exact impacts are still largely uncertain due to lack of in-situ observations. Here we report the detailed in-situ characterization on vertical profiles of BC-related properties including the BC mass, size distribution and mixing state over Beijing by successive flights, during which a full process of haze initialization, development and ceasing were captured and processes of BC properties during this typical haze event was in detail investigated. We found the shallow PBL and the temperature inversion importantly enhanced the BC mass loading in the polluted day and these BC particles were significantly coated with mass ratio of coating over refractory BC increasing from about 1 to 10, whereas when the capping was released the BC was dispersed throughout the column and the coating was reduced. The coatings may cause the enhancement of BC absorption by 95% and introduce additional heating rate as high as 0.1 K/h during hazy day. The absorbing power efficiency and heat rate of BC showed positive vertical gradient during peak pollution, which may enhance the temperature inversion at upper level of the PBL. These results provide impacts of BC mixing state on atmospheric heating, and emphasize the importance of including BC mixing state, especially under highly polluted environment, to model the aerosol-boundary layer interaction over urban environment with high BC emission.

Marine shipping emissions exert important air quality and climate impacts. This study characterized the ambient pollutants predominant by emissions from a variety of marine vessel types near the mid-latitude East China Sea. Two discernible primary shipping emissions were identified by factorization analysis on detailed mass spectra of organic aerosol (OA), as emissions in maneuvering and cruise, highly linked with NOx (and less oxidized OA, black carbon, BC) or CO (and more oxidized OA), respectively. Using radio-recorded quantities and activities of 3566 vessels mixed with slow and high-speed diesel engines, we found emission of NOx or BC per vessel was positively correlated with vessel speed, while CO emission peaked at moderate speed. The approach here based on vessel operation mode directly linked the vessel activities to ambient concentrations of pollutants from marine shipping emission, and may synthesize the complex vessel types in shipping emission inventory.

After class, there are frequent cases of people walking but still lighting. In order to reduce the occurrence of this phenomenon, this paper proposes a classroom lighting energysaving system based on YOLOv3. The system uses the installed monitoring equipment in the existing public area as the information collector, controls the lamps through the wireless control switch, and uses the Internet as a bridge to intelligently control the lamps. The system can judge the area where the lights need to be turned off and automatically turn off the equipment in the case of people leaving the lights. While ensuring lighting, the system not only prolongs the service life of lamps, but also reduces the cost of school funds. When the system is popularized to the country, it will save a lot of electric energy, and the future development force cannot be underestimated. It is of great significance to carry out energy conservation and emission reduction in China.

The absence of emission factors (EFs) with high-time resolution primarily hinders developing high time-resolution emission inventory for air pollutants, which further restricted the accuracy of air quality modeling, especially for a pollution process. The real-time emission concentration of volatile organic compounds (VOCs) in the combustion process of eleven kinds of residential biomass fuels (RBFs) were studied using a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS). The dynamic EFs for 18 types of VOCs were firstly obtained with the records of fuel consuming amounts by a balance of high precision. The RBFs burning lasted for about 3–15 min for each experiment with 53–130 g fuels burned. The VOCs concentrations of biomass combustion varied in 0–10 ppm, and exhibited single peak values at about 1–4 min for the entire burning processes. Aldoketones accounted for the largest proportion of the 18 types of VOCs (46.6%–53.6%), followed by methanol (29.2%–44.6%) and alkene (26.2%–31.7%). The real-time EFs of VOCs from RBFs burning firstly decreased to the lowest value of 0.001–3.84 mg/g, and then increased to about 0.23–148 mg/g until the end of combustion processes. The VOCs EFs of all biomass combustion in flaming (1.65 ± 1.55 mg/g) were lower than those in smoldering (16.0 ± 11.3 mg/g). The benzene to toluene (B/T) ratios peaked at 100–200 s of biomass burning processes and changed in 0.07–4.06 for different burning stages. It should be noted that isoprene which was always regarded as the marker for VOCs emitted from biogenic evaporation, can also be released from biomass fuels burning, with real time EFs of 3.16 ± 5.16 mg/g. Its emission amounts and relative importance from combustion sources should be assessed. The high time-resolution of VOCs emission concentrations, emission factors and specific species ratios provide new datasets. They would be useful for dynamic source apportionment and developing high-time resolution emission inventory of VOCs.

Mitigation of ozone in urban agglomerations of developing countries remains challenging, due partly to inadequate knowledge of the relative importance of local sources versus transboundary transport, aggravated by lack of synchronous measurements of ozone and precursors. Here we investigate the spatial-temporal characteristics of ozone and its precursors measured synchronously at five cities of Wuhan City Cluster (WCC) in Central China during the high-ozone months of May–June 2018, facilitated by multiple models of different complexities. We find substantial cross-city diversities in the measured maximum daily averaged 8-h (MDA8) ozone, nitrogen oxides (NOx = NO + NO2), volatile organic compounds (VOCs), VOCs/NOx ratios, and ozone formation potentials of VOCs, which are tied to distinctive local emission sources. GEOS-Chem simulations suggest that local anthropogenic emissions contribute 26.8–29.5% of ozone in each city averaged over May–June 2018, with higher values during ozone episodes (up to 32.0%). Transboundary transport from non-WCC Asian regions (18.5–19.2%) contributes much more than cross-city transport within WCC (2.5–3.1%) to ozone concentrations in the five cities. The contributions of background ozone from non-Asian anthropogenic emissions and global natural sources reach 48.9–51.6%. Thus local mitigation actions alone can substantially reduce city-level ozone; whereas the majority of ozone must be mitigated by country-wide or worldwide collaborations. Collaborations within an urban agglomeration alone may not effectively mitigate ozone.

The Beijing-Tianjin-Hebei (BTH) region in China has been frequently suffering from severe haze events (observed daily mean surface fine particulate matter PM2.5 concentrations larger than 150 μg m−3) partially caused by certain types of large-scale synoptic patterns. Black carbon (BC), as an important PM2.5 component and a primarily emitted species, is a good tracer for investigating sources and formation mechanisms leading to severe haze pollutions. We apply GEOS-Chem model and its adjoint to quantify the source contributions to BC concentrations at the surface and at the top of the planetary boundary layer (PBL) during typical types of severe haze events for April 2013–2017 in BTH. Four types of severe haze events, mainly occurred in December–January-February (DJF, 62.3%) and in September–October-November (SON, 26.3%), are classified based on the associated synoptic weather patterns using principal component analysis. Model results reasonably capture the daily variations of BC measurements at three ground sites in BTH. The adjoint method attributes BC concentrations to emissions from different source sectors and from local versus regional transport at the model spatial and temporal resolutions. By source sectors, the adjoint method attributes the daily BC concentrations during typical severe haze events (in winter heating season) in Beijing largely to residential emissions (48.1–62.0%), followed by transportation (16.8–25.9%) and industry (19.1–29.5%) sectors. In terms of regionally aggregated source influences, local emissions in Beijing (59.6–79.5%) predominate the daily surface BC concentrations, while contributions of emissions from Beijing, Hebei, and outside BTH regions are comparable to the daily BC concentrations at the top of PBL (~200–400 m). Our adjoint analyses would provide a scientific support for joint regional and targeted control policies on effectively mitigating the particulate pollutions when the dominant synoptic weather patterns are predicted.

Biomass burning (BB) has significant impacts on air quality, climate and human health. In China, the BB emission has changed substantially over the past decades while the multi-year variation held high uncertainty and the driving forces have addressed little attention. Here, this research aimed to conduct a comprehensive and systematic analysis of BB variation in China and provided precise and targeted BB emission reduction suggestions. The moving of high emission for BB from 2003 to 2014 was clearly identified, by the view of reliable emission estimation and anthropogenic impacts. Multiple satellite products, field survey, time varying biomass loading data and measured emission factors were adopted to better estimating BB emission and reducing the uncertainty. Social-economic analysis was added to assess the anthropogenic impacts on high emission variation quantitatively. Results showed that the cumulative BB emissions of OC, EC, CH4, NOX, NMVOC, SO2, NH3, CO, CO2, PM2.5 and PM10 during 2003-2014 were 1.6 × 104, 5.64 × 103, 3.57 × 104, 1.7 × 104, 5.44 × 104, 2.96 × 103, 6.77 × 103, 6.5 × 105, 1.15 × 107, 5.26 × 104 and 6.04 × 104 Gg, respectively. Crop straw burning (in-field and domestic) in northeast China plain (NEP), north China plain (NCP), northern arid and semiarid region and loess plateau were the key sources, averagely contributed 73% for all the pollutants emission. While domestic straw burning and firewood burning in Sichuan basin (SB), Yunnan-Guizhou plateau and southern China were main contributors, averagely accounting for 70% of all the pollutants emission. On regional level, high emissions were mainly found in SB, NCP and NEP. Temporally, high emissions were mainly found in crop sowing harvesting and heating seasons. From 2003 to 2014, the BB emission for different biomass species has changed significantly in different regions. High emission has gradually moved from SB to NCP and NEP. Firewood burning and domestic straw burning emission decreased by 47% and 14% in SB, respectively. In-field straw burning emission increased by 52% and 231% in NCP and NEP respectively and domestic straw burning emission increased by 62% in NEP. Emissions from heating season have decreased while emissions in corn harvest season were continuously increased. Analysis of Environmental kuznets curve, agricultural productivity level, human burning habits, rural energy structure and local control policies revealed the internal human driving strength of the variation for BB emission. The unbalanced development of social economy and the policy bias were primary drivers of limiting the BB management. BB emission will alleviate in NCP and aggravate in NEP. For the further emission reduction, effective measures for corn sources management, straw returning and rural energy utilization should be systematically considered. This research provides a clear evidence for the multi-year variation pattern of BB emissions, which is critical for pollution prediction, air quality modeling and targeted mitigation strategies for the key regions of China.

This study investigates the impacts of black carbon (BC) properties (vertical concentration, shape, size, and mixing state) and atmospheric variables (cloud and aerosol loading, surface albedo, and solar zenith angle) on BC radiative effects. Observations from aircraft measurements, lidar, and the Aerosol Robotic Network (AERONET) are used to constrain BC and aerosol properties. The library for radiative transfer (Libradtran) model is used to calculate BC radiative forcing (RF). BC optical properties are obtained from numerical modeling with aggregate or spherical structures and different size distributions. By modifying the optical properties, different BC geometries and size distributions result in uncertainties in RF and heating rate less than 30%, while the uncertainty in heating rate due to different BC mixing states is as large as ~80%. The vertical distribution of BC concentrations explains less than 10% of the relative differences in RF and heating rate in the atmosphere, but can induce different heating rate vertical profiles, thus different planetary boundary layer (PBL) stabilities. Due to the significant influence of cloudy and aerosol conditions on incident solar radiation, atmospheric conditions play an important role in determining the BC heating rate. Meanwhile, the effects of surface albedo and solar zenith angle on the BC heating rate are most significantly near the surface. Taking the above factors into account, we introduce an empirical approximation of the BC heating rate to estimate its influence on the atmosphere. With the simple formula, the BC heating rate for a particular atmospheric layer can be approximated when the vertical condition is known, and this can be further applied to determine whether BC promotes or suppresses PBL development. Considering the importance of the BC vertical concentration in its heating rate, we suggest that light-absorbing aerosols and their vertical distributions must be better measured and modeled to improve the understanding of their radiative effects and interaction with PBL.

After releasing the Air Pollution Prevention Control and Action Plan (APPC) in China since 2013, the role of source emission control strategies and meteorological conditions on the reduction of air pollutants has received wide attention. Using an Aethalometer (AE31), equivalent black carbon (eBC) was monitored for 5.5-year after the APPC at Wuhan, a megacity in Central China, to identify its levels, sources, and variations trends. eBC varied in the range of 0.03–12.3 μg m−3, with the highest and lowest values in January (1.98 ± 1.70 μg m−3) and July (0.87 ± 0.61 μg m−3), respectively. The Kolmogorov-Zurbenk (KZ) filter and multiple-linear-regression were adopted to isolate the impacts of source emission control strategies and meteorological conditions on eBC variation. A long-term linear trend showed that emission-related reduction (7.79% yr−1) rather than meteorology-related reduction (4.51% yr−1) dominated the decreasing of eBC in the past years. Combining the KZ filter and Aethalometer model, the trends of eBC from fossil fuel combustion (eBCff) and biomass burning (eBCbb) were calculated. eBCbb and eBCff both showed decreasing trends with the reduction rates of 7.78% yr−1 and 7.76% yr−1, respectively. Backward trajectory analysis indicated that the air masses transported to the observational site from different regions in China all showed decreasing trend (1.64–18.7% yr−1) for eBC due to both the reduction from eBCbb (5.74–16.0% yr−1) and eBCff (7.38–19.7% yr−1), suggesting the positive role of pollution control measures in migrating air pollution across China.

With the continuous development of the intelligent water conservancy industry, it is urgently to “make up the shortcomings and strengthen the weaknesses” for the traditional water conservancy project construction. This paper takes the kiwifruit planting base in Heilin Town, Ganyu District, Lianyungang City as the control object, and uses Schneider TM221 integrated PLC module as a controller to build an intelligent irrigation system. The system uses sensors to collect data such as irrigation flow, soil moisture, meteorological information, the water level of the reservoir and water quality, and the collected data is monitored by the designed upper computer monitoring software. So that users can switch valves remotely. This system meets users’ needs for monitoring during the irrigation process, irrigation quality analysis and improvement of irrigation processes, so as to achieve automatic operation of irrigation, analysis and other processes, and achieve a double harvest of social and economic benefits.

The contributions to aerosols and major chemical compositions (e.g. water-soluble ions-WSIs) from residential coal combustion (RCC) are still now existing large uncertainty in air quality modeling. The lake of reliable emission inventories for primary WSIs from RCC in China with measured emission factors (EFs) adopted is a major obstacle. With simulating burning test and dilution sampling method, this study detected the emission factors of nine size-segregated aerosols (0.43–10 μm) and associated WSIs emission factors from residential honeycomb briquettes and chunk coal burning, considering smoldering and flaming combustion status. Then a 1 km × 1 km grid cell-based emission inventory of RCC, including size-segregated particles and associated WSIs in China was established. The contributions of RCC to ambient fine particles were estimated by GEOS-Chem model. Results indicated that compared with anthracite coal combustion emission, bituminous coal burning emission can reduce the EFs of particles, while may increase the EFs of WSIs. The averaged EF of WSIs from honeycomb coal combustion was found 1.15 times higher than those for chunk coal burning. The total emission amounts of NH4+, Na+, K+, Mg2+, Ca2+, Cl−, NO3− and SO42− in PM2.1 from residential coal combustion in 2015 were 1915.3, 101.8, 1180.8, 50.1, 96.8, 4956.1, 552.4 and 7430.3 t, respectively, totally accounting for 2.03% of PM2.1. SO42− was the most important WSIs in fine particles released from RCC, occupied by 45.6% of the total WSIs. GEOS-Chem simulation indicated that RCC emission in China averagely accounted for 25.7% of ambient PM2.5 and 7.1% for sulfate. Our results show that RCC emission is an important source for primary PM2.5 and sulfate, suggesting the primary emission of WSI should be included in air quality modeling. More EFs monitoring of RCC of different types and regions in China should be conducted, for updating emission inventory and optimizing modeling results.

Black carbon (BC), from the incomplete combustion sources (mainly fossil fuel, biofuel and open biomass burning), is chemically inertness and optical absorbance in the atmosphere. It has significant impacts on global climate, regional air quality, and human health. During the transportation, its physical-chemical characteristics, optical properties and sources would change dramatically. To investigate the BC properties (i.e., mass concentration, sources and optical properties) during the intra-regional transport between the south edge of North China Plain (SE-NCP) and Central China (CC), simultaneous observations of BC at a megacity (Wuhan, WH) in CC, three borderline cities (Xiangyang, XY, Suixian, SX and Hong'an, HA, distributing from the west to east) between SE-NCP and CC and a city (Luohe, LH) in SE-NCP were conducted during the typical winter haze episodes. Using Aethalometer, the highest equivalent BC (eBC) mass concentrations and aerosol absorption coefficients (σabs) were found in the city (LH) at SE-NCP, followed by the borderline cities (XY, SX and HA) and megacity (WH). The levels, sources, optical properties (i.e., σabs and absorption Ångström exponent, AAE) and geographic origins of eBC were different between clean and pollution episodes. Compared to clean days, the higher eBC levels (increased by 26.4–163 %) and σabs (increased by 18.2–236 %) were found during pollution episodes due to more combustion of fossil fuel (contributing for 51.1–277 %), supported by the decreased AAE (by 7.40–12.7 %). Non-parametric wind regression (NWR) and concentration-weighted trajectory (CWT) results showed that the geographic origins of biomass burning (BCbb) and fossil fuel (BCff) combustion derived BC were different. Based on cluster analysis of trajectories, air parcels from south direction dominated for border sites during clean days, with contributions of 46.0–58.2 %, while trajectories from the northeast had higher contributions (37.5–51.2 %) during pollution episodes. At the SE-NCP site (LH), transboundary influences from south direction (CC) exhibited more frequent impact (with the air parcels from this direction contributed 47.8 % of all the parcels) on the ambient eBC levels during pollution episodes. At WH, eBC was mainly from the northeast transport route during the whole observation period. Two transportation cases showed that from upwind to downwind direction, the mass concentrations of eBC, BCbb and BCff all increased, while AAE decreased. This study highlighted that intra-regional prevention and control for dominated sources of specific sites should be considered to improve the regional air quality.

An elevated pollution layer (EPL) at altitude ∼1700 m was observed over the North China Plain (NCP) in November 2016. The vertical profiles of aerosol loadings, chemical compositions and meteorological parameters were in-situ measured at both ground and aircraft platforms. The EPLs were observed simultaneously over Beijing and Baoding city (∼150 km distance between) with similar aerosol concentration and size distribution, indicating the impact of the EPL at regional scale. The synoptic and remote sensing analysis suggest the pollutants in the EPL may result from regional transport from the polluted southwest, and then elevated by the influence of anticyclone circulation and surrounding terrain. The descent air mass next day may lead to EPL entrainment and contribute to increased aerosol concentration at lower level. The non-refractory compositions measured by aerosol mass spectrometer showed more significant fraction of nitrate and secondary organics in the EPL compared to the other layers. The pollutants in the EPL was then mixed into the developed planetary boundary layer (PBL), leading to uniform distribution of aerosol composition. Such atmospheric stratification at high level and its subsequent impact on the lower level needs to be considered for the future radiative forcing study over this region.

Aerosol acidity affects the chemical transformation of aerosols and subsequent haze formation. High resolution (1-h) observation of water-soluble inorganic ions in fine particles, gaseous pollutants, and meteorological parameters was conducted from September 2015 to August 2016 at Wuhan, a megacity of Central China with high relative humidity and ambient temperature, compared with north Chinese cities. By adopting thermodynamic model ISOROPPIA-II, the aerosol acidity for different time scales, pollution episodes, and air mass directions was calculated. Aerosols in Wuhan were moderate acidic, with pH averaged as 3.30 ± 0.49. The aerosol acidity was higher in July (pH as 2.64 ± 0.31), September (pH as 2.75 ± 0.30) and August (pH as 2.79 ± 0.29), and lower in January (pH as 3.77 ± 0.28) and March (pH as 3.70 ± 0.16). It decreased with the air pollution increasing, with the pH values of 3.07 ± 0.45, 3.63 ± 0.27 and 3.84 ± 0.22 for clean, transition and polluted episodes, respectively. The air masses in Wuhan transported from North China exhibited higher aerosol acidity, with pH averaged as 3.17–3.22. The unique environmental and meteorological conditions (high humidity, annual averaged RH as 0.74 ± 0.13) lead to excess ammonium (on average of 6.06 ± 4.51 μg m−3) and abundant aerosol water content (AWC, on average of 71.0 ± 82.8 μg m−3) in Wuhan, which can explain the lower PM2.5 acidity in Wuhan than other megacities of China. At lower AWC level (less than ~ 15 μg m−3), the particle pH showed a decreasing trend with AWC increased. When the AWC continuous increased from ~ 15 to ~ 380 μg m−3, there was an obvious increase of particle pH. Then no significant growth of pH was found when AWC was higher than ~ 380 μg m−3. With atmospheric RH increasing, the aerosol pH exhibited decreasing trend firstly and then increased, with the turning point RH as about 0.48. There was a logarithmic growth of aerosol pH with total NHx (NH3 + NH4+) increasing. From the fitted logarithmic curve, the aerosol pH of Wuhan was at the range of pH rapid growth stage with NHx increasing, indicating that the control of ammonia emission in Wuhan could be an effective way to reduce the aerosol pH and further mitigate air pollution. This paper firstly obtained the aerosol acidity properties at a megacity under abundant ammonium and high humidity with high time-resolution, which is an important supplementary for the current aerosol acidity research around the world.

BACKGROUND The 2017 high blood pressure (BP) clinical practice guideline reported by the American College of Cardiology/American Heart Association put forward new categories of BP. This study aimed to assess the applicability of the new guideline in a nondialysis chronic kidney disease (CKD) population. METHODS This is a nationwide, multicenter, cross-sectional study with a large sample. A total of 8927 nondialysis CKD patients in 61 tertiary hospitals in all 31 provinces, municipalities and autonomous regions of China (except Hong Kong, Macao and Taiwan) were analyzed. The categories of BP were defined as normal BP (

Under great efforts in fighting against serious haze problem of China since 2013, decreasing of air pollutants especially for fine particles (PM2.5) has been revealed for several key regions. This study tried to answer whether the reduction of PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) was coincident with PM2.5 because of long-term pollution control measures (PCM), and to assess source-oriented health risks associated with inhalation exposure to PAHs. Field measurements were carried out before and after the publishing of local air pollution protection plan for Nanjing, a mega-city in east China. Results indicated that the air quality was substantially improving, with a significant reduction in annual average PM2.5 by 34%, and moreover, PM2.5-bound PAHs significantly reduced by 63% (p

Black carbon aerosol (BC) is the principle absorber to modify the shortwave radiative balance between the lower atmosphere and the surface in polluted environment, which was in-situ characterized by aircraft measurements using a single particle soot photometer (DMT inc., SP2) throughout the boundary layer up to 3 km over the North China Plain around Beijing megacity. The flights were conducted in both hot season (late spring, Apr.–Jun. 2012, surface temperature > 20 °C, 10 flights) and cold season (winter, Dec. 2016, surface temperature The BCPBL in winter showed systematically larger core size (mass median diameter, MMD = 217 ± 4 nm) than in late spring (209 ± 7 nm), which may be due to a higher contribution from the residential emission sector in cold season. The high BC mass loadings were mostly associated with a high fraction of thick coatings (Fcoating), and the higher air moisture enhanced the coating content of BCPBL. These suggest the primary sources with a range of co-emitted species significantly contributed to the coatings of BC, and the secondary formation which could be enhanced by elevated RH also played important role. The BC after significant removal showed much lower Fcoating (~ 0.06) and smaller core size (MMD ~ 193 nm), implying that the coated and larger BC particle was preferentially removed. The scavenging efficiency of BC in the entrainment zone (EZ) showed positive correlation with the change of coatings between PBL and EZ for both seasons (Fcoating,PBL > Fcoating,EZ), however showed seasonally different behaviors in terms of core size (MMDPBL > MMDEZ in late spring, but the opposite in winter). These results provide the basis to evaluate the BC direct radiative forcing in the polluted planetary boundary layer over this region and also the indirect forcing of BC by interacting with low-level clouds.

Due to rapid economic development in recent years, China has become a major global source of refractory black carbon (rBC) particles. However, surface rBC measurements have been limited, and the lower troposphere suffers from a complete lack of measurements, especially in heavily rBC-polluted regions such as China’s capital, Beijing (BJ). In this study, we present the first concentration measurements using an airborne Single Particle Soot Photometer (SP2) instrument, including vertical distributions, size distributions, and the mixing state of rBC particles in the lower troposphere in BJ and its surrounding areas. The measurements were conducted from April to June 2012 during 11 flights. The results show that the vertical rBC distributions had noticeable differences between different air masses. When an air mass originated from the south of BJ (polluted region), the rBC particles were strongly compressed in the planetary boundary layer (PBL), and showed a large vertical gradient at the top of the PBL. In contrast, when an air mass originated from the north of BJ (clean region), there was a small vertical gradient. This analysis suggests that there was significant regional transport of rBC particles that enhanced the air pollution in BJ, and the transport not only occurred near the surface but also in the middle levels of the PBL (around 0.5 to 1 km). The measured size distributions show that about 80% of the rBC particles were between the diameters of 70 and 400 nm, and the mean diameter of the peak rBC concentrations was about 180–210 nm. This suggests that the rBC particles were relatively small particles. The mixing state of the rBC particles was analyzed to study the coating processes that occurred on the surface of these particles. The results indicate that the air mass strongly affected the number fraction (NF) of the coated particles. As for a southern air mass, the local air pollution was high, which was coupled with a lower PBL height and higher humidity. Consequently, hygroscopic growth occurred rapidly, producing a high NF value (~65%) of coated rBC particles. The correlation coefficient between the NF and the local relative humidity (RH) was 0.88, suggesting that the rBC particles were quickly converted from hydrophobic to hydrophilic particles. This rapid conversion is very important because it suggests a shorter lifetime of rBC particles under heavily polluted conditions. In contrast, under a northern air mass, there was no clear correlation between the NF and the local humidity. This suggests that the coating process occurred during the regional transport in the upwind region. In this case, the lifetime was longer than the southern air mass condition.

The causes of haze formation in Beijing, China were analyzed based on a comprehensive measurement, including PBL (planetary boundary layer), aerosol composition and concentrations, and several important meteorological parameters such as visibility, RH (relative humidity), and wind speed/direction. The measurement was conducted in an urban location from Nov. 16, 2012 to Jan. 15, 2013. During the period, the visibility varied from >20 km to less than a kilometer, with a minimum visibility of 667 m, causing 16 haze occurrences. During the haze occurrences, the wind speeds were less than 1m/s, and the concentrations of PM2.5 (particle matter with radius less than 2.5 μm) were often exceeded 200 μg/m(3). The correlation between PM2.5 concentration and visibility under different RH values shows that visibility was exponentially decreased with the increase of PM2.5 concentrations when RH was less than 80%. However, when RH was higher than 80%, the relationship was no longer to follow the exponentially decreasing trend, and the visibility maintained in very low values, even with low PM2.5 concentrations. Under this condition, the hygroscopic growth of particles played important roles, and a large amount of water vapor acted as particle matter (PM) for the reduction of visibility. The variations of meteorological parameters (RH, PBL heights, and WS (wind speed)), chemical species in gas-phase (CO, O3, SO2, and NOx), and gas-phase to particle-phase conversions under different visibility ranges were analyzed. The results show that from high visibility (>20 km) to low visibility (

Under great efforts in fighting against serious haze problem of China since 2013, decreasing of air pollutants especially for fine particles (PM

A comprehensive measurement was carried out to analyze the heavy haze events during 2012–2013 winter in Beijing. The measured variables include some important meteorological parameters, such wind directions, wind speeds, relative humidity (RH), planetary boundary layer (PBL), solar radiation, and visibility. The aerosol composition and concentrations (including particular matters (PM2.5), nitrate (NO3), sulfate (SO4), ammonium (NH4)) as well as their gas-phase precursors (including nitrogen oxides (NOx) and sulfur dioxide (SO2)) were analyzed during the period between Nov. 16, 2012 and Jan. 15, 2013. The results show that the hourly mean concentrations of PM2.5 often exceeded 200 μg/m3, with a maximum concentration of 600 μg/m3 on Jan. 13, 2013. The relative humidity was increased during the haze events, indicating that both aerosol concentrations and RH had important effect on the reduction of visibility, causing the occurrence of the haze events. Because the wind speeds were generally low (less than 1 m/s) during the haze event, the vertical dispersion and the PBL heights were very important factors for causing the strong variability of aerosol concentrations. This study also finds that under the lower visibility condition, the conversion from the gas-phase of NOx and SO2 to the particle phase of NO3 and SO4 were higher than the values under the higher visibility condition. Because the lower visibility condition was corresponding to the lower photochemical activity than the higher visibility condition, the higher conversion from gas phase to particle phase in the lower visibility condition indicated that there was important heterogeneous formation of NO3 and SO4 during the heavy haze events.

For decades, southern China has been considered to be an important source for emerging influenza viruses since key hosts live together in high densities in areas with intensive agriculture. However, the underlying conditions of emergence and spread of avian influenza viruses (AIV) have not been studied in detail, particularly the complex spatiotemporal interplay of viral transmission between wild and domestic ducks, two major actors of AIV epidemiology. In this synthesis, we examine the risks of avian influenza spread in Poyang Lake, an area of intensive free-ranging duck production and large numbers of wild waterfowl. Our synthesis shows that farming of free-grazing domestic ducks is intensive in this area and synchronized with wild duck migration. The presence of juvenile domestic ducks in harvested paddy fields prior to the arrival and departure of migrant ducks in the same fields may amplify the risk of AIV circulation and facilitate the transmission between wild and domestic populations. We provide evidence associating wild ducks migration with the spread of H5N1 in the spring of 2008 from southern China to South Korea, Russia, and Japan, supported by documented wild duck movements and phylogenetic analyses of highly pathogenic avian influenza H5N1 sequences. We suggest that prevention measures based on a modification of agricultural practices may be implemented in these areas to reduce the intensity of AIV transmission between wild and domestic ducks. This would require involving all local stakeholders to discuss feasible and acceptable solutions.

The fast development of a secondary aerosol layer was observed over megacities in eastern Asia during summertime. Within three hours, from midday to early afternoon, the contribution of secondary aerosols above the planetary boundary layer (PBL) increased by a factor of three to five, and the coatings on black carbon (BC) also increased and enhanced its absorption efficiency by 50%. This tended to result from the intensive actinic flux received above the PBL which promoted photochemical reactions. The absorption of BC could be further amplified by the strong reflection of solar radiation over the cloud top across the PBL. This enhanced heating effect of BC introduced by combined processes (intensive solar radiation, secondary formation and cloud reflection) may considerably increase the temperature inversion above the PBL. This mechanism should be considered when evaluating the radiative impact of BC, especially for polluted regions receiving strong solar radiation.

Due to its twofold effects on climate change and air quality, black carbon (BC) is of wide concern in the atmospheric sciences. Considerable uncertainty exists as to the health effects of atmospheric BC for the limited epidemiological and toxicological studies. As combustion-derived BC is one important component of PM2.5 (particles with aerodynamic diameters less than 2.5 μm), the question remains of whether or not BC may play an important role in PM2.5-related health risks. To quantitatively analyze the short-term health effects of BC and PM2.5, a confounder-adjusted semi-parametric generalized additive model (GAM) of a time series study was used to calculate the concentration-response relationship between BC and PM2.5 and daily cardiovascular disease (CVD) mortality from 2006 to 2011 in Beijing. During the study period, the mean daily concentrations of BC and PM2.5 were 6.8 μg/m3 and 75.9 μg/m3, respectively. The results showed that BC was significantly associated with CVD mortality, and an interquartile range (IQR) increase in BC (5.7 μg/m3) and PM2.5 (64. 5 μg/m3) were associated with 2.70% (95% CI: 2.20, 3.21) and 4.06% (95% CI: 3.47, 4.65) increase in CVD mortality. The health risk associated with BC may less than that of PM2.5. When adjusted for nitrogen dioxide (NO2) and sulfur dioxide (SO2), the effects of BC remained statistically significant. It showed the relatively difference between BC and PM2.5 when it comes to the modification effects of age, gender and educational attainment. These findings provide valuable evidence to the rare studies of the concentration-response relationship of BC with human health in developing countries.

A high sensitive method has been developed for measuring atmospheric BTEX (Benzene, Toluene, Ethylbenzene, Xylenes) by using Gas Chromatography equipped with Photo-Ionization Detector (GC-PID). The Method Detection Limits (MDLs) were: Benzene 0.66 ng m(-3), Toluene 2.03 ng m(-3), Ethylbenzene 5.91 ng m(-3), m,p-Xylene 6.49 ng m(-3) and o-Xylene 5.45 ng m(-3). Vertical distribution of BTEX from ground level to 3600 m around Beijing city was measured during flight of aircraft in July and November, 2011. Remarkable decrease of each BTEX species with increasing height was observed, and the sum concentration of BTEX decreased from 21.7 mu g m(-3) at ground level to 0.19 mu g m(-3) at height of 3600 m. The ratio of benzene to toluene (B/T) also increased pronouncedly with increasing altitude, but became flat above 1800 m. The vertical distribution characters of BTEX and B/T were ascribed to diffusion and photochemical consumption of BTEX. (C) 2013 Elsevier Ltd. All rights reserved.

A field experiment was conducted in Tianjin, China from September 9–30, 2010, focused on the evolution of Planetary Boundary Layer (PBL) and its impact on surface air pollutants. The experiment used three remote sensing instruments, wind profile radar (WPR), microwave radiometer (MWR) and micro-pulse lidar (MPL), to detect the vertical profiles of winds, temperature, and aerosol backscattering coefficient and to measure the vertical profiles of surface pollutants (aerosol, CO, SO2, NOx), and also collected sonic anemometers data from a 255-m meteorological tower. Based on these measurements, the evolution of the PBL was estimated. The averaged PBL height was about 1000–1300 m during noon/afternoon-time, and 200–300 m during night-time. The PBL height and the aerosol concentrations were anti-correlated during clear and haze conditions. The averaged maximum PBL heights were 1.08 and 1.70 km while the averaged aerosol concentrations were 52 and 17 μg/m3 under haze and clear sky conditions, respectively. The influence of aerosols and clouds on solar radiation was observed based on sonic anemometers data collected from the 255-m meteorological tower. The heat flux was found significantly decreased by haze (heavy pollution) or cloud, which tended to depress the development of PBL, while the repressed structure of PBL further weakened the diffusion of pollutants, leading to heavy pollution. This possible positive feedback cycle (more aerosols → lower PBL height → more aerosols) would induce an acceleration process for heavy ground pollution in megacities.

The development of agricultural monitoring tools is a focus of the Group on Earth Observations for the Global Earth Observation System of Systems (GEOSS). This requires combining synthetic aperture radar (SAR) and optical satellite sensors to provide more meaningful information in an operational context. The goal of this research was to characterize paddy rice agro-ecological attributes in an operational context. A decision tree framework combined multitemporal and multiscale PALSAR, MODIS, and Landsat observations to map rice extent, hydroperiod, crop calendar, and cropping intensity. The study was carried out in the Poyang Lake Watershed, Jiangxi Province, China. A multiseason field campaign was carried out to calibrate algorithms and validate the rice maps. The field data corresponded relatively well with the remote sensing metrics and validation found that the derived rice paddy maps possessed a high overall accuracy of 89%. The rice maps indicate that the watershed has 25% rice agriculture with 85% o...

Poyang Lake is situated within the East Asian Flyway, a migratory corridor for waterfowl that also encompasses Guangdong Province, China, the epicenter of highly pathogenic avian influenza (HPAI) H5N1. The lake is the largest freshwater body in China and a significant congregation site for waterfowl; however, surrounding rice fields and poultry grazing have created an overlap with wild waterbirds, a situation conducive to avian influenza transmission. Reports of HPAI H5N1 in healthy wild ducks at Poyang Lake have raised concerns about the potential of resilient free-ranging birds to disseminate the virus. Yet the role wild ducks play in connecting regions of HPAI H5N1 outbreak in Asia is hindered by a lack of information about their migratory ecology. During 2007-08 we marked wild ducks at Poyang Lake with satellite transmitters to examine the location and timing of spring migration and identify any spatiotemporal relationship with HPAI H5N1 outbreaks. Species included the Eurasian wigeon (Anas penelope), northern pintail (Anas acuta), common teal (Anas crecca), falcated teal (Anas falcata), Baikal teal (Anas formosa), mallard (Anas platyrhynchos), garganey (Anas querquedula), and Chinese spotbill (Anas poecilohyncha). These wild ducks (excluding the resident mallard and Chinese spotbill ducks) followed the East Asian Flyway along the coast to breeding areas in northern China, eastern Mongolia, and eastern Russia. None migrated west toward Qinghai Lake (site of the largest wild bird epizootic), thus failing to demonstrate any migratory connection to the Central Asian Flyway. A newly developed Brownian bridge spatial analysis indicated that HPAI H5N1 outbreaks reported in the flyway were related to latitude and poultry density but not to the core migration corridor or to wetland habitats. Also, we found a temporal mismatch between timing of outbreaks and wild duck movements. These analyses depend on complete or representative reporting of outbreaks, but by documenting movements of wild waterfowl, we present ecological knowledge that better informs epidemiological investigations seeking to explain and predict the spread of avian influenza viruses.

The role of wild birds in the spread of highly pathogenic avian influenza H5N1 has been greatly debated and remains an unresolved question. However, analyses to determine involvement of wild birds have been hindered by the lack of basic information on their movements in central Asia. Thus, we initiated a programme to document migrations of waterfowl in Asian flyways to inform hypotheses of H5N1 transmission. As part of this work, we studied migration of waterfowl from Qinghai Lake, China, site of the 2005 H5N1 outbreak in wild birds. We examined the null hypothesis that no direct migratory connection existed between Qinghai Lake and H5N1 outbreak areas in central Mongolia, as suggested by some H5N1 phylogeny studies. We captured individuals in 2007 from two of the species that died in the Qinghai Lake outbreaks and marked them with GPS satellite transmitters: Bar-headed Geese Anser indicus (n = 14) and Ruddy Shelduck Tadorna ferruginea (n = 11). Three of 25 marked birds (one Goose and two Shelducks) migrated to breeding grounds near H5N1 outbreak areas in Mongolia. Our results describe a previously unknown migratory link between the two regions and offer new critical information on migratory movements in the region.

Previous work suggests domestic poultry are important contributors to the emergence and transmission of highly pathogenic avian influenza throughout Asia. In Poyang Lake, China, domestic duck production cycles are synchronized with arrival and departure of thousands of migratory wild birds in the area. During these periods, high densities of juvenile domestic ducks are in close proximity to migratory wild ducks, increasing the potential for the virus to be transmitted and subsequently disseminated via migration. In this paper, we use GPS dataloggers and dynamic Brownian bridge models to describe movements and habitat use of free-grazing domestic ducks in the Poyang Lake basin and identify specific areas that may have the highest risk of H5N1 transmission between domestic and wild birds. Specifically, we determine relative use by free-grazing domestic ducks of natural wetlands, which are the most heavily used areas by migratory wild ducks, and of rice paddies, which provide habitat for resident wild ducks and lower densities of migratory wild ducks. To our knowledge, this is the first movement study on domestic ducks, and our data show potential for free-grazing domestic ducks from farms located near natural wetlands to come in contact with wild waterfowl, thereby increasing the risk for disease transmission. This study provides an example of the importance of movement ecology studies in understanding dynamics such as disease transmission on a complicated landscape.