Linking atmospheric emission and deposition to accumulation of soil cadmium in the Middle-Lower Yangtze Plain,China

Cadmium(Cd)is one of the most toxic heavy metals in the environment.Atmospheric deposition has been found to be the main source of Cd pollution of soil on a large scale in China,and identification of the relationships between anthropogenic emission,atmospheric deposition,and Cd accumulation in soil is important for developing ways to mitigate Cd non-point pollution.In this study,the relationship between atmospheric emission,atmospheric deposition,and soil Cd accumulation in the Middle-Lower Yangtze Plain in China was investigated using datasets of atmospheric emission,deposition,and soil accumulation from the literatures published between 2000 and 2020.The results showed that the soil Cd accumulation rate in the study area exceeded the national average(4.0μg kg^(–1)yr^(–1))and continued to accumulate in recent decades,although the average accumulation rate decreased from 9.45μg kg^(–1)yr^(–1)(2000–2010 period)to8.86μg kg^(–1)yr^(–1)(2010–2020 period).The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22–29%,with the atmospheric deposition flux decreasing from 0.54 mg m^(–2)yr^(–1)(2000–2010)to 0.48 mg m^(–2)yr^(–1)(2010–2020),both values being greater than the national average.Atmospheric Cd deposition and emission were highly correlated in a provincial administrative region,which is close to a ratio of 1.0.Emission factors may be in a state of dynamic change due to the influences of new Cd emission control technologies and environmental policies.As the main sources of Cd emissions,dust,and smoke emissions per ton of non-ferrous metal production decreased by 64.7%between the 2000–2010 and 2010–2020 periods.Although new environmental policies have been instigated,atmospheric emission of Cd is still excessive.It was hoped that the findings of this work would provide a scientific basis for the rational control of atmospheric emissions and Cd pollution of soil.

Relation between Atmospheric Deposition and Accumulation of Heavy Metals in Rice in Mining Areas of Guangxi

Firstly, the concept, sources and damage of atmospheric deposition were introduced, and then the relation between atmospheric deposition and accumulation of heavy metals in rice in Guangxi was analyzed to provide reference for the implementation of effective risk early warning of pollution from heavy metal deposition and safe production of rice in mining areas of Guangxi.

Contribution of Atmospheric Nitrogen Compounds to N Deposition in a Broadleaf Forest of Southern China

A one-year study in a typical red soil region of southern China was conducted to determine atmospheric nitrogen (N) fluxes of typical N compounds (NH3, NH4-N, NO3-N, and NO2) and contribution of three sources (gas, rainwater, and particles) to N deposition. From July 2003 to June 2004, the total atmospheric N deposition was 70.7 kg N ha-1, with dry deposition accounting for 75% of the total deposition. Dry NH3 deposition accounted for 73% of the dry deposition and 55% of the total deposition. Moreover, NO2 contributed 11% of the dry deposition and 8% of the total deposition. Reduced N compounds (NH4+ and NH3) were the predominate contributors, accounting for 66% of the total deposition. Therefore, atmospheric N deposition should be considered when soil acidification and critical loads of atmospheric deposition on soils are estimated.

Atmospheric Sulfur Deposition on Farmland in East China

Atmospheric sulfur deposition onto typical farmland in East China was investigated using both field measurements and numerical modeling. The field measurements were conducted at the Experiment Station of Red Soil Ecology, Chinese Academy of Sciences, 10 km from Yingtan, Jiangxi Province, East China, between November 1998 and October 1999, and at the Changshu Ecological Experiment Station, Chinese Academy of Sciences, in a rapidly developing region of Jiangsu Province, East China, between April 2001 and Marc…

Enhanced atmospheric phosphorus deposition in Asia and Europe in the past two decades

There is increasing interest in understanding atmospheric phosphorus(P)deposition and its impacts on plant pro-ductivity and carbon sinks in ecosystems.However,the global pattern of P deposition remains poorly understood,primarily due to the sparseness of data in Asia.In this study,the authors compiled 396 published observations of atmospheric P deposition from 1959 to 2020 on the global scale.The results gave a geometric mean bulk P deposition value of 0.32 kg ha−1 yr−1,or a global P budget of 4.4 Tg yr−1.Compared with the period 1959-2000,the authors found an elevated P deposition in Europe and Asia during 2001-2020,likely due to the increas-ing agricultural emissions and fossil fuel combustion-related sources in addition to dust emissions.The findings highlight the need to quantify the impacts of elevated P deposition from anthropogenic emissions on long-term ecosystem development in the context of carbon neutrality and clean-air actions.

Grain-size Characteristics of Sediment in Daniugou Peatland in Changbai Mountains,Northeast China:Implications for Atmospheric Dust Deposition

The grain-size distribution characteristics and grain-size parameters of sediment in two vertical sections of Daniugou peatland in the Changbai Mountains were systematically investigated.A comparative analysis of the sediment granularity using a discriminative function with Hongyuan peat,red clay,loess-paleosol,fluvial deposit as well as lacustrine deposit was also conducted.It turns out that the vertical section of Daniugou peat ash is primarily constituted by clay and silt particles,and the content of sand is relatively small.Grain-size frequency curves generally show a single-peak modality while a bimodal pattern is detected in the upper layer.The grain-size component and peak pattern of grain-size frequency curves also illustrate that peat ash materials were transported to the peatland by long-range aeolian dust during the deposition process,while there existed short-distance dust influence in peat deposition of the upper layer.Comparisons of grain-size parameters and the discriminative Y-value of Daniugou peat ash with those of typical aeolian sediments show close similarities,suggesting the possibility that atmospheric dust transport processes were involved in the accumulation of peat again.Moreover,the variations of grain-size distribution suggest the local environmental deterioration which is just the driving force of local dust elevation.Grain-size analysis of peatland sediment is demonstrated to be one effective method to extract information about regional and global environmental evolution,and more attention should be paid to current local ecological environment and to seeking a balance between economic development and environmental protection in Northeast China.

Atmospheric Sulfur Deposition for a Red Soil Broadleaf Forest in Southern China

A two-year study in a typical red soil region of Southern China was conductedto determine 1) the dry deposition velocity (V_d) for SO_2 and particulate SO_4^(2-) above abroadleaf forest, and 2) atmospheric sulfur fluxes so as to estimate the contribution of variousfractions in the total. Using a resistance model based on continuous hourly meteorological data,atmospheric dry sulfur deposition in a forest was estimated according to V_d and concentrations ofboth atmospheric SO_2 and particulate SO_4^(2-). Meanwhile, wet S deposition was estimated based onrainfall and sulfate concentrations in the rainwater. Results showed that about 99% of the drysulfur deposition flux in the forest resulted from SO_2 dry deposition. In addition, the observeddry S deposition was greater in 2002 than in 2000 because of a higher average concentration of SO_2in 2002 than in 2000 and not because of the average dry deposition velocity which was lower for SO_2in 2002. Also, dry SO_2 deposition was the dominant fraction of deposited atmospheric sulfur inforests, contributing over 69% of the total annual sulfur deposition. Thus, dry SO_2 depositionshould be considered when estimating sulfur balance in forest ecological systems.

SWAT Modeling of Nitrogen Dynamics Considering Atmospheric Deposition and Nitrogen Fixation in a Watershed Scale

The Soil and Water Assessment Tool (SWAT) nitrogen (N) water quality model considers the artificial inputs associated with human activities, including point and nonpoint source pollution loads. Although SWAT has the ability to simulate atmospheric N deposition and fixation, they were not considered in the modeling research. N deposition from the air is an important and considerable pathway for the input of N species into watersheds and water bodies, causing soil and water body acidification and the leaching of N into surface and groundwater, resulting in eutrophication and degraded water quality. The goal of this study is to assess the effects of atmospheric and agricultural N loads on stream water quality at the watershed scale. For a 6642 km2 Chungju dam watershed, SWAT was calibrated for 4 years (2003-2006) and validated for another 4 years (2007-2010) using daily anthropogenic N data (sewage discharge pollutants and fertilizer) and monthly measured atmospheric deposition data for NO3ˉ, NH4+, and dissolved organic N (DON). At the watershed outlet, the Nash-Sutcliffe (1970) efficiency (NSE) of daily streamflow during the validation period was 0.74. The coefficient of determination (R2) of total N was 0.69 considering atmospheric deposition, whereas it was 0.33 when removing the deposition effect. The results of this study demonstrate the potential for using the N dynamics between the atmosphere and land for SWAT assessments of nonpoint source pollution and for modeling stream water quality.

Atmospheric deposition of inorganic nitrogen in a semi-arid grassland of Inner Mongolia, China

Due to increasing global demand for crop production and energy use, more and more reactive nitrogen（Nr） has been generated and emitted to the environment. As a result, global atmospheric nitrogen（N） deposition has tripled since the industrial revolution and the ecological environment and human health have been harmed. In this study, we measured dry and wet/bulk N deposition from July 2013 to December 2015 in a semi-arid grassland of Duolun County, Inner Mongolia, China. The samples of dry and wet/bulk N deposition were collected monthly with a DELTA（DEnuder for Long Term Atmospheric sampling） system and with Gradko passive samplers and a precipitation gauge. The measured results show that the annual mean concentrations of NH_3, NO_2, HNO_3, particulate NH_4~＋（pNH_4~＋） and particulate NO_3^-（pNO_3^-） in atmosphere were 2.33, 1.90, 0.18, 1.42 and 0.42 μg N/m3, respectively, and that the annual mean volume-weighted concentrations of NH_4~＋-N and NO_3^--N in precipitation were 2.71 and 1.99 mg N/L, respectively. The concentrations of Nr components（including NH_3, NO_2, HNO_3, p NH_4~＋, pNO_3^-, NH_4~＋-N and NO_3^--N） exhibited different seasonal variations. Specifically, NO_2 and HNO_3 exhibited higher concentrations in autumn than in summer, while the other Nr components（NH_3, pNH_4~＋, pNO_3^-, NH_4~＋-N and NO_3^--N） showed the highest values in summer. Based on measured concentrations of Nr components and their deposition velocities estimated using the GEOS-Chem global atmospheric chemical transport model, the calculated annual mean dry deposition fluxes were 3.17, 1.13, 0.63, 0.91 and 0.36 kg N/（hm^2·a） for NH_3, NO_2, HNO_3, p NH_4~＋ and pNO_3^-, respectively, and the calculated annual mean wet/bulk deposition fluxes were 5.37 and 3.15 kg N/（hm^2·a） for NH_4~＋-N and NO_3^--N, respectively. The estimated annual N deposition（including dry N deposition and wet/bulk N deposition） reached 14.7 kg N/（hm^2·a） in grassland of Duolun County, approaching to the upper limit of the N critical load（10–15 kg N/（hm^2·a））. Dry and wet/bulk deposition fluxes of all Nr components（with an exception of HNO_3） showed similar seasonal variations with the maximum deposition flux in summer and the minimum in winter. Reduced Nr components（e.g., gaseous NH_3 and p NH_4~＋ in atmosphere and NH_4~＋-N in precipitation） dominated the total N deposition at the sampling site（accounted for 64% of the total N deposition）, suggesting that the deposited atmospheric Nr mainly originated from agricultural activities. Considering the projected future increases in crop and livestock production in Inner Mongolia, the ecological and human risks to the negative effects of increased N deposition could be increased if no mitigation measures are taken.

Relationship between Nitrogen Atmospheric Deposition, Discharge and Concentration, and Monthly Change of Those in a River

The hypothesis that the product of discharge and concentration of nitrogen (N) in river water is equal to the atmospheric deposition was verified in the mountainous basin of the Tedori River in Japan. To verify this relationship, long-term data?are required to eliminate the effect of short-term variation of the N components. The basin has very high mountains, including Mount Hakusan (2702 maltitude), which is covered with deep snow in winter. Therefore, limited data were used for the estimation of the deposition of the entire basin by assuming a linear relationship of altitude. As a result, it was found that the estimated N concentration coincided well with observed concentrations at six sites—the Shiramine and Kuwajima (upper stream), Nakajima (lower stream) and Dainichi dam, Tedori dam and Senami sites (middle stream). The seasonal variation of N concentrations was low in the snowmelt period and high in autumn through to winter. This was not due to the larger discharge in snowmelt season as it was also found that N deposition was high in winter and low in spring, which indicated a clear relationship between N concentration and monthly atmospheric deposition including N storage in snow pack.

Deposition of Thin Titania Films by Dielectric Barrier Discharge at Atmospheric Pressure

A homogeneous atmospheric pressure dielectric barrier discharge is studied. It is in argon with small admixtures of titanium tetrachloride vapour and oxygen for the deposition of thin titania films on glass substrates. A special electrode configuration was applied in order to deposit the titania film uniformly. The sustaining voltage （6 kV to 12 kV）, current density （about 3 mA/cm^2） and total optical emission spectroscopy were monitored to characterize the discharge in the gap of 2 mm. Typical deposition rates ranged from approximately 30 nm/min to 120 nm/min. The film morphology was investigated by using scanning electron microscopy （SEM） and the composition was determined with an energy dispersive x-ray spectroscopy （EDS） analysis tool attached to the SEM. The crystal structure and phase composition of the films were studied by x-ray diffraction （XRD）. Several parameters such as the discharge power, the ratio of carrier gas to the precursor gas, the deposition time on the crystallization behavior, the deposition rate and the surface morphology of the titania film were extensively studied.

Characterization of Crystalline Nanoparticles/Nanorods Synthesized by Atmospheric Plasma Enhanced Chemical Vapor Deposition of Perfluorohexane

A mass of nanoparticles/nanorods were formed on a simultaneously deposited gran- ular film by plasma enhanced chemical vapor deposition （PECVD） of perfluorohexane at atmo- spheric pressure without any catalysts or templates. Scanning electron microscopy （SEM） and X-ray photoelectron spectroscopy （XPS） were used to characterize the morphology and the chem- ical compositions of nanoparticles. The average size of particles is about 100 nm and the length of synthesized nanorods is between 1 μm and 2.5/tm. The analyses of transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM）, selected area electron diffraction（SAED） and X-ray diffraction （XRD） reveals that the nanoparticles and nanorods are crystalline.

Atmospheric nitrogen deposition in Yangtze River Delta:insights gained from the nitrogen content and isotopic composition of the moss Haplocladium microphyllum

Simple and inexpensive estimation of the rates and sources of atmospheric nitrogen(N)deposition is critical for its effective mitigation in a region with different land-use types.In this study,the N content and N isotopic composition(δ15N)of moss(Haplocladium microphyllum)tissues and precipitation at six sites with three land-use types(urban,suburban,and rural)were measured in the Yangtze River Delta.A significant linear relationship between moss N content and wet N deposition,and a consistent decrease trend for moss N content and wet N deposition from urban to suburban to rural areas were observed.More negativeδ15N of suburban and rural mosses indicated N mainly released from agriculture and effluent,while the less negativeδ15N of urban mosses were mainly influenced by fossil fuel combustion and traffic emissions.Although the negative mossδ15N indicates that reduced N dominates wet N deposition,there was no significant correlation between mossδ15N and the ratio of ammonium to nitrate(NH4+/NO3−).These results reveal that the moss N content andδ15N can be used as a complementary tool for estimating the rates and sources of wet N deposition in a region with different land-use types.

The Impact of Atmospheric Deposition of Cadmium on Dominant Algal Species in the East China Sea

Cadmium(Cd) mainly derived from anthropogenic emissions can be transported through atmospheric pathway to marine ecosystem,affecting the phytoplankton community and primary productivity.In this study,we identified the toxicity threshold of Cd for phytoplankton under seawater conditions of the coastal East China Sea(ECS) through both laboratory and in situ mesocosm incubation experiments.The mesocosm experiment showed that Cd in low concentration(0.003 μg per μg chl a) was conducive to the growth of natural community and increased chl a productivity.In high concentration(0.03 μg per μg chl a) Cd acted as an inhibiting factor which decreased the total chl a productivity.The diatom community was found to be more sensitive to Cd toxicity than dinoflagellate,as the low concentration Cd showed toxicity to diatom but enhanced dinoflagellate growth.We noticed that the soluble Cd estimated from atmosphere deposition to the coastal ECS was below the toxicity threshold and the Cd deposition might promote phytoplankton growth in this region.In our laboratory experiments,adding Cd,similar to aerosol deposition,stimulated the growth of both dominant algal species Prorocentrum donghaiense Lu(dinoflagellate) and Skeletonema costatum(diatom).Adding Cd on a higher level inhibited the growth of both the species,but Skeletonema costatum seemed obviously more sensitive to toxicity.This indicates the potential impact of atmospheric deposition Cd on phytoplankton community succession in the ECS.

Wet Deposition Fluxes and Related Atmospheric Chemistry at Three Sites in Mexico

Wet deposition was collected in Mexico City (MC), Metropolitan Area of Monterrey (MAM) and El Chico National Park (ECNP), during 2009 and 2010. pH, conductivity, Cl-, , Na+, K+, Ca2+ and Mg2+ were determined. In MC, sulphate levels were greater than nitrate levels, and NH4 had mixed sources (vehicular emissions and agriculture activities). MAM had markedly alkaline atmospheric deposition, Na+ and Cl-levels were unexpectedly high, especially during hurricane “Alex”. Low pH values were found in ECNP and nitrate concentrations were high, suggesting the influence of a local source (forest fires). Deposition fluxes (Kg.ha-1yr-1) for N-NO3, N-NH4 and S-SO4 were 1.36, 2.74 and 4.84 for MAM;7.27, 0.57 and 4.32 for ECNP;and 5.97, 4.96 and 6.78 for MC, respectively. Nitrogen deposition fluxes in ECNP were high considering that this site is a natural reserve.

External Influence to Geochemical Assessment of the Land Quality—Atmospheric Dry and Wet Deposition

The heavy metals in the atmosphere mainly come from the gas and dust which involved by the energy costs,transport,metallurgy and building materials production.Other than the element of Hg,the heavy metals come into the atmosphere in the form of aerosol basically and go into the soil through

Influence of acid deposition on atmospheric corrosion of zinc

Site exposure tests both open and sheltered have been carried out in acid deposition area in Southwest China. Results from six sites show that acid deposition exerts a great influence on atmospheric corrosion of Zn, and it is more serious in wet condition. Basically, Zn corrosion is directly proportional to time of exposure. While SO2 is the main pollutant of the atmosphere environment, Zn corrosion has a linear relationship to SO2 depositing rate and a hyperbolic to rain pH value.Observations by SEM, EDAX and X-ray diffraction show that under sheltered exposure condition, the corrosion products of Zn in heavy acid deposition area principally are sulphates.Based on the corrosion rates measured, the working life of galvanized steel can be predicated.

Spatio-Temporal Variation of Atmospheric Nutrient Deposition in Different Land Uses/Covers around Lake Kivu

Atmospheric deposition of nutrients, particularly nitrogen and phosphorus has the capacity to significantly affect the productivity and biogeochemistry of aquatic ecosystems. The objective of this study was to assess the impact of land use/cover types on the atmospheric deposition of nutrients around Lake Kivu. Dry and wet atmospheric deposition samples were collected from four different land use/cover types (forest, wetland, agricultural and urbanized area) at four stations (Goma, Lwiro, Bukavu and Iko) around the Lake Kivu basin. The highest annual loading of dry total phosphorus (TP) was recorded at a station located in an urban area at Goma (4.4 ± 3.9 μmol/m2/yr) and the highest dry deposition of total nitrogen (TN) was recorded at Iko (84.5 ± 41.2 μmol/m2/yr). High wet TP and TN were at Bukavu (0.7 ± 1.1 μmol/m2/yr) and Iko (21.7 ± 34.7 μmol/m2/yr) respectively. High dry TP loads were recorded in the forest area of Goma and the highest dry TN at Lwiro. High wet TP loads were record in agriculture at Goma and high values of wet TN in agriculture at Iko. Phosphorus and nitrogen deposition rates around Lake Kivu were similar to those reported for other African lakes. The highest rate of TP was recorded mainly in the forest area for dry deposition while high TN was recorded in all types of land use/cover in the basin. This study found out that forest traps high concentration of nutrient than other land uses/covers.

Assessing the Impact of Sulfur Atmospheric Deposition on Terrestrial Ecosystems Close to an Industrial Corridor in the Southeast of Mexico

The main objective of this research work was to diagnose the vulnerability of terrestrial ecosystems to S deposition in Atasta region in Campeche State, Mexico, comprising two simultaneous sampling programs in both, soil and atmospheric deposition on an annual basis during three climatic periods: dry, rainy and cold fronts seasons. From the estimation of soil properties estimation (pH, texture, mineralogy, cationic exchange capacity, and basis saturation %), critical loads and sensitivity classes were assigned to sampled soils based according to the empirical methodology proposed by UNECE. During the dry season, 10 sites fell into sensitivity class 2 (moderately sensitive) and 3 (sensitive). On the other hand, during the rainy season, 8 sites showed a sensitivity class 1 (highly sensitive) and 2 sites presented a sensitivity class 2 (moderately sensitive);whereas along cold fronts season, 12 sites fell into sensitivity class 1 that corresponds to highly sensitive. Sensitivity classes showed a seasonal trend, with a higher sensitivity during rainy and cold fronts seasons;this agrees with the kind of sources influencing on the study area as a result of the prevailing meteorology during these climatic periods. Likewise, S concentration in atmospheric deposition was determined by turbidimetric method, and S deposition fluxes were estimated from surface area of the funnel opening of the sampling device and the sampling period. S deposition fluxes ranged from 0.29 and 14.06 kg S ha-1·yr-1;with a mean value of 8.57 kg S ha-1·yr-1. From the comparison between the current deposition rates and proposed critical loads, exceedances percentages were obtained (from 1.65% to 62.8%) and mapped to identify critical zones of S deposition in the studied area. It was established the important role which mangrove vegetation plays in the attenuation of the potential ecological effects on terrestrial ecosystems of the study area associated to atmospheric deposition.

Adsorption experiment of water-soluble rare earth elements in atmospheric depositions and implications for source tracing in South China

The distribution patterns of rare earth elements(REEs)in fine-grained materials in various depositions were often found to be similar to those of the aeolian sediments deposited in the Loess Plateau in North China and the fine-grained materials were suggested to be derived from wind-blown dust.However,increasing evidence indicated that the REEs in the water-soluble portion of atmospheric depositions also displayed similar patterns to those of aeolian sediments.In this study,water-soluble REEs in three atmospheric depositions collected from different climatic zones in China were adsorbed with two adsorbents with distinct adsorption capacity,glass powder,and co-precipitated iron hydroxide.The results showed that the REEs adsorbed by the two adsorbents displayed patterns similar to those of the original atmospheric depositions.The typical characteristics of the REE patterns of atmospheric deposition can be well reproduced in the adsorbed REEs.The higher the REE concentrations in the atmospheric depositions,or the higher adsorption efficiency of the adsorbents,the better reproducibility of the REEs patterns.The results suggest that the REEs of the fine-grained materials in various sediments,which have a high adsorption capacity,especially those deposited in South China,may come from the water-soluble REEs in atmospheric deposition,and may not be appropriate tracers of wind-blown dust from North China.