Vegetable fields have a high risk of heavy metal contamination from pollution sources in suburban and industrial areas of cities. Eighty-seven soil samples, 106 leafy vegetables and 48 road dust ...samples were collected from industrial areas of Shanghai, China. We studied the levels of heavy metals, health risk through consumption of leafy vegetables, and sources of Pb in soils, road dust and leafy vegetables. Soil Cd, Zn, Pb, Cu, Hg and As concentrations exceeded the soil background values in 73.6%, 97.7%, 52.3%, 37.8%, 95.1% and 20.2% soil samples, respectively, but were below the criteria for agricultural soil in China, with the exception of Hg. The concentrations of Cd, Zn, Pb, Cu and As in road dust were significantly higher than concentrations in soils, while Hg concentration in road dust was lower. Cd, Zn, Pb, Hg and Cu concentrations in soils and Zn, Pb and Cu concentrations in road dust were greatest near the municipal solid waste incineration power plant. Heavy metal concentrations in the edible tissues of vegetables were not correlated with their total values in soils and varied among vegetable species. The trends in transfer factors (TFs) in different vegetables were Cd>Zn>Cu>As>Hg>Pb. There was low health risk from heavy metal exposure by consumption of vegetables based on Hazard Quotients (HQM): As was the major contributor to HQM, followed by Cd and Pb. Parent material of the Yangtze River Estuary was the major source of Pb in soils, while coal-fired, stationary industrial emissions and municipal waste incineration emissions were the major sources of Pb in dust and vegetables based on use of the lead isotopic tracing method. Accumulation of Pb in leafy vegetables was through foliar uptake and directly related to atmospheric Pb.
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•Hg in soils and Zn and Cu in road dust were present at relatively high levels.•There was low health risk by consumption of vegetables.•Industrial and combustion emissions were the major sources of Pb in dust and vegetables.•Pb in leafy vegetables was mainly through foliar uptake.
From July 2009 through September 2010, PM10 and PM2.5 were collected at two different functional areas in Shanghai (Baoshan district, an industrial area, and Putuo district, a mixed-use area of ...residential, commercial, and educational compounds). In our analysis, 15 elements were determined using a 710-ES Inductively Coupled Plasma-Emission Spectrometer (ICP-AES). The contents of PM2.5, PM10, and metal elements at the two different sites were comparatively analyzed. The results show that the mean annual concentrations of PM10 and PM2.5 (149.22 μg m−3 and 103.07 μg m−3, respectively) in Baoshan district were significantly higher than those in Putuo district (97.44 μg m−3 and 62.25 μg m−3 respectively). The concentrations of PM10 and PM2.5 were both greatest in winter and lowest in summer, with the two different sites exhibiting the same seasonal variation. It was found that the proportions of 15 metal elements in PM10 and PM2.5 in Baoshan district were 20.49% and 20.56%, respectively, while the proportions in Putuo district were higher (25.98% and 25.93%, respectively). In addition, the proportions of eight heavy metals in PM10 and PM2.5 were 5.50% and 3.07%, respectively, for Baoshan district, while these proportions in Putuo district were 3.18% and 2.77%, respectively, indicating that heavy metal pollution is more pronounced in Baoshan district. Compared with cities in developed countries, the total levels of PM10, PM2.5 and heavy metals in Shanghai were slightly higher. Scanning electron microscopy (SEM) and principal component analysis (PCA) suggested that the possible sources of PM10 in Baoshan district were ground level fugitive dust, traffic sources, and industrial activities, whereas PM2.5 mainly originated from industrial activities, coal combustion, and traffic sources. The sources are same for PM10 and PM2.5 in Putuo region, which originate from traffic sources and ground level fugitive dust.
► Analyzed the contents of PM2.5, PM10, metal elements at different functional areas. ► Compared the levels of PM10, PM2.5, heavy metals with cities in other countries. ► The total levels of PM and heavy metals were slightly higher than developed countries. ► Identify the possible sources of PM10 and PM2.5 with SEM and PCA. ► Preliminary source apportionment results suggested that PM mainly from local sources.
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•HCB, p,p’-DDD and δ-HCH were the primary OCPs contaminants in soil.•DDTs and HCHs have undergone an aging process in Larsemann Hills.•Local station activities contributing to the ...organic pollutants are limited to specific areas.
Antarctica is widely regarded as a sink for persistent organic pollutants (POPs). However, there is a scarcity of data on the occurrence and spatial pattern of POPs in Antarctica, especially in the cold-xeric East Antarctica. Here, organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) in soils from the Larsemann Hills, the second-largest ice-free area along East Antarctica, were investigated. It is shown that the main OCP contaminants were HCB, p,p’-DDD and δ-HCH (3.7–1522.3 pg g−1, 38.2–2276.6 pg g−1 and < LOD–570 pg g−1, respectively). OCPs in soils were primarily caused by long-distance atmospheric transport, but local sources can be found in areas heavily impacted by local human activities. Among DDTs and HCHs, only p,p’-DDD and δ-HCH were detected, indicating that DDTs and HCHs have aged. For PCBs (14.1–993.4 pg g−1), low-chlorinated PCB congeners were found in soil samples far from the station areas (Zhongshan, Progress II, and Progress I), possibly due to long-range atmospheric transport, while high levels of high-chlorinated PCB were found in the soils inside the station area (Law Base) and close to the main road, possibly associated with local station activities. Among the measured PBDEs (81.8–695.5 pg g−1), BDE-209 was the most frequently observed species, and the low-BDE found in soil samples could be from BDE-209 photodegradation. The majority of samples containing high concentrations of BDE-209 are concentrated in the station areas, implying that its source may be related to local station activities.
A detailed investigation was conducted to understand the contamination characteristics of a selected set of potentially toxic metals in Shanghai. The amount of Pb, Zn, Cu, Cr, Cd and Ni were ...determined from 273 soil/dust samples collected within urban area. The results indicated that concentration of all metals except Ni in soils was significant, and metal pollution was even severer in roadside dust. A series of metal spatial distribution maps were created through geostatistical analysis, and the pollution hotspots tended to associate with city core area, major road junctions, and the regions close to industrial zones. In attempt of identifying the source of metals through geostatistical and multivariate statistical analyses, it was concluded as follows: Pb, Zn and Cu mainly originated from traffic contaminants; soil Ni was associated with natural concentration; Cd largely came from point-sourced industrial pollution; and Cr, Ni in dust were mainly related to atmospheric deposition.
Human activities have led to high accumulation of potentially toxic metals in urban soils and roadside dust of Shanghai.
Urban and suburban road dust samples were collected in the most populated city of China, Shanghai. Size fractions of dust particles were analyzed; metal levels of the dust were also measured. Human ...exposure to individual toxic metals through road dust was assessed for both children and adults. The results showed that dust particles from urban and suburban road were presented similar size distribution pattern, with most particles in the range of 100–400
μm. Urban road dust consisted of higher proportions of inhalable, thoracic and respirable particles with increased risk of adverse effects to human. In general, mean grain sizes of urban road dust were smaller than suburban dust. Total organic carbon contents and levels of Pb, Cd, Cu, Zn, Ni, Cr in urban dust were higher than those of suburban dust. But the concentrations of As and Hg from suburban dust were higher, indicting a different main source. The exposure pathway which resulted in the highest level of risk for human exposed to road dust was ingestion of this material, which was followed by dermal contact. Except for some locations, risk values of both cancer and non-cancer obtained in this study were in the receivable range on the whole. Children had greater health risks than adults. The overall risks of non-cancer in urban area were higher than those in suburban area, but the values of cancer in the two areas were comparable. As for the aggregate noncarcinogenic risk, Pb was of most concern regarding the potential occurrence of health impacts. Of the three carcinogenic metals As, Cr and Cd, the only mean risk higher than 10
−6 was Cr, accounting for a great percentage (95%) of the overall risk of cancer. Hence, potentially adverse health effects arising from Pb and Cr in road dust should arouse wide concern.
Abstract
In recent years, the emissions control in nitrogen oxides (NO
x
) was conducted across China, but how the concentrations of NO
x
and its product ozone (O
3
) in the atmosphere varied in ...space and time remains uncertain. Here, the spatial and temporal distributions of nitrogen dioxide (NO
2
) and O
3
in 348 cities of China based on the hourly concentrations data during 2015–2020 were investigated, and the relationships among NO
2
, O
3
and meteorological and socioeconomic parameters were explored. It is shown that higher NO
2
and O
3
concentrations were mainly distributed in North, East and Central China, which are economically developed and densely populated regions. The annual mean concentrations of NO
2
increased from 2015 to 2017 but decreased from 2017 to 2020. The annual variations in O
3
generally exhibited an upward trend in 2015–2019 but decreased by 5% from 2019 to 2020. About 74% and 78% of cities had a decline in NO
2
and O
3
in 2020, respectively, compared to 2019, due to the limits of the motorized transports and industrial production activities during COVID-19 lockdown. The monthly mean concentrations of NO
2
showed an unusual decrease in February in all regions due to the reduced emissions during the Chinese Spring Festival holidays. Compared to 2019, the mean concentrations of NO
2
in January, February and March, 2020 during COVID-19 lockdown decreased by 16%, 28% and 20%, respectively; O
3
increased by 13% and 14% in January and February, respectively, but decreased by 2% in March, 2020. NO
2
and O
3
concentrations are likely associated with anthropogenic and natural emissions. In addition, meteorological parameters can affect NO
2
and O
3
concentrations by influencing the production process, the diffusion and local accumulation, and the regional circulations.
Global nitrogen (N) enrichment has resulted in increased nitrous oxide (N2O) emission that greatly contributes to climate change and stratospheric ozone destruction, but little is known about the N2O ...emissions from urban river networks receiving anthropogenic N inputs. We examined N2O saturation and emission in the Shanghai city river network, covering 6300 km2, over 27 months. The overall mean saturation and emission from 87 locations was 770% and 1.91 mg N2O‐N m−2 d−1, respectively. Nitrous oxide (N2O) saturation did not exhibit a clear seasonality, but the temporal pattern was co‐regulated by both water temperature and N loadings. Rivers draining through urban and suburban areas receiving more sewage N inputs had higher N2O saturation and emission than those in rural areas. Regression analysis indicated that water ammonium (NH4+) and dissolved oxygen (DO) level had great control on N2O production and were better predictors of N2O emission in urban watershed. About 0.29 Gg N2O‐N yr−1 N2O was emitted from the Shanghai river network annually, which was about 131% of IPCC's prediction using default emission values. Given the rapid progress of global urbanization, more study efforts, particularly on nitrification and its N2O yielding, are needed to better quantify the role of urban rivers in global riverine N2O emission.
While nitrate (NO3-) serves as a vital nutrient for soil organisms, the lack of knowledge on its sources and cycling in Antarctic soils does not allow to predict the possible effects of climate and ...environmental changes on the functioning of terrestrial ecosystems. Thus, the NO3- and its stable isotopes of Δ17ONO3, δ15NNO3, and δ18ONO3 were analyzed in Antarctic soils, collected in coastal ice-free areas of East Antarctica and the tip of the northern Antarctic Peninsula. The soil NO3- concentrations and isotopic values of Δ17ONO3, δ15NNO3, and δ18ONO3 were comparable across the latitudinal gradient except for soils collected beneath moss cushions in the Fildes Peninsula. The proportional calculation of Δ17ONO3 indicated that 93–97% of soil NO3- derived from nitrification process, whereas atmospheric deposition probably contributed to the NO3- budget for a fraction <10 %. The linear relationship between δ18ONO3 and δ15NNO3 suggested the occurrence in Antarctic soils of denitrification process and active cycling between NO3- and nitrite (NO2-). The NO3- assimilation in soil likely occurred, but at minimal rates. These findings provide new insights in the biogeochemical cycle of nitrogen (N) in Antarctic terrestrial ecosystems and seem to indicate that despite climatic and environmental changes along the wide latitudinal gradient, the sources and cycling of NO3- maintain a rather consistent pattern along coastal ice-free areas. The noteworthy increase of NO3- concentrations and δ15NNO3, δ18ONO3, and Δ17ONO3 values in soils collected under moss in the Fildes Peninsula could also suggest that the warming and the increased availability of liquid water will likely favor the developments of soil biotic communities and changes in the biogeochemical cycle of N in Antarctic terrestrial ecosystems.
Atmospheric samples and surface seawater collected on a Chinese Antarctic Research Expedition (CHINARE) transect are used to investigate sources and production of nitrate (NO3−) in the atmosphere and ...its contribution to the surface NO3− pool in the ocean. Most atmospheric NO3− is concentrated on intermediate size particles, and much higher concentrations were observed in the northern hemisphere than in the high southern latitudes. Isotopes of NO3− (δ15N, δ18O and Δ17O) suggest that elevated atmospheric NO3− in coastal areas was associated with human activities, while NO3− in the high southern latitudes tends to be influenced by precursor Antarctic snowpack emissions driven by photolysis. In general, no clear association was found between the isotopes of surface seawater and atmospheric NO3−, suggesting that the ocean is unlikely to be an important direct source of atmospheric NOx on this transect. A significant linear relationship between δ18O and Δ17O of NO3− is used to interpret important pathways for NO3− production. In the tropics, >59% of atmospheric NO3− is produced via OH oxidation of NO2, while the elevated oxygen isotopic ratios (δ18O and Δ17O) in the high southern latitudes suggest increased NO3− production via BrO and/or DMS pathways assuming a minor contribution of the N2O5 channel. In surface seawater, high NO3− concentrations are present in the coastal areas and in the Southern Ocean. In coastal areas of China, positive Δ17O values in seawater NO3− (1.7 ± 1.0‰) provide direct evidence of uncycled atmospheric deposition contribution, with a calculated contribution of at least 2-3% to total surface NO3−. A Δ17O=0 was found everywhere else in seawater, suggesting that atmospheric deposition has a minimal presence in the surface NO3− pool. Near Antarctica, deposition of atmospheric NO3− with extremely low δ15N (<−30‰) could lower δ15N found in sea ice, and this process could be isotopically important to evaluate nitrogen cycling in sea ice.
•Concentration and isotopic composition of NO3− show notable latitudinal gradients.•Atmospheric NO3− is mainly produced via OH oxidation in the tropics.•The high southern latitudes show an increased importance of BrO or DMS pathways.•Positive Δ17O of seawater NO3− is found in coastal waters and Δ17O≈0 in other areas.•Atmospheric deposition near Antarctica can lower δ15N of NO3− in sea ice.
•Snowpack emissions due to photolysis dominate atmospheric NO3− production in summer.•Stratospheric inputs contribute 55±21% of atmospheric NO3− budget in winter.•Atmospheric NO3− is mainly produced ...via reactions of O3 and H2O/OH with NOx.•Oxygen isotopes of snowfall NO3− are close to those for the atmosphere year-round.•Differences in δ15N of NO3− between snowfall and the atmosphere vary between seasons.
Atmospheric samples and snowfall collected in coastal East Antarctica over two years are used to investigate the sources, production of atmospheric nitrate (NO3−) and its link with snowfall NO3− based upon the isotopic composition of NO3− (δ15N, δ18O, and Δ17O). Snowfall and the atmosphere show similar seasonal trends in concentrations and isotopic composition of NO3−. In summer, atmospheric NO3− is closely associated with snowpack emissions of NOx from photolysis of snow NO3−. In winter, linear relationships between δ15N and δ18O (or Δ17O) of NO3− in both snowfall and the atmosphere indicate mixing between stratospheric inputs and tropospheric sources contributing to NO3−, with stratospheric inputs contributing 55±21% of the atmospheric NO3− budget. The linear relationships suggest that the lower limits of δ15N, δ18O, and Δ17O of stratospheric-sourced NO3− are close to ∼18, ∼120, and ∼45‰, respectively. Concentration correlates well with the isotopic composition of NO3− in winter, indicating less variable contribution of tropospheric sources. A significant linear correlation between δ18O and Δ17O of NO3− suggests a mix of oxidation processes by O3 and H2O/OH which can influence NOx cycling and the production of NO3−. Lower values of Δ17O of atmospheric NO3− were observed during O3 depletion events in September, suggesting that oxygen isotopes of NO3− could be more sensitive to the changes in surface O3 compared to BrO concentrations. Oxygen isotopic composition of NO3− in snowfall is close to that of the atmosphere throughout the year, suggesting that snowfall NO3− can relay information on oxidative chemistry of NOx in the atmosphere. Snowfall δ15N is close in value to that in the atmosphere during winter, but ∼20‰ higher than that in the atmosphere during summer, possibly associated with seasonal changes in the gas-aerosol partitioning of atmospheric NO3−. This suggests that the interpretation of δ15N in snow needs to consider seasonal changes in sources and chemistry.
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