Contribution of marine and continental aerosols to the content of major ions in the precipitation of the central Mediterranean

Wet deposition chemistry and neutralization potential in oil producing region of southern Nigeria

The aim of this work is to evaluate the atmospheric rainwater chemistry and neutralization potential in oil producing areas of southern region of Nigeria. Rainwater samples were analysed for pH, EC, Cl^-, SO₄²⁺, NO₃^-, Ca₂⁺, and NH₄⁺. Correlation, principal component analysis (PCA) and neutralization indicators as source apportionment methods were used to determine atmospheric acid precursors . Results show that the collected samples were severely acidified with pH value of 5.5 in oil producing communities and weak acid: pH 6.5 in non oil producing areas and varied with seasons. Fractional acidity (FA) constituted 98-99% of neutralizing ability, neutralization factor (NF) recorded Cl^-, Ca²⁺ and NH₄⁺ in values of 0.41, 0.43 and 0.003 with Ca²⁺ from sea salt, being the most neutralizing substance than NH₄⁺from agricultural practice. The neutralizing and acidifying potentials (NP/AP) recorded a mean of 0.4, showing weak alkaline effect on atmospheric acid rain in oil producing communities. The positive correlation among ionic species implicates pH, SO₄²⁺and NO₃ as causes of severe atmospheric acidity. Conclusions were made that enforcement of the existing environmental laws to checkmate the emission of acid precursors is crucial for the survival of man and entire ecosystem.

Factors affecting the chemical composition of precipitation in Syria

Concentrations of the major ions (Ca²⁺, Mg²⁺, Na⁺, K⁺, NH₄⁺, Cl^-, HCO₃^-, SO₄^2- and NO₃^-), pH and electrical conductivity (EC) values in the rainwater (RW) samples at 16 stations in Syria were determined for characterizing the principal factors affecting the chemical composition of precipitation (P) in this country. Collection of the RW samples was made on a monthly basis during the period (1989-2006). The volume-weighted mean (VWM) values calculated for the different parameters at all stations show VWM values of 6.84 and 96 μS/cm for pH and EC, respectively. The ionic trend of the VWM concentrations (μeq/L) in the RW samples of entire dataset follows the descending order: Ca²⁺ ≥ HCO₃^- > SO₄^2- > Mg²⁺ > Cl^- > Na⁺ > NO₃^- > K⁺ > NH₄⁺. The lowest pH and EC values were found for the southern mountainous stations, while the highest were reported for the interior inland stations, depending on the amount of carbonate dust present in the atmosphere. The major part of the RW salinity (> 70%) was due to Ca²⁺, HCO₃^- and SO₄^2- concentrations. The highest concentrations of Na⁺ and Cl^- were found for the Tartous coastal station, where the Na⁺/Cl^- ratio (0.84 ± 0.16) was remarkably very close to that of the Mediterranean Sea (MS) value (0.86), implying thus the sea spray effect. The highest NO₃^- concentrations (≈ 8-9 mg/L), with relatively high SO₄^2-/NO₃^- ratios (> 2 ± 1), were found for the major cities (Damascus, Homs and Aleppo), implying hence the influence of intensive traffics and urban pollutions. The pH parameter was moderately linked with Ca²⁺ and HCO₃^- (R² ≈ 0.36), while EC was correlated with all ions, except NH₄⁺. This later ion was weakly correlated with NO₃^- (R² ≈ 0.23). Strong correlations were found between Ca²⁺ and SO₄^2- (R² ≈ 0.80) and between Cl^- and Na⁺ (R² ≈ 0.95). Ca²⁺ and Mg²⁺ ions were the most responsible for neutralizing the RW acidity. The role of K⁺ and NH₄⁺ as acidity neutralizers was small. By using the principal component analysis (PCA), five major factors, explaining ≈ 87% of the total variance, were suggested for the possible sources affecting the chemical composition of RW in this country. The factors are (1) crustal natural materials, (2) sea salts, (3) fossil fuel combustion, (4) rural activity, and (5) biomass burning.

Evidence of Natural and Anthropogenic Impacts on Rainwater Trace Metal Geochemistry in Central Mexico: A Statistical Approach

Trace metals Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd, and As were determined on a monthly basis in a total of 52 rain samples collected from six different locations in the central region of Mexico during March 2016–April 2017. The average concentrations of trace metals (mg/L) in the rainwater samples showed an order of Zn (0.873) > Fe (0.395) > Mn (0.083) > Cr (0.041) ≥ Cu (0.041) > Pb (0.031) > Ni (0.020) > Co (0.013) > As (0.0003) > Cd (0.002). The differences observed in metal concentrations are related to variations in the influence of continental air masses, local transport, regional advection, and the solubility of trace metals. High concentrations of metals were observed in the months of March to May at all sites, probably due to the less extensive removal of air/air pollutants. The values obtained from the enrichment factor (EF) per metal showed relatively high values for Cd, Zn, Cu, Pb, Co, Ni, and Cr, suggesting anthropogenic origin. Pearson’s correlation matrix validated the distribution of trace metal sources and their relationships with local/regional meteorological characteristics. This paper presents relevant basic information for the evaluation of the toxic potential of rainwater and the possible health risks when using this source of water for human consumption.

The effect of atmospheric particulates on the rainwater chemistry in the Yangtze River Delta, China

To investigate the effect of atmospheric particulates on the chemistry and acidity of rainwater during the washout process in areas with highly acidic rainfall, rainwater and particulates (before, during and after rain) were sampled and analyzed from June 2008 to June 2009 in the Yangtze River Delta region, China. The volume-weighted mean pH of the rainwater was only 4.44 in Hangzhou, and the average concentrations of TSP (total-suspended particulates) and PM₁₀ (particulates with aerodynamic equivalent diameters of less than 10 μm) during the study period were 191 μg/m³ and 155 μg/m³, respectively. The measured acid buffering capacities of PM₁₀ and TSP were 1.31 ± 0.45 and 1.61 ± 0.84 ml/mg, on average, respectively, indicating that both had a certain acid buffering capacity. Rain appeared to have a pronounced scouring effect on particulates, except for F^- and Cl^- in PM₁₀. Upon combining the correlation analysis between ions in particulates and rainwater with Enrichment Factor and Principal Component Analysis of the rainwater chemistry, the results suggested that the components of rainwater were mainly derived from washout processes acting on particulates from crustal dust and building industry sources (Ca²⁺), marine sources (Na⁺, K⁺ (in spring), Mg²⁺ and Cl^-) and anthropogenic sources, especially secondary aerosols emitted from agricultural land, motor vehicles and industrial plants (NO₃^-, SO₄^2-, and NH₄⁺). The F^- in rainwater was mainly contributed by gaseous pollutants, such as HF from cooling systems, coal burning and surrounding factories.Implications: The interaction between particulates and rain in areas with highly acidic rainfall include the following: rain appears to have a pronounced scouring effect on most components in the particulates; the components of the rainwater are mainly derived from washout processes acting on PM contributed by crustal dust, sea salt and secondary aerosol subcloud; and the acid buffering capacities of PM₁₀ and TSP in Hangzhou are 1.31 ± 0.45 and 1.61 ± 0.84 ml/mg, respectively, and had a certain acid buffering capacity toward rainwater.

Wash effect of atmospheric trace metals wet deposition and its source characteristic in subtropical watershed in China

In order to better understand air pollution in deve-loping regions, such as China, it is important to investigate the wet deposition behavior of atmospheric trace metals and its sources in the subtropical watershed. This paper studies the seasonal change of trace metal concentrations in precipitation and other potential sources in a typical subtropical watershed (Jiazhuhe watershed) located in the downstream of the Yangtze River of China. The results show that typical crustal elements (Al, Fe) and trace element (Zn) have high seasonal variation patterns and these elements have higher contents in precipitation as compared to other metals in Jiazhuhe watershed. In addition, there is no observed Pb in base flow in this study, and the concentration magnitudes of Al, Ba, Fe, Mn, Sr, and Zn in base flow are significantly higher than that of other metals. During different rainfall events, the dynamic export processes are also different for trace metals. The various trace metals dynamic export processes lead to an inconsistent mass first flush and a significant accumulative variance throughout the rainfall events. It is found that in this region, most of the trace metals in precipitation are from anthropogenic emission and marine aerosols brought by typhoon and monsoon.

Investigation of rainwater contamination sources in the southern part of Brazil

Rainwater quality is influenced by air pollutants and can affect sensitive ecosystems. This study was conducted to identify the sources of rainwater contamination in a receptor investigated in the southern part of Brazil. A total of 22 rainwater samples were collected at Florianópolis, Brazil. The sampling station is influenced by continental emissions (soil resuspension, traffic emissions and combustion) and marine aerosols. Over the sampling period, the average pH and electrical conductivity (EC) of the precipitation was found to be 4.97 +/- 0.41 and 14.68 microS cm(-1) +/- 13.47, respectively. In addition topH and EC, ions and trace metals in the collected rainwater were quantified. The results were investigated by a combination of techniques including principal component analysis (PCA), a back trajectory model and other statistical and graphical interpretation methodologies. A PCA showed that Cl(-), Na+, Mg2+ and part of the K+ and SO4(2-) content were mainly contributed by marine aerosols, whereas the contribution from continental sources (combustion, traffic emissions and other urban activities) was dominant in the content of NO3(-) and part of the SO4(2-) and Mn content. Soil resuspension was responsible for the concentrations of most of the trace metals (apart from Mn) and Ca2+ in the rainwater. An inverse correlation among the elemental concentrations, amount of rainfall and wind speed was observed. The northern transport pathway was identified as being associated with high concentrations of NO3(-) and slightly decreased pH values. However, the low standard deviation observed for the pH values during the sampling campaign also showed a small variation in the data, suggesting that the acidity is most probably being constantly sourced from a natural origin, such as organic acids.

Investigation of PM10 sources in Santa Catarina, Brazil through graphical interpretation analysis combined with receptor modelling

Epidemiological studies have documented that elevated airborne particulate matter (PM) concentrations, especially those with an aerodynamic diameter less than 10 microm (PM10), are associated with adverse health effects. Two receptor models, UNMIX and positive matrix factorization (PMF), were used to identify and quantify the sources of PM10 concentrations in Tubarão and Capivari de Baixo, Santa Catarina, Brazil. This region is known for its high pollution levels due to intense industrial activity and exploitation of natural resources. PM10 samples were collected using high volume samplers at two sites in the region and statistical exploratory analysis techniques were applied to identify and assess PM10 sources. The two primary PM10 sources were identified as soil re-suspension/road dust emissions and coal burning emissions, contributing 65-75% and 15-25% of the PM10, respectively. The study confirmed the significance of the influence of local PM10 emissions (power plants, soil re-suspension and road dust emissions) on regional air quality, although no violations of the Brazilian PM10 standards (limit of 150 microg/m3) were observed, with a mean concentration of 27.6 microg/m3 measured in this study. This study demonstrated the usefulness of statistical exploratory analysis techniques in assessing the validity of modelling results and contributing to the interpretation of ambient air quality data.

The dominant contribution on wet deposition of water-soluble main ions in the South-Eastern Adriatic region

The results of content of water-soluble ions measured in 604 samples of precipitation collected in South-Eastern Adriatic region during 6 years have been analyzed. The HYSPLIT model was used to study the air mass paths. Although the ion concentrations of investigated ions in precipitation of air masses from the continental parts of Europe were significant, the total wet deposition is dominated by precipitation coming over the Mediterranean Sea. The sea salt components are significantly correlated. The correlations between Ca2+ and Mg2+, Ca2+ and SO42− and Ca2+ and K+ indicate the main terrigeneous ions.

Evaluation of trace elements contamination in cloud/fog water at an elevated mountain site in Northern China

Totally 117 cloud/fog water samples were collected at the summit of Mt. Tai (1534m a.s.l.)-the highest mountain in the Northern China Plain. The results were investigated by a combination of techniques including back trajectory model, regional air quality and dust storm models, satellite observations and Principal Component Analysis. Elemental concentrations were determined by Inductively Coupled Plasma Mass Spectrometry, with stringent quality control measures. Higher elemental concentrations were found at Mt. Tai compared with those reported by other overseas studies. The larger proportions and higher concentrations of toxic elements such as Pb and As in cloud/fog water compared with those in rainwater at Mt. Tai suggests higher potential hazards of cloud/fog water as a source of contamination in polluted areas to the ecosystem. Peak concentrations of trace elements were frequently observed during the onset of cloud/fog events when liquid water contents of cloud/fog water were usually low and large amount of pollutants were accumulated in the ambient air. Inverse relationship between elemental concentrations and liquid water contents were only found in the samples with high electrical conductivities and liquid water contents lower than 0.3gm(-3). Affected mainly by the emissions of steel industries and mining activities, air masses transported from south/southwest of Mt. Tai were frequently associated with higher elemental concentrations. The element Mn is attributed to play an important role in the acidity of cloud/fog water. The composition of cloud/fog water influenced by an Asian dust storm event was reported, which was seldom found in the literature.

Water-soluble main ions in precipitation over the southeastern Adriatic region: chemical composition and long-range transport

BACKGROUND, AIM AND SCOPE

Precipitation samples collected from 1995 to 2000 at meteorological station in the eastern outskirts of Herceg Novi (Montenegro) were analysed on Na(+), K(+), Mg(2+), Ca(2+), Cl(-), SO(4) (2-), NO(3)(-) and NH(4)(+). Four-day backward trajectory simulations were conducted during the precipitation period to investigate the regional transport of main ions and their deposition in the region of the southeastern Adriatic Sea. The air mass trajectories were classified into six trajectory categories by the origin and direction of their approach to Herceg Novi.

MATERIALS AND METHODS

A bottle and funnel with a small net between them was used for sampling at a height of 1.5 m above the ground. The concentrations of Cl(-), NO(3)(-), NH(4)(+) and SO(4)(2-) were determined spectrophotometrically, the concentrations of Na(+) and K(+) were determined by the FAES method and the concentrations of Mg(2+) and Ca(2+) by the FAAS method. The factor analysis technique (PCA analysis) based on the calculation of the factors was employed to differentiate the contribution of emission sources to the content of the main ions in the precipitation. The obtained data sets were processed using the SPSS 11.5 statistical program. The Hybrid Single-Particle Lagrangian Integrated Trajectory model was used to study the air origin for the city of Herceg Novi (42°27'N, 18°33'E), Montenegro.

DISCUSSION

The following origins of the air masses were considered: northern Europe (NE), eastern Europe-northeastern Europe (EE-NE); eastern Mediterranean-southeastern Europe (EM-SE); Africa-Central Mediterranean (A-CM); western Mediterranean (WM); western Europe-Central Europe (WE-CE) and undefined. The heights and frequencies of precipitation coming by air masses from northern Europe and eastern-northeastern Europe are the lowest. On the contrary, the heights and frequencies of precipitation coming by air masses from the western Mediterranean (36.6%) and Africa and the Central Mediterranean (30.6%) are the highest. The sea salt components (Na(+), Cl(-), Mg(2+)) are significantly correlated, except for air masses originating from the northern and eastern European regions. Significant correlations between SO(4)(2-) and NO(3)(-) are found in air masses coming from the western Europe and North Africa, over the Mediterranean.

CONCLUSIONS

The highest volume-weighted mean (VWM) of: SO(4)(2-), NH(4)(+) and Mg(2+) are for precipitation from EE-NE while the highest values of VWM of Cl(-) are from WM and of K(+) are from WE-CE. Long-range transport of Sahara dust is confirmed.

RECOMMENDATIONS AND PERSPECTIVES

For better estimation of origins of water-soluble ions in precipitation expanding list of analysis on anions of organic acids, such as HCOO(-), CH(3)COO(-), and C(2)H(2)COO(-), could be indicative of volatile organic compounds emitted by vegetation but also traffic. The chemical composition of precipitation together with a study of air backward trajectories is the proper tool for tracking the long-range transport of water-soluble ions and estimating transboundary pollution.