Temporal and spatial shifts in the chemical composition of urban coastal rainwaters of Kuwait: The role of air mass trajectory and meteorological variables

Geochemical signatures and their spatial variations in groundwater adjoining major Kuwait oil fields

Kuwait depends on two major aquifers for the groundwater resources, the younger Kuwait aquifer and the older Dammam formation. The groundwater is brackish to saline in Kuwait aquifers with a probability of contamination adjoining the oil field region. In this context, groundwater samples were collected from three major oil fields in Kuwait (North, Southeast, and West). Sulfate and nitrate were dominant in all three regions. The geochemical signatures indicate the predominance of Na-Cl-SO4 water type in the North (NK), Na-Ca-Cl in the Southeast (SEK) and Na-Ca-Mg-Cl-SO4 type in the West (WK). The dolomite and gypsum saturation index dominated the sulfate and carbonate minerals, irrespective of the regions. The log pCO2 of the groundwater samples ranged from - 1.8 to - 6.2, reflecting the mineral dissolution and microbial process, which mainly contained lower values and governed the carbonate mineral saturation. The common ion effect of Ca has influenced the saturation of carbonate and sulfate minerals. Correlation between EC, pH, and a few major ions was identified, while CH4 and C2H6 were correlated with these parameters only in NK. The principal component analysis indicates that the dissolution of ions from the aquifer matrix leads to brackish groundwater, followed by silicate weathering in NK and hydrogenation in SEK and WK. Further, the study also identified the dissolution of carbonate minerals and fluoride in the NK, sulfate minerals in the SEK, and silicate minerals in the WK. Hence, the study infers that geochemical variation is due to lithology, groundwater salinity, and the physicochemical conditions prevailing in the aquifer.

Association of early life co-exposure to ambient PM2.5 and O3 with the offspring's growth within two years of age: A birth cohort study

BACKGROUND

Previous studies indicated that early life exposure to particulate matter of 2.5 μm or less (PM2.5) could impair children's growth. However, the adverse effects of maternal ozone (O3) and its interplay with PM2.5 on offspring's growth are unclear.

OBJECT

We aimed to investigate the independent and combined association of early-life exposure to PM2.5 and O3 with offspring growth in early childhood.

METHODS

This study included 632 Chinese mother-child pairs. Residential PM2.5 and O3 exposure concentrations in pregnancy and postanal 2 years were estimated by an established spatiotemporal model. During each exposure period, we also calculated the exceedance rate, the accumulative proportion of over-standard days (Exceedance standard: PM2.5>35 μg/m3, O3 > 100 μg/m3). We repeatedly measured the offspring's weight and length from birth to 2 years old and calculated the age-standardized Z-score of weight for height (WFL), body mass index (BMI), and overweight risk (BMI Z-score >85th percentile).

RESULTS

The adjusted generalized estimating equations showed that the concentration (an IQR increase) and exceedance rate (per 10% increase) of PM2.5 in prenatal (especially the second trimesters) and postnatal periods were associated with increased WFL, BMI Z-score, and overweight risk (βs/ORs ranging from 0.10 to 0.41/1.23 to 1.62, P < 0.05) in children within age 2 years. Although early-life exposure to O3 was not associated with growth outcomes, it showed multiplicative and additive interactions with PM2.5 on offspring growth, particularly in the 2nd trimester and early life 1000 days. The associations with WFL and BMI Z-score were greatest in the higher exceedance rates group of PM2.5 and O3 (βs ranging from 0.21 to 0.37, Pforinteraction<0.01).

CONCLUSION

This study demonstrated that early-life PM2.5 exposure, especially exceedance rate, was associated with increased offspring growth within 2 years of age. Furthermore, we discovered that O3 may strengthen the adverse effect of PM2.5 exposure on children's growth.

Characteristics and sources of chemical composition in precipitation on the Loess Plateau of China

Knowing the sources of precipitation chemical composition is essential to understand the biogeochemical cycle and control air pollution. Despite this issue has been directly investigated with precipitation ion contents, the effects of water vapor transport have not been fully considered. Taking the Loess Plateau of China (LPC) as an example study area, this study established nine precipitation monitoring sites considering the variability in topography and rainfall amounts, and collected 435 precipitation samples during 2020-2022 to measure the chemical composition. The correlation analysis, positive matrix factorization model and backward trajectory model were combined to analyze the characteristics, sources and vapor transport effects of precipitation chemical composition. Seasonally, except for NH4+, the concentration of other ions in the dry season was significantly higher than that in the rainy season. Spatially, the concentrations of Ca2+, Na+, K+, SO42- and NO3- peaked in the Mu Us Sandy Land and industrial areas, while the high level of NH4+ was concentrated in the agricultural areas. The source apportionment found that the primary source of precipitation ions was crust (33 %), followed by coal combustion/vehicle (30 %), aged sea salt (21 %) and agriculture (16 %). The trajectory analysis showed that water vapor paths significantly varied with the seasons, but were primarily dominated by the northwestern air mass with proportions of >40 %. The dust aerosols transported by the northwestern air mass were the main contributor to crust-source precipitation ions. The eastern and southeastern air masses transported anthropogenic pollutants to the LPC, and the southeastern air mass also carried sea-salt precipitation ions. This study provides a framework to incorporate hydrochemical method with vapor source identification method for precipitation chemical source identification, and the results can be a theoretical basis for the treatment of atmospheric environmental problems.

Atmospheric precipitation chemistry and environmental significance in major anthropogenic regions globally

In order to investigate the spatiotemporal distribution and influencing factors of global precipitation chemistry, we conducted a comprehensive analysis using multiple data sources, revealing the impact of human activities on the natural environment. The results indicate a decreasing trend in global precipitation acidity over the past 20 years. The distribution of global precipitation is influenced by both natural and anthropogenic factors. Alkaline cation concentrations are higher in desert and arid regions, while high concentrations of SO42- and NO3- are primarily found in industrial areas, and agricultural areas exhibit higher NH4+ concentrations. Coastal regions have higher Na+ and Cl- concentrations compared to inland areas. However, the increased Na + and Cl- concentrations due to inland salinization should not be overlooked. Additionally, influenced by atmospheric circulation, transboundary pollution from South Asia leads to higher SO42- and NO3- concentrations in precipitation over the Tibetan Plateau. Meteorological factors have a weaker influence on precipitation chemistry compared to geographical and human activity factors, although ion concentrations in snowfall are higher than in rainfall.