Chemical characterisation and source identification of atmospheric aerosols in the Snowy Mountains, south-eastern Australia

Impact of Particulate Pollution on Aquatic Invertebrates

A serious global problem, air pollution poses a risk to both human and environmental health. It contains hazardous material like heavy metals, nanoparticles, and others that can create an impact on both land and marine environments. Particulate pollutants, which can enter water systems through a variety of ways, including precipitation and industrial runoff, can have a particularly adverse influence on aquatic invertebrates. Once in the water, these particles can harm aquatic invertebrates physically, physiologically, and molecularly, resulting in developmental problems and multi-organ toxicity. Further research at the cellular and molecular levels in numerous locations of the world is necessary to completely understand the impacts of particle pollution on aquatic invertebrates. Understanding how particle pollution affects aquatic invertebrates is vital as the significance of ecotoxicological studies on particulate contaminants increases. This review gives a comprehensive overview of the current understanding of how particle pollution affects aquatic invertebrates.

Characterisation of bushfire residuals in source water and removal by coagulation

A bushfire is a spontaneous vegetation fire that can fundamentally affect lives, property, the environment, and even the global climate. Ash from fire carries hazardous pollutants like metal oxides/hydroxides, minerals, black carbons, and by-products of partial combustion, such as hydrocarbons and colloidal charcoal. Bushfire gases and residues can heavily pollute surface and groundwater resources. This paper focuses on the impact of bushfire residue on water quality and explores methods to remediate impacted water supplies. Soils burned in controlled furnace conditions between 150 °C, and 600 °C were characterised, suspended in water, and changes in water quality was measured following leaching from the burned residues. Results indicate that once the soil is burned at temperatures above 300 °C, there is little evidence of leached organic matter. At temperatures below 300 °C, the water discolouration was evident after 24 h leaching, and much higher quantities of leached organic matter were measured. Higher burning temperatures resulted in more alkaline residues. Leachate and charred sample characterisation data shows that the charcoal is highly porous and mainly consists of- amorphous material. The ash is a heterogeneous concoction of smaller particles and comprises significant mineral content. The results also indicate that the primary pollutant among the brushfire residuals is ash which increases pH, alkalinity, turbidity, and UV₂₅₄. Coagulation experiments reveal that dual coagulation systems with metal salts- organic polyelectrolyte reduced the turbidity by 84 %, and dissolved organic carbon (DOC) reduced by 68 % of water containing ash residues. However, some other treatments are needed to reduce the alkalinity.

Two decades of trends in urban particulate matter concentrations across Australia

Australia is a highly developed country with low population density. Capital cities are situated mainly around the coastline and are subjected to different meteorological conditions. This complex set of drivers is expected to result in varying trends in particulate matter (PM) mass concentrations in urban ambient air across the country. Thus, the aim of this study was to determine the long-term trends in PM₁₀ and PM_2.5 concentrations in capital cities, and to analyse the factors that influenced such trends. The spatial variability of PM concentrations within the capital cities was first established to identify representative stations. Then trends were determined using the Mann-Kendall trend test, Sen's slope, and the generalised additive model. The results show that, in general, the PM concentrations in Australian cities are relatively low (12.1-21.7 μg m^-3 mean daily PM₁₀ and 4.6-8.7 μg m^-3 mean daily PM_2.5) and within the WHO daily limit 95% of the time. Over the past two decades, very small declines of 8.0 × 10^-5-1.1 × 10^-3 μg m^-3.yr^-1 for PM₁₀ and 7.7 × 10^-5-2.6 × 10^-3 μg m^-3.yr^-1 for PM_2.5 were observed while some stations exhibited increase in concentration based on available data; more stations showed a significant monotonic decline for PM₁₀ than PM_2.5. This is attributed to the effectiveness of the implemented emission reduction policies particularly for vehicle exhaust and power generation, given the simultaneous increase in the demand for energy and the number of vehicles over the last two decades. Regarding climate, in the coastal cities of Sydney and Brisbane, high rainfall and strong winds aid in maintaining low PM concentrations despite the significant anthropogenic emissions, while higher PM levels in Darwin can be attributed to its tropical savannah climate, which makes it prone to bushfires and necessitates regular prescribed burnings. PM concentrations increase when exceptional events such as bushfires and dust storms are induced by the extreme climate variability. Further reduction of PM concentrations in Australian cities is unlikely, considering the expanding urbanisation and the changing climate.

Research Progress of HP Characteristics, Hazards, Control Technologies, and Measures in China after 2013

In recent years, hazy weather (hazy weather (HW) has frequently invaded peoples’ lives in China, resulting in the disturbance of social operation, so it is urgent to resolve the haze pollution (HP) problem. A comprehensive understanding of HP is essential to further effectively alleviate or even eliminate it. In this study, HP characteristics in China, after 2013, were presented. It was found that the situation of HP is getting better year by year while it has been a pattern of high levels in the north and low levels in the south. In most regions of China, the contribution of a secondary source for HP is relatively large, and that of traffic is greater in the regions with rapid economic development. Hazards of HP were then summarized. Not only does HP cause harm to human health, but it also has effects on human production and quality of life, furthermore, property and atmospheric environment cannot be ignored. Next, the source and non-source control technologies of HP were first reviewed to recognize the weakness of HP control in China. This review provides more systematic information about HP problems and the future development directions of HP research were proposed to further effectively control HP in China.

In vitro toxicity evaluation of heavy metals in urban air particulate matter on human lung epithelial cells

Heavy metals are widely recognized as toxic components in urban air particulate matter (PM). However, the major toxic metals and their interactions are poorly understood. In this study, we attempted to explore the toxicity contribution and combined effects of PM-bounded metals in human lung epithelial cells (A549). Real-time cell analysis indicated that the critical toxic concentration (EC₅₀) of PM detected in this study was 107.90 mg/L (r² = 1.00, p < 0.01). The cell viability of A549 increased significantly (12.3%) after metal removal in PM, demonstrating an important contribution of metal components to PM toxicity. Among eleven elements examined (Zn, Cr, Mn, Fe, Ni, Cu, As, Se, Sr, Cd, and Pb), six heavy metals (Zn, Cr, Mn, Fe, Cu, and Pb) might account for PM toxicity in A549 cells, and their co-exposure led to a high mortality of A549 cells (36.5 ± 7.3%). For combination treatments, cell mortality caused by single or multiple metal mixtures was usually alleviated by Fe addition, while it was often aggravated in the presence of Mn. The varying effects of other metals (Zn, Cu, Pb and Cr) on different metal mixtures might be explained by their interactions (e.g., similar or dissimilar membrane transporters and intracellular targets). Furthermore, the concentration addition model (CA), independent action model (IA), integrated addition model (IAM) and integrated addition and interaction model (IAI) were used to predict mixture toxicity, and the IAI model exhibited the least variation between observed and predicted toxic effects (r² = 0.87, p < 0.01). Our results highlight the potential contribution from heavy metals and their interactions to PM toxicity, and promote the application of toxicity prediction models on metal components in PM.

Cave drip water solutes in south-eastern Australia: Constraining sources, sinks and processes

Constraining sources and site-specific processes of trace elements in speleothem geochemical records is key to an informed interpretation. This paper examines a 10-year data set of drip water solutes from Harrie Wood Cave, south-eastern Australia, and identifies the processes that control their response to El Niño-Southern Oscillation events which varies the site water balance. The contributions of aerosol and bedrock end-members are quantified via hydrochemical mass balance modelling. The parent bedrock is the main source for the drip water solutes: Mg, Sr, K and trace elements (Ba, Al, V, Cr, Mn, Ni, Co, Cu, Pb and U), while atmospheric aerosol inputs also contribute significantly to drip water trace elements and Na, K and Zn. A laboratory investigation evaluating water-soluble fractions of metals in soil samples and soil enrichment factors provided a basis for understanding metal retainment and release to solution and transport from the soil zone. These results identified the role of the soil as a sink for: trace metals, Na and K, and a secondary source for Zn. Further, soil processes including: cation exchange, K-fixation, metal adsorption to colloids and the release of Zn associated with organic matter degradation further modify the chemical composition of the resultant drip waters. This research is significant for the south-eastern Australian region, as well as other sites in a karst setting with clay-rich soil. In particular these results reveal that the response of drip water chemistry to hydroclimatic forcing is non-linear, with the greatest response observed when the long-term gradient in the cumulative water balance reverses. This longer-term drip water monitoring dataset is significant because it provides the pivotal framework required to reliably identify suitable trace element proxies for interpretation in geochemical speleothem records on multi-decadal timescales.

Mechanisms of low-temperature vapor-gas streams formation from sulfide mine waste

This paper presents experimental data that revealed the potential for chemical element transport by low-temperature vapor-gas streams. The study was conducted on sulfide waste heap sites located in the Kemerovo region, Russia. Condensates of vapor-gas streams were collected and analyzed in the air above the waste heaps and during laboratory experiments using samplers specially designed for this purpose. The gas streams from a waste heaps are complex mixtures consisting of water vapor, sulfur- and selenium-containing compounds (sulfur dioxide SO₂, dimethyl sulfide C₂H₆S, carbon disulfide CS₂, dimethyl disulfide C₂H₆S₂, dimethyl selenide C₂H₆Se, and dimethyl diselenide C₂H₆Se₂), elemental sulfur (S₆, S₇, and S₈) and various chemical elements, including rock-forming elements (Ca, Mg, Na, K, Si, Fe, Al, and Mn), metals (Cu, Zn, Pb, Ni, and Sn), and metalloids (As, Te, and Sb). The main sources of chemical elements in the gas streams are unstable secondary minerals associated with crystalline hydrates: gypsum CaSO₄ × 0.5H₂O, sideronatrite Na₂Fe(SO₄)₂(OH) × 3H₂O, serpierite CaCu₃Zn(SO₄)₂(OH)₆ × 3H₂O, and copiapite (Mg,Zn,Fe²⁺Fe³⁺)₄(SO₄)₆(OH)₂ × 20H₂O that formed during the oxidation of sulfide minerals. Some of the elements come from pore waters that are acidic, highly mineralized solutions. The mechanism of element migration from the pore waters is as follow: the water vapor phase transports elements in the form of aqueous ions, but complexed species (such as MeSO₄(aq), MeCl(aq), Me(OH)⁺, etc.) remain in the salt residue. A significant contribution to the processes of transformation and transport of elements is made by biochemical methylation reactions, which occur in the presence of bacteria producers of methyl groups and are accompanied by the formation of volatile compounds of arsenic, selenium, sulfur, and tellurium.

The impact of fire on the geochemistry of speleothem-forming drip water in a sub-alpine cave

Fire dramatically modifies the surface environment by combusting vegetation and changing soil properties. Despite this well-documented impact on the surface environment, there has been limited research into the impact of fire events on karst, caves and speleothems. Here we report the first experiment designed to investigate the short-term impacts of a prescribed fire on speleothem-forming cave drip water geochemistry. Before and after the fire, water was collected on a bi-monthly basis from 18 drip sites in South Glory Cave, New South Wales, Australia. Two months post-fire, there was an increase in B, Si, Na, Fe and Pb concentrations at all drip sites. We conclude that this response is most likely due to the transport of soluble ash-derived elements from the surface to the cave drip water below. A significant deviation in stable water isotopic composition from the local meteoric water line was also observed at six of the sites. We hypothesise that this was due to partial evaporation of soil water resulting in isotopic enrichment of drip waters. Our results demonstrate that even low-severity prescribed fires can have an impact on speleothem-forming cave drip water geochemistry. These findings are significant because firstly, fires need to be considered when interpreting past climate from speleothem δ¹⁸O isotope and trace element records, particularly in fire prone regions such as Australia, North America, south west Europe, Russia and China. Secondly, it supports research that demonstrates speleothems could be potential proxy records for past fires.

Hepatoprotective Effect of Loquat Leaf Flavonoids in PM2.5-Induced Non-Alcoholic Fatty Liver Disease via Regulation of IRs-1/Akt and CYP2E1/JNK Pathways

Ambient air particulate matter (PM) represents a class of heterogeneous substances present in polluted air, which contains many harmful components. Exposure to ambient particulate matter in fine rages (PM_2.5) is associated with non-alcoholic fatty liver disease (NAFLD). Loquat Leaf possesses pharmacological actions on NAFLD. As the main biological active ingredients, the potential therapeutic role of total flavonoids (TF) isolated from Loquat Leaf in PM_2.5-induced NAFLD model remains unclear. The present study was designed to explore the hepatoprotective effect of TF in PM_2.5-induced NAFLD mice with its related mechanisms of action. Mice were exposed to PM_2.5 to induce NAFLD, and body weight, the ratio of liver to body weight, and blood lipids increased significantly compared with the control group. It was found that TF significantly reduced the above parameters in PM_2.5-induced NAFLD mice. TF treatment alleviated oxidative stress by preventing the accumulation of oxidative product malondialdehyde (MDA) and by strengthening the anti-oxidative capacity of superoxide dismutase (SOD). TF was also found to reduce the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in the PM_2.5 group. In addition, TF repaired the PM_2.5-induced decline of insulin receptor substrate-1 (IRs-1) and protein kinase B (Akt) phosphorylation. Meanwhile, the data showed TF suppressed the expression of cytochrome P450 2E1(CYP2E1) and the phosphorylation of c-jun N-terminal kinase (JNK) in PM_2.5-induced NAFLD. Taken together, these findings show that TF alleviate PM_2.5-induced NAFLD via regulation of IRs-1/Akt and CYP2E1/JNK pathways, which may have potential for further development as novel therapeutic agents for NAFLD.