Semivolatile Organic Contaminants in the Hawaiian Atmosphere

Assessing pesticides in the atmosphere: A global study on pollution, human health effects, monitoring network and regulatory performance

Pesticides are widely used in agriculture, but their impact on the environment and human health is a major concern. While much attention has been given to their presence in soil, water, and food, there have been few studies on airborne pesticide pollution on a global scale. This study aimed to assess the extent of atmospheric pesticide pollution in countries worldwide and identify regional differences using a scoring approach. In addition to analyzing the health risks associated with pesticide pollution, we also examined agricultural practices and current air quality standards for pesticides in these countries. The pollution scores varied significantly among the countries, particularly in Europe. Asian and Oceanic countries generally had higher scores compared to those in the Americas, suggesting a relatively higher level of air pollution caused by pesticides in these regions. It is worth noting that the current pollution levels, as assessed theoretically, pose minimal health risks to humans. However, studies in the literature have shown that excessive exposure to pesticides present in the atmosphere has been associated with various health problems, such as cancer, neuropsychiatric disorders, and other chronic diseases. Interestingly, European countries had the highest overall pesticide application intensities, but this did not necessarily correspond to higher atmospheric pesticide pollution scores. Only a few countries have established air quality standards specifically for pesticides. Furthermore, pollution scores across states in the USA were investigated and the global sampling sites were mapped. The findings revealed that the scores varied widely in the USA and the current sampling sites were limited or unevenly distributed in some countries, particularly the Nordic countries. These findings can help global relevant environmental agencies to set up comprehensive monitoring networks. Overall, the present research highlights the need to create a pesticide monitoring system and increase efforts to enhance pesticide regulation, ensure consistency in standards, and promote international cooperation.

Development and calibration of a modifiable passive sampler for monitoring atmospheric tritiated water vapor in different environments

Anthropogenic release of tritium from nuclear facilities is expected to increase significantly in the coming decades, which may cause radiation exposure to humans through the contamination of water and food chains. It is necessary and urgent to acquire detailed information about tritium in various environments for studying its behavior and assessing the potential radiation risk. In the atmosphere, although the passive sampling technique provides a low-cost and convenient way to characterize the dynamics of tritiated water vapor (HTO), a single, simple sampler configuration makes it difficult to collect sufficient and representative samples within the expected period from different environments. In this study, we systematically studied the impacts of sampler configurations on sampling performance and proposed a modifiable sampler design by scaling sampler geometry and adjusting absorbent to achieve different monitoring demands. The samplers were subsequently deployed at five sites in China and Germany for the field calibration and the measured results exhibited a good agreement between the adsorption process obtained in sites corrected with diffusion coefficient and the one calibrated in Shanghai. This suggests the feasibility of predicting sampling performance in the field based on known data. Finally, we developed a strategy for sampler modification and selection in different environments and demonstrated that using easily obtainable environmental data, our sampler can be optimized for any area without any time-consuming preliminary experiments. This work provides a scientific basis for establishing high-resolution atmospheric HTO database and expands the conventional empirical sampler design paradigm by demonstrating the feasibility of using quantitative indices for sampler performance customization.

Changes and distribution of gas-phase polycyclic aromatic hydrocarbons and organochlorine compounds in a high-mountain gradient over a three-year period (Pyrenees, 2017-2020)

The atmospheric gas-phase concentrations of several polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene (HCB), and pentachlorobenzene (PeCB) were measured in six high-mountain sites in the Pyrenees (1619-2453 m). Polyurethane foam passive air samplers were used for this purpose, providing continuous records spanning over three years (2017-2020). The mean concentrations of ∑PCBs, HCB, and PeCB, 13 ± 4 pg m^-3, 44 ± 18 pg m^-3, and 23 ± 20 pg m^-3, respectively, were of the order of those reported in other mountain sites and similar to those measured 20 years ago in the same area, evidencing the persistence of these compounds despite the international regulatory actions. The mean concentration of ∑PAHs was 631 ± 238 pg m^-3, representing between two- and three-times lower values than 20 years ago in the same area, but still in the range of other mountain regions. Statistically significant increases in gas-phase concentrations at higher temperatures were observed for most compounds. The experimental phase-change pseudo-enthalpies calculated from the slopes of the regressions between the natural logarithm of the concentrations and the reciprocal of temperature were lower than the reference values for nearly all compounds. This difference suggested a main contribution of long-range atmospheric transport of the gas-phase PAH and organochlorine concentrations in this mountain area. However, the less volatile compounds such as benz[a]anthracene, PCB138, and PCB180 showed a closer similarity between experimental and laboratory enthalpies, indicating that a significant portion of the variations in concentration of these compounds originated from temperature-dependent diffusive exchange by re-volatilization from local surfaces. The concentrations found in these sentinel ecosystems demonstrate that long-range transport of organic pollutants remains a risk in remote continental environments.

Pesticides in the atmosphere and seawater in a transect study from the Western Pacific to the Southern Ocean: The importance of continental discharges and air-seawater exchange

The global oceans are known as terminal sink or secondary source for diffusive emission of organochlorine pesticides (OCPs) and selected current used pesticides (CUPs) into the overlaying atmosphere. Many pesticides have been widely produced worldwide, subsequently applied, and released into the environment. However, information on the occurrence patterns, spatial variability, and air-seawater exchange of pesticides is limited to easily accessible regions and, hence, only few studies are reported from the remote Southern Ocean. To fill this information gap, a large-scale ship-based sampling campaign was conducted. In the samples from this campaign, we measured concentrations of 221 pesticides. Both gaseous and aqueous samples were collected along a sampling transect from the western Pacific to the Southern Ocean (19.75° N-76.16° S) from November 2018 to March 2019. Twenty-seven individual pesticides were frequently (≥ 50%) detected in gaseous and aqueous samples. Tebuconazole, diphenylamine, myclobutanil, and hexachlorobenzene (HCB) dominated the composition profile in both phases. Spatial trends analysis in atmospheric and seawater concentrations showed a substantial level reduction from the western Pacific towards the Southern Ocean. Back-trajectory analysis showed that atmospheric pesticide concentrations were strongly influenced by air masses origins. Continental and riverine inputs are important sources of pesticides in the western Pacific and Indian Oceans. Atmospheric and seawater concentrations for the target pesticide residues in the Southern Ocean are low and evenly distributed due to the large distance from potential pollution sources as well as the effective isolation by the Antarctic Convergence (AC). Air-seawater fugacity ratios and fluxes indicated that the western Pacific and Indian Oceans were secondary sources for most pesticides emitted to the atmosphere, while the Southern Ocean was still considered to be a sink.

Passive air sampling for semi-volatile organic chemicals

During passive air sampling, the amount of a chemical taken up in a sorbent from the air without the help of a pump is quantified and converted into an air concentration. In an equilibrium sampler, this conversion requires a thermodynamic parameter, the equilibrium sorption coefficient between gas-phase and sorbent. In a kinetic sampler, a time-averaged air concentration is obtained using a sampling rate, which is a kinetic parameter. Design requirements for kinetic and equilibrium sampling conflict with each other. The volatility of semi-volatile organic compounds (SVOCs) varies over five orders of magnitude, which implies that passive air samplers are inevitably kinetic samplers for less volatile SVOCs and equilibrium samplers for more volatile SVOCs. Therefore, most currently used passive sampler designs for SVOCs are a compromise that requires the consideration of both a thermodynamic and a kinetic parameter. Their quantitative interpretation depends on assumptions that are rarely fulfilled, and on input parameters, that are often only known with high uncertainty. Kinetic passive air sampling for SVOCs is also challenging because their typically very low atmospheric concentrations necessitate relatively high sampling rates that can only be achieved without the use of diffusive barriers. This in turn renders sampling rates dependent on wind conditions and therefore highly variable. Despite the overall high uncertainty arising from these challenges, passive air samplers for SVOCs have valuable roles to play in recording (i) spatial concentration variability at scales ranging from a few centimeters to tens of thousands of kilometers, (ii) long-term trends, (iii) air contamination in remote and inaccessible locations and (iv) indoor inhalation exposure. Going forward, thermal desorption of sorbents may lower the detection limits for some SVOCs to an extent that the use of diffusive barriers in the kinetic sampling of SVOCs becomes feasible, which is a prerequisite to decreasing the uncertainty of sampling rates. If the thermally stable sorbent additionally has a high sorptive capacity, it may be possible to design true kinetic samplers for most SVOCs. In the meantime, the passive air sampling community would benefit from being more transparent by rigorously quantifying and explicitly reporting uncertainty.

The occurrence of polybrominated diphenyl ether (PBDE) contamination in soil, water/sediment, and air

As a kind of brominated flame retardants (BFRs), polybrominated diphenyl ethers (PBDEs) are extensively used in different types of electronic equipment, furniture, plastics, and textiles. PBDEs are ubiquitous environmental contaminants that may impact human health and ecosystems. Here we highlight recent findings on the occurrence, contamination status, and transport of PBDEs in soil, water/sediment, and air. Four aspects are discussed in detail: (1) sources of PBDEs to the environment; (2) occurrence and transport of PBDEs in soil; (3) PBDEs in aquatic ecosystems (water/sediment) and their water-sediment partitioning; and (4) the occurrence of PBDEs in the atmosphere and their gas-particle partitioning. Future prospects for the investigation on PBDEs occurrence are also discussed based on current scientific and practical needs.