The persistent presence of nitrates in the atmosphere has long been a concern for environmental scientists. Despite efforts to reduce emissions over the past few decades, nitrate levels remain stubbornly high. A recent study published in Nature Communications sheds light on this enigma, revealing that chemical processes within the atmosphere are responsible for the persistence of these pollutants.

The research team led by Hokkaido University’s Professor Yoshinori Iizuka examined nitrate deposition history from 1800 to 2020 in an ice core taken from southeastern Greenland. The results showed a gradual increase in nitrates up to the 1970s, followed by a slower decline after the 1990s. This trend mirrors the changes in emissions of nitrate precursors over the same period.

The study’s findings suggest that factors other than emission reductions are driving the persistence of atmospheric nitrates. The researchers used a global chemical transport model to investigate these factors and discovered that atmospheric acidity is the key culprit. As acidity levels rise, more nitrates become trapped in particulate form, enabling them to persist longer and travel farther.

The implications of this study are significant. Accurate measurements of particulate nitrates in ice cores provide valuable data for refining climate modeling predictions. Moreover, the findings suggest that atmospheric nitrates will soon replace sulfates as the primary aerosol in the Arctic, further amplifying warming in the region.

As Professor Iizuka notes, “Ours is the first study to present accurate information for records of particulate nitrates in ice cores.” The persistence of these pollutants highlights the importance of continued research into atmospheric chemistry and climate modeling. By understanding the complex interactions within our atmosphere, we can better predict and prepare for the challenges that lie ahead.

The air we breathe has long been a concern for public health, but a recent study by Emory University researchers sheds light on a specific and alarming link between air pollution and pregnancy risks. Published in Environmental Science & Technology, the research reveals that exposure to tiny particles in air pollution during pregnancy can disrupt maternal metabolism, leading to increased risk of various negative birth outcomes.

The study analyzed blood samples from 330 pregnant women in the Atlanta metropolitan area, providing a detailed insight into how ambient fine particulate matter (PM2.5) affects the metabolism of pregnant women and contributes to increased risks of preterm and early term births. This pioneering work marks the first time researchers have been able to investigate the specific fine particles responsible for these adverse outcomes.

“The link between air pollution and premature birth has been well established, but for the first time we were able to look at the detailed pathway and specific fine particles to identify how they are reflected in the increased risk of adverse birth outcomes,” says Donghai Liang, PhD, study lead author and associate professor of environmental health. “This is important because if we can figure out the ‘why’ and ‘how,’ then we can know better how to address it.”

Previous research has shown that pregnant women and fetuses are more vulnerable than other populations to exposure to PM2.5, which is emitted from combustion sources such as vehicle exhaust, industrial processes, and wildfires. This increased vulnerability is linked to a higher likelihood of preterm births, the leading cause of death globally among children under the age of five.

Preterm birth is associated with complications such as cerebral palsy, respiratory distress syndrome, and long-term noncommunicable disease risks. Early term births (37-39 weeks of gestation) are also linked to increased neonatal morbidity and developmental challenges. Approximately 10% of preterm births worldwide are attributable to PM2.5 exposure.

As an air pollution scientist, Liang emphasizes the importance of addressing this issue beyond simply asking people to move away from highly polluted areas. “From a clinical intervention standpoint, it’s critical to gain a better understanding on these pathways and molecules affected by pollution,” he says. “In the future, we may be able to target some of these molecules to develop effective strategies or clinical interventions that could help reduce these adverse health effects.”

This groundbreaking study highlights the urgent need for policymakers and healthcare providers to take action against air pollution, particularly in areas with high levels of PM2.5 exposure. By understanding the molecular link between air pollution and pregnancy risks, we can work towards developing targeted solutions to mitigate these negative outcomes and protect the health of future generations.

The Hidden Impact of Anoxic Pockets on Sandy Shores

Human activities have dramatically increased nitrogen inputs into coastal seas, leading to a significant amount of this human-derived nitrogen being removed by microorganisms in coastal sands through denitrification. However, research has shown that this process can also occur in oxygenated sands, and scientists from the Max Planck Institute for Marine Microbiology in Bremen, Germany, have now revealed how this happens.

The scientists used a method called microfluidic imaging to visualize the diverse and uneven distribution of microbes and the oxygen dynamics on extremely small scales. “Tens of thousands of microorganisms live on a single grain of sand,” explains Farooq Moin Jalaluddin from the Max Planck Institute for Marine Microbiology. The researchers could show that some microbes consume more oxygen than is resupplied by the surrounding pore water, creating anoxic pockets on the surface of the sand grains.

These anoxic microenvironments have so far been invisible to conventional techniques but have a dramatic effect: “Our estimates based on model simulations show that anaerobic denitrification in these anoxic pockets can account for up to one-third of the total denitrification in oxygenated sands,” says Jalaluddin.

The researchers calculated how relevant this newly researched form of nitrogen removal is on a global scale and found that it could account for up to one-third of total nitrogen loss in silicate shelf sands. Consequently, this denitrification is a substantial sink for anthropogenic nitrogen entering the oceans.

In conclusion, the hidden impact of anoxic pockets on sandy shores has been revealed by scientists, highlighting the importance of these microenvironments in removing nitrogen from coastal seas and emphasizing the need to consider them when assessing the overall nitrogen budget of our planet.