Pusan National University study finds pollution shifts rainfall from land to sea in Southeast Asia

Aerosols intensify ocean rainfall while delaying land storms until midnight, altering Southeast Asia’s climate balance.

 News Release 16-Oct-2025

Pusan National University

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High aerosol concentrations from pollution and biomass burning alter atmospheric stability, cooling land more than ocean. This enhances low-level convergence at sea, drawing moisture offshore, intensifying oceanic rainfall, and delaying land precipitation from late afternoon to midnight, as shown in high-resolution model simulations and satellite observations.

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Credit: Professor Kyong-Hwan Seo from Pusan National University, Korea

Tiny airborne particles known as aerosols, from biomass burning, urban pollution, and industrial emissions, can dramatically alter rainfall, cloud formation, and atmospheric stability. A new study led by Professor Kyong-Hwan Seo of Pusan National University, Korea, shows that aerosols profoundly reshape precipitation over the Maritime Continent, a region including Indonesia, Malaysia, Singapore, Vietnam, Thailand, the Philippines, and surrounding seas, where millions rely on predictable rainfall for water, food, and flood protection.

Published online in npj Climate and Atmospheric Science on September 25, 2025, the study combined a 2-km-resolution atmospheric model with NASA TRMM satellite data and MERRA-2 reanalysis to simulate how varying aerosol levels influence convection and precipitation. The team analyzed a 2011 Madden-Julian Oscillation event and tested other phases and years, finding that high aerosols consistently increased rainfall over the ocean while suppressing it over land.

“As aerosol concentrations rise, the precipitation pattern shifts from a land-enhanced to an ocean-dominant one,” said Seo.

In high-aerosol simulations, oceanic rainfall intensified by up to 50%, while land precipitation declined, producing a markedly higher sea-to-land rainfall ratio, a novel discovery confirmed by both model simulations and satellite observations.

The mechanism behind this shift is primarily radiative. Aerosols cool the land surface more strongly than the ocean, stabilizing the lower atmosphere over islands while leaving the sea relatively unstable. This difference enhances low-level convergence and convection at sea, drawing moisture away from land.

Seo explained, “Aerosols act like a brake on daytime heating over land, but the ocean hardly feels that brake.”

High aerosol levels also delay the peak of the diurnal precipitation cycle over land from late afternoon to around midnight, a counterintuitive pattern linked to reduced daytime heating and nighttime buildup of moist static energy.

“We’re seeing a delay from the usual late-afternoon storms to a midnight peak,” noted Seo.

Some observed high-aerosol events exhibit similar behavior, now revealed in detail through combined modeling and satellite data.

These findings carry important practical applications. In densely populated and flood-prone regions such as Jakarta or Manila, understanding aerosol-driven shifts toward more oceanic rainfall can improve disaster management, irrigation planning, and urban flood preparedness. Short-term forecasts may become more accurate during haze or pollution episodes, helping authorities allocate resources and mitigate risks to infrastructure and transportation. Incorporating these aerosol effects into climate and weather models may also improve predictions of the Madden–Julian Oscillation (MJO), monsoons, and extreme tropical rainfall events, which influence seasonal weather patterns far beyond Southeast Asia.

Over the longer term, this research could transform tropical climate forecasting. The study suggests smoother MJO propagation across the Maritime Continent by revealing how aerosols weaken land-based convection—potentially enabling more reliable seasonal rainfall predictions. These insights could support water resource management, food security, and energy planning for millions of people. On a global scale, integrating aerosol impacts into climate models could refine projections of precipitation changes amid rising emissions, helping communities reduce vulnerability to floods and droughts and adapt to climate-driven water challenges in tropical regions.

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Reference

DOI: 10.1038/s41612-025-01215-5

 

About Pusan National University

Pusan National University, located in Busan, South Korea, was founded in 1946 and is now the No. 1 national university of South Korea in research and educational competency. The multi-campus university also has other smaller campuses in Yangsan, Miryang, and Ami. The university prides itself on the principles of truth, freedom, and service and has approximately 30,000 students, 1,200 professors, and 750 faculty members. The university comprises 14 colleges (schools) and one independent division, with 103 departments in all.

Website: https://www.pusan.ac.kr/eng/Main.do

About the author

Dr. Kyong-Hwan Seo is a Professor of Atmospheric Sciences and the Director of the Institute for Future Earth at Pusan National University. His research spans a broad range of topics in climate and atmospheric dynamics, tropical meteorology, climate change and modeling, aerosol–cloud–circulation interactions, and polar processes. His major areas of focus include the Hadley circulation, Madden–Julian Oscillation, Rossby wave dynamics, teleconnections, monsoon dynamics, extreme weather and climate events, and the impacts of aerosols on weather and climate. Before coming to Pusan National University, he worked as a Climate Scientist at the Climate Prediction Center/NCEP/NOAA in the USA. Kyong-Hwan Seo received a PhD in Atmospheric Sciences from Texas A&M University in 2001 and was awarded a Presidential Commendation in 2023 in recognition of contributions to monsoon dynamics.

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Journal

npj Climate and Atmospheric Science

DOI

10.1038/s41612-025-01215-5 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Aerosol effects on Maritime Continent precipitation: Oceanic intensification and land diurnal cycle delay

 

Air pollution during pregnancy is associated with slower brain maturation in newborns

Greater exposure of mothers to airborne This is highlighted by the first study to measure neonatal brain myelination using magnetic resonance imaging (MRI). Myelination is a key marker of brain development.

IMIM (Hospital del Mar Medical Research Institute)

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A study published in Environment International concludes that air pollution during pregnancy is associated with slower brain maturation in newborns. It is the first study to analyze brain development within the first month of life and stems from the collaboration between researchers at Hospital del Mar, the Barcelona Institute for Global Health (ISGlobal) —a center promoted by the “la Caixa” Foundation—, and the CIBER area of Epidemiology and Public Health (CIBERESP).

Myelination is a key process in brain maturation, in which myelin coats neuronal connections and makes them more efficient for transmitting information. Newborns of mothers exposed to higher levels of fine airborne particles during pregnancy show slower myelination at this very early stage of life. Both a slowdown and an excessive acceleration of brain maturation can be harmful for the child. It remains to be determined whether the effect observed in this study will have negative consequences for children’s later abilities.

The analyzed pollution includes extremely small particles—about thirty times thinner than a human hair—composed of harmful elements from combustion processes and toxic organic compounds, but also of essential elements for brain development such as iron, copper, and zinc. Therefore, further research is needed to understand how each of these components affects the development of the newborn brain. In this regard, according to Gerard Martínez-Vilavella, researcher at the MRI Unit of the Radiology Department at Hospital del Mar, part of the dibi network and the Hospital del Mar Research Institute, “our study shows that the myelination process—a progressive indicator of brain maturation—occurs at a slower rate in newborns most exposed to PM2.5 during pregnancy.”

Magnetic resonance imaging in the first month of life

To conduct the study, pregnant women receiving prenatal care at Hospital Clínic de Barcelona, Hospital de la Santa Creu i Sant Pau, and Hospital Sant Joan de Déu were recruited. Levels of air pollutants to which they were exposed during pregnancy were monitored, and after delivery, 132 newborns were selected. These infants underwent MRI scans before their first month of life to assess the degree of brain maturation through their levels of myelination.

The results show a clear correlation between higher maternal exposure to PM2.5 during pregnancy and lower myelination in newborns’ brains. “Air pollution, specifically PM2.5, is associated with alterations in the myelination process, a fundamental mechanism of brain maturation. Therefore, it is essential to continue controlling pollution levels and to study how this slowdown may affect the later brain development of children”, explains Martínez-Vilavella. The study also indicates that this effect results from the combination of the different components of PM2.5, without identifying a single element as the main cause.

Dr. Jesús Pujol, head of the MRI Unit of the Radiology Department at Hospital del Mar, adds, “In the early stages of life, brain changes are large and complex. Both excessive slowdown and acceleration of brain maturation can be harmful to the child. However, it remains to be determined whether the observed effect is necessarily detrimental. This study opens an exciting new field of research aimed at determining the optimal speed of brain maturation during pregnancy and understanding how the mother and placenta may act as effective filters to protect and optimize this process”.

Meanwhile, ISGlobal researcher Jordi Sunyer emphasizes that “the findings in these newborns, born in Barcelona after the first phase of the low-emission zone, warn us that we cannot slacken our efforts to clean up city air. Further steps are needed to meet the new air quality standards”.

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DOI

10.1016/j.envint.2025.109801 

Article Title

Unraveling the impact of prenatal air pollution for neonatal brain maturation

 

Gene mutations increase in puppies with older fathers

University of Helsinki

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Labrador retriever puppy.

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Credit: Hannes Lohi.

A study completed at the University of Helsinki and the Folkhälsan Research Center analysed 390 parent–offspring trios. Trio denotes a design where the genomes of the puppy and both parents are sequenced. This enables accurately identifying gene mutations that do not occur in either parent’s genome – mutations that have taken place in the sperm, the ovum or soon after conception. While these rare mutations are the basis of evolution, they can also predispose their carriers to hereditary diseases.

“By combining the extended family trees in our biobank with exceptionally comprehensive DNA sequencing, we identified how and where in the genome de novo mutations occur,” says Professor Hannes Lohi from the University of Helsinki and the Folkhälsan Research Center.

The results also show why dogs differ from humans in certain genomic regions and what the findings mean for canine health and breeding.

Parental age affects the number of changes in the genome

The study demonstrated that, on average, only a few dozen entirely new DNA changes occur in puppies per birth, and that the generational mutation rate is surprisingly similar in different breeds, regardless of intense breeding selection.

Parental age is clearly linked to the number of new mutations. Higher paternal age in particular increased the number of new gene mutations in puppies more than previously reported in humans. A separate, albeit less pronounced, maternal effect was observed also.

In terms of size, large breeds appeared to accumulate relatively more early-life mutations, while the number of de novo mutations in small breeds grew faster with age. However, the total number of mutations per generation remained at the same level, regardless of breed.

New insights on the canine genome

A clear emphasis on gene regulatory regions known as CpG islands was seen in the location of these new mutations. In dogs, there was a clear increase in new mutations in these ‘on/off’ regions compared with other parts of the genome – in contrast to humans. A protein called PRDM9 plays a key role in humans and other mammals: it regulates genetic recombination in meiosis, or the production of gametes. This regulator is absent in dogs, which partly explains differences in the location of de novo mutations.

An exceptional case was also observed in the data: one puppy carried many times more mutations than usual, most of which originated in the dam. The case matches the possibility of a temporary disturbance in DNA repair during ovum differentiation. This phenomenon has also been observed in humans.

Applying the results to analyse the evolutionary history of dogs and wolves achieved an increasingly precise estimate of the dog–wolf divergence, indicating it to have taken place 23,000–30,000 years ago.

“Understanding when and where new DNA mutations occur helps to refine breeding decisions, including taking into account parental age,” concludes Lohi.

The results provide a baseline for research on the human genome as well.

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Journal

Genome Biology

DOI

10.1186/s13059-025-03804-2 

Subject of Research

Animals

Article Title

Determinants of de novo mutations in extended pedigrees of 43 dog breeds

SPAGYRIC HERBALISM

Manchurian walnut tree holds key to eco-friendly weed control

The discovery of 2Z-decaprenol, which disrupts weed growth on a molecular level, could pave the way for a new class of sustainable herbicides.

Kyushu University

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The Manchurian walnut tree (Juglans mandshurica Maxim.) in Kyushu University's herbal garden. Researchers studied its leaf extracts in their search for eco-friendly herbicides.

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Credit: Associate Professor Seiichi Sakamoto, Kyushu University

Fukuoka, Japan—In the search for eco-friendly alternatives to synthetic herbicides, researchers from Kyushu University, Japan, have identified a potent, weed-inhibiting compound in the leaves of the Manchurian walnut tree (Juglans mandshurica Maxim.). The discovery of the compound, 2Z-decaprenol, and its unique mode of action on plants could lead to the development of more sustainable herbicides. The study was conducted in collaboration with researchers from Juntendo University in Japan and Chulalongkorn University in Thailand and was published in the Journal of Agricultural and Food Chemistry.

“This research was inspired by an observation from our former professor, who noticed that there were areas around some trees where other plants did not grow,” explains Assistant Professor Poomraphie Nuntawong from Kyushu University’s Faculty of Pharmaceutical Sciences and the first author of the study. “This sparked our curiosity into allelopathy, the phenomenon where plants release chemicals, known as allelochemicals, to suppress competitors.”

In Japan, one naturally abundant and allelopathic tree is the Manchurian walnut, making it a promising candidate as a local source for an eco-friendly herbicide. For many species in the walnut genus (Juglans), a chemical called juglone has been widely recognized as the primary allelochemical, but whether this chemical was responsible for the Manchurian walnut's allelopathic effects was not yet known.

To investigate this, the researchers developed a soil-based bioassay designed to simulate the natural process of a leaf falling onto the ground and releasing its chemical contents into the soil. “Many traditional lab assays don’t include soil, which can absorb or break down compounds, altering their effectiveness,” explains Nuntawong. “We realized that to find the active compounds that work in nature, we needed a model that acts like nature. This is particularly important for compounds like juglone, which are known to degrade in soil.”

In their model, a filter paper treated with leaf extracts was placed on top of a soil layer, mimicking a fallen leaf. They then embarked on a process called bioassay-guided fractionation, which involved separating the crude extract from the walnut leaves into distinct chemical groups and repeatedly testing each group’s ability to inhibit the growth of tobacco seedlings, a plant chosen for its reliable germination rate.

The team observed that the most potent chemical group—the nonpolar n-hexane fraction—did not contain juglone, while the chloroform fraction that contained juglone showed a smaller inhibitory effect on tobacco seedling growth. Moreover, testing juglone alone based on its natural concentration in the leaves did not impact the tobacco seedling’s weight. This suggested to the research team that an alternative, more potent compound was responsible for the Manchurian walnut’s allelopathic effects.

After six successive rounds of purification and testing, the team isolated the single compound responsible for the most potent activity, 2Z-decaprenol, marking the first time this compound has been reported as an allelochemical. When tested, 2Z-decaprenol significantly inhibited the growth of the tobacco seedlings, causing reduced weight and a distinctive curling of the roots from the filter paper.

To see how 2Z-decaprenol operates at the molecular level, the team analyzed the genetic activity in the model plant Arabidopsis thaliana after treatment. They discovered that 2Z-decaprenol forced the plant to activate some defenses, such as producing protective chemicals and reinforcing its physical structure. Yet at the same time, the compound crippled other essential pathways the plant needs to manage stress and mount an effective immune response, effectively stopping the plant from growing.

Although the discovery of 2Z-decaprenol’s growth-inhibiting mechanism opens a new avenue for bioherbicide development, the team emphasizes that their research is still at its foundational stage.

“While these findings are promising, this is the first step on a long path,” concludes senior author Associate Professor Seiichi Sakamoto, also from the Faculty of Pharmaceutical Sciences. “To develop 2Z-decaprenol into a viable bioherbicide, we must conduct extensive safety and toxicity testing for humans and animals, further clarify its precise mechanism, and overcome challenges in producing the compound on a large scale. Our ultimate goal is to continue searching for potent, biodegradable compounds from nature that can contribute to a more sustainable future for agriculture.”

(Written by Science Communicator Intern, Ken Eguchi)

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For more information about this research, see, “Allelochemical from Leaves of Juglans mandshurica Maxim. And Its Transcriptomic Effects in Plants.” Poomraphie Nuntawong, Kosei Ando, Tomofumi Miyamoto, Keisuke Matsuura, Thi Huynh Anh Huynh, Varalee Yodsurang, Satoshi Morimoto, and Seiichi Sakamoto. Journal of Agricultural and Food Chemistry 2025, 73, 19527-19538. https://doi.org/10.1021/acs.jafc.5c08261

About Kyushu University 
Founded in 1911, Kyushu University is one of Japan's leading research-oriented institutes of higher education, consistently ranking as one of the top ten Japanese universities in the Times Higher Education World University Rankings and the QS World Rankings. The university is one of the seven national universities in Japan, located in Fukuoka, on the island of Kyushu—the most southwestern of Japan’s four main islands with a population and land size slightly larger than Belgium. Kyushu U’s multiple campuses—home to around 19,000 students and 8000 faculty and staff—are located around Fukuoka City, a coastal metropolis that is frequently ranked among the world's most livable cities and historically known as Japan's gateway to Asia. Through its VISION 2030, Kyushu U will “drive social change with integrative knowledge.” By fusing the spectrum of knowledge, from the humanities and arts to engineering and medical sciences, Kyushu U will strengthen its research in the key areas of decarbonization, medicine and health, and environment and food, to tackle society’s most pressing issues.'

Assistant Professor Poomraphie Nuntawong observes the effects of Manchurian walnut leaf extracts on seedling growth.

Credit

Associate Professor Seiichi Sakamoto, Kyushu University

Journal

Journal of Agricultural and Food Chemistry

DOI

10.1021/acs.jafc.5c08261 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Allelochemical from Leaves of Juglans mandshurica Maxim. And Its Transcriptomic Effects in Plants