Water and Environmental Engineering Laboratory, KIT, Japan

24/02/2026

🌊❄️ 2026 Sea Ice Conditions in the Sea of Okhotsk ❄️🌊

📕Our study published in Cold Regions Science and Technology analyzed 23 years (1989–2012) of wave–ice interactions in the Sea of Okhotsk.

The study suggested that:
✔ Stronger waves fragment sea ice into smaller floes
✔ Smaller floes melt more rapidly
✔ Increased open water enhances wave development

— indicating a potential wave–ice feedback mechanism.

🔗 Read the paper here:
https://doi.org/10.1016/j.coldregions.2024.104219

In 2026, sea ice conditions were spatially variable rather than uniformly “late.”
However, satellite observations indicate:

📉 Slightly reduced overall ice extent
🌊 Broader marginal ice zones exposed to wave activity

These conditions are consistent with scenarios in which wave influence becomes more significant, particularly when ice is thinner or more fragmented.

🚢 In Abashiri, sea ice is currently visible along the coast, although the appearance of ice can vary significantly depending on daily weather conditions, wind direction, and visibility.

🌏The Sea of Okhotsk is one of the southernmost seasonal sea ice regions in the Northern Hemisphere, making it especially sensitive to atmospheric and oceanic variability.

Rather than focusing on whether a single year was “late,” it may be more meaningful to interpret 2026 within the framework of wave–ice dynamics and long-term variability.

24/02/2026

📘🌊 Physicochemical Controls on Nutrient Activity in Sediment in Coastal Lagoon

This study extends our previously proposed modified Fick’s First Law into the complex world of intertidal sediments ⚗️

In tidal flats, porewater is not “ideal.”
Salinity gradients 🧂 and ionic interactions reshape how nutrients actually move beneath the surface.

By introducing thermodynamic activity into the framework, we move beyond textbook diffusion and toward a physically consistent description of nutrient transport — especially for phosphorus in saline sediments 🌱

🔬 What emerges is a clearer picture:

• Effective diffusion changes with salinity
• Depth-dependent chemistry controls mobility
• Phosphorus behavior can deviate significantly from ideal assumptions

Transport theory meets sediment geochemistry 🌍 And the dynamics below the surface become a little less invisible.

👉 Please check out our paper here:
https://doi.org/10.3390/environments13020117

17/01/2026

📢 Improving Hydraulic Performance, Agricultural Water Management, and Salinity Control to Enhance Irrigation Sustainability and Economic Resilience in Ethiopia, Africa

The PhD public defense of a doctoral international student in our laboratory will be held as follows.

📌 PhD Public Defense
Candidate: Gezimu Gelu Otoro
Title: Improving Hydraulic Performance, Agricultural Water Management, and Salinity Control to Enhance Irrigation Sustainability and Economic Resilience in Ethiopia
Date & Time: January 30, 2026, 14:45
Venue: A101, Bldg. 1, Kitami Institute of Technology, Japan
Supervisor: Prof. Katsuaki Komai

During his doctoral studies, he conducted research on irrigation systems, water management, and salinity control in arid and semi-arid regions, and published the following peer-reviewed international journal articles:

🌏📗
• https://doi.org/10.1007/s41748-025-00907-5
• https://doi.org/10.3390/agriculture15222378
• https://doi.org/10.1002/ird.3100
• https://doi.org/10.1007/s10661-024-13576-0

The public defense represents the culmination of his doctoral research conducted in our laboratory.

12/01/2026

Applications Open Next Week for Master’s and Doctoral Programs at Kitami Institute of Technology, Japan🎓

Our laboratory is dedicated to understanding and solving water resources💧and environmental 🌿 problems based on solid scientific fundamentals and a wide range of state-of-the-art approaches, including:

• Field observations 🌲🌊
• Laboratory experiments 🗃️
• Advanced chemical and biogeochemical analyses 🧪
• Remote sensing 🛰️
• Statistical analysis and machine learning 🧠
• Numerical and process-based modeling 💻

We welcome motivated students who wish to tackle real-world water💧and environmental 🌿 issues from an international perspective 🌏 and who are willing to make sustained efforts toward publishing in international peer-reviewed journals. 📗

Before applying, all applicants are required to discuss their prospective research topics with us. ✉️

🔗 Application guidelines (Kitami Institute of Technology, Japan)
https://www.kitami-it.ac.jp/en/admission/

🌐 Official laboratory webpage (Japanese)
https://cee.civil.kitami-it.ac.jp/study/mizusyori/

📩 Contact
Entrance Examination Unit, Education Affairs Section,
Kitami Institute of Technology
[email protected]

🔍 Research profiles
ResearchGate: https://www.researchgate.net/profile/Katsuaki-Komai
researchmap: https://researchmap.jp/kkomai?lang=en
Google Scholar: https://scholar.google.com/citations?user=PbL-z7QAAAAJ&hl=en

10/01/2026

What Can We See in A Tiny Earth on a Rotating Table ? 🌏
(Vertical Remaster)

This is NOT just diffusion.
Earth’s rotation is freezing this fluid motion.
👇 Full explanation below.

🧪 After the water tank reaches steady solid-body rotation, blue dye is gently injected.

Instead of spreading randomly, the dye forms a thin vertical curtain that rotates with the flow.

Once the flow is in geostrophic balance, the Taylor–Proudman theorem applies:
velocity becomes nearly uniform with depth, so vertically aligned structures
cannot be deformed and are preserved as columns.

🌍 This same physics underlies:
• Ocean currents 🌊
• Jet streams ☁️
• Columnar motions inside planets 🪐

In 2025, several marine heatwaves were observed around the world, contributing to record ocean heat. 🔥
This column visualizes how Earth’s rotation reduces vertical deformation, making it difficult for ocean heat to mix downward and allowing it to remain near the surface.

01/01/2026

What Does a Big River Mean in a Japanese Legend?— Human Emotions and the Temple Bell of Dojoji in Wakayama, Japan 🇯🇵

In Japan, there are many Buddhist legends about temple bells 🔔. One of the most famous bell legends is the story of Anchin and Kiyohime (安珍と清姫).

A young monk named Anchin stayed at the house of a girl called Kiyohime during his journey 🏠. When he left, he said, “I will come back for you.”

But Anchin never returned 😔.

Kiyohime followed him with deep sadness and anger 💔😠. She reached the big Hidaka River (日高川), the longest second class river 🌊 in Japan, and changed into a snake 🐍 to swim across the river while chasing Anchin‼️

Anchin escaped into a temple named Dojoji (道成寺) and hid inside a large bell 🔔. Kiyohime wrapped herself around the bell and burned it with fire 🔥.
Anchin died inside the bell 💀.

It tells us how strong — and how painful — human feelings can be ❤️.
This legend also became a famous Kabuki (歌舞伎) play 🎭, and it appears in the film Kokuho (国宝), which is currently showing in cinemas in Japan.

In temples with bells 🔔, such as Shingon (真言宗) temples, people begin and end their practice 🙏 with the sound of the bell. On New Year’s Eve, temple bells are rung 108 times (除夜の鐘) to reflect on our human weaknesses and to welcome the new year with a calm and clear heart 🌅.

Happy New Year! 🎍✨

29/12/2025

🌋 How Volcanoes and Coastal Lakes Are Connected by Sulfur Chemistry ✨🌊

The white “smoke” rising from volcanic fields is not smoke. It is high-temperature steam containing sulfur gases released from magma.
In these vapors, sulfur mainly exists as H₂S (hydrogen sulfide) and SO₂ (sulfur dioxide).
Inside fumaroles they react forming elemental sulfur (S⁰) that precipitates as familiar yellow crystals around vents.

⸻

A very similar sulfur redox process occurs in stratified semi-enclosed bay and brackish lakes around the world.

🟦 In the anoxic bottom waters of such lakes, sulfate (SO₄²⁻) is reduced by microorganisms to H₂S.
🌬 When this sulfide-rich water rises into oxygenated layers, oxidation proceeds.
During this process, nanometer-scale elemental sulfur particles (S⁰) are produced and remain suspended as colloids. These tiny particles scatter short-wavelength light, turning the water surface milky blue — a phenomenon often called a “blue tide.”

⸻

🌏In volcanic fields and in brackish or coastal lakes, the energy sources are completely different, yet the same chemistry operates:
the sulfur redox cycle linking H₂S, S⁰, and SO₄²⁻.

Sometimes sulfur appears as yellow crystals on volcanic rocks, sometimes as blue-white suspended particles in lakes. Mt. Io in eastern Hokkaido and the blue tides of brackish Lake Abashiri are just two beautiful examples of this universal sulfur cycle.

The Earth quietly repeats the same chemistry in very different places.

Amazing ❣️

26/12/2025

💧Tracing the Origins of Water Using Dissolved Ions: A New Framework for Protecting the Kushiro Wetland 🦢

📖 Last month, our research group has published a new paper in the international journal “Hydrology.”

In this study, we developed a new method to trace the origins of river water and pollutants using dissolved ions such as F⁻, Cl⁻, SO₄²⁻, and Na⁺ 🔬. By combining PCA 📊, neural networks 🤖, and non-parametric statistics 📈, we quantitatively evaluated how different sub-basins contribute to downstream water quality.

Our study area is the Kushiro River basin, which includes the Kushiro Wetland — 🇯🇵 the largest wetland in Japan, 🦢 home to the iconic red-crowned crane, 🌏 and a Ramsar-listed wetland recognized worldwide.

This watershed is influenced by both 🌋 natural geological sources from Lake Kussharo, a large caldera lake, and 🌾 anthropogenic loads such as agricultural nutrients. We found that caldera-lake regions are the major sources of dissolved ions 💎, while nitrate shows strong seasonal variability related to human activities 🚜.

We hope that dissolved-ion-based water source tracing will become a powerful tool for
🌱 watershed management,
🛡️ ecosystem conservation, and
🤝 sustainable use of precious wetlands like Kushiro.

👉 Please check out our paper here:
https://doi.org/10.3390/hydrology12120310

This study presents a unique approach for characterizing ion distribution within the Kushiro River catchment basin, which is characterized by exceptionally high dissolved ion concentrations. principal component analysis, Mann–Whitney U test, and neural network modeling were employed to analyze dat...

24/12/2025

🧪 Teardown of an IC Suppressor: Why Is This Black Box $2,000?

📦 A suppressor in an integrated circuit in ion chromatography is used to reduce unwanted noise and transient disturbances. It suppresses voltage spikes, high-frequency switching noise, and crosstalk, thereby improving signal integrity, stability, and the reliability of the circuit.

💥 Inside, we found years of river history trapped in a completely clogged channel.

This “broken” device wasn’t just a failure. It stored real environmental fingerprints: salts, organics, and traces of pollution.

🌊 Instruments don’t just stop working.
They quietly record the life of water. Have you ever opened a device and felt like it was telling you a story?

29/11/2025

✨ Implementing Water and Environmental Engineering in Agriculture, Forestry, and Fisheries 🌏💧🌿

Today, we participated in the annual academic meeting hosted by the Research Center for Okhotsk Agriculture-, Forestry- and Fisheries-Engineering Collaboration (CAFFE) at Kitami Institute of Technology 🎓🏫.

CAFFE plays a vital role as a collaborative platform connecting research in
🌾 agriculture,
🌲 forestry,
🐟 and fisheries.

This year, in addition to our core CAFFE faculty groups from four research fields—information science, applied chemistry, civil and environmental engineering, and mechanical engineering—we also welcomed faculty members and students from Otaru University of Commerce, Obihiro University of Agriculture and Veterinary Medicine, and Tokyo University of Agriculture, along with regional stakeholders. 🤝🏞️. This diverse participation created a truly interdisciplinary atmosphere, which made the discussions even more stimulating and meaningful 🌟🌏.

This year’s meeting featured 54 poster presentations 📑✨, and our laboratory also shared several of our recent research activities 📊🧪. It was inspiring to see students presenting their work with such clarity, confidence, and enthusiasm 😊🙌.

We will continue working step by step toward scientific understanding, environmental insight, and sustainable communities 🌱💡🌍. Thank you very much to everyone who joined and supported the event! 🙏🤗

23/11/2025

🔍 Rising Hypoxia Risk: What One Month of Stratification Data Reveals in the Brackish Lake Abashiri

This week, we retrieved the salinity sensors that had been recording conditions in Lake Abashiri over the past month. 👍
As a brackish lake, seawater regularly intrudes into the system, forming a strong salt–freshwater stratification layer. 🧂➕💧

🔵 Unusually High Stratification and Blue Tide Risk
Throughout the monitoring period, the salt–freshwater boundary remained unusually high in the water column. This condition increases the likelihood of blue tide — a phenomenon caused by the upwelling of low-oxygen (hypoxic) bottom water. In such events, the water turns pale blue, and hypoxia can lead to mass mortality of brackish-water clams. ⚠️

🐚 Implications for the Local Shellfish Fishery
Lake Abashiri sustains an essential fishery for Corbicula japonica. Because these clams are extremely sensitive to low-oxygen conditions, even short-term upwelling of hypoxic water poses a direct threat to their survival and to the stability of the local fishery.

💨 Wind Events and Their Influence
Several strong wind events were recorded during the deployment period. Such winds can either disrupt stratification or, depending on timing and direction, enhance vertical shear — both of which influence the potential for hypoxic water to rise toward the surface.

🚧 Role of the Ōmagari Weir
Located at the mouth of the Abashiri River, the Ōmagari Weir has played a key role in lake management since FY2013 as part of the Lake Abashiri Water Environment Improvement Project. By lifting the gate during reverse flow (high tide), the structure limits seawater intrusion while allowing river water to discharge during normal flow.

This year, the weir was operated earlier than usual, likely reducing seawater inflow. This may have helped suppress further stratification and reduced the potential for blue tide events. ⬆️

🌡️ Climate Change and Long-Term Trends
Recent hydrological studies indicate that warmer winters — a consequence of climate change 🌍️ — are reducing snow accumulation, resulting in smaller spring snowmelt floods. These high-flow events normally help flush saline water from the lake. Their weakening in recent years may be contributing to the gradual upward shift of the salt–freshwater interface.

📦 Next Steps
All sensors have now been collected and will be analyzed in detail. These data will help clarify the mechanisms driving stratification and hypoxia in Lake Abashiri, and support sustainable management of this ecologically and economically important system. ✨