Conceptual models of dissolved carbon fluxes in a two-layer stratified lake: interannual typhoon responses under extreme climates DOI Creative Commons
Hao‐Chi Lin, Keisuke Nakayama, Jeng‐Wei Tsai

et al.

Biogeosciences, Journal Year: 2023, Volume and Issue: 20(20), P. 4359 - 4376

Published: Oct. 25, 2023

Abstract. Extreme climates affect the seasonal and interannual patterns of carbon (C) distribution in lentic ecosystems due to regimes river inflow thermal stratification. Typhoons rapidly load substantial amounts terrestrial C into smaller subtropical lakes (i.e., Yuan-Yang Lake Taiwan, hereafter referred as YYL), renewing mixing water column. We developed a conceptual dissolved model hypothesized that allochthonous loading intrusion may inorganic (DIC) organic (DOC) distributions small lake under these extreme climates. A two-layer was explore how DIC DOC fluxes respond typhoon disturbances on timescales YYL while simultaneously considering autochthonous processes such algal photosynthesis, remineralization, vertical transformation. To compare temporal between years (2015–2016) non-typhoon (2017–2018), monthly field samples were obtained their DIC, DOC, chlorophyll (Chl a) concentrations measured. The results demonstrated net ecosystem production 3.14 times higher than years. These suggested most crucial driver variation because changes physical biochemical processes, mineralization, transportation. However, lowered transportation rate shaped stratification within this lake.

Language: Английский

Effects of rotation on internal solitary waves DOI
Keisuke Nakayama,

Kento Tashita,

Tetsuya SHINTANI

et al.

Applied Ocean Research, Journal Year: 2024, Volume and Issue: 149, P. 104061 - 104061

Published: May 25, 2024

Language: Английский

Citations

0
Quantification of Mixing Depth Using the Gradient Richardson Number in Submerged Aquatic Vegetation Meadows DOI Creative Commons
Hiroki Matsumoto, Keisuke Nakayama

Water Resources Research, Journal Year: 2024, Volume and Issue: 60(8)

Published: July 31, 2024

Abstract Upper layer thickness (mixing depth) is an essential parameter for estimating the dissolved inorganic carbon and flux at water surface based on their association with vertical of carbon. Previous studies quantified mixing depth without SAV meadow or penetration in stratification wind stress. However, related to interaction submerged aquatic vegetations (SAVs), stratification, stress has yet be previous studies. Our study first quantify theoretical SAVs according stress, height, drag coefficient. Theoretical was from modeled temperature profile, profile horizontal velocity, gradient Richardson number ( Ri g,veg ). We found that a 100 demonstrated good agreement numerical results average, estimated this h U ,this ) showing high applicability observations Komuke Lagoon. Moreover, increased increasing decreasing coefficient height. Further, we meadows could divided into four hydrodynamic regimes: non‐vegetated layers, upper vegetated thermoclines, benthic boundary layers. findings help us estimate complicated simulation understand flow SAV, stratification.

Language: Английский

Citations

0
DIC方程式を用いた純一次生産速度の推定手法の開発 DOI

Momoka MARUYAMA,

Keisuke Nakayama,

Taketoshi SHIMIZU

et al.

Japanese Journal of JSCE, Journal Year: 2023, Volume and Issue: 79(18), P. n/a - n/a

Published: Jan. 1, 2023

海水域のみならず,淡水も含めた低塩分な領域における炭素貯留効果が注目されているが,現在確立しているのは海草・海藻藻場における年間の炭素隔離量の推定手法のみである.そこで,本論文ではすべての水域に用いることができる手法を開発し,検証することを目的とした.北海道・コムケ湖におけるアマモのDIC方程式を用いて,光量子束密度や水温,アマモの現存量の変化を仮定し,1年間のDICの変化量を推定したところ,いくつかの改善点はあるものの,過去の研究でのリーフマーキング法による北海道・厚岸湖や全国平均の純一次生産速度の推定値と比較して良好な結果を得ることができた.提案手法は植生密度や長さを定量的に容易に把握できるという利点を有しており,新たな手法となる可能性が示された.

Citations

0
ASSESSMENT OF PATCH SIZE’S IMPACT ON CARBON ABSORPTION BY SUBMERGED AQUATIC VEGETATION DOI

Keita MATSUMURA,

Keisuke Nakayama, Tetsuya SHINTANI

et al.

Japanese Journal of JSCE, Journal Year: 2023, Volume and Issue: 79(18), P. n/a - n/a

Published: Jan. 1, 2023

気候変動の緩和策として,水圏における生態系の光合成活動によって吸収・貯留される炭素である"ブルーカーボン"が注目されている.ブルーカーボンを形成している水生植物(Submerged Aquatic Vegetation : SAV)は,生息する沿岸浅水域や湖の空間スケールと比較し,小さなスケールでパッチ状に存在することも多く,流れとの相互干渉で複雑な流況を作り出す可能性が高い.その結果,水域における炭素吸収量および大気から水中への炭素隔離量も大きく影響を受け,その正確な見積もりを困難にしている.そのため,SAVが空間の一部に存在する場合における流動場の理解と,物質輸送に関する詳細な解析を行う必要がある.これに対し,SAV と流れ場の相互作用を詳細に再現したSAV modelがこれまでの研究で構築されてきた.そこで本研究では,SAV modelを利用し,パッチ状に存在するSAV(SAVパッチ)が水路幅を占める割合(占有率)およびSAVのたわみが,流動場と炭素吸収量の両者に与える影響について検討を行った.その結果,占有率とSAVのたわみが炭素吸収量と炭素隔離量に影響を与える重要な要因であることが明らかになった.加えて,占有率とSAVの弾性係数が大きいほど大気から水中への炭素隔離が促進されることが示された.

Citations

0
Conceptual models of dissolved carbon fluxes in a two-layer stratified lake: interannual typhoon responses under extreme climates DOI Creative Commons
Hao‐Chi Lin, Keisuke Nakayama, Jeng‐Wei Tsai

et al.

Biogeosciences, Journal Year: 2023, Volume and Issue: 20(20), P. 4359 - 4376

Published: Oct. 25, 2023

Abstract. Extreme climates affect the seasonal and interannual patterns of carbon (C) distribution in lentic ecosystems due to regimes river inflow thermal stratification. Typhoons rapidly load substantial amounts terrestrial C into smaller subtropical lakes (i.e., Yuan-Yang Lake Taiwan, hereafter referred as YYL), renewing mixing water column. We developed a conceptual dissolved model hypothesized that allochthonous loading intrusion may inorganic (DIC) organic (DOC) distributions small lake under these extreme climates. A two-layer was explore how DIC DOC fluxes respond typhoon disturbances on timescales YYL while simultaneously considering autochthonous processes such algal photosynthesis, remineralization, vertical transformation. To compare temporal between years (2015–2016) non-typhoon (2017–2018), monthly field samples were obtained their DIC, DOC, chlorophyll (Chl a) concentrations measured. The results demonstrated net ecosystem production 3.14 times higher than years. These suggested most crucial driver variation because changes physical biochemical processes, mineralization, transportation. However, lowered transportation rate shaped stratification within this lake.

Language: Английский

Citations

0