Seasonal changes in carbon and nitrogen productivity in the north basin of Lake Biwa, Japan

2006 ◽  
Vol 29 (4) ◽  
pp. 1913-1920 ◽  
Author(s):  
Osamu Mitamura ◽  
Hiroto Maeda ◽  
Yasushi Seike ◽  
Kunio Kondo ◽  
Naoshige Goto ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Lake Biwa ◽  
Carbon And Nitrogen ◽  
The North ◽  
Nitrogen Productivity

scholarly journals Increasing benthic vent formation: a threat to Japan’s ancient lake

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michio Kumagai ◽  
Richard D. Robarts ◽  
Yasuaki Aota
Keyword(s):  
Lake Biwa ◽  
Autonomous Underwater Vehicle ◽  
Tohoku Earthquake ◽  
Water Source ◽  
Tectonic Activity ◽  
Drinking Water Source ◽  
Sudden Increase ◽  
The North ◽  
Slow Earthquakes ◽  
Near Future

AbstractAn autonomous underwater vehicle (AUV) was deployed in Lake Biwa from 2000 to 2012. In December 2009, ebullition of turbid water was first found in the deepest area (> 90 m) of the North Basin. Follow-up investigations in April and December 2010 and January 2012 confirmed the existence of benthic vents similar to the vents observed in other deep lakes. Importantly, vent numbers per unit travel distance in Lake Biwa dramatically increased from only two vents (0.37 vents km−1) in December 2009 to 54 vents (5.28 vents km−1) in January 2012, which could be related to recent tectonic activity in Japan, e.g., the M9.1 Tohoku earthquake in March 2011 and slow earthquakes along the Nankai Trough from 2006 to 2018. Continuous back-up investigations from 2014 to 2019 revealed additional benthic vents in the same area. The sudden increase in benthic vent activity (liquid and gaseous ebullitions) have significant potential to alter lake biogeochemistry and, ultimately, degrade Japan’s major drinking water source and may be a harbinger of major crustal change in the near future.

Spatial and seasonal changes of dissolved and particulate organic C in the North Sea

Hydrobiologia ◽  
2009 ◽  
Vol 628 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Suhaimi Suratman ◽  
Keith Weston ◽  
Tim Jickells ◽  
Liam Fernand
Keyword(s):  
North Sea ◽  
Seasonal Changes ◽  
Organic C ◽  
The North ◽  
The North Sea

scholarly journals Spatial and Seasonal Variations of Sedimentary Organic Matter in a Subtropical Bay: Implication for Human Interventions

2020 ◽  
Vol 17 (4) ◽  
pp. 1362 ◽  
Author(s):  
Xuan Lu ◽  
Fengxia Zhou ◽  
Fajin Chen ◽  
Qibin Lao ◽  
Qingmei Zhu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Surface Sediment ◽  
Seasonal Variations ◽  
Seasonal Changes ◽  
Nitrogen Isotope ◽  
Anthropogenic Influences ◽  
Stable Carbon ◽  
Δ13c And Δ15n ◽  
Carbon And Nitrogen ◽  
Induced Changes

Elemental (total organic carbon (TOC) and total nitrogen (TN)) and stable carbon and nitrogen isotope compositions (δ13C and δ15N, respectively) in the surface sediment of Zhanjiang Bay (ZJB) in spring and summer were measured to study the spatial and seasonal changes of organic matter (OM) and assess the human-induced and environment-induced changes in the area. The OM in the surface sediment of ZJB was a mixture of terrestrial and marine sources, and was dominated by marine OM (54.9% ± 15.2%). Compared to the central ZJB, the channel and coastal ZJB areas had higher δ13C and δ15N values, higher TOC and TN concentrations, and lower TOC/TN ratios, indicating higher primary productivity and higher percentages of marine OM in the latter two subregions. Mariculture activities, sewage inputs, and dredging were responsible for these phenomena. Clear seasonal variations in OM were observed in ZJB. The average proportions of terrestrial OM in summer increased by 10.2% in the ZJB channel and 26.0% in the coastal ZJB area compared with those in spring. Heavy rainfall brought a large amount of terrestrial OM into the channel and coastal ZJB areas, leading to the increase of the terrestrial OM fraction in these two subregions in summer. In summary, anthropogenic influences had a significant influence on the spatial and seasonal variations of sedimentary OM in ZJB.

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