Recent mechanisms of surface ecological changes driven by climate change and human activities in Lake Biwa, Japan

Lake Biwa, Japan represents a crucial example of the complex climatic and anthropogenic drivers influencing lake ecological transformations, vital to informing Sustainable Development Goals globally. This study utilizes 2002–2022 Landsat, MODIS and in situ Lake Biwa monitoring data to analyze surface layer spatiotemporal dynamics across interrelated vegetation, water quality and meteorological indicators—encompassing Normalized Difference Vegetation Index (NDVI), nitrogen (N), phosphorus (P), chlorophyll-a (Chl) and water temperature (W-TEM). Upward NDVI raster trends were found over 20 years alongside prevalent N, P and Chl declines—although some increases did occur spatially in P and Chl—while W-TEM mostly rose lakewide. Southwest–northeast gradients typified distributions. Further attribution analyses revealed W-TEM as the primary N, P and Chl driver, while agricultural expansion and urbanization mediated crucial N and P changes. Moreover, wind speed (WS), Crop, W-TEM, minimum temperature (TMMN), Chl and N constituted top NDVI raster influence factors respectively. These novel integrated models quantifying Lake Biwa ecological responses to multifaceted environmental change provide new perspectives to inform sustainable management of Lake Biwa itself and critical freshwater resources worldwide

Detecting groundwater level changes related to the 2016 Kumamoto Earthquake

Abstract This study presented the first attempt to detect precursory changes in groundwater level before the 2016 Kumamoto Earthquake. This detection was achieved by accurately determining the relationship between long-term groundwater level fluctuation and crustal deformation over 16 years through analysis of groundwater level time-series data acquired at 17 sites within the study area. Here, we show that the observed groundwater levels were lower than the modelled levels in aquifers composed of porous strata (Togawa lava and part of the pre-Aso volcanic rocks), and that there were larger differences until 2014, which diminished until the occurrence of the Kumamoto Earthquake. The initial reduction in the modelled groundwater level and the latter recovery were most likely caused by crustal strain relaxation associated with the large 2011 earthquake off the Pacific coast of Tohoku (Mw 9.0) and the strain accumulation prior to the 2016 Kumamoto Earthquake

Cities and geodiversity: coexistence of humans and abiotic nature in urban territories

La urbanització és un procés global irreversible. Els elements i sistemes naturals presents en els territoris de la ciutat o en llocs no urbans atenen les demandes d’actius naturals dels processos d’urbanització. L’atenció renovada als impactes de l’organització urbana de les societats és essencial per a promoure la supervivència harmoniosa de la urbanització amb processos naturals. Encara que la presència d’humans en el planeta representa només una xicoteta fracció de la història de la Terra, l’aglomeració humana a les ciutats ha causat impactes a escala mundial. Les ciutats demanden serveis i productes d’àrees naturals a vegades situades en àrees rurals llunyanes, que afecten els entorns geològics com a platges, rius i aqüífers, i altres processos com els cicles hidrològics o la circulació atmosfèrica. L’impacte antropogènic en les àrees de captació urbanes pot induir una degradació ambiental inesperada en les àrees urbanes que afecta el cicle hidrològic. Encara que relativament noves pel que respecta al temps de vida de la Terra, les ciutats són un hàbitat humà privilegiat, amb mecanismes de manteniment intrínsecs que formen la base de l’organització moderna de les societats i economies del món. El present article adopta una perspectiva geològica i un paradigma d’ètica de la terra per a discutir alternatives per a una existència harmoniosa entre les ciutats i la naturalesa abiòtica.Urbanization is an irreversible global process. Natural elements and systems present in city territories or at non-city sites attend to the demands for natural assets from urbanization processes. Renewed attention to the impacts of the urban organization of societies is essential to promote the harmonious survival of urbanization with natural processes. Although the presence of humans on the planet represents just a small fraction of the Earth’s history, human agglomeration in cities has caused impacts on a global scale. Cities demand services and products from natural areas that are sometimes located in faraway rural areas, affecting geological environments such as beaches, rivers and aquifers, and other processes such as hydrological cycles or atmospheric circulation. The anthropogenic impact on urban catchment areas may induce unexpected environmental degradation in urban areas that affects the hydrological cycle. Although relative newcomers in terms of the Earth’s lifetime, cities are a privileged human habitat, with intrinsic maintenance mechanisms that form the basis of the modern organization of the world’s societies and economies. The present article adopts a geological perspective and a land ethic paradigm to discuss alternatives for a harmonious existence between cities and abiotic nature.La urbanización es un proceso global irreversible. Los elementos y sistemas naturales presentes en los territorios de la ciudad o en lugares no urbanos atienden las demandas de activos naturales de los procesos de urbanización. La atención renovada a los impactos de la organización urbana de las sociedades es esencial para promover la supervivencia armoniosa de la urbanización con procesos naturales. Aunque la presencia de humanos en el planeta representa solo una pequeña fracción de la historia de la Tierra, la aglomeración humana en las ciudades ha causado impactos a escala mundial. Las ciudades demandan servicios y productos de áreas naturales en ocasiones ubicadas en áreas rurales lejanas, que afectan los entornos geológicos como playas, ríos y acuíferos, y otros procesos como los ciclos hidrológicos o la circulación atmosférica. El impacto antropogénico en las áreas de captación urbanas puede inducir una degradación ambiental inesperada en las áreas urbanas que afecta el ciclo hidrológico. Aunque relativamente nuevas por lo que respecta al tiempo de vida de la Tierra, las ciudades son un hábitat humano privilegiado, con mecanismos de mantenimiento intrínsecos que forman la base de la organización moderna de las sociedades y economías del mundo. El presente artículo adopta una perspectiva geológica y un paradigma de ética de la tierra para discutir alternativas para una existencia armoniosa entre las ciudades y la naturaleza abiótica

Cities and geodiversity: coexistence of humans and abiotic nature in urban territories

Urbanization is an irreversible global process. Natural elements and systems present in city territories or at non-city sites attend to the demands for natural assets from urbanization processes. Renewed attention to the impacts of the urban organization of societies is essential to promote the harmonious survival of urbanization with natural processes. Although the presence of humans on the planet represents just a small fraction of the Earth’s history, human agglomeration in cities has caused impacts on a global scale. Cities demand services and products from natural areas that are sometimes located in faraway rural areas, affecting geological environments such as beaches, rivers and aquifers, and other processes such as hydrological cycles or atmospheric circulation. The anthropogenic impact on urban catchment areas may induce unexpected environmental degradation in urban areas that affects the hydrological cycle. Although relative newcomers in terms of the Earth’s lifetime, cities are a privileged human habitat, with intrinsic maintenance mechanisms that form the basis of the modern organization of the world’s societies and economies. The present article adopts a geological perspective and a land ethic paradigm to discuss alternatives for a harmonious existence between cities and abiotic nature.La urbanización es un proceso global irreversible. Los elementos y sistemas naturales presentes en los territorios de la ciudad o en lugares no urbanos atienden las demandas de activos naturales de los procesos de urbanización. La atención renovada a los impactos de la organización urbana de las sociedades es esencial para promover la supervivencia armoniosa de la urbanización con procesos naturales. Aunque la presencia de humanos en el planeta representa solo una pequeña fracción de la historia de la Tierra, la aglomeración humana en las ciudades ha causado impactos a escala mundial. Las ciudades demandan servicios y productos de áreas naturales en ocasiones ubicadas en áreas rurales lejanas, que afectan los entornos geológicos como playas, ríos y acuíferos, y otros procesos como los ciclos hidrológicos o la circulación atmosférica. El impacto antropogénico en las áreas de captación urbanas puede inducir una degradación ambiental inesperada en las áreas urbanas que afecta el ciclo hidrológico. Aunque relativamente nuevas por lo que respecta al tiempo de vida de la Tierra, las ciudades son un hábitat humano privilegiado, con mecanismos de mantenimiento intrínsecos que forman la base de la organización moderna de las sociedades y economías del mundo. El presente artículo adopta una perspectiva geológica y un paradigma de ética de la tierra para discutir alternativas para una existencia armoniosa entre las ciudades y la naturaleza abiótica

Spatiotemporal distribution and fluctuation of radiocesium in Tokyo Bay in the five years following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident

<div><p>A monitoring survey was conducted from August 2011 to July 2016 of the spatiotemporal distribution in the 400 km² area of the northern part of Tokyo Bay and in rivers flowing into it of radiocesium released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. The average inventory in the river mouth (10 km²) was 131 kBq⋅m^-2 and 0.73 kBq⋅m^-2 in the central bay (330 km²) as the decay corrected value on March 16, 2011. Most of the radiocesium that flowed into Tokyo Bay originated in the northeastern section of the Tokyo metropolitan area, where the highest precipitation zone of ¹³⁷Cs in soil was almost the same level as that in Fukushima City, then flowed into and was deposited in the Old-Edogawa River estuary, deep in Tokyo Bay. The highest precipitation of radiocesium measured in the high contaminated zone was 460 kBq⋅m^-2. The inventory in sediment off the estuary of Old-Edogawa was 20.1 kBq⋅m^-2 in August 2011 immediately after the accident, but it increased to 104 kBq⋅m^-2 in July 2016. However, the radiocesium diffused minimally in sediments in the central area of Tokyo Bay in the five years following the FDNPP accident. The flux of radiocesium off the estuary decreased slightly immediately after the accident and conformed almost exactly to the values predicted based on its radioactive decay. Contrarily, the inventory of radiocesium in the sediment has increased. It was estimated that of the 8.33 TBq precipitated from the atmosphere in the catchment regions of the rivers Edogawa and Old-Edogawa, 1.31 TBq migrated through rivers and was deposited in the sediments of the Old-Edogawa estuary by July 2016. Currently, 0.25 TBq⋅yr^-1 of radiocesium continues to flow into the deep parts of Tokyo Bay.</p></div

Study areas and sampling points.

<p>Geographical distribution of the radiocesium precipitation is indicated by the values for eight months after the accident, adapted from “Extension Site of Distribution Map of Radiation Dose, etc.” [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193414#pone.0193414.ref003" target="_blank">3</a>]. (a) Study area. (b) Sampling points in the Edogawa river system. (c) Sampling points in the Tokyo Bay area. V: Tamagawa estuary, W: Sumidagawa estuary, X: Old-Edogawa estuary, Y: Off the Old-Edogawa estuary, Z: Center of Tokyo Bay, Aqua Line: Cross road of Tokyo Bay. River water in Old-Edogawa flows in the direction of the blue arrow in Fig 1C.</p

Balance of the radiocesium precipitated in the Edogawa watershed.

<p>Balance of the radiocesium precipitated in the Edogawa watershed.</p

Relationship between the ^134+137Cs activity and the grain size of surface sediments in the Tokyo Bay water system.

<p>So: Soil in the Sakagawa catchment area, S: Sakagawa river, E: Edogawa and Old-Edogawa rivers, X: Old-Edogawa estuary, Y: Off the Old-Edogawa estuary, Z: Center of Tokyo Bay, V: Tamagawa estuary, W: Sumidagawa estuary. If the radiocesium is adsorbed on the suspended materials in water owing to the grain size effect [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193414#pone.0193414.ref056" target="_blank">56</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193414#pone.0193414.ref058" target="_blank">58</a>], the relationship should obey the inverse square law. The vertical arrow in the Fig 8A indicates the range of the radiocesium background referred from the JCG report [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193414#pone.0193414.ref023" target="_blank">23</a>].</p

Inventory and flux of radiocesium in the sediment of the Tokyo Bay water system.

<p>Inventory and flux of radiocesium in the sediment of the Tokyo Bay water system.</p

Temporal changes in the vertical distribution of ^134+137Cs in the sediment core collected at Point D.

<p>A large amount of suspended materials flowed in owing to the Kanto-Tohoku heavy rainfall event from September 9 to 11, 2015 and was deposited in the Old-Edogawa estuary. The red circle in the core collected on November 13, 2015 shows the flood sedimentary layer that flowed in due to the flood.</p