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| Open AccessClimatic pacing of extreme Nile floods during the North African Humid Period
Extreme and highly variable summer floods in the Nile River valley through the North African Humid Period were modulated by both interannual and multi-decadal climate modes, according to an offshore sedimentary archive.
- Cécile L. Blanchet
- , Arne Ramisch
- & Achim Brauer
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Research Briefing |
Inundation risk from continued lake expansion on the Tibetan Plateau
Lakes on the Tibetan Plateau are projected to expand significantly, increasing in area by approximately 50% by 2100 under a low emissions scenario. This expansion will reshape the hydrological connectivity of the lake basins, and submerge a large number of roads, settlements, and ecological components.
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Article |
Canal networks regulate aquatic losses of carbon from degraded tropical peatlands
Canal networks are a hotspot for the loss of carbon from tropical peatlands following disturbance, according to measurements of oxidation rates for dissolved organic carbon to carbon dioxide in drainage canals in Southeast Asia.
- Jennifer C. Bowen
- , Putri J. Wahyudio
- & Alison M. Hoyt
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Article
| Open AccessPleistocene climate variability in eastern Africa influenced hominin evolution
Over the past 620,000 years, three distinct phases of climate variability in eastern Africa coincided with shifts in hominin evolution and dispersal, according to an analysis of environmental proxy records from a core collected in the Chew Bahir basin of Ethiopia.
- Verena Foerster
- , Asfawossen Asrat
- & Martin H. Trauth
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Research Briefing |
Preferential phosphorus retention in lakes alters the balance of global nutrient cycles
Preferential P retention emerges in almost 90% of global lakes. This retention leads to a strong elevation in the N:P ratios in lakes outflow, exacerbates the imbalance of the nutrient cycles and can potentially result in biodiversity losses and algal blooms in lakes and downstream ecosystems.
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Article |
Imbalance of global nutrient cycles exacerbated by the greater retention of phosphorus over nitrogen in lakes
Lakes preferentially retain phosphorous over nitrogen, amplifying the imbalance of nutrient cycles caused by anthropogenic inputs, according to analyses of more than 5,000 lakes globally.
- Zhen Wu
- , Jincheng Li
- & Yong Liu
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Article |
Global mapping reveals increase in lacustrine algal blooms over the past decade
Algal blooms are occurring more frequently, as seen in a global database compiled from satellite imagery from the past few decades.
- Xuejiao Hou
- , Lian Feng
- & Chunmiao Zheng
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Article |
Development of ice-shelf estuaries promotes fractures and calving
Ice-shelf surface rivers can form estuaries that promote fracturing and enhance calving, according to observations from the Petermann and Ryder ice shelves in Greenland.
- Alexandra L. Boghosian
- , Lincoln H. Pitcher
- & Robin E. Bell
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Article |
Attribution of global lake systems change to anthropogenic forcing
Anthropogenic climate change is impacting the temperature and ice cover of lakes across the globe, according to an attribution analysis based on hindcasts and projections from lake models.
- Luke Grant
- , Inne Vanderkelen
- & Wim Thiery
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Article
| Open AccessGlobal carbon budget of reservoirs is overturned by the quantification of drawdown areas
Globally, reservoirs are net emitters of carbon when drawdown areas are taken into account, according to an analysis of satellite observations of reservoir surface area.
- Philipp S. Keller
- , Rafael Marcé
- & Matthias Koschorreck
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Article |
Global carbon dioxide efflux from rivers enhanced by high nocturnal emissions
Failing to account for emission differences between day and night will lead to an underestimate of global CO2 emissions from rivers by up to 0.55 PgC yr–1, according to analyses of high-frequency CO2 measurements.
- Lluís Gómez-Gener
- , Gerard Rocher-Ros
- & Ryan A. Sponseller
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Article
| Open AccessCo-variation of silicate, carbonate and sulfide weathering drives CO2 release with erosion
Unlike sulfide and carbonate, silicate weathering does not increase with physical erosion, which could result in a net release of carbon dioxide associated with uplift, according to stream-water chemistry of southern Taiwan.
- Aaron Bufe
- , Niels Hovius
- & Jui-Ming Chang
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Article |
Half of global methane emissions come from highly variable aquatic ecosystem sources
Methane emissions from aquatic systems contribute approximately half of global methane emissions, according to meta-analysis of natural, impacted and human-made aquatic ecosystems and indicating potential mitigation strategies to reduce emissions.
- Judith A. Rosentreter
- , Alberto V. Borges
- & Bradley D. Eyre
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Editorial |
Valuing wetlands
Wetlands provide a wealth of societal and climatic benefits. Balanced conservation strategies are needed to ensure their protection in the twenty-first century and beyond.
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News & Views |
Fidelity of turbidites as earthquake records
Turbidites record ground motion in the 2016 Kaikōura earthquake. Recent events are now revealing how turbidites record earthquakes, but turbidites are triggered in many ways, and testing if ancient turbidites are earthquake-triggered remains challenging.
- Peter J. Talling
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Article |
Mobilization of aged and biolabile soil carbon by tropical deforestation
Tropical deforestation induces the loss and transport of old and biolabile soil organic carbon into rivers, suggest analyses of dissolved organic matter in deforested and pristine catchments in the Congo Basin. The mobilized soil carbon is likely to turn into a carbon source.
- Travis W. Drake
- , Kristof Van Oost
- & Robert G. M. Spencer
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Article |
Worldwide alteration of lake mixing regimes in response to climate change
Many lakes that currently mix once or twice a year may become permanently stratified or mix only once in a warming climate, suggest numerical simulations of lake mixing regimes. Mixing regimes are most affected by ice-cover duration and surface temperatures.
- R. Iestyn Woolway
- & Christopher J. Merchant
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Article |
Distinct air–water gas exchange regimes in low- and high-energy streams
Bubble-mediated gas exchange in high-energy streams accelerates faster as energy dissipation intensifies than does turbulent-diffusion-driven gas exchange in low-energy streams, according to an analysis of new measurements and published data.
- Amber J. Ulseth
- , Robert O. Hall Jr
- & Tom J. Battin
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Article |
Negligible cycling of terrestrial carbon in many lakes of the arid circumpolar landscape
Many lakes in arid, organic-poor permafrost landscapes have a negligible role in mineralizing terrestrial carbon, according to metabolic analyses of lakes in the arid Yukon Flats Basin.
- Matthew J. Bogard
- , Catherine D. Kuhn
- & David E. Butman
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News & Views |
World’s landlocked basins drying
Most of the net water transferred over the past 15 years from non-glaciated land to the oceans has originated from landlocked basins, according to satellite data. This source of sea-level rise is often overlooked.
- Tamlin M. Pavelsky
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Article |
Recent global decline in endorheic basin water storages
Hydrologically landlocked basins worldwide have experienced widespread decline in water storage over the past decade.
- Jida Wang
- , Chunqiao Song
- & Yoshihide Wada
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Article |
Low buffering capacity and slow recovery of anthropogenic phosphorus pollution in watersheds
Watersheds have a low buffering capacity for phosphorus inputs, and their recovery from phosphorus pollution can take over 2,000 years, according to an analysis of phosphorus data from a large North American river.
- J. -O. Goyette
- , E. M. Bennett
- & R. Maranger
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Article |
High riverine CO2 emissions at the permafrost boundary of Western Siberia
Rivers in the Western Siberian Lowland, the world’s largest peatland, play a significant role in the release of terrestrial carbon to the atmosphere, according to in situ measurements of carbon dioxide emissions from rivers.
- S. Serikova
- , O. S. Pokrovsky
- & J. Karlsson
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Article |
Holocene dynamics of the Southern Hemisphere westerly winds and possible links to CO2 outgassing
The strength of the Southern Hemisphere westerly winds varied throughout the Holocene, according to a reconstruction from lake sediments, with periods of stronger winds coincident with higher atmospheric CO2 levels.
- Krystyna M. Saunders
- , Stephen J. Roberts
- & Dominic A. Hodgson
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Editorial |
Connect the drops
The world's inland waters are under siege. A system-level view of watersheds is needed to inform both our scientific understanding and management decisions for these precious resources.
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Perspective |
Decline of the world's saline lakes
Many of the world's saline lakes have been shrinking due to consumptive water use. The Great Salt Lake, USA, provides an example for how the health of and ecosystem services provided by saline lakes can be sustained.
- Wayne A. Wurtsbaugh
- , Craig Miller
- & Johnnie Moore
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Article |
Variability in organic carbon reactivity across lake residence time and trophic gradients
The production and consumption of organic carbon in inland waters varies with water residence time and biotic processes, suggest analyses of dissolved organic carbon from Northern Hemisphere water bodies. Inland waters mediate carbon transport between land and ocean.
- Chris D. Evans
- , Martyn N. Futter
- & Dolly N. Kothawala
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Article |
Microbial oxidation as a methane sink beneath the West Antarctic Ice Sheet
Subglacial lakes contain active microbial ecosystems capable of cycling methane. In a subglacial lake in West Antarctica, methane that is produced is subsequently consumed, limiting the potential for methane emissions during lake drainage.
- Alexander B. Michaud
- , John E. Dore
- & John C. Priscu
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Article |
Substantial inorganic carbon sink in closed drainage basins globally
Dissolved inorganic carbon is buried in dryland basins that do not drain to the sea. Based on measurements of sediment chemistry in twelve of these sites, closed basins are estimated to store 0.15 Pg of dissolved inorganic carbon annually.
- Yu Li
- , Chengqi Zhang
- & Wangting Ye
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Article |
Iron-dependent nitrogen cycling in a ferruginous lake and the nutrient status of Proterozoic oceans
Fixed nitrogen is lost from oxygen minimum zones. Experimental data from an anoxic lake show that the presence of Fe(II) limits this loss, suggesting that ancient anoxic and iron-rich oceans may not have been nitrogen limited.
- Céline C. Michiels
- , François Darchambeau
- & Sean A. Crowe
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Article |
Carbon sequestration in an expanded lake system during the Toarcian oceanic anoxic event
The Toarcian anoxic event was linked to a massive release of carbon to the atmosphere. Geochemical data suggest that organic carbon burial in large lacustrine systems was key to the recovery of the carbon cycle.
- Weimu Xu
- , Micha Ruhl
- & Erdem F. Idiz
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Letter |
Organic carbon decomposition rates controlled by water retention time across inland waters
Organic carbon decays as it travels through inland waters from soils to the sea. Analysis of data from across the continuum of inland and marine aquatic systems reveals that the rate of organic carbon decay depends on water retention time.
- Núria Catalán
- , Rafael Marcé
- & Lars. J. Tranvik
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Letter |
Large contribution to inland water CO2 and CH4 emissions from very small ponds
Very small ponds have been omitted from greenhouse gas budgets. Estimates of CO2 and CH4 emissions from 427 lakes and ponds show that very small ponds account for 15% of CO2 and 40% of diffusive CH4 emissions, but 8.6% of lake and pond area.
- Meredith A. Holgerson
- & Peter A. Raymond
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Article |
Globally significant greenhouse-gas emissions from African inland waters
Inland waters are important sources of greenhouse gases. Measurements over eight years suggest that African inland waters are a substantial source of greenhouse gases, equivalent to a quarter of the global land and ocean carbon sink.
- Alberto V. Borges
- , François Darchambeau
- & Steven Bouillon
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Letter |
Carbonate weathering as a driver of CO2 supersaturation in lakes
Carbon dioxide emissions from lakes contribute to the continental carbon balance. Water chemistry analyses of reservoirs in Spain suggest that carbonate weathering causes CO2 supersaturation in lakes above a threshold alkalinity.
- Rafael Marcé
- , Biel Obrador
- & Joan Armengol
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News & Views |
Building bacterial bridges
The classical view of fluvial sediment transport considers only physical interactions between the river flow and riverbed particles. Experiments and theory suggest that microbial biofilms reduce sediment mobility by binding many grains together.
- Aaron Packman
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Letter |
Linking the historic 2011 Mississippi River flood to coastal wetland sedimentation
In spring 2011, a record-breaking flood necessitated diversion of water from the lower Mississippi River to the Atchafalaya River Basin. A comparison between the dynamics in the two basins based on field-calibrated satellite observations and in situ data suggests that river-mouth dynamics and wetland sedimentation are directly linked.
- Federico Falcini
- , Nicole S. Khan
- & Douglas J. Jerolmack
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Commentary |
An expanded role for river networks
Estimates of stream and river area have relied on observations at coarse resolution. Consideration of the smallest and most dynamic streams could reveal a greater role for river networks in global biogeochemical cycling than previously thought.
- Jonathan P. Benstead
- & David S. Leigh
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Letter |
Dependence of riverine nitrous oxide emissions on dissolved oxygen levels
Nitrous oxide is a potent greenhouse gas that destroys stratospheric ozone. Measurements of nitrous oxide emissions from a Canadian river suggest that future increases in nitrate export to rivers will not necessarily lead to higher nitrous oxide emissions, but more widespread hypoxia most likely will.
- Madeline S. Rosamond
- , Simon J. Thuss
- & Sherry L. Schiff
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News & Views |
Flood-built land
The southeastern US coastline is under threat as land subsides and sea level rises. Measurements of the 2011 Mississippi River flood suggest that the river carries enough sandy sediment to offset some of this coastal drowning.
- Wonsuck Kim
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Article |
Evolution of fixed-channel alluvial plains in response to Carboniferous vegetation
The expansion of land plants led to the development of new river and floodplain morphologies. Field studies suggest that the expansion of tree habitats in the Carboniferous period caused the development of river systems dominated by multiple channels and stable alluvial islands.
- Neil S. Davies
- & Martin R. Gibling
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News & Views |
Coastal flow
How groundwater flow varies when long-term external conditions change is little documented. Geochemical evidence shows that sea-level rise at the end of the last glacial period led to a shift in the flow patterns of coastal groundwater beneath Florida.
- Ward E. Sanford
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Letter |
Groundwater reorganization in the Floridan aquifer following Holocene sea-level rise
Sea-level fluctuations can have a profound impact on coastal groundwater circulation. The geochemistry of groundwater in the Floridan aquifer system suggests that the fresh water in the upper aquifer was emplaced primarily during the last glacial period, when sea level was more than 100 m lower than at present.
- Sheila K. Morrissey
- , Jordan F. Clark
- & Martin Stute
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Letter |
Rapid formation of a modern bedrock canyon by a single flood event
River canyons are thought to be cut slowly over millions of years. However, at Lake Canyon Gorge, Texas, a seven-metre-deep canyon was cut in just three days in 2002, providing insight into the erosion processes operating during megaflood events.
- Michael P. Lamb
- & Mark A. Fonstad
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News & Views |
Anthropogenic arsenic
Arsenic occurs naturally in the groundwater of southern Asia. Analyses of an agricultural site in Bangladesh suggest that human activities, including widespread farming practices, can dictate where elevated arsenic is found.
- Shawn Benner