scholarly journals Global geographic variability in freshwater methane hydrogen isotope ratios and its implications for emissions source apportionment and microbial biogeochemistry

2020 ◽  
Author(s):  
Peter M. J. Douglas ◽  
Emerald Stratigopoulos ◽  
Jenny Park ◽  
Dawson Phan
Keyword(s):  
Hydrogen Isotope ◽  
Environmental Water ◽  
Freshwater Ecosystems ◽  
Rice Paddies ◽  
Source Attribution ◽  
Atmospheric Measurements ◽  
Ch4 Emissions ◽  
Spatially Resolved ◽  
Hydrogenotrophic Methanogenesis ◽  
Freshwater Environments

Abstract. There is growing interest in developing spatially resolved methane (CH4) isotopic source signatures to aid in geographic source attribution of CH4 emissions. CH4 hydrogen isotope measurements (δ2H-CH4) have the potential to be a powerful tool for spatial resolution of CH4 emissions from freshwater environments, as well as other microbial sources. This is because microbial δ2H-CH4 values are partially dependent on the δ2H of environmental water (δ2H-H2O), which exhibits large and well-characterized spatial variability globally. We compiled a comprehensive global dataset of paired CH4 δ2H and δ13C measurements from freshwater environments, including wetlands, inland waters, and rice paddies, comprising a total of 131 different ecosystems, and compared these with measurements and estimates of δ2H-H2O. We found that the estimated δ2H of annual precipitation (δ2Hp) explained approximately 35 % of the observed variation in δ2H-CH4, and that the relationship between δ2H-CH4 and δ2Hp led to significant differences in the distribution of freshwater δ2H-CH4 between the northern high latitudes (60–90º N) relative to other global regions. Residual variability in δ2H-CH4 is partially explained by differences in the dominant methanogenic pathway and CH4 oxidation, as inferred from carbon isotope fractionation between CH4 and carbon dioxide (αC). Our results imply that hydrogenotrophic methanogenesis is characterized by a steeper slope of δ2H-CH4 vs. δ2Hp than acetoclastic methanogenesis, a pattern that is consistent with previous predictions. Biogeochemical sources of variability in δ2H-CH4 are reflected in apparent differences between different freshwater ecosystems, with relatively high values in rivers and bogs, and low values in fens and rice paddies, although more data is needed to verify whether these differences are significant. To estimate how changes in the spatial distribution of freshwater emissions would influence global atmospheric CH4 isotopic measurements, we developed a bottom-up mixing model of global CH4 δ2H and δ13C sources, including spatially resolved signatures for freshwater CH4 sources. This model implies that changes in high-latitude freshwater CH4 emissions would have an especially strong influence on global source δ2H-CH4. We estimate that global CH4 emissions sources have a combined δ2H value of −277±8 ‰, which is consistent with top-down estimates based on atmospheric measurements. In contrast our estimated δ13C value of −56.4±1.4 ‰ is not consistent with atmospheric measurements, suggesting possible errors in either emissions inventories or estimates of sink fluxes and isotopic fractionations. Overall our results emphasize the value of δ2H-CH4 measurements to help constrain atmospheric CH4 budgets.

scholarly journals Geographic variability in freshwater methane hydrogen isotope ratios and its implications for global isotopic source signatures

2021 ◽  
Vol 18 (11) ◽  
pp. 3505-3527
Author(s):  
Peter M. J. Douglas ◽  
Emerald Stratigopoulos ◽  
Sanga Park ◽  
Dawson Phan
Keyword(s):  
Hydrogen Isotope ◽  
Inland Waters ◽  
Top Down ◽  
Ch4 Oxidation ◽  
Bottom Up ◽  
Isotopic Signatures ◽  
Ch4 Emissions ◽  
Spatially Resolved ◽  
Freshwater Environments ◽  
Global Source

Abstract. There is growing interest in developing spatially resolved methane (CH4) isotopic source signatures to aid in geographic source attribution of CH4 emissions. CH4 hydrogen isotope measurements (δ2H–CH4) have the potential to be a powerful tool for geographic differentiation of CH4 emissions from freshwater environments, as well as other microbial sources. This is because microbial δ2H–CH4 values are partially dependent on the δ2H of environmental water (δ2H–H2O), which exhibits large and well-characterized spatial variability globally. We have refined the existing global relationship between δ2H–CH4 and δ2H–H2O by compiling a more extensive global dataset of δ2H–CH4 from freshwater environments, including wetlands, inland waters, and rice paddies, comprising a total of 129 different sites, and compared these with measurements and estimates of δ2H–H2O, as well as δ13C-CH4 and δ13C–CO2 measurements. We found that estimates of δ2H–H2O explain approximately 42 % of the observed variation in δ2H–CH4, with a flatter slope than observed in previous studies. The inferred global δ2H–CH4 vs. δ2H–H2O regression relationship is not sensitive to using either modelled precipitation δ2H or measured δ2H–H2O as the predictor variable. The slope of the global freshwater relationship between δ2H–CH4 and δ2H–H2O is similar to observations from incubation experiments but is different from pure culture experiments. This result is consistent with previous suggestions that variation in the δ2H of acetate, controlled by environmental δ2H–H2O, is important in determining variation in δ2H–CH4. The relationship between δ2H–CH4 and δ2H–H2O leads to significant differences in the distribution of freshwater δ2H–CH4 between the northern high latitudes (60–90∘ N), relative to other global regions. We estimate a flux-weighted global freshwater δ2H–CH4 of −310 ± 15 ‰, which is higher than most previous estimates. Comparison with δ13C measurements of both CH4 and CO2 implies that residual δ2H–CH4 variation is the result of complex interactions between CH4 oxidation, variation in the dominant pathway of methanogenesis, and potentially other biogeochemical variables. We observe a significantly greater distribution of δ2H–CH4 values, corrected for δ2H–H2O, in inland waters relative to wetlands, and suggest this difference is caused by more prevalent CH4 oxidation in inland waters. We used the expanded freshwater CH4 isotopic dataset to calculate a bottom-up estimate of global source δ2H–CH4 and δ13C-CH4 that includes spatially resolved isotopic signatures for freshwater CH4 sources. Our bottom-up global source δ2H–CH4 estimate (−278 ± 15 ‰) is higher than a previous estimate using a similar approach, as a result of the more enriched global freshwater δ2H–CH4 signature derived from our dataset. However, it is in agreement with top-down estimates of global source δ2H–CH4 based on atmospheric measurements and estimated atmospheric sink fractionations. In contrast our bottom-up global source δ13C-CH4 estimate is lower than top-down estimates, partly as a result of a lack of δ13C-CH4 data from C4-plant-dominated ecosystems. In general, we find there is a particular need for more data to constrain isotopic signatures for low-latitude microbial CH4 sources.

scholarly journals Knowledge about Microplastic in Mediterranean Tributary River Ecosystems: Lack of Data and Research Needs on Such a Crucial Marine Pollution Source

2020 ◽  
Vol 8 (3) ◽  
pp. 216 ◽  
Author(s):  
Cristiana Guerranti ◽  
Guido Perra ◽  
Tania Martellini ◽  
Luisa Giari ◽  
Alessandra Cincinelli
Keyword(s):  
Marine Pollution ◽  
Distribution Patterns ◽  
Pollution Source ◽  
Freshwater Ecosystems ◽  
Abundance Distribution ◽  
Plastic Pollution ◽  
Marine Systems ◽  
Final Destination ◽  
Lack Of Information ◽  
Freshwater Environments

Plastic debris occurring in freshwater environments, which can either come from the surrounding terrestrial areas or transported from upstream, has been identified as one of the main sources and routes of plastic pollution in marine systems. The ocean is the final destination of land- based microplastic sources, but compared to marine environments, the occurrence and effects of microplastics in freshwater ecosystems remain largely unknown. A thorough examination of scientific literature on abundance, distribution patterns, and characteristics of microplastics in freshwater environments in Mediterranean tributary rivers has shown a substantial lack of information and the need to apply adequate and uniform measurement methods.

scholarly journals Odonata (Insecta) from Nova Xavantina, Mato Grosso, Central Brazil: Information on species distribution and new records

Check List ◽  
2014 ◽  
Vol 10 (2) ◽  
pp. 299 ◽  
Author(s):  
Lenize Batista Calvão ◽  
Paulo De Marco Júnior ◽  
Joana Darc Batista
Keyword(s):  
Species Distribution ◽  
New Records ◽  
Freshwater Ecosystems ◽  
Species List ◽  
Mato Grosso ◽  
Central Brazil ◽  
Fixed Area ◽  
Freshwater Environments ◽  
Tropical Freshwater

Odonates are found in all freshwater environments, and are specially species rich in tropical freshwater ecosystems. Currently about 800 odonate species are known to Brazil, but only 29% of the Brazil territory have been surveyed for this group. Here we provide a species list with information on distribution and new records for Odonata in nine streams in Nova Xavantina, Mato Grosso, Central Brazil. We used the scan procedure with a fixed area for three days in each stream between 10:00 and 14:00h. We collected 1038 dragonfly specimens belonging to 67 species, which represents 8% of the known Brazil odonate fauna. Additionally, five new records for the study area are presented.

scholarly journals Ubiquity, Diversity, and Genomic Complexity of Cyanophages in Freshwater Environments

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 105
Author(s):  
Qi-Ya Zhang
Keyword(s):  
Morphological Diversity ◽  
Freshwater Ecosystems ◽  
Open Reading Frames ◽  
Morphological Observation ◽  
Filamentous Cyanobacterium ◽  
Putative Orfs ◽  
Virus Like Particles ◽  
Blue Green Algae ◽  
Short Tail ◽  
Freshwater Environments

Cyanophages are viruses that infect cyanobacteria (also known as blue-green algae) and are ubiquitious in marine and freshwater environments. In recent years, freshwater cyanophages have attracted more attention because they can affect global freshwater ecosystems. The spatial distribution and morphological diversity of cyanophage populations were examined in Lake Donghu with three trophic regions: hypertrophic, eutrophic, and mesotrophic regions. The surprisingly high viral abundance (ranging from 108 to 109 phage mL−1) and morphological diversity were detected. Most of them have tails and belong to the families Siphoviridae, Myoviridae, and Podoviridae. Various morphotypes were observed, such as prolate-headed virus-like particles and lemon-shaped virus-like particles. In addition, some cyanophages were studied by virological experiments and whole-genome analyses, combined with morphological observation. For example, three cyanophages were isolated and their whole genomes were sequenced. Contractile tail myonophage MaMV-DC infects bloom-forming cyanobacterium Microcystis aeruginosa. Tailless cyanophage Planktothrix agardhii virus isolated from Lake Donghu (PaV-LD) infects filamentous cyanobacterium. Short-tail podovirus A-4L can infect the model cyanobacterium Anabaena sp. strain PCC 7120. The MaMV-DC genome contains 169,223 bp encoding 170 putative open reading frames (ORFs). The PaV-LD genome posseses 95,299 bp encoding 142 putative ORFs. The genome of short-tail podovirus A-4L has 41,750 bp encoding 38 putative ORFs. There are significant differences in their genomic size and encoded tail proteins, but all three cyanophages contain genes that are not commonly found in phages. By studying the vast biodiversity of viruses in freshwater environments, these novel findings of cyanophages broaden our insights, and allow us to gain more useful knowledge about the global impact of these viruses in freshwater ecosystems.

scholarly journals Inverse modelling of national and European CH<sub>4</sub> emissions using the atmospheric zoom model TM5

2005 ◽  
Vol 5 (1) ◽  
pp. 1007-1066 ◽  
Author(s):  
P. Bergamaschi ◽  
M. Krol ◽  
F. Dentener ◽  
A. Vermeulen ◽  
F. Meinhardt ◽  
...  
Keyword(s):  
High Frequency ◽  
A Priori ◽  
A Priori Estimate ◽  
European Countries ◽  
Synoptic Scale ◽  
Source Attribution ◽  
Top Down ◽  
Priori Estimate ◽  
Ch4 Emissions ◽  
Model Driven

Abstract. A synthesis inversion based on the atmospheric zoom model TM5 is used to derive top-down estimates of CH4 emissions from individual European countries for the year 2001. We employ a model zoom over Europe with 1°&amp;times1° resolution that is two-way nested into the global model domain (with resolution of 6°×4°). This approach ensures consistent boundary conditions for the zoom domain and thus European top-down estimates consistent with global CH4 observations. The TM5 model, driven by ECMWF analyses, simulates synoptic scale events at most European and global sites fairly well, and the use of high-frequency observations allows exploiting the information content of individual synoptic events. A detailed source attribution is presented for a comprehensive set of 56 monitoring sites, assigning the atmospheric signal to the emissions of individual European countries and larger global regions. The available observational data put significant constraints on emissions from different regions. Within Europe, in particular several Western European countries are well constrained. The inversion results suggest up to 50–90% higher anthropogenic CH4 emissions in 2001 for Germany, France and UK compared to reported UNFCCC values, but the derived EU-15 totals are relatively close to UNFCCC values (within 10–30%). The derived top-down estimate for Finland is distinctly smaller than the a priori estimate, suggesting much smaller CH4 emissions from Finnish wetlands than derived from the bottom-up inventory.

scholarly journals Using carbon-14 and carbon-13 measurements for source attribution of atmospheric methane in the Athabasca Oil Sands Region

2021 ◽  
Author(s):  
Regina Gonzalez Moguel ◽  
Felix Vogel ◽  
Sébastien Ars ◽  
Hinrich Schaefer ◽  
Jocelyn Turnbull ◽  
...  
Keyword(s):  
Oil Sands ◽  
Surface Mining ◽  
Atmospheric Methane ◽  
Source Attribution ◽  
Athabasca Oil Sands ◽  
Ch4 Emissions ◽  
Athabasca Oil Sands Region ◽  
Carbon 14 ◽  
Isotopic Characterization ◽  
Tailings Ponds

Abstract. The rapidly expanding and energy intensive production from the Canadian oil sands, one of the largest oil reserves globally, accounts for almost 12 % of Canada’s greenhouse gas emissions according to inventories. Developing approaches for evaluating reported methane (CH4) emission is crucial for developing effective mitigation policies, but only one study has characterized CH4 sources in the Athabasca Oil Sands Region (AOSR). We tested the use of 14C and 13C carbon isotope measurements in ambient CH4 from the AOSR to estimate source contributions from key regional CH4 sources: (1) tailings ponds, (2) surface mines and processing facilities, and (3) wetlands. The isotopic signatures of ambient CH4 indicate that the CH4 enrichments measured at the site were mainly influenced by fossil CH4 emissions from surface mining and processing facilities (53 ± 18 %), followed by fossil CH4 emissions from tailings ponds (36 ± 18 %), and to a lesser extent by modern CH4 emissions from wetlands (10 < 1 %). Our results confirm the importance of tailings ponds in regional CH4 emissions and show that this method can successfully separate wetland CH4 emissions. In the future, the isotopic characterization of CH4 sources, and measurements from different seasons and wind directions are needed to provide a better source attribution in the AOSR.

scholarly journals Multiple Lines of Evidence Indicate Limited Natural Recruitment of Golden Perch (Macquaria ambigua) in the Highly Regulated Lachlan River

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1636
Author(s):  
Foyez Shams ◽  
Fiona Dyer ◽  
Ross Thompson ◽  
Richard P. Duncan ◽  
Jason D. Thiem ◽  
...  
Keyword(s):  
Habitat Restoration ◽  
Population Decline ◽  
Environmental Water ◽  
Stock Enhancement ◽  
Freshwater Ecosystems ◽  
Factors Affecting ◽  
Management Actions ◽  
Natural Spawning ◽  
Murray Darling Basin ◽  
Lines Of Evidence

Freshwater ecosystems and their associated biota have been negatively impacted by the human development of water resources. Fundamental to restoration activities for target species is an understanding of the factors affecting population decline or recovery. Within Australia’s Murray–Darling Basin, recovery efforts to address the population decline of native freshwater fish include stock enhancement, habitat restoration, and the delivery of environmental water. Essential to guiding future management actions is information to assess the efficacy of these efforts. We undertook a study to investigate whether natural spawning and recruitment, stock enhancement, or a combination of the two is contributing to sustaining populations of golden perch (Macquaria ambigua) in the highly regulated Lachlan River, Australia. Otolith microchemistry and genetic analyses were used as complementary tools to determine the source (hatchery origin or wild-spawned) of existing populations in the catchment. We identified that natural spawning and recruitment was contributing to riverine populations in some years but that populations were heavily reliant on stocking. It was not possible to distinguish hatchery and wild-born fish using genetic tools, highlighting the value of using multiple lines of evidence to establish causal mechanisms contributing to population recovery.

scholarly journals Inverse modelling of national and European CH<sub>4</sub> emissions using the atmospheric zoom model TM5

2005 ◽  
Vol 5 (9) ◽  
pp. 2431-2460 ◽  
Author(s):  
P. Bergamaschi ◽  
M. Krol ◽  
F. Dentener ◽  
A. Vermeulen ◽  
F. Meinhardt ◽  
...  
Keyword(s):  
A Priori ◽  
A Priori Estimate ◽  
European Countries ◽  
Synoptic Scale ◽  
Source Attribution ◽  
Top Down ◽  
Ch4 Emissions ◽  
Model Driven ◽  
Good Agreement ◽  
The Eu

Abstract. A synthesis inversion based on the atmospheric zoom model TM5 is used to derive top-down estimates of CH4 emissions from individual European countries for the year 2001. We employ a model zoom over Europe with 1° × 1° resolution that is two-way nested into the global model domain (with resolution of 6° × 4°. This approach ensures consistent boundary conditions for the zoom domain and thus European top-down estimates consistent with global CH4 observations. The TM5 model, driven by ECMWF analyses, simulates synoptic scale events at most European and global sites fairly well, and the use of high-frequency observations allows exploiting the information content of individual synoptic events. A detailed source attribution is presented for a comprehensive set of 56 monitoring sites, assigning the atmospheric signal to the emissions of individual European countries and larger global regions. The available observational data put significant constraints on emissions from different regions. Within Europe, in particular several Western European countries are well constrained. The inversion results suggest up to 50-90% higher anthropogenic CH4 emissions in 2001 for Germany, France and UK compared to reported UNFCCC values (EEA, 2003). A recent revision of the German inventory, however, resulted in an increase of reported CH4 emissions by 68.5% (EEA, 2004), being now in very good agreement with our top-down estimate. The top-down estimate for Finland is distinctly smaller than the a priori estimate, suggesting much smaller CH4 emissions from Finnish wetlands than derived from the bottom-up inventory. The EU-15 totals are relatively close to UNFCCC values (within 4-30%) and appear very robust for different inversion scenarios.

scholarly journals What do Environmental Flows Mean for Long-term Freshwater Ecosystems’ Protection? Assessment of the Mexican Water Reserves for the Environment Program

2021 ◽  
Vol 13 (3) ◽  
pp. 1240
Author(s):  
Sergio A. Salinas-Rodríguez ◽  
Everardo Barba-Macías ◽  
Dulce Infante Mata ◽  
Mariana Zareth Nava-López ◽  
Iris Neri-Flores ◽  
...  
Keyword(s):  
Water Use ◽  
Water Policy ◽  
Environmental Flows ◽  
Environmental Water ◽  
River Basins ◽  
Annual Runoff ◽  
Freshwater Ecosystems ◽  
Environmental Objectives ◽  
Ecological Protection ◽  
Mexican Government

Almost a decade ago, the Mexican government targeted to establish environmental water reserves (EWR)—a volume of water allocated for ecological protection based on the Environmental Flow Mexican Norm (eflows, NMX-AA-159-SCFI-2012, ratified in 2017)—in strategic low-pressured for water use and high conservation importance river basins throughout the country. To date, 12 EWRs have been declared for up to 50 years, which encompass 295 river basins and ~55% of the national mean annual runoff (MAR). In this article, we conducted a quality evaluation of the EWRs established. First, the EWR level was analyzed against the MAR and according to wider hydrological conditions. The EWR fulfillment was evaluated by comparing the volumes enacted against the theoretical (Norm implementation). Our findings revealed that independently of individual and regional water use and conservation merits context, ~75% of the EWRs met theoretical volumes at least at an acceptable level, of which medians ranged from 24% to 73% MAR (natural parametrization and A–D environmental objectives). These outcomes prove the usefulness and consistency of the Mexican strategic hierarchical approach for eflow assessments. We aim for them to be considered as the baseline for future on-site eflow implementation and environmental water policy assessments, to show the nationwide potential benefits for protecting free-flowing rivers and to encourage a regional escalation of the strategy.

scholarly journals Shifting Goalposts: Setting Restoration Targets for Waterbirds in the Murray-Darling Basin Under Climate Change

2021 ◽  
Vol 9 ◽  
Author(s):  
Gilad Bino ◽  
Kate Brandis ◽  
Richard T. Kingsford ◽  
John Porter
Keyword(s):  
Climate Change ◽  
Environmental Sustainability ◽  
Life Histories ◽  
River System ◽  
Biodiversity Loss ◽  
Environmental Water ◽  
Freshwater Ecosystems ◽  
Future Climate Change ◽  
Restoration Targets ◽  
Murray Darling Basin

The Murray-Darling Basin (the Basin) is the largest river system in Australia, supplying about 40% of the country’s irrigated agricultural output. Associated water resource development has come with a heavy price for the Basin’s freshwater ecosystems degrading them over decades. Australian governments are attempting to achieve environmental sustainability by returning water to the environment through buy-back of irrigation licences and improved water efficiencies. To determine effectiveness, basin-wide management objectives were established for key indicators, including waterbird populations and life histories which can effectively indicate ecosystem function and condition, driven by flow and flooding regimes. Ongoing monitoring of waterbird numbers indicates continued declines. We evaluated the feasibility of meeting established waterbird objectives under existing and predicted climates. We modelled long-term waterbird numbers using one of the world’s largest ongoing waterbird surveys (1983–2020), covering about 13.5% of the area of the entire Basin. Our findings suggest that under near future climate change projections, waterbird numbers will likely continue to decline, and remain below restoration targets set for the Basin. We discuss the current policy settings for using environmental water to support waterbird populations, recommending adjustments to restore the Basin’s waterbird populations and their wetlands in order to meet Australia’s conservation targets in relation to the ongoing global crisis of biodiversity loss.

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