scholarly journals Synthesis of limnological data from lakes and ponds across Arctic and Boreal Canada

2018 ◽  
Vol 4 (2) ◽  
pp. 167-185
Author(s):  
Stefana Aurora Dranga ◽  
Simon Hayles ◽  
Konrad Gajewski
Keyword(s):  
Water Chemistry ◽  
Dissolved Inorganic Carbon ◽  
Specific Conductivity ◽  
Large Variability ◽  
Continental Scale ◽  
Rock Types ◽  
Forested Landscapes ◽  
Significant Patterns ◽  
Shallow Lakes And Ponds ◽  
Vegetation And Climate

A compilation of published and new limnological data from 1489 shallow lakes and ponds in northern Canada, sampled between 1979 and 2009, revealed significant patterns that correlated with landscape features and climate. Lakes and ponds underlain by Archean or Proterozoic bedrock had lower specific conductivity and pH. Vegetation cover had a lesser influence on these parameters. Forested landscapes tended to have higher phosphorus and nitrogen, as did younger rock types. Dissolved organic carbon was higher, but dissolved inorganic carbon was lower in forested regions. Phytoplankton biomass of the surface waters, as estimated by chlorophyll a concentrations, was positively correlated with July air temperature and nutrients, and was higher in forested relative to polar desert regions. There were no significant differences in the measured limnological variables between shallow (<2 m depth) and deep lakes (>2 m); however, all water chemistry parameters were negatively correlated with depth. Despite large variability within and among regions, spatial trends in water chemistry were associated with geology, vegetation, and climate at a continental scale.

scholarly journals Continental-scale variation in otolith geochemistry of juvenile American shad (Alosa sapidissima)

2008 ◽  
Vol 65 (12) ◽  
pp. 2623-2635 ◽  
Author(s):  
Benjamin D. Walther ◽  
Simon R. Thorrold
Keyword(s):  
Water Chemistry ◽  
Classification Accuracy ◽  
High Spatial Resolution ◽  
American Shad ◽  
Native Range ◽  
Large Spatial Scale ◽  
Alosa Sapidissima ◽  
Continental Scale ◽  
Average Classification Accuracy ◽  
Annual Cohort

We assembled a comprehensive atlas of geochemical signatures in juvenile American shad ( Alosa sapidissima ) to discriminate natal river origins on a large spatial scale and at a high spatial resolution. Otoliths and (or) water samples were collected from 20 major spawning rivers from Florida to Quebec and were analyzed for elemental (Mg:Ca, Mn:Ca, Sr:Ca, and Ba:Ca) and isotope (87Sr:86Sr and δ18O) ratios. We examined correlations between water chemistry and otolith composition for five rivers where both were sampled. While Sr:Ca, Ba:Ca, 87Sr:86Sr, and δ18O values in otoliths reflected those ratios in ambient waters, Mg:Ca and Mn:Ca ratios in otoliths varied independently of water chemistry. Geochemical signatures were highly distinct among rivers, with an average classification accuracy of 93% using only those variables where otolith values were accurately predicted from water chemistry data. The study represents the largest assembled database of otolith signatures from the entire native range of a species, encompassing approximately 2700 km of coastline and 19 degrees of latitude and including all major extant spawning populations. This database will allow reliable estimates of natal origins of migrating ocean-phase American shad from the 2004 annual cohort in the future.

scholarly journals Evaluation of Northern Hemisphere snow water equivalent in CMIP6 models with satellite-based SnowCCI data during 1982–2014

2021 ◽  
Author(s):  
Kerttu Kouki ◽  
Petri Räisänen ◽  
Kari Luojus ◽  
Anna Luomaranta ◽  
Aku Riihelä
Keyword(s):  
Snow Cover ◽  
Northern Hemisphere ◽  
Climate Models ◽  
Snow Water Equivalent ◽  
Global Climate ◽  
Dominant Factor ◽  
Large Variability ◽  
Cold Temperatures ◽  
Continental Scale ◽  
Snow Water

Abstract. Seasonal snow cover of the Northern Hemisphere (NH) is a major factor in the global climate system, which makes snow cover an important variable in climate models. Monitoring snow water equivalent (SWE) at continental scale is only possible from satellites, yet substantial uncertainties have been reported in NH SWE estimates. A recent bias-correction method significantly reduces the uncertainty of NH SWE estimation, which enables a more reliable analysis of the climate models' ability to describe the snow cover. We have intercompared the CMIP6 (Coupled Model Intercomparison Project Phase 6) and satellite-based NH SWE estimates north of 40° N for the period 1982–2014, and analyzed with a regression approach whether temperature (T) and precipitation (P) could explain the differences in SWE. We analyzed separately SWE in winter and SWE change rate in spring. The SnowCCI SWE data are based on satellite passive microwave radiometer data and in situ data. The analysis shows that CMIP6 models tend to overestimate SWE, however, large variability exists between models. In winter, P is the dominant factor causing SWE discrepancies especially in the northern and coastal regions. This is in line with the expectation that even too cold temperatures cannot cause too high SWE without precipitation. T contributes to SWE biases mainly in regions, where T is close to 0 °C in winter. In spring, the importance of T in explaining the snowmelt rate discrepancies increases. This is to be expected, because the increase in T is the main factor that causes snow to melt as spring progresses. Furthermore, it is obvious from the results that biases in T or P can not explain all model biases either in SWE in winter or in the snowmelt rate in spring. Other factors, such as deficiencies in model parameterizations and possibly biases in the observational datasets, also contribute to SWE discrepancies. In particular, linear regression suggests that when the biases in T and P are eliminated, the models generally overestimate the snowmelt rate in spring.

Dissipation of Permethrin in Limnocorrals

1985 ◽  
Vol 42 (1) ◽  
pp. 70-76 ◽  
Author(s):  
K. R. Solomon ◽  
J. Y. Yoo ◽  
D. Lean ◽  
N. K. Kaushik ◽  
K. E. Day ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Water Chemistry ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Secchi Disk ◽  
Secchi Disk Depth ◽  
Southern Ontario ◽  
First Order ◽  
First Order Kinetics ◽  
Rate Of Dissipation

Permethrin (3-phenoxybenzyl(1RS)-cis,trans-3-(2,2-dimethy[-3-dichlorovinyl)-2,2-dimethylcyciopropanecarboxylate) applied to approximately 100-m3 enclosures (limnocorrals) in a small mesotrophic lake in Southern Ontario (47°51′25″N; 77°25′30″W) at concentrations of 500, 50, 5, and 0.5 μ∙L−1 dissipated from the water rapidly and approximated first-order kinetics in the first 8–12 d. Time taken for 50 and 90% dissipation ranged from 1.65 and 3.65 d, respectively, at 0.5 μ∙L−1 to 3.5 and 6.75 d, respectively, at 50 μ∙L−1. Inter- and intra-seasonal replication of dissipation patterns was good. Rate of dissipation varied slightly with depth, normally being slower at greater depth. Absorption of permethrin to sediments was rapid, penetration shallow, and disappearance slow. Permethrin had no effect on water chemistry but there was an increase in the Secchi disk depth in the treated limnocorrals. Dissolved inorganic carbon decreased in all limnocorrals, including controls after treatment, suggesting precipitation of calcium carbonate which may act as a scavenging agent for permethrin in the water. Limnocorrals are a useful tool for evaluating the behavior of pesticides in the aquatic system.

Multi-isotope (15N, 18O and 13C) indicators of sources and fate of nitrate in the upper stream of Chaobai River, Beijing, China

2014 ◽  
Vol 16 (11) ◽  
pp. 2644-2655 ◽  
Author(s):  
Cai Li ◽  
Yongbin Jiang ◽  
Xinyue Guo ◽  
Yang Cao ◽  
Hongbing Ji
Keyword(s):  
Water Chemistry ◽  
Carbon Isotopes ◽  
North China ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Beijing China

Dual isotopes of nitrate (15N and 18O) and carbon isotopes of dissolved inorganic carbon (13C) together with water chemistry were used to identify the sources and fate of nitrate in the upper stream of Chaobai River, north China.

scholarly journals Mechanism of O and C isotope fractionation in magnesian calcite skeletons of <i>Octocorallia</i> corals and an implication on their calcification response to ocean acidification

2015 ◽  
Vol 12 (1) ◽  
pp. 389-412 ◽  
Author(s):  
T. Yoshimura ◽  
A. Suzuki ◽  
N. Iwasaki
Keyword(s):  
Ocean Acidification ◽  
Isotope Fractionation ◽  
Inorganic Carbon ◽  
Environmental Changes ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Ambient Seawater ◽  
Large Variability ◽  
Coral Skeletons ◽  
Δ18o And Δ13c

Abstract. Coral calcification is strongly dependent on both the pH and the dissolved inorganic carbon (DIC) of the calcifying fluid. Skeletal oxygen and carbon isotope fractionation of high-Mg calcite skeletons of \\textit{Octocorallia} corals directly record the biological manipulation on sources of DIC in response to environmental changes. The coral skeletons were enriched in light isotopes (16O and 12C) relative to the expected values based on habitat environmental parameters and Mg/Ca of the skeletons. The differences between the expected and observed values ranged from −4.66 to −1.53 for δ18O and from −7.34 to −1.75 for δ13C. The large variability cannot be explained by the ambient environment, the contribution of metabolic carbon, or the precipitation rate of the skeleton. Therefore, the most plausible explanation for the observed O and C isotope differences in high-Mg calcite coral skeletons is the existence of two carbon sources, aqueous carbon dioxide in the calcifying fluid and dissolved inorganic carbon in seawater. Positive correlations of B/Ca with δ18O and δ13C suggest that skeletal isotopic compositions are enriched in light isotopes when conditions are less alkaline. Therefore, the relative contribution of isotopically heavy DIC from seawater through the skeleton and pericellular channels decreases under the reduced pH of the extracytoplasmic calcifying fluid. Our data suggest an even stronger biological effect under lower pH. Skeletal δ18O and δ13C values record the response of the sources of DIC in the coral calcifying fluids to ambient seawater pH. These changes give insight into how ocean acidification impacts the physiological mechanisms as well as the pH offset between calcifying fluid and seawater in response to ocean acidification.

scholarly journals Apports En Carbone Et Azote Dans Le Fleuve Niger À Tondibia (Niamey) : Résultats De Deux (2) Ans D’observations

2016 ◽  
Vol 12 (21) ◽  
pp. 167
Author(s):  
Alhou B ◽  
Issiaka Boukari ◽  
Darchambeau F.
Keyword(s):  
Organic Carbon ◽  
Suspended Matter ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
First Year ◽  
Nitrogen And Phosphorus ◽  
Temperature Conductivity ◽  
Continental Scale ◽  
The Mean ◽  
Hydrographic Regions

The Niger River is the third more important river in Africa and drains a surface of about 2,120,000 km². It includes six hydrographic regions representing West African ecosystems. Despite the importance of this river at the regional and continental scale, little information has been collected on its biogeochemical characteristics and particularly on its role in the transportation and the transformation of matter (carbon, nitrogen and phosphorus). This study present the results of two years investigation, April 2011 to March 2013 in the middle Niger, upstream Niamey (Niger) city [2.01° E, 13.57° N], according to a bi-weekly observation frequency. The variables measured are temperature, conductivity, dissolved oxygen, pH, suspended matter, dissolved inorganic carbon (C) and nitrogen (N) and particulars organics C and N as well as isotopic composition of these elements. Daily discharges of the river come from hydrologic station measurement of the Niger authority Basin (NBA) at Niamey city. Hydrologic situation was strongly contrasted between the 2 years of survey. The mean discharge of the first year was only 673 m3 s-1 (one of the weakest discharge recorded on the river Niger at Niamey since 1940), while the mean discharge of the second year was 1,096 m3 s-1. Our results show that suspended matter, particular organic carbon, dissolved organic carbon and dissolved inorganic carbon are transported mainly during the local flood, induced by precipitations in July and August. The second flood (Guinean flood) which occurred, during November to January, is characterized by low temperatures and clean waters.

scholarly journals Evaluating the Arabian Sea as a regional source of atmospheric CO<sub>2</sub>: seasonal variability and drivers

2021 ◽  
Author(s):  
Alain de Verneil ◽  
Zouhair Lachkar ◽  
Shafer Smith ◽  
Marina Lévy
Keyword(s):  
Summer Monsoon ◽  
Arabian Sea ◽  
Dissolved Inorganic Carbon ◽  
Co2 Flux ◽  
Co2 Exchange ◽  
Total Alkalinity ◽  
Global Ocean ◽  
Seasonal Temperature ◽  
Large Variability

Abstract. The Arabian Sea (AS) was confirmed to be a net emitter of CO2 to the atmosphere during the international Joint Global Ocean Flux Study program of the 1990s, but since then little in situ data has been collected, leaving data-based methods to calculate air-sea exchange with fewer data and potentially out-of-date. Additionally, coarse-resolution models underestimate CO2 flux compared to other approaches. To address these shortcomings, we employ a high-resolution (1/24°) regional model to quantify the seasonal cycle of air-sea CO2 exchange in the AS by focusing on two main contributing factors, pCO2 and winds. We compare the model to available in situ pCO2 data and find that uncertainties in dissolved inorganic carbon (DIC) and total alkalinity (TA) lead to the greatest discrepancies. Nevertheless, the model is more successful than neural network approaches in replicating the large variability in summertime pCO2 because it captures the AS's intense monsoon dynamics. In the seasonal pCO2 cycle, temperature plays the major role in determining surface pCO2, except where DIC delivery is important in summer upwelling areas. Since seasonal temperature forcing is relatively uniform, pCO2 differences between the AS's sub-regions are mostly caused by geographic DIC gradients. We find that primary productivity during both summer and winter monsoon blooms, but also generally, is insufficient to off-set the physical delivery of DIC to the surface, resulting in limited biological control of CO2 release. The most intense air-sea CO2 exchange occurs during the summer monsoon where outgassing rates reach ~6 molCm−2 yr−1 in the upwelling regions of Oman and Somalia, but the entire AS contributes CO2 to the atmosphere. Despite a regional spring maximum of pCO2 driven by surface heating, CO2 exchange rates peak in summer due to winds, which account for ~90 % of the summer CO2 flux variability versus 6 % for pCO2 in a Reynolds decomposition. In comparison with other estimates, we find that the AS emits ~160 TgCyr−1, slightly higher than previously reported. Altogether, there is 2x variability in annual flux magnitude across methodologies considered. Future attempts to reduce the variability in estimates will likely require more in situ carbon data. Since summer monsoon winds are critical in determining flux both directly and indirectly through temperature, DIC, TA, mixing, and primary production effects on pCO2, studies looking to predict CO2 emissions in the AS with ongoing climate change will need to correctly resolve their timing, strength, and upwelling dynamics.

Tree death as a crucial geomorphic agent in temperate forests: effects of weak and severe disturbances from local to continental scale

2020 ◽  
Author(s):  
Pavel Šamonil ◽  
Pavel Daněk ◽  
James A. Lutz ◽  
Jakub Jaroš ◽  
Anna Rousová ◽  
...  
Keyword(s):  
Terrestrial Ecosystem ◽  
Terrestrial Ecosystems ◽  
Ecosystem Dynamics ◽  
Retention Capacity ◽  
Tree Species Composition ◽  
Continental Scale ◽  
Standing Trees ◽  
Forested Landscapes ◽  
Tree Uprooting ◽  
Hillslope Processes

&lt;p&gt;Hillslope processes in terrestrial ecosystems are significantly modified by changes in climate and land use. At the same time they strongly influence ecosystem retention capacity, pedocomplexity and biodiversity. This undoubtedly makes hillslope processes one of the crucial components of terrestrial ecosystem dynamics. In this study we focus on the long overlooked biogeomorphological impact of tree death in forested landscapes. Tree uprooting caused by strong storms affects soil and regolith formation and movement quite differently from the decomposition of intact root systems of standing trees that died due to e.g. fire or bark beetle infestation. We quantify the biogeomorphic processes associated with tree death in various terrestrial forest ecosystems and specifically assess (i) the significance of these processes in hillslope dynamics (e.g. slope denudation) of forested landscapes and (ii) the extent to which infrequent severe disturbances can shape these dynamics.&lt;/p&gt;&lt;p&gt;We used data from repeated tree censuses carried out in ten permanent forest plots (13&amp;#8211;74 ha in area) located in Central Europe and North America, differing in a range of characteristics such as tree species composition, climate and disturbance regime. In total, life history of more than 134,000 trees was recorded over periods of up to 47 years, during which about one third of these trees died. Using this information together with empirical models and allometric equations we were able to quantify the average areas and volumes of soil annually affected by dying trees. These quantities differed markedly between sites with different disturbance regimes. Tree uprooting-related volumes accounted annually for 0.01&amp;#8211;13.5 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; reaching maximum values on sites with occurrence of infrequent strong windstorms (Zofin and Boubin primeval forests, Czech Republic). Volumes related to trees that died standing ranged anually between 0.17 and 20.7 m&lt;sup&gt;3&lt;/sup&gt;ha&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; and were highest in the presence of stand-replacing fires (Yosemite National Park, U.S.). Comparison of these quantities with long-term erosion rates derived using cosmogenic nuclides (&lt;sup&gt;10&lt;/sup&gt;Be) suggests that on certain sites, over the last few millennia, tree uprooting can be the main driver of soil erosion.&lt;/p&gt;

Vegetation patterns in the North Black River peatland, northern Minnesota

1983 ◽  
Vol 61 (8) ◽  
pp. 2085-2104 ◽  
Author(s):  
Paul H. Glaser
Keyword(s):  
Water Chemistry ◽  
Landsat Imagery ◽  
Specific Conductivity ◽  
Aerial Photographs ◽  
Raised Bogs ◽  
The North ◽  
Poor Fen ◽  
Wide Range ◽  
Vegetation Water ◽  
Ph Range

Raised bogs and water tracks in the 193-km2 North Black River peatland in northern Minnesota were examined in relation to the vegetation, water chemistry, and surficial water movements as inferred from infrared aerial photographs, LANDSAT imagery, and orthophoto topographic maps. Two noda of bog vegetation were distinguished by the Braun–Blanquet system; both bog noda are associated with relatively dilute, acidic waters (pH range 3.9–4.1; Ca2+ concentration range 0.6–1.6 mg L−1; specific conductivity, Kcorr range 1.3–83 μS cm−1). Rich-fen vegetation in contrast is more variable within this peatland and generally occurs in water tracks with a correspondingly wide range of pH (range 5.0–6.2), Ca2+ concentration (range 3.6–30.4 mg L−1), and Kcorr (range 31 to 182 μS cm−1). Poor-fen vegetation was most distinguishable by the transitional nature of its vegetation and water chemistry with at least a few minerotrophic indicator species present in all cases and intermediate ranges in pH (3.7–5.2), Ca2+ concentration (0.6–5.5 mg L−1), and Kcorr (16–72 μS cm−1). Bog and fen patterns in this peatland are consistently related to topographic features along the upland crest of each peatland watershed, indicating that topography controls the path of minerotrophic runoff draining onto the peatland, and thus creating zones with either enriched minerotrophic flow (in which water tracks develop) or stagnation zones (where bogs develop) on the peatland downslope.

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