Geochemistry of Mercury in Two Hydroelectric Reservoirs in Quebec, Canada

1993 ◽  
Vol 50 (2) ◽  
pp. 269-281 ◽  
Author(s):  
Patrick Louchouarn ◽  
Marc Lucotte ◽  
Alfonso Mucci ◽  
Pierre Pichet
Keyword(s):  
Close Association ◽  
Organic Matter Content ◽  
Matter Content ◽  
Depth Interval ◽  
Flooded Soils ◽  
Hydroelectric Reservoirs ◽  
Erosion Processes ◽  
Natural Lakes ◽  
Mechanical Erosion ◽  
Atmospheric Inputs

Carbon, nitrogen, phosphorus, and iron oxyhydroxide profiles were used to explain the retention of Hg in sediments of natural lakes and flooded soils in Quebec. In lake sediments, Hg levels increased from background concentrations of approximately 100 ng/g beneath the 10- to 16-cm depth interval to 150–490 ng/g near the surface. This increase was attributed to atmospheric inputs to the environment. In forest soils, the close association of Hg with the surficial organic horizon appears to be a potential source of contamination for the aquatic system through the transport of particulate matter by surface runoff. High organic matter content observed in the flooded soil of LG-2 Reservoir suggests that postsedimentation biodegradation is a slow process. In contrast, at Cabonga Reservoir, an 80% reduction in C, N, and Hg concentrations was observed between the flooded and the adjacent forest soil. Mechanical erosion processes (marling, waves, ice) rather than biodegradation seem responsible for the observed loss in C, N, and Hg. We propose that suspension of the humic horizon from flooded soils could constitute a significant source of Hg contamination to the overlying waters and biota until the exposed littoral zone stabilizes.

Contribution of suspended particulate matter and zooplankton to MeHg contamination of the food chain in midnorthern Quebec (Canada) reservoirs

1997 ◽  
Vol 54 (4) ◽  
pp. 821-831 ◽  
Author(s):  
Y Plourde ◽  
M Lucotte ◽  
P Pichet
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Continuous Flow ◽  
Methyl Mercury ◽  
Organic Matter Content ◽  
Matter Content ◽  
Flooded Soils ◽  
Natural Lakes ◽  
Suspended Particulate ◽  
Organic Particles

Suspended particulate matter (SPM) retained by continuous-flow centrifugation, suspended matter of 20-150 mu m diameter, and zooplankton exceeding 150 mu m were sampled in the LG-2 and LA-1 reservoirs and in four natural lakes in northern Quebec during June, August, and September 1992 and 1993. Inorganic Hg concentrations in the three compartments did not differ significantly between the reservoirs and natural lakes, but methyl mercury (MeHg) concentrations in SPM (mean of 0.05 ppm) and zooplankton (up to 0.84 ppm) from LG-2 were 7 and 5 times higher, respectively, than in the natural lakes. The MeHg bioamplification factors between SPM and zooplankton ranged from 4 to 9 in the reservoirs and natural lakes. MeHg concentrations in SPM reached a maximum during August and were positively correlated with organic matter content. High MeHg concentrations were observed in the SPM and zooplankton sampled in August in a small impoundment separated from LA-1 by the LA-40 dike, which had been flooded for about 1 year. These data suggest that methylation and transfer of MeHg from flooded soils to SPM and zooplankton are rapidly accomplished. The process involves the bioaccumulation of MeHg by phytoplankton and (or) the ingestion of suspended soil-derived organic particles by zooplankton.

scholarly journals Physico-chemical characteristics of the seasonally flooded soils of Bangladesh and their management implications

1970 ◽  
Vol 20 (2) ◽  
pp. 173-182
Author(s):  
KF Akhter ◽  
ZH Khan ◽  
MS Hussain ◽  
AR Mazumder
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Chemical Properties ◽  
Exchange Capacity ◽  
Matter Content ◽  
Flooded Soils ◽  
Management Implications ◽  
Available N ◽  
Physico Chemical ◽  
Seasonally Flooded

The seasonally flooded soils of Bangladesh are unique in respect of several specific characteristics and contribute toward producing bulk of its staple food - mainly rice. Having fine texture these soils are similar to the “paddy soils” of Southeast Asian floodplains and have high production potential under proper management. Six representative soil series, viz. Arial, Debidwar, Naraibag, Jalkundi, Siddirganj and Tippera from the central region of Bangladesh have been studied to evaluate some of their intrinsic physico-chemical properties and their sustainable management requirements. These soils are slightly acidic to neutral and are negatively charged with ΔpH values ranging between –0.2 and –1.2. The organic matter content in the surface soil is relatively low that decreases steadily with depth. The cation exchange capacity (CEC) of the soils varies on the basis of their clay and organic matter contents while base saturation per cent (BSP) is high. The contents of available N, P, K and S and DTPA-extractable Fe, Mn, Cu and Zn in soils are moderate and are commensurate with the contents of colloidal fractions. These soils receive several mineral nutrients annually with the sediments deposited during the monsoon floods. The characteristics like organic matter content, particle size distribution, CEC, pH and BSP that have important management implications have been discussed. Key words: Seasonally flooded soils; Physical and chemical attributes; Management implications DOI: http://dx.doi.org/10.3329/dujbs.v20i2.8978 DUJBS 2011; 20(2): 173-182

scholarly journals Initial limnological observations at five small lakes in southern Pacific Costa Rica

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Sally P. Horn ◽  
Erik N. Johanson ◽  
Kurt A. Haberyan ◽  
Mathew S. Boehm ◽  
Jessie L. Johanson ◽  
...  
Keyword(s):  
Costa Rica ◽  
Environmental History ◽  
Global Climate ◽  
Sediment Cores ◽  
Organic Matter Content ◽  
Plant Macrofossils ◽  
Matter Content ◽  
Radiocarbon Dates ◽  
Natural Lakes ◽  
Lake Formation

Costa Rica has hundreds of lakes, many of which have never been described or sampled by limnologists. Here we summarize initial observations of five small (0.2–1.7ha) lakes located at low elevation (365–490m) in the cantón of Buenos Aries. We collected basic limnological data and samples during visits in 2013 and 2014, and compiled environmental and archaeological data for their surroundings as a contribution to the documentation of lake diversity in Costa Rica, and to support parallel investigations of indicators of environmental history preserved in the sediments of the lakes. Lagunas Carse, Los Mangos, Danta, and Ojo de Agua all appear to owe their origin to landslide events, while Laguna Junquillo is an artificial impoundment. Radiocarbon dates on plant macrofossils near the bases of sediment cores from three of the natural lakes provide minimum ages for lake formation; results indicate that Laguna Los Mangos formed over 4 100 years ago, while Laguna Danta formed prior to 1 320 CE and Laguna Carse formed ca. 1 550 CE, near the time of the Spanish Conquest. More than two dozen archaeological sites are located within 1–3Km of the natural lakes, documenting pre-Columbian human occupation and likely use of lake resources. Lake water temperatures and water chemistry were in keeping with observations at lakes throughout Costa Rica. All five lakes are probably polymictic lakes that turn over frequently; none evinced stratification. The surface lake sediments showed similar organic matter content (22,1–28,8%), with values falling near the middle of the range of lakes previously sampled in Costa Rica. Phytoplankton samples included taxa previously reported from small lowland lakes, but differed between lakes and included dominant taxa that were subdominant or uncommon at other lakes surveyed. Our investigation adds to knowledge of lake characteristics and diversity in Costa Rica, and provides benchmarks for assessing future changes in these lakes and their watersheds resulting from human activity, natural disturbances, and regional and global climate change.

scholarly journals Organic-Matter Activity of Some Typical Soils of Puerto Rico

1969 ◽  
Vol 39 (2) ◽  
pp. 65-76
Author(s):  
Fernando Abruña-Rodríguez ◽  
José Vicente-Chandler
Keyword(s):  
Organic Matter ◽  
Puerto Rico ◽  
Soil Organic Matter ◽  
Close Association ◽  
C:N Ratio ◽  
Organic Matter Content ◽  
Exchange Capacity ◽  
Matter Content ◽  
Soil Samples ◽  
Considerable Portion

The exchange capacity of the organic matter in typical soils of Puerto Rico was evaluated from: (1) The variation in the exchange capacity of soil samples following destruction of the organic matter, (2) titration curves of extracted organic matter, (3) and the correlations between exchange capacity and organic-matter content of soil samples. The first method was the most practical and gave fairly accurate results. The second method gave results which were in all cases too high. The third method, though probably the most accurate, is impractical. Results obtained with the first and third methods were similar. The exchange capacity of the organic matter varied rather widely, but was generally between 100 and 150 m.e. per 100 gm. On the average it accounted for about 25 percent of the total exchange capacity of the soils studied. The organic matter removed by flotation had the highest exchange capacity and the more readily oxidizable portions generally appeared to be the most active. This suggests the importance of conserving the more readily lost portions of the soil organic matter. A considerable portion of the soil organic matter was extremely resistant to oxidation, had a narrow C:N ratio, and apparently little exchange capacity. This suggests a close association between the organic matter and the inorganic soil colloids. The marked resistance to oxidation of a considerable portion of the organic matter may partly explain the high contents found even in continuously cultivated soils in Puerto Rico.

scholarly journals Assessment of crusting effects on interrill erosion by laser scanning

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8487
Author(s):  
Yaxian Hu ◽  
Wolfgang Fister ◽  
Yao He ◽  
Nikolaus J. Kuhn
Keyword(s):  
Laser Scanning ◽  
Laser Scanner ◽  
Organic Matter Content ◽  
Aggregate Stability ◽  
Soil Surface ◽  
Matter Content ◽  
Crust Formation ◽  
Essential Information ◽  
Erosion Processes ◽  
Interrill Erosion

Background Crust formation affects soil erosion by raindrop impacted flow through changing particle size and cohesion between particles on the soil surface, as well as surface microtopography. Therefore, changes in soil microtopography can, in theory, be employed as a proxy to reflect the complex and dynamic interactions between crust formation and erosion caused by raindrop-impacted flow. However, it is unclear whether minor variations of soil microtopography can actually be detected with tools mapping the crust surface, often leaving the interpretation of interrill runoff and erosion dynamics qualitative or even speculative. Methods In this study, we used a laser scanner to measure the changes of the microtopography of two soils placed under simulated rainfall in experimental flumes and crusting at different rates. The two soils were of the same texture, but under different land management, and thus organic matter content and aggregate stability. To limit the amount of scanning and data analysis in this exploratory study, two transects and four subplots on each experimental flume were scanned with a laser in one-millimeter interval before and after rainfall simulations. Results While both soils experienced a flattening, they displayed different temporal patterns of crust development and associated erosional responses. The laser scanning data also allowed to distinguish the different rates of developments of surface features for replicates with extreme erosional responses. The use of the laser data improved the understanding of crusting effects on soil erosional responses, illustrating that even limited laser scanning provides essential information for quantitatively exploring interrill erosion processes.

scholarly journals Some features of the influence of Robinia pseudoacacia L. on soils in arid conditions

2018 ◽  
Vol 29 (1) ◽  
pp. 47-51 ◽  
Author(s):  
V. A. Gorban ◽  
A. O. Huslystyi
Keyword(s):  
Black Locust ◽  
Robinia Pseudoacacia ◽  
Organic Matter Content ◽  
Forest Litter ◽  
Matter Content ◽  
Organic Carbon Content ◽  
Erosion Processes ◽  
Arid Conditions ◽  
Deep Layers ◽  
Robinia Pseudoacacia L

Some features of the influence of Robinia pseudoacacia L. (black locust) on soils in arid conditions The modern scientific sources concerning the peculiarities of the influence of Robinia pseudoacacia L. on soils under arid conditions have been analyzed. As a result of the performed analysis, it turned out that the largest number of scientific sources is devoted to the highlighting of the specifics of the influence of plantings on the content of organic substances, nitrogen, phosphorus, potassium, soil moisture, as well as erosion processes and the process of recultivation of disturbed lands. The main influence of Robinia pseudoacacia L. on the organic matter content is manifested in increasing the soil organic carbon content in the upper layers of soils, as well as in its increase in soil content, preferably up to a depth of 50 cm, compared with some other trees and herbaceous plants. Nitrogen is the main biophilic chemical element that is actively accumulated by black locust plantings. At the same time, the positive effect of Robinia pseudoacacia L. on the accumulation of phosphorus and potassium in soils was found, which positively affects the increase of soil fertility under plantings. An analysis of literary sources has revealed that there are results of researches that confirm the use of black locust from moisture from both surface and deep layers of soils. Plantings of Robinia pseudoacacia L. are actively used in arid conditions to overcome the manifestations of erosion processes. In this case, an additional mechanism of anti-erosion stability of the plantation, some authors consider the formation of forest litter in black locust forest stands. Robinia pseudoacacia L. due to its adaptations is successfully used in the recultivation of disturbed lands, actively improving their properties and increasing their fertility. It should be noted, however, that most European countries regard Robinia pseudoacacia L. as an invasive species whose invasion negatively affects indigenous plant communities. At the same time, the countries, a significant part of which falls on arid lands, actively use black locust for afforestation and improvement of the state of their soils.

scholarly journals Optimization of Agriculture Land Use Development Basing on Natural-resource Potential (On the Example of the Stavropol Territory)

2019 ◽  
Author(s):  
E V Pismennaya ◽  
V A Stukalo ◽  
I A Volters ◽  
M Yu Azarova ◽  
V M Perederieva ◽  
...  
Keyword(s):  
Organic Matter ◽  
Crop Production ◽  
Organic Matter Content ◽  
Matter Content ◽  
Current Status ◽  
Agricultural Enterprises ◽  
Erosion Processes ◽  
Lower Fertility ◽  
Land Use Development ◽  
Leguminous Crops

Natural resources potential of the territory and natural-historical mechanism of its development are pacing factors in agriculture differentiation and AIC-development. Key branches in the Stavropol Territory are crop production, sheep breeding and meat and milk cattle breeding. To meet the market demands “equating” differentiation of agricultural enterprises is implemented. Thus, in Stavropol Territory crop lands have been increased for crops required in the market that disbalanced the crop rotation, disturbed agro technologies and resulted in reduction in yields and grain quality. In the Territory 70 % of tillage is in risky agriculture. About 65 % of crop production (wheat, barley and others) are in draughty areas where out of 141 years (1861–2002) 41 % draughty, which determine high natural-climatic dependence of grain economy [1]. Annual and areal variability of grain production is also determined by topsoil heterogeneity and variety of relief. At present production of the basic market crop – winter wheat, which takes 75 % of acreage for cereals and leguminous crops, the productivity of the cultivated crop is 22.4–39.5 centner/hectare. It results in top soil changes such as compaction, fertilizer impoverishment and organic matter content (organic matter deficit is 400–700 kg/ha). Intensification of agrarian production results in quicker erosion processes, soil properties decline and lower fertility. The total area of eroded lands in the Territory is 1792000 ha [2]. That is why it is important to develop a new model of the economic use of Stavropol Territory. The main methods of study are analysis of the current status and organization of the agricultural zones of the Territory. The data were preceded with the software Statistica.

Accumulation of total mercury and methyl mercury in insect larvae of hydroelectric reservoirs

1997 ◽  
Vol 54 (4) ◽  
pp. 832-841 ◽  
Author(s):  
A Tremblay ◽  
M Lucotte
Keyword(s):  
Methyl Mercury ◽  
Total Mercury ◽  
Dry Weight ◽  
Insect Larvae ◽  
Flooded Soils ◽  
Hydroelectric Reservoirs ◽  
Natural Lakes ◽  
Suspended Particulate ◽  
Total Variability ◽  
Total Hg

Mean total mercury (Hg) and methyl mercury (MeHg) concentrations in insect larvae from hydrolelectric reservoirs were 3-5 times (up to 10 times) higher than in their counterparts from natural lakes. Taxonomic differences, which may be related to feeding behavior, and substrate type (lake sediment or flooded soils) together explained a large part of the total variability of total Hg (r2 = 0.64) and MeHg (r2 = 0.79) concentrations in insects. MeHg concentrations in flooded soils increased from 0.3-2 ng Hg cdot g dry weight-1 after 1-2 years of flooding to 15-2 ng Hg cdot g dry weight-1 after 16 years of impoundment. Total Hg and MeHg concentrations in insect larvae followed a similar pattern, but only weak correlations of both total Hg and MeHg concentrations were found between flooded soils and insect larvae, suggesting that factors other than MeHg content of flooded soils also affect the accumulation of these compounds in insects. Our results indicate that suspended particulate matter eroded from flooded soils by wave and ice action and bacterial activity enhanced by the release of labile carbon and nutrients from the flooded soils may indirectly transfer MeHg from flooded soils to insect larvae.

HEAVY METAL SPECIATION IN BOTTOM SEDIMENTS OF THE VYSHNEVOLOTSKY RESERVOIR

2018 ◽  
pp. 46-54
Author(s):  
O. A. Lipatnikova
Keyword(s):  
Heavy Metal ◽  
Organic Matter ◽  
Bottom Sediments ◽  
Metal Speciation ◽  
Organic Matter Content ◽  
Water Reservoir ◽  
Matter Content ◽  
Heavy Metal Speciation ◽  
Mobile Forms ◽  
Manganese Hydroxides

The study of heavy metal speciation in bottom sediments of the Vyshnevolotsky water reservoir is presented in this paper. Sequential selective procedure was used to determine the heavy metal speciation in bottom sediments and thermodynamic calculation — to determine ones in interstitial water. It has been shown that Mn are mainly presented in exchangeable and carbonate forms; for Fe, Zn, Pb и Co the forms are related to iron and manganese hydroxides is played an important role; and Cu and Ni are mainly associated with organic matter. In interstitial waters the main forms of heavy metal speciation are free ions for Zn, Ni, Co and Cd, carbonate complexes for Pb, fulvate complexes for Cu. Effects of particle size and organic matter content in sediments on distribution of mobile and potentially mobile forms of toxic elements have been revealed.

Changes in organic matter content of soil as a result of long-term fertilization

2005 ◽  
Vol 33 (1) ◽  
pp. 53-55
Author(s):  
Katalin Berecz ◽  
Katalin Debreczeni
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Matter Content
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