Deciphering the impact of land-uses on terrestrial organic matter and mercury inputs to large boreal lakes of central Québec using lignin biomarkers

2014 ◽  
Vol 41 ◽  
pp. 34-48 ◽  
Author(s):  
Matthieu Moingt ◽  
Marc Lucotte ◽  
Serge Paquet ◽  
Bassam Ghaleb
Keyword(s):  
Organic Matter ◽  
Boreal Lakes ◽  
Land Uses ◽  
Terrestrial Organic Matter ◽  
Lignin Biomarkers ◽  
The Impact

Ocean carbon cycle during the last deglaciation in the Max Planck Institute Earth System Model

2020 ◽  
Author(s):  
Bo Liu ◽  
Katharina Six ◽  
Tatiana Ilyina
Keyword(s):  
Organic Matter ◽  
Marine Sediment ◽  
Water Discharge ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Dust Deposition ◽  
Max Planck ◽  
Terrestrial Organic Matter ◽  
The Impact

<p>The deglacial atmospheric CO2 increase has been attributed to a combination of mechanisms, many of which relate to the ocean outgassing triggered by changing marine physical and biogeochemical states. To quantify the impact of proposed processes and feedback on the deglacial CO2 rise, previous modelling studies mostly conducted time-slice sensitivity experiments. Here, we present results from a transient deglaciation simulation (24 kB.P. - 1850) using the comprehensive Max Planck Institute Earth System Model (MPI-ESM). We force the model with the deglacial atmospheric greenhouse gases (CO2, CH4, N2O) concentrations, obital parameters, ice sheet reconstruction and transient dust deposition. The ocean biogeochemical component of MPI-ESM is using the same automatical adjustment of bathymetry and land-sea mask in response to deglacial continental runoff and melt water discharge. In and around the areas of changing land-sea mask, we redistribute the marine biogeochemical tracers in accord with the simulated salinity. Terrestrial organic matter is transferred from flooded land areas to the ocean, which guarantees mass conservation with respect to carbon. We also include 13C tracers in the ocean biogeochemical component to evaluate the simulated ocean state against proxy data. The initial marine nutrients and carbon inventories are set the same as those in the present-day ocean. <br>During the first 3 kyr, the climate and ocean state show, as expected, only modest variations. Some flooding events of coastal areas bring terrestrial organic matter to the ocean and lead locally to CO2 outgassing for several decades. Terrestrial organic matter has a higher carbon to nutrient stoichiometry as compared to marine organic matter, thus its remineralization favours CO2 outgassing. Additionally, the accumulation of terrestrial organic matter in the top layers of the marine sediment reduces the replenishment of the water-column nutrients by the re-flux of remineralization products from marine sediment. Consequently, the strength of the local biological pump decreases. Further results will be presented and discussed. </p>

scholarly journals Effect of Land Use on Organic Carbon Storage Potential of Soils with Contrasting Native Organic Matter Content

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Sabina Yeasmin ◽  
Eshara Jahan ◽  
Md. Ashik Molla ◽  
A. K. M. Mominul Islam ◽  
Md. Parvez Anwar ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Organic Carbon ◽  
Carbon Storage ◽  
Organic Matter Content ◽  
Fallow Land ◽  
Land Uses ◽  
Storage Potential ◽  
The Impact ◽  
Native Organic Matter

This study aimed to determine the impact of land use on organic carbon (OC) pools of soils with contrasting native organic matter (OM) content. Surface (0–15 cm) soils of four land uses (cropland, orchard, grassland, and fallow) were collected from four agroecological zones (AEZs) of Bangladesh with different OM content (AEZ-7: very low, −3: low, −9: medium, and −5: high). Bulk soils were physically fractionated into particulate and mineral associated OM (POM and MOM: >53 and <53 µm, respectively). Both bulk and fractionated soils were analyzed for OC and nitrogen (N). Among the land uses, undisturbed soils (grassland and fallow land) had significantly higher total OC (0.44–1.79%) than disturbed soils (orchard and cropland) (0.39–1.67%) in all AEZs. The distribution of OC and N in POM and MOM fractions was significantly different among land uses and also varied with native OM content. In all AEZs, cropland soils showed the lowest POM-C content (0.40–1.41%), whereas the orchard soils showed the highest values (0.71–1.91%). The MOM-C was highest (0.81–1.91%) in fallow land and lowest (0.53–1.51%) in orchard, and cropland had a moderate amount (0.70–1.61%). In croplands, distribution of a considerable amount of OC in the MOM pool was noticeable. These findings reveal that total OC in soils can be decreased with cultivation but does not inevitably indicate the loss of OC storage in the stable pool. Carbon storage potential of soils with both high- and low-native OM contents can be increased via proper land use and managements.

scholarly journals No evidence of a human influence on the mineralization of terrestrial dissolved organic matter (DOM) in Alpine fluvial networks

2021 ◽  
Author(s):  
Thibault Lambert ◽  
Pascal Perolo ◽  
Nicolas Escoffier ◽  
Marie-Elodie Perga
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Human Disturbance ◽  
Human Activities ◽  
Bacterial Respiration ◽  
Inland Waters ◽  
Land Uses ◽  
Lake Geneva ◽  
Basin Scale ◽  
The Impact

Abstract. The influence of human activities on the role of inland waters in the global carbon (C) cycle is poorly constrained. In this study, we investigated the impact of human land use on the degradation of terrestrial dissolved organic matter (DOM) and its potential impact on bacterial respiration in ten independent catchments of the Lake Geneva Basin. Sites were selected along a gradient of human disturbance (agriculture and urbanization), and we monitored bacterial respiration in parallel to DOM bioavailability. Fluorescence spectroscopy was used to determine the influence of human land uses on DOM sources and composition as well as the dynamic of degradation or production of the fluorophores identified in our study sites. Higher bacterial respiration measured in agro-urban streams related to a short-term bioreactive pool (0–6 days of incubation) from autochthonous origin, whose the size increased with human disturbance. On the other hand, the degradation of terrestrial DOM was not impacted by human activities and was not found to contribute substantially to aquatic bacterial respiration. Although human land uses controlled DOM sources, composition and bioavailability at the basin scale, our results showed that human activities in the Lake Geneva Basin had a limited impact on the net C exchanges between inland waters and the atmosphere related to DOM mineralization. Considering that greater proportion of autochthonous-DOM signature is a common feature in human-impacted catchments, the implications of our results likely apply more widely. Yet, on a global scale, the influence of human activities remains to be determine given the large diversity of effects of agriculture and urbanization on freshwater DOM depending on the local environmental context.

The effect of permafrost area and types on flux and composition of dissolved organic matter in stream from alpine catchments, northeastern Qinghai-Tibet Plateau

2021 ◽  
Author(s):  
Yanxi Pan ◽  
Ziyong Sun
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
River Water ◽  
Frozen Soil ◽  
Tibet Plateau ◽  
Vegetation Coverage ◽  
Permafrost Degradation ◽  
Terrestrial Organic Matter ◽  
The Impact ◽  
Qinghai Tibet Plateau

&lt;p&gt;Understanding&amp;#160;optical&amp;#160;characteristics,&amp;#160;composition&amp;#160;and&amp;#160;source&amp;#160;of&amp;#160;dissolved&amp;#160;organic&amp;#160;matter&amp;#160;(DOM)&amp;#160;in&amp;#160;rivers&amp;#160;is&amp;#160;important&amp;#160;for&amp;#160;region&amp;#160;and&amp;#160;global&amp;#160;carbon&amp;#160;cycle,&amp;#160;especially&amp;#160;in&amp;#160;the&amp;#160;inland&amp;#160;rivers&amp;#160;of&amp;#160;the&amp;#160;Qinghai-Tibet&amp;#160;Plateau. In order to understand the impact of permafrost degradation on river DOM output under the background of climate warming, we selected 34 typical sub-basins in the upper reaches of the Heihe River basin on the Qinghai-Tibet Plateau according to the different proportion of permafrost area in the basin. Water&amp;#160;samples&amp;#160;were&amp;#160;collected&amp;#160;at&amp;#160;the&amp;#160;outlet&amp;#160;of&amp;#160;each&amp;#160;sub-basin&amp;#160;in&amp;#160;October&amp;#160;2018,&amp;#160;January,&amp;#160;April&amp;#160;and&amp;#160;July&amp;#160;2019,&amp;#160;respectively. The variations of DOM structure and source identification in different permafrost basin were investigated using UV&amp;#8211;visible absorbance and fluorescence spectroscopy. The results showed that: (1) The concentration of C1 and C2 components and the values &amp;#8203;&amp;#8203;of SUVA&lt;sub&gt;254&lt;/sub&gt;, HIX and FI increased with the decrease of the percentage of permafrost area. , Indicating that with the degradation of frozen soil, the runoff path deepens, and more terrestrial organic matter is dissolved into the water body, which increases the terrestrial DOM in the river water, which in turn leads to the increase of DOM concentration, humification degree and aromaticity; (2) As the proportion of permafrost area decreases, the S&lt;sub&gt;R&lt;/sub&gt; value shows a decreasing trend, indicating that the DOM of rivers in permafrost regions has the characteristics of low molecular weight and low humic acid, while the DOM of rivers in seasonally frozen soil regions is the opposite, indicating a frozen soil Melting may lead to the increase of terrestrial DOM in river water, and the increase in the depth of freeze-thaw cycle may release aromatic substances containing fused ring structure in frozen soil, which will enter the river with runoff, resulting in increased aromaticity and molecular weight of DOM in river water; (3) The concentrations of C1 and C2 components are positively correlated with vegetation coverage, and vegetation coverage is negatively correlated with the percentage of permafrost area. It shows that the degradation of frozen soil will increase the coverage of vegetation, thereby increasing the DOM from terrestrial&amp;#160;sources. This study shows that the optical characteristics, composition and source of DOM have important indications for the degradation of permafrost under the background of global warming.&lt;/p&gt;

The impact of urban effluents on the coastal marine environment of Mediterranean islands

1995 ◽  
Vol 32 (9-10) ◽  
pp. 85-94 ◽  
Author(s):  
Michael O. Angelidis
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Marine Environment ◽  
Suspended Particle ◽  
Pollution Source ◽  
Mediterranean Islands ◽  
Coastal Marine Environment ◽  
Coastal Marine ◽  
The Impact ◽  
The City

The impact of the urban effluents of Mytilene (Lesvos island, Greece) on the receiving coastal marine environment, was evaluated by studying the quality of the city effluents (BOD5, COD, SS, heavy metals) and the marine sediments (grain size, organic matter, heavy metals). It was found that the urban effluents of Mytilene contain high organic matter and suspended particle load because of septage discharge into the sewerage network. Furthermore, although the city does not host important industrial activity, its effluents contain appreciable metal load, which is mainly associated with the particulate phase. The city effluents are discharged into the coastal marine environment and their colloidal and particulate matter after flocculation settles to the bottom, where is incorporated into the sediments. Over the years, the accumulation of organic matter and metals into the harbour mud has created a non-point pollution source in the relatively non-polluted coastal marine environment of the island. Copper and Zn were the metals which presented the higher enrichment in the sediments of the inner harbour of Mytilene.

Fish farming in Denmark: environmental impact of regulative legislation

1995 ◽  
Vol 31 (10) ◽  
pp. 73-84 ◽  
Author(s):  
T. M. Iversen
Keyword(s):  
Organic Matter ◽  
Environmental Impact ◽  
Freshwater Fish ◽  
Aquatic Environment ◽  
Action Plan ◽  
Fish Farming ◽  
Fish Farms ◽  
Nitrogen And Phosphorus ◽  
Local Impact ◽  
The Impact

The main environmental problems associated with fish farming in Denmark are attributable to the dam, the “dead reach” and nutrient and organic matter discharge. The environmental regulation of fish farming in Denmark started with the Environmental Protection Act of 1974, the Statutory Order of 1985 forbidding wet feed, and the Action Plan on the Aquatic Environment of 1987. In the case of freshwater fish farms, the latter was implemented through the measures stipulated in the 1989 Statutory Order on Fish Farms. The impact of Danish legislative measures to reduce and regulate the environmental effects of freshwater fish farms can be summarized as follows: - the number of fish farms has been reduced from about 800 in 1974 to about 500 at present; - production has tripled since 1974 and has been stable since 1989; - a change from wet to dry feed has reduced the environmental impact of the farms; - the national goals of the Action Plan on the Aquatic Environment of 1987 for reducing fish farm discharges of organic matter, nitrogen and phosphorus have been fulfilled. The main remaining problems are that: - the local impact of fish farms on downstream stream quality is still much too high in about 15% of cases; - the problem of the passage of migrating invertebrates and fish is still unsolved at some farms; - the problems posed by “dead reaches” are still unsolved. It is concluded that sustainable fish farming is possible in Denmark, but with the present technology production will have to be significantly reduced.

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