Abstract Details
(2020) Tracking Fluvial Sediment Sources Through the Lanthanide Traces. Experimental Method Applied on the Jiu River Basin (Romania)
Morosanu GA, Traistă E, Zaharia L & Belleudy P
https://doi.org/10.46427/gold2020.1850
The author has not provided any additional details.
10f: Plenary Hall, Thursday 25th June 23:24 - 23:27
Gabriela Adina Morosanu
View abstracts at 3 conferences in series
Eugen Traistă View abstracts at 3 conferences in series
Liliana Zaharia View abstracts at 3 conferences in series
Philippe Belleudy View abstracts at 3 conferences in series
Eugen Traistă View abstracts at 3 conferences in series
Liliana Zaharia View abstracts at 3 conferences in series
Philippe Belleudy View abstracts at 3 conferences in series
Listed below are questions that have been submitted by the community that the author will try and cover in their presentation. To submit a question, ensure you are signed in to the website. Authors or session conveners approve questions before they are displayed here.
Submitted by Marisa Repasch on Thursday 25th June 17:18
Thanks for sharing your sediment provenance work in the Jiu River. It is an interesting approach and I have a few questions: 1) What is the significance of the trend lines you show in figure 4? Are the elements on the x-axis ordered by mass, and does the mass distribution of the samples allow you to better characterize the different sources? 2) How do you actually compare the sources (tributaries) to the main stem river bed samples and the alluvial deposits? I am missing a step in the methods that allows you to determine the relative contributions of each source to the main channel. Thanks!
Hello, Marisa. Thank you for your questions. Before answering them, I need to apologize for maybe not being very precise, as I am not the geochemist of the group. We are most of us hydrologists and there is only Prof. Traista who can answer you better. I will try to provide you some answers and in case it is not very obvious and you want to talk more, don't hesitate to tell me and I will ask in more details Mr. Traista. 1. The trendlines show us the importance of each lanthanide in the mixed proportion of lanthanides isolated from each sample. It is just a visual way to put it, as we found the trendline type graphs more compelling. If you are more familiar with this kind of data treatment and can indicate us other types of graphical representations, we are open to discussions. The elements on the X-axis are ordered by atomic number, but indeed the mass distribution allows us to better characterize the sediment sources. We did it in this stage of the research not graphically, but numerically, by calculating the light (first 7) to heavy lanthanides (last 7) ratio and trying to map the obtained values by regions in the end. 2. That's actually a tough question as it also intrigued us throughout the setting of the sampling protocol according to our hydrological purposes. The river basin is huge, so we cannot chase every possible sediment source area, so we just focused on the "hot sports", let's say. We have a prior knowledge about the main contributing areas in terms of fine sediment supply, which are the two coal extraction basins from upstream (Carpathians) and middle sector of the watershed (the lignite extraction area from Motru - Jilt sub-catchments in the piedmont), followed by a few important tributaries, such as Motru, Western Jiu, Jilt, Amaradia rivers. So, we concentrated specifically on those tributaries and coal basins to sample our fine sediments from the riverbeds mainly. We also organized a second sampling campaign for slope - coal extraction areas (so no fluvial environments), but this makes the object of the other part of the study which I presented last year (coal proportion and heavy minerals). So for lanthanides, we only used the riverine fine sediment samples. They are indeed not genuine "source samples", as the rivers themselves are fed by the upstream sources, but in a cascade fluvial system of this size, we may assume this compromise of intermediary sources. The overall objective was to find the contributing sub-catchments, as we were aware of the difficulty to go to the first order source (headwatersheds e.g.). As for the alluvial deposit, we needed an element of comparison, to see where all those fine sediments go. So they travel all along the main rivers and Jiu River to finally and mainly get accumulated approx. 60 km upstream its confluence with Danube River. Upstream, there are no good conditions for massive deposition and natural riverbanks formation during floods, as the river is often canalized. Further downstream Podari alluvial deposit, the valley gets too narrow in the plain sector and there are hardly any temporary small rivers which can contribute to sediment supply and increase the velocity and competence of the river to continue the solid flux transport. I will show in my presentation these fluvial upstream - downstream characteristics and the consideration of the sampling sites choice, so I hope everything will be clear then. Thank you for your questions and see you at the session! Kind regards, Gabriela Morosanu
Thanks for sharing your sediment provenance work in the Jiu River. It is an interesting approach and I have a few questions: 1) What is the significance of the trend lines you show in figure 4? Are the elements on the x-axis ordered by mass, and does the mass distribution of the samples allow you to better characterize the different sources? 2) How do you actually compare the sources (tributaries) to the main stem river bed samples and the alluvial deposits? I am missing a step in the methods that allows you to determine the relative contributions of each source to the main channel. Thanks!
Hello, Marisa. Thank you for your questions. Before answering them, I need to apologize for maybe not being very precise, as I am not the geochemist of the group. We are most of us hydrologists and there is only Prof. Traista who can answer you better. I will try to provide you some answers and in case it is not very obvious and you want to talk more, don't hesitate to tell me and I will ask in more details Mr. Traista. 1. The trendlines show us the importance of each lanthanide in the mixed proportion of lanthanides isolated from each sample. It is just a visual way to put it, as we found the trendline type graphs more compelling. If you are more familiar with this kind of data treatment and can indicate us other types of graphical representations, we are open to discussions. The elements on the X-axis are ordered by atomic number, but indeed the mass distribution allows us to better characterize the sediment sources. We did it in this stage of the research not graphically, but numerically, by calculating the light (first 7) to heavy lanthanides (last 7) ratio and trying to map the obtained values by regions in the end. 2. That's actually a tough question as it also intrigued us throughout the setting of the sampling protocol according to our hydrological purposes. The river basin is huge, so we cannot chase every possible sediment source area, so we just focused on the "hot sports", let's say. We have a prior knowledge about the main contributing areas in terms of fine sediment supply, which are the two coal extraction basins from upstream (Carpathians) and middle sector of the watershed (the lignite extraction area from Motru - Jilt sub-catchments in the piedmont), followed by a few important tributaries, such as Motru, Western Jiu, Jilt, Amaradia rivers. So, we concentrated specifically on those tributaries and coal basins to sample our fine sediments from the riverbeds mainly. We also organized a second sampling campaign for slope - coal extraction areas (so no fluvial environments), but this makes the object of the other part of the study which I presented last year (coal proportion and heavy minerals). So for lanthanides, we only used the riverine fine sediment samples. They are indeed not genuine "source samples", as the rivers themselves are fed by the upstream sources, but in a cascade fluvial system of this size, we may assume this compromise of intermediary sources. The overall objective was to find the contributing sub-catchments, as we were aware of the difficulty to go to the first order source (headwatersheds e.g.). As for the alluvial deposit, we needed an element of comparison, to see where all those fine sediments go. So they travel all along the main rivers and Jiu River to finally and mainly get accumulated approx. 60 km upstream its confluence with Danube River. Upstream, there are no good conditions for massive deposition and natural riverbanks formation during floods, as the river is often canalized. Further downstream Podari alluvial deposit, the valley gets too narrow in the plain sector and there are hardly any temporary small rivers which can contribute to sediment supply and increase the velocity and competence of the river to continue the solid flux transport. I will show in my presentation these fluvial upstream - downstream characteristics and the consideration of the sampling sites choice, so I hope everything will be clear then. Thank you for your questions and see you at the session! Kind regards, Gabriela Morosanu
Sign in to ask a question.