| 1. |
- Almeida, Rafael M., et al.
(författare)
-
Carbon dioxide emission from drawdown areas of a Brazilian reservoir is linked to surrounding land cover
- 2019
-
Ingår i: Aquatic Sciences. - : Springer Science and Business Media LLC. - 1015-1621 .- 1420-9055. ; 81
-
Tidskriftsartikel (refereegranskat)abstract
- Reservoir sediments exposed to air due to water level fluctuations are strong sources of atmospheric carbon dioxide (CO2). The spatial variability of CO2 fluxes from these drawdown areas are still poorly understood. In a reservoir in southeastern Brazil, we investigated whether CO2 emissions from drawdown areas vary as a function of neighboring land cover types and assessed the magnitude of CO2 fluxes from drawdown areas in relation to nearby water surface. Exposed sediments near forestland (average = 2733 mg C m−2 day−1) emitted more CO2 than exposed sediments near grassland (average = 1261 mg C m−2 day−1), congruent with a difference in organic matter content between areas adjacent to forestland (average = 12.2%) and grassland (average = 10.9%). Moisture also had a significant effect on CO2 emission, with dry exposed sediments (average water content: 13.7%) emitting on average 2.5 times more CO2 than wet exposed sediments (average water content: 23.5%). We carried out a systematic comparison with data from the literature, which indicates that CO2 efflux from drawdown areas globally is about an order of magnitude higher than CO2 efflux from adjacent water surfaces, and within the range of CO2 efflux from terrestrial soils. Our findings suggest that emissions from exposed sediments may vary substantially in space, possibly related to organic matter supply from uphill vegetation, and that drawdown areas play a disproportionately important role in total reservoir CO2 emissions with respect to the area they cover.
|
|
| 2. |
- Baptista-Salazar, Carluvy, et al.
(författare)
-
Insights into the factors influencing mercury concentrations in tropical reservoir sediments
- 2021
-
Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2050-7887 .- 2050-7895. ; 23:10, s. 1542-1553
-
Tidskriftsartikel (refereegranskat)abstract
- Thousands of dams are currently under construction or planned worldwide to meet the growing need for electricity. The creation of reservoirs could, however, lead to conditions that promote the accumulation of mercury (Hg) in surface sediments and the subsequent production of methylmercury (MeHg). Once produced, MeHg can bioaccumulate to harmful levels in organisms. It is unclear to what extent variations in physical features and biogeochemical factors of the reservoir impact Hg accumulation. The objective of this study was to identify key drivers of the accumulation of total Hg (THg) in tropical reservoir sediments. The concentration of THg in all analyzed depth intervals of 22 sediment cores from the five contrasting reservoirs investigated ranged from 16 to 310 ng g(-1) (n = 212, in the different sediment cores, the maximum depth varied from 18 to 96 cm). Our study suggests reservoir size to be an important parameter determining the concentration of THg accumulating in tropical reservoir sediments, with THg ranging up to 50 ng g(-1) in reservoirs with an area exceeding 400 km(2) and from 100 to 200 ng g(-1) in reservoirs with an area less than 80 km(2). In addition to the reservoir size, the role of land use, nutrient loading, biome and sediment properties (e.g., organic carbon content) was tested as potential drivers of THg levels. The principal component analysis conducted suggested THg to be related to the properties of the watershed (high degree of forest cover and low degree of agricultural land use), size and age of the reservoir, water residence time and the levels of nutrients in the reservoir. A direct correlation between THg and tested variables was, however, only observed with the area of the reservoir.
|
|
| 3. |
- Paranaiba, Jose R., et al.
(författare)
-
Cross-continental importance of CH4 emissions from dry inland-waters
- 2022
-
Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 814
-
Tidskriftsartikel (refereegranskat)abstract
- Despite substantial advances in quantifying greenhouse gas (GHG) emissions from dry inland waters, existing estimates mainly consist of carbon dioxide (CO2) emissions. However, methane (CH4) may also be relevant due to its higher Global Warming Potential (GWP). We report CH4 emissions from dry inland water sediments to i) provide a cross-continental estimate of such emissions for different types of aquatic systems (i.e., lakes, ponds, reservoirs, and streams) and climate zones (i.e., tropical, continental, and temperate); and ii) determine the environmental factors that control these emissions. CH4 emissions from dry inland waters were consistently higher than emissions observed in adjacent uphill soils, across climate zones and in all aquatic systems except for streams. However, the CH4 contribution (normalized to CO2 equivalents; CO2-eq) to the total GHG emissions of dry inland waters was similar for all types of aquatic systems and varied from 10 to 21%. Although we discuss multiple controlling factors, dry inland water CH4 emissions were most strongly related to sediment organic matter content and moisture. Summing CO2 and CH4 emissions revealed a cross-continental average emission of 9.6 +/- 17.4 g CO2-eqm(-2) d(-1) from dry inland waters. We argue that increasing droughts likely expand the worldwide surface area of atmosphere-exposed aquatic sediments, thereby increasing global dry inland water CH4 emissions. Hence, CH4 cannot be ignored if we want to fully understand the carbon (C) cycle of dry sediments.
|
|
| 4. |
- Quadra, Gabrielle R., et al.
(författare)
-
Environmental Risk of Metal Contamination in Sediments of Tropical Reservoirs
- 2019
-
Ingår i: Bulletin of Environmental Contamination and Toxicology. - : Springer Science and Business Media LLC. - 0007-4861 .- 1432-0800. ; 103:2, s. 292-301
-
Tidskriftsartikel (refereegranskat)abstract
- Reservoir sediment can work as both sink and source for contaminants. Once released into the water column, contaminants can be toxic to biota and humans. We investigate potential ecological risk to benthic organisms by metals contamination in six reservoirs in Southeast Brazil. Results of the bioavailable fraction of copper (Cu), chromium (Cr), cadmium (Cd), lead (Pb), zinc (Zn), and iron (Fe) in sediment samples are presented. Considering Cu, Cd, and Zn concentrations, about 6% of the samples exceeded the threshold effect levels of sediment quality guidelines. The comparison to sediment quality guidelines is conservative because we used a moderate metal extraction. Control of contaminant sources in these reservoirs is key because they are sources of water and food. The mixture toxicity assessment showed an increased incidence of toxicity to aquatic organisms showing that mixture toxicity should be taken into account in sediment assessment criteria.
|
|
| 5. |
- Quadra, Gabrielle R., et al.
(författare)
-
High organic carbon burial but high potential for methane ebullition in the sediments of an Amazonian hydroelectric reservoir
- 2020
-
Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 17:6, s. 1495-1505
-
Tidskriftsartikel (refereegranskat)abstract
- Reservoir sediments sequester significant amounts of organic carbon (OC), but at the same time, high amounts of methane (CH4) can be produced and emitted during the degradation of sediment OC. While the greenhouse gas emission of reservoirs has received a lot of attention, there is a lack of studies focusing on OC burial. In particular, there are no studies on reservoir OC burial in the Amazon, even though hydropower is expanding in the basin. Here we present results from the first investigation of OC burial and CH4 concentrations in the sediments of an Amazonian hydroelectric reservoir. We performed sub-bottom profiling, sediment coring and sediment pore water analysis in the Curuá Una (CUN) reservoir (Amazon, Brazil) during rising- and falling-water periods. The spatially resolved average sediment accumulation rate was 0.6 cm yr−1, and the average OC burial rate was 91 g C m−2 yr−1. This is the highest OC burial rate on record for low-latitude hydroelectric reservoirs. Such a high rate probably results from a high OC deposition onto the sediment, which compensates the high OC mineralization at a 28–30 ∘C water temperature. Elevated OC burial was found near the dam and close to major river inflow areas. C:N ratios between 10.3 and 17 (average ± SD: 12.9±2.1) suggest that both land-derived and aquatic OC accumulate in CUN sediments. About 23 % of the sediment pore water samples had dissolved CH4 above the saturation concentration. This represents a higher share than in other hydroelectric reservoirs, indicating a high potential for CH4 ebullition, particularly in river inflow areas.
|
|
| 6. |
- Quadra, Gabrielle Rabelo, et al.
(författare)
-
Micropollutants in four Brazilian water reservoirs
- 2021
-
Ingår i: Limnologica. - : Elsevier BV. - 0075-9511 .- 1873-5851. ; 90
-
Tidskriftsartikel (refereegranskat)abstract
- The concern about emerging contaminants such as pharmaceuticals is growing, mainly due to the increased global consumption of synthetic chemicals and the potential risk to environmental and human health. Although developing countries may be hotspots of pharmaceutical pollution, the knowledge about the occurrence of pharmaceuticals is still limited and patchy. Brazil holds one of the largest freshwater volumes globally, yet, little is known about the occurrence of pharmaceuticals in reservoirs although they make up key water sources. The aim of this study was, therefore, to investigate micropollutant occurrence, mainly pharmaceuticals, in four freshwater reservoirs distributed in Brazil. Water samples were collected in the Curuá-Una (CUN, Amazon region), Chapéu D’Uvas (CDU, Atlantic Forest region), Funil (FUN, Atlantic Forest region), and Simplício (SIM, Atlantic Forest region) reservoirs. The occurrence of 28 different micropollutants, including 26 pharmaceuticals, was investigated with target analysis on a UHPLC-Orbitrap-MS/MS, and a non-target screening approach was performed on all water samples to identify the presence of additional contaminants. The highest micropollutant concentrations were observed in FUN and SIM, which are the reservoirs with the largest population size in the catchment. Only caffeine was detected in CDU and CUN, which are reservoirs less influenced by urbanization. Metformin was the pharmaceutical with the highest concentrations, reaching 2 191 ng L−1 in FUN. The non-target screening identified 125 chemicals, of which most were pharmaceuticals. The numbers of compounds identified and which were above the LOQ were higher in FUN and SIM, in agreement with results from the target analysis. Metformin is the compound with the highest risk to affect FUN reservoir negatively, based on calculated risk quotients. Considering that the reservoirs are used for multiple purposes, including water supply, irrigation, and aquaculture, it is important to continue investigating micropollutant occurrence to guarantee environmental and human health.
|
|
| 7. |
- Rabelo Quadra, Gabrielle, et al.
(författare)
-
Temporal and Spatial Variability of Micropollutants in a Brazilian Urban River
- 2021
-
Ingår i: Archives of Environmental Contamination and Toxicology. - : Springer Science and Business Media LLC. - 0090-4341 .- 1432-0703. ; 81:1, s. 142-154
-
Tidskriftsartikel (refereegranskat)abstract
- In Brazil, environmental occurrence of micropollutants, such as pharmaceuticals, is rarely studied, and these compounds are not part of national water quality guidelines. In this study, we evaluated the occurrence of micropollutants in the Paraibuna River, located in the southeast region of Brazil, which is the most populated region of the country. Surface water samples were taken every 3 months for 1.5 years at four different sites downstream the city of Juiz de Fora. A total of 28 compounds were analyzed on an UHPLC-Orbitrap-MS/MS using a direct injection method. Nine substances were found in at least one water sample, with concentrations ranging from 11 to 4471 ng L-1. The micropollutants found in the river were not detected at the reference site upstream of the city, except for caffeine, which was present at low concentrations in the reference site. Additionally, a nontarget screening of the river samples was applied, which resulted in the identification of 116 chemicals, most of which were pharmaceuticals. Concentrations of most of the micropollutants varied with season and correlated significantly with rainfall events, which caused dilution in the river. The highest observed concentrations were for pharmaceuticals used for treating chronic diseases, such as metformin, which is used to treat diabetes, and were among the most consumed in Juiz de Fora during the study period. Moderate ecotoxicological risks were found for metformin, oxazepam, triclosan, and tramadol. Considering the complex mixture of micropollutants in the environment, more knowledge is needed to elucidate their ecological risk in aquatic ecosystems.
|
|
