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| Author(s): |
Daniele Frascareli
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Sorocaba. 2021-06-23. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Ciência e Tecnologia. Sorocaba |
| Defense date: | 2021-06-16 |
| Advisor: | André Henrique Rosa; Viviane Moschini Carlos |
| Abstract | |
Reservoir bottom sediments retain natural and antrophic compounds from the water column, and thus record the processes of the area where it is located. But they can also act as sources of contamination by remobilization of metals and nutrients, causing changes in the chemical conditions in the water column. Therefore, reservoir sediments can be used as good indicators of pollution derived from diffuse sources. Therefore, the objective of this thesis was to determine the temporal and spatial geochemistry of anions and cations, and nutrients in sediments from Itupararanga-SP reservoir. For this, surface sediment samples were collected in the horizontal extension of the reservoir (entrance to the dam). Interstitial waters were extracted from the sediments and analyzed. In order to establish the influence of land uses on the surroundings of the reservoir, soil samples were collected. The sediments and soil were analyzed for trace and major elements by X-ray fluorescence (XRF), dry weight (DW), organic material by loss on ignition (LOI), porosity. Of the nutrients, total phosphorus (PT) was analyzed photometrically while total organic carbon (TC), total nitrogen (TN) and total sulfate (TS) were determined (Cl- , SO4 2- , Ca2+, Mg2+, Na+ , K+ ) with a CNS analyzer (Dimatoc 2000). The particle size distribution was obtained by laser diffraction. In the interstitial water the dissolved anions and cations were measured by chromatography and the trace metals by inductively coupled plasma atomic optical emission spectrometry (ICPOAES). Soluble reactive phosphorus (SRP), NO3 and NH4+ were analyzed according to Murphy & Riley (1962) by acc spectrophotometry Herzsprung et al. (1998). Determination of the influence of use and occupation on physicochemical characteristics of surface sediments indicated horizontal spatial heterogeneities that were mainly attributed to sand (>26.7%), Si (568.8 g kg-1 ) and Cr (336 mg kg-1 ) in S1 (input zone). In addition, fine particles of silt and clay leached from agricultural activities were enriched with OM, TP, TN, TC, As, and Cr. These types of sediments were deposited in the transition and lake zones. In addition, urban soils acted as a source of sand and phosphorus for the sediments. Regarding the sediment samples, only As and Cr indicated possible anthropic contamination at point 5 (near the dam and exclusively agricultural area). Also at point 5 was verified a release of phosphorus from the sediment to the water column, explained by the degradation of organic matter by oxide pathways. The Itupararanga reservoir has called attention in relation to the availability of water in quantity and quality, exactly for this reason, this study pointed out that the use of the surroundings by agricultural and urban activities has caused a reduction in the quality of the sediments. Nevertheless, the sediments indicated that they act as a source of contamination, which is worrying for the continued use of this environment. (AU) | |
| FAPESP's process: | 16/15397-1 - Organic Carbon cycling in Water Reservoirs of Brazil and Germany: influence of land use and hydrology- ORCWAR |
| Grantee: | Daniele Frascareli |
| Support Opportunities: | Scholarships in Brazil - Doctorate |