The effect of hydrostatic pressure on the decomposition of inundated terrestrial plant detritus of different quality in simulated reservoir formation

Abstract

The formation of reservoirs usually incorporates the inundation of terrestrial vegetation in the basin. The decomposition of organic matter from the flooded vegetation may have several implications for reservoir functioning, including eutrophication and dissolved oxygen depletion. The hydrostatic pressure increases with depth in a reservoir, and its influence on the decomposition process has not previously been evaluated. This study was undertaken to evaluate the decomposition of terrestrial plant detritus of different qualities (leaves and branches) under different hydrostatic pressure conditions. Detritus were placed separately in glass bottles in the laboratory and incubated in tight stainless steel pressure vessels, simulating three different depths (surface, 30 and 100 m). The masses (mg) of particulate organic carbon (POC), dissolved organic carbon (DOC) and inorganic carbon (IC) were determined for the 4 months of the detritus decomposition simulated in this study. The mass values were transformed in percentages of the initial detritus carbon. The results of temporal variations of the compounds studied were fitted to a first-order biphasic decay model. The hydrostatic pressure exhibited no significant effects on litter decomposition. On the other hand, the detritus chemical composition (i.e. the presence of labile and refractory compounds) was the determining factor for the decomposition curve shape and for the differences observed between the leaves and branches. The greatest POC loss from leaves, and resulting larger DOC mass, indicated the leaves were more labile than the branches. The results also indicated the branches are the main detritus remaining in a reservoir over time.

Changes in the Dissolved Organic Matter Characteristics Released from Sediment According to Precipitation in the Namhan River with Weirs: A Laboratory Experiment

“…In the rainy season, a large amount of contaminants flows into rivers with surface runoff by rainfall [46,47]. In addition, the inflow of surface runoff increases the flow rate of a river, which affects the transport and accumulation of sediment [48].…”

Changes in the characteristics of dissolved organic matter released from sediment according to precipitation in the Namhan River, South Korea.

“…In the rainy season, a large amount of contaminants ows into rivers with surface runoff by rainfall (Jorgensen, 2003;Fonseca et al, 2016). In addition, the in ow of surface runoff increases the ow rate of a river, which affects the transport and accumulation of sediment (Zhao et al, 2018).…”

Avaliação do Índice de Estado Trófico e parâmetros de qualidade da água no reservatório da Usina Hidrelétrica de Sá Carvalho, Minas Gerais, Brasil

“…Ademais, pontuam quanto à importância de práticas capazes de promover a aeração do hipolímnio, a desnitrificação e a remoção de águas profundas e de macrófitas e algas -processos mecânicos capazes de revitalizar o reservatório e melhorar a qualidade da água. Fonseca et al (2016) reforçam que o manejo do reservatório com o emprego de processos químicos e biológicos pode ser eficaz e repercutir positivamente em toda a bacia de captação. Como estratégias mitigadoras cabíveis, os pesquisadores indicam o uso de algicidas, a precipitação de nutrientes e o uso de peixes herbívoros, de cianófagos e de biomanipulação (combinação de organismos vivos, comumente peixes que possam agir diretamente na cadeia alimentar).…”