Modification of the biogeochemical cycle of silica with eutrophication

Dj, Conley; Schelske, C.L.; Stoermer, E.F.

doi:10.3354/meps101179

Cited by 435 publications

(239 citation statements)

References 50 publications

(89 reference statements)

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“…the higher enhanced pH, a result of enhanced primary production, corresponding to the lower concentration of DSi. Generally, the retention of DSi in lentic waters is greater in eutrophic lakes, due to the increased diatom production (Conley et al, 1993). Presently, both HJD and DF reservoirs are still in the oligo-trophic condition, and SFY has the meso-trophic status.…”

Section: Discussionmentioning

confidence: 99%

Dissolved silicate retention and transport in cascade reservoirs in Karst area, Southwest China

Wang

Liu

et al. 2010

Science of The Total Environment

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Presently, the fluvial fluxes of Dissolved silicate (DSi) by many famous rivers in the world have been reported significantly decreased in the past several decades. DSi retention by river damming hence becomes a great concern. In this study, the impact on DSi retention and transport by cascade reservoirs in the Karst area were investigated. Based on the monitoring data for four seasons, budget of DSi in these reservoirs were calculated. Results showed that, only the downstream eutrophic Wujiangdu reservoir (WJD) was the sink for DSi, with a value of ca. 3.5 kT DSi trapped annually. The new Hongjiadu reservoir (HJD) in the headwater area revealed to be an important source for DSi. Both Dongfeng (DF) and Suofengyin (SFY) reservoirs also released more DSi to the downstream than entering them. The great discrepancy of DSi source and sink effects among these reservoirs indicates that, (i) DSi was obviously taken up in summer and spring, and the concentration of DSi could be dropped down to below 30 μΜ; (ii) during the period of thermal stratification, the concentration stratification of DSi is also developed along the water column. Possibly DSi releasing from inundation soil and bottom sediment was the important compensation for the silicon depletion in the epilimnion. In the newly constructed reservoirs (e.g. HJD and SFY), the releasing flux of DSi can significantly exceed the assimilating flux by diatom; and (iii) due to the hypolimnion introducing for hydropower operation, water leaving the dam generally had high DSi content, and then masked the DSi taking up in the epilimnion. This process also decreased the ratio of DIN to DSi, mitigating the silicon limiting situation in the downstream.

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Section: Discussionmentioning

confidence: 99%

Dissolved silicate retention and transport in cascade reservoirs in Karst area, Southwest China

Wang

Liu

et al. 2010

Science of The Total Environment

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“…This rate is directly proportional to the increase in depth (Conley et al, 1993). However, a low Bsi fl ow may be related to increased diatom preservation as a result of less frustule dissolution, explaining why many authors (e.g.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Taphonomic signatures and paleoecology of Holocene diatom assemblages in the Llano Grande Basin, northwestern Andean Cordillera, Colombia

Sierra-Arango¹,

Souza²,

Ruiz³

2014

Rev. bras. paleontol.

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-This paper presents the results of a taphonomic study of Holocene diatoms in the Llano Grande Basin, Páramo de Frontino, which is located 3,460 m above sea level in the northwestern Andean Cordillera (6º29'N/76º6'W), Colombia. Samples measuring 1 cm 3 from 57 levels distributed over a core depth of 8.5 m (LLG3) were randomly collected from sediment representing a paleolake that developed on the Llano Grande Basin. The density of diatoms and the number of fragmented and dissolved valves were estimated from 10 μL of each sample. A high variability in the density and preservation of the diatom assemblages was verifi ed along the core, which is related to temperature variation, macroinvertebrates grazing, volcanic ash infl ux, and water-level fl uctuations over the 11.000 C 14 years BP. Fragmentation was higher than dissolution, which indicates the predominance of lotic environments and grazing. The substantial decrease in the diatoms on specifi c level is interpreted as a result of the limitation of silica, decreased water levels, intense herbivory, dry environment or dissolution. In these cases, it is impossible to recognize most of the periphytic diatoms due to the high degree of fragmentation of the frustules. The authors conclude that the high degree of variation of the taphonomic damage in the diatoms of Páramo de Frontino represents different environmental events along the Holocene. Therefore, in the early Holocene, input from ash and high temperatures favored reproduction, which resulted in the high density of diatoms. In the last 4,000 years, the water level in the lake has decreased, and probably the predation on diatoms has increased as evidenced by the increasing of fragmentation of the state 3.Key words: taphonomy, diatom paleoecology, peats, Holocene.RESUMO -Este trabalho apresenta os resultados do estudo tafonômico das diatomáceas holocênicas da Bacia Llano Grande, Páramo de Frontino, localizado a 3.460 m acima do nível do mar, noroeste da Cordilheira dos Andes (6°29'N/76°6'O), Colômbia. Foram coletadas aleatoriamente amostras de 1 cm 3 de sedimentos, distribuídas em 57 níveis ao longo dos 8,5 m do testemunho LLG3, as quais representam um paleolago que se desenvolveu na bacia. A densidade das diatomáceas e o número de valvas fragmentadas e dissolvidas foram estimados a partir de 10 uL de cada amostra. A alta variabilidade na densidade e preservação das assembleias de diatomáceas no testemunho está relacionada com variação de temperatura, consumo por macroinvertebrados, aporte de cinzas vulcânicas e fl utuações no nível de água ao longo dos 11.000 anos AP (C 14 ). A fragmentação foi superior à dissolução, o que indica predominância de ambientes lóticos e consumo por herbívoros. O decréscimo substancial das diatomáceas em nível específi co é interpretado como resultado da limitação de sílica, diminuição dos níveis de água, intensa herbivoria, ambiente seco ou dissolução. Nestes casos, é impossível reconhecer a maioria das diatomáceas perifíticas devido ao grau de fragmentação das frústulas...

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“…The results also emphasis good correlation between soil available nitrogen and SGW contamination with nitrate (r 2 = 0.80 and 0.73 for winter and summer, respectively). Based on these results, we can expect that the Siwa drain is subject to be suffering from eutrophication, especially in winter seasons (Schelske and Stoermer, 1971, Schindler, 1971, Schindler, 1974and Conleyl et al, 1993. …”

Section: Fig 2 the Interrelationship And Correlation Between Sgw Dementioning

confidence: 99%

Impact of Irrigation Management on Shallow Groundwater Fluctuation and Soil Salinity: The Saltmed Model

2014

Egypt.J. Soil Sci.

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N SIWA OASIS, situated in Egypt, secondary salinization of irrigated lands is a crucial problem. The results found that the Siwa shallow groundwater (SGW) and high summer evapotranspiration is considered the main cause of soil salinization, however, the irrigation water sodicity is considered the main causes of soil sodicity. The SGW depth generally decreased in winter and increased in summer seasons. High correlation was found between the soil EC (dS m -1 ) and soil SAR and Cl (meq L -1 ) (R 2 = 0.89 and 0.91 for SAR and Cl, respectively), consequently, the dominant ions in Siwa soil solution are Na and Cl. The results also emphasis good correlation between soil available nitrogen and SGW contamination with nitrate (r 2 = 0.80 and 0.73, winter and summer, respectively). The eutrophication is expected in the study area especially in winter seasons due to nitrate concentrations increase. A conceptual, daily, semi-distributed hydrologic Saltmed model was found to be successful under Siwa climatic conditions. The model recorded that the quantity of irrigation water used in traditional irrigation is more than requirement. The traditional irrigation applies 300 L/m 2 /14 days, however, the quantity of 50 L/m 2 /14 days is adequate for olive crop water requirement and soil salinity removal. The results of this research could be applicable to similar situations worldwide.

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Modification of the biogeochemical cycle of silica with eutrophication

Cited by 435 publications

References 50 publications

Dissolved silicate retention and transport in cascade reservoirs in Karst area, Southwest China

Dissolved silicate retention and transport in cascade reservoirs in Karst area, Southwest China

Taphonomic signatures and paleoecology of Holocene diatom assemblages in the Llano Grande Basin, northwestern Andean Cordillera, Colombia

Impact of Irrigation Management on Shallow Groundwater Fluctuation and Soil Salinity: The Saltmed Model

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