The distribution of phosphate in sediments and its relation with eutrophication of a Mediterranean coastal lagoon

Mesnage, Valérie; Picot, B.

doi:10.1007/bf00033499

Cited by 54 publications

(27 citation statements)

References 18 publications

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“…In the Thau benthos was largely responsible for the 24-fold differlagoon, the release of phosphates adsorbed onto ence between ratios in porewater and those in the Fe(OOH), but also onto CaCO,, is maximum in sumwater column measured before anoxia. During anoxia mer due to minimum redox and pH (Mesnage & (August), the [NH,+]:[SRP] ratio in porewater dropped Picot 1995). The extension of h~g h [SRP] in porewater to at least 1 mo after the end of the anoxic pcriod Table 3.…”

Section: Dissolved Inorganic Nitrogen Dissolved Inorganic Nitrogenmentioning

confidence: 98%

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Souchu¹,

Gasc²,

Collos³

et al. 1998

Mar. Ecol. Prog. Ser.

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Physical and chemical characteristics (temperature, salinity, dissolved oxygen), nutrients [dissolved inorganic nitrogen (DIN), soluble reactive phosphorus (SRP) and silicate], dissolved organic nitrogen (DON) and phosphorus and particulate matter [particulate organic carbon (POC) and nitrogen (PON) and chlorophyll a] were measured at a station located in the deepest part of the Thau lagoon (8.5 m), France, during a 10 d period of bottom anoxia in summer 1994. The upper 8 cm of sediment were also analyzed for ammonium (NH,') and SRP concentrations in the pore.water. The study period was characterized by mean wlnd speed under 4 m S-' which induced an increase of surface temperature from 18 to 2g°C with the formation of a thermocline. The correlation (p < 10-4) between the wind speed averaged over the previous day and the difference between bottom and surface temperatures showed that the wind conshtuted the main vector of vertical mixing. The lack of wind led to dissolved oxygen depletion in the bottom 2 m and to a strong porosity increase in the upper 10 cm of sediment (80 to >95%). Anoxic conditions increased NH,+ and SRP concentrations in porewater from 231 + 89 to 1305 + 305 (+ SD) ).]M and from 6.6 + 0.8 to 108 t 43 PM respectively. The potential increase of NH,' concentrations in porewater estimated from the mineralization of the microphytobenthos explained 30% of the measured increase in the upper 8 cm of porewater. The study period was characterized by an increase in NH4+, SRP and dissolved Si concentratlons in the bottom water column (maxima respectively 24.2, 4.9 and 57 PM). Linear regressions between nutrient concentrations in the water column and temperature revealed a strong enhancement of bottom fluxes during anoxia. Nitrate + nitrite (No3-+ NO2-) were absent in anoxic waters and remained below 0.5 pM in oxic waters. Monthly concentrations of SRP in the water column of the Thau lagoon from 1970 to 1994 revealed anoxia events by summer peak values corresponding to strong bottom anoxia. Nevertheless, the general trend was a decrease due to the gradual control of eutrophication which should lead to the disappearance of bottom anoxia within the next decade. A fraction of the nutrients of benthic origin was transformed into planktonic particulate matter vla prlmary production whlch increased the concentrations of chl a from about 1 to 15 pg I-'. Concentrations of DON and PON in the water column were significantly correlated, suggest~ng that DON compounds were released by the pelagic food web but not directly by the sediment. The increase of total nitrogen (DIN + DON + PON), considering the water column as a closed box during 10 d of winds under 5 m S-', was estimated at 1.7 pm01 N 1-' d-' and would correspond to a benthic flux of 600 pm01 N m-2 h-' for 10 d.

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Section: Dissolved Inorganic Nitrogen Dissolved Inorganic Nitrogenmentioning

confidence: 98%

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Souchu¹,

Gasc²,

Collos³

et al. 1998

Mar. Ecol. Prog. Ser.

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“…Dry season BK2 AS4 BS12 SR18 SR22 PT28 MP32 MP35 MP36 TP38 TP40 KG45 KG46 CB47 CB48 VR49 VR50 TD51 BK2 AS4 BS12 SR18 SR22 PT28 MP32 MP35 MP36 TP38 TP40 KG45 KG46 CB47 CB48 VR49 VR50 TD51 TD52 Station % Total P Residual P Ca-P Fe and Al-P Adsorbed-P immobile form in sediments 4 , it may become available for algae growth by a mineralization process involving microbial activity 1,4,6 . Moreover, the results obtained here show negative correlation of available P with organic matter (r = -0.431, p<0.01) and with dissolved oxygen (r = -0.257, p<0.05) ( Table 7).…”

Section: Sediment Samplingmentioning

confidence: 99%

“…Dissolved inorganic P is considered bioavailable, whereas organic and particulate P forms generally must undergo a transformation into inorganic forms before being considered bioavailable 3 . Phosphorus adsorbed onto sediments can be released into the overlying water depending on the chemical forms in the sediments 4,5 and the environmental conditions 5,6 , such as pH, redox potential, microbes, bioturbation etc. The released P may become available to algae and stimulate blooms of phytoplankton, and excess can lead to eutrophication of the water body.…”

Section: Introductionmentioning

confidence: 99%

“…Knowledge of chemical speciation of sedimentbound P, is necessary to evaluate the bioavailable P which is the amount of P that is biologically usable, because each chemical form has its own ability of release from the sediments 4 . Sediment fractionation helps in identifying the chemical forms of P and can highlight the pathways it takes into the coastal waters 7 .…”

Section: Introductionmentioning

confidence: 99%

“…The available P was also extracted from the sediments by direct chemical leaching with a dilute acid-fluoride solution, a combination of HCl and NH 4 Selected sediment characteristics were determined as follows: pH in water at a sediment to solution ratio of 1:2.5, calcium carbonate by the approximate gravimetric method for loss of carbon dioxide 14 , organic matter by the acid-dichromate oxidation method 15 , particle size distribution by the hydrometer method 16 and sediment texture was classified according to the U.S. Agriculture texture triangle 17 . Extractable iron (Fe) and manganese (Mn) oxides were also examined in the sediments.…”

Section: Introductionmentioning

confidence: 99%

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Thongra-ar¹,

Musika²,

Mokkongpai³

et al. 2004

ScienceAsia

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ABSTRACT:The amount of total phosphorus (P) and its chemical forms were investigated in sediments of the Eastern Coast of Thailand in the dry (April 2001) and wet (July 2001) seasons. The amounts of total P ranged from 55.83 to 2,575.83 and from 30.0 to 2,672.50 µg g -1 dry weight for the dry and wet seasons, respectively. The P in sediments was mainly in an inorganic rather than organic form. Sediment inorganic P fractions were determined by a sequential extraction technique. In the estuarine sediments, the major form of P was Fe, Albound P and the second most abundant form was organic P, whereas the other sediments showed different relative dominant P forms depending on the sediment characteristics of each location. The seasonal change had an influence on the chemical form of P available. In the dry season the available fractions were derived from organic P, those in the wet season were derived largely from Fe, Al-bound P. The available concentrations found for both seasons were very similar in terms of the percentage of total P. It was also found that in most samples, the available forms were very low, comprising less than 10 % of total P.In this study Fe oxides were found to be the major P sorbent of the sediments, followed by clay contents, while organic matter and CaCO 3 were less effective in sorbing P. In addition, the sediment P concentrations decreased with increasing sediment pH and salinity of the overlying water.

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Environmental Variables and Planktonic Communities in Two Ponds of El Hondo Wetland (SE Spain)

Rodrigo

Armengol-Díaz

Oltra

et al. 2001

Internat. Rev. Hydrobiol.

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The annual cycle of physical and chemical variables and plankton dynamics was studied in two shallow ponds (East and West Ponds) of the El Hondo wetland, an ecosystem of international importance. Water conductivity increased up to 31–49 mS cm–1 as water level decreased due to high evaporation and minimal water inputs. Initially considered mesohaline, the waters were reclassified as polyhaline during the hot season. EP was subject to successive desiccation‐flooding cycles, and flooding of the dried sediment caused the release of high concentrations of nitrogen and phosphorus compounds, which quickly depleted. The algal species composition was typical of eutrophic ecosystems, and the chlorophyll content indicated that EP was eutrophic and WP mesotrophic. Phytoplanktonic species richness and diversity were low in both ponds. Algal assemblages, in terms of biovolume, were mainly dominated by Dinophyceae in EP and by Cryptophyta in WP. The zooplankton community was dominated by Rotifers (Brachionus and Hexarthra), although Copepods and Ciliates were also important. Different water inputs to the ponds, partial drying in EP during the warm season with the subsequent higher increment of salinity, and the presence of dense populations of submerged macrophytes in WP, explain the differences in plankton communities found between the two ponds.

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The distribution of phosphate in sediments and its relation with eutrophication of a Mediterranean coastal lagoon

Cited by 54 publications

References 18 publications

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Biogeochemical aspects of bottom anoxia in a Mediterranean lagoon (Thau, France)

Untitled

Environmental Variables and Planktonic Communities in Two Ponds of El Hondo Wetland (SE Spain)

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