scholarly journals Transportation and Transformation of Arsenic Species at the Intertidal Sediment-Water Interface of Bohai Bay, China

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Xiaoping Yu ◽  
Yafei Guo ◽  
Qin Wang ◽  
Tianlong Deng
Keyword(s):  
Environmental Conditions ◽  
Intertidal Zone ◽  
Stable State ◽  
Arsenic Species ◽  
Intertidal Sediment ◽  
Bohai Bay ◽  
Diffusive Flux ◽  
Water Interface ◽  
Overlying Water ◽  
Vertical Distributions

Arsenic species including arsenite As(III), arsenate As(V), monomethylarsenate (MMA), dimethylarsenate (DMA), and some diagenetic constituents (Fe, Mn, and S2−) in porewaters along with the unstable arsenic species in sediments collected from a typical intertidal zone of Bohai Bay in China were measured. Their vertical distributions were subsequently obtained to reveal the transportation and transformation characteristics of arsenic at the intertidal sediment-water interface (SWI). Results show that the reduction of As(V) by microorganisms occurred in sediments, but the methylation of arsenic by microorganisms was weak in the intertidal zone. The distribution of As(V) was mainly controlled by Mn, whereas As(III) appeared to be more likely controlled by Fe. Arsenic in sediments mainly existed in a stable state, so that only little arsenic could be released from sediments when the environmental conditions at the SWI are changed. As(III) diffused from porewaters to the overlying water while the opposite was true for As(V) at that time when the samples were collected. The total diffusion direction for arsenic across the SWI was from porewaters to the overlying water with a total diffusive flux estimated at 1.23 mg·m−2·a−1.

Factors Influencing Desorption of Mercury from Bed Sediments

1975 ◽  
Vol 12 (6) ◽  
pp. 1036-1040 ◽  
Author(s):  
Akira Kudo ◽  
D. C. Mortimer ◽  
J. Sanford Hart
Keyword(s):  
Environmental Conditions ◽  
Total Mercury ◽  
Exposure Period ◽  
Desorption Rate ◽  
Overlying Water ◽  
Bed Sediments ◽  
Ottawa River ◽  
Factors Influencing ◽  
River Bed

The desorption rate of mercury from bed sediments was determined by a 10 week experiment. The rates ranged from 0.1 ng/cm2/day to 1.0 ng/cm2/day for Ottawa River bed sediments, depending on the environmental conditions. The rates decreased with an increase of exposure period to the water, but increased with an increase in the depth of bed sediments. The amount of mercury desorbed from bed sediments to overlying water was highly dependent on the volume (depth) of bed sediments. Calculations based on the experiment showed the half-lives of total mercury associated with bed sediments from as short as 2.1 years to as long as 1.8 × 102 years, depending on the depth of the bed sediments.

scholarly journals Behaviour of Metal(loid)s at the Sediment-Water Interface in an Aquaculture Lagoon Environment (Grado Lagoon, Northern Adriatic Sea, Italy)

2021 ◽  
Vol 11 (5) ◽  
pp. 2350
Author(s):  
Elisa Petranich ◽  
Matteo Crosera ◽  
Elena Pavoni ◽  
Jadran Faganeli ◽  
Stefano Covelli
Keyword(s):  
Sediment Cores ◽  
Fish Farm ◽  
Trophic Chain ◽  
Water Interface ◽  
Northern Adriatic Sea ◽  
Overlying Water ◽  
Northern Adriatic ◽  
In Situ Experiments ◽  
Diffusive Fluxes ◽  
Lagoon Environment

The cycling of metal(loid)s at the sediment–water interface (SWI) was evaluated at two selected sites (VN1 and VN3) in an active fish farm in the Grado Lagoon (Northern Adriatic, Italy). In situ experiments using a transparent benthic chamber and the collection of short sediment cores were performed, to investigate the behavior of metal(loid)s in the solid (sediments) and dissolved (porewaters) phases. Total and labile concentration of metal(loid)s were also determined in sediments, to quantify their potential mobility. Comparable total concentrations were found at both sites, excluding As, Mn, Pb and V, which were higher at VN3. Metal(loid) porewater profiles showed a diagenetic sequence and a close dependence with redox (suboxic/anoxic) conditions in the surface sediments. Positive diffusive fluxes along with benthic fluxes, particularly at the more oxic site, VN1, were found for almost all metal(loid)s, indicating their tendency to migrate towards the overlying water column. Despite sediments at two sites exhibiting high total metal(loid) concentrations and moderate effluxes at the SWI, the results suggest that they are hardly remobilized from the sediments. Recycling of metal(loid)s from the SWI would not constitute a threat for the aquatic trophic chain in the fish farm.

scholarly journals Sediment-water column fluxes of carbon, oxygen and nutrients in Bedford Basin, Nova Scotia, inferred from <sup>224</sup>Ra measurements

2013 ◽  
Vol 10 (1) ◽  
pp. 53-66 ◽  
Author(s):  
W. J. Burt ◽  
H. Thomas ◽  
K. Fennel ◽  
E. Horne
Keyword(s):  
Organic Matter ◽  
Nova Scotia ◽  
Water Column ◽  
Explicit Knowledge ◽  
Dissolved Inorganic Carbon ◽  
Chemical Constituents ◽  
Water Interface ◽  
Benthic Fluxes ◽  
Pore Waters ◽  
Overlying Water

Abstract. Exchanges between sediment pore waters and the overlying water column play a significant role in the chemical budgets of many important chemical constituents. Direct quantification of such benthic fluxes requires explicit knowledge of the sediment properties and biogeochemistry. Alternatively, changes in water-column properties near the sediment-water interface can be exploited to gain insight into the sediment biogeochemistry and benthic fluxes. Here, we apply a 1-D diffusive mixing model to near-bottom water-column profiles of 224Ra activity in order to yield vertical eddy diffusivities (KZ), based upon which we assess the diffusive exchange of dissolved inorganic carbon (DIC), nutrients and oxygen (O2), across the sediment-water interface in a coastal inlet, Bedford Basin, Nova Scotia, Canada. Numerical model results are consistent with the assumptions regarding a constant, single benthic source of 224Ra, the lack of mixing by advective processes, and a predominantly benthic source and sink of DIC and O2, respectively, with minimal water-column respiration in the deep waters of Bedford Basin. Near-bottom observations of DIC, O2 and nutrients provide flux ratios similar to Redfield values, suggesting that benthic respiration of primarily marine organic matter is the dominant driver. Furthermore, a relative deficit of nitrate in the observed flux ratios indicates that denitrification also plays a role in the oxidation of organic matter, although its occurrence was not strong enough to allow us to detect the corresponding AT fluxes out of the sediment. Finally, comparison with other carbon sources reveal the observed benthic DIC release as a significant contributor to the Bedford Basin carbon system.

scholarly journals Oxygen consumption and nutrient fluxes in coastal marine sediments off the Mejerda River delta (Gulf of Tunis)

2015 ◽  
Vol 16 (3) ◽  
pp. 636 ◽  
Author(s):  
M. A. HELALI ◽  
N. ZAABOUB ◽  
W. OUESLATI ◽  
A. ADDED ◽  
L. ALEYA
Keyword(s):  
Oxygen Consumption ◽  
General Scheme ◽  
Benthic Flux ◽  
River Delta ◽  
Diffusive Flux ◽  
Water Interface ◽  
Gulf Of Tunis ◽  
Coastal Marine ◽  
Benthic Chambers

The authors studied benthic flux of oxygen, alkalinity, and nutrients in situ at three points in the Mejerda River Delta at depths of 10m, 20m and 40m in March and August 2012. Three sedimentary cores were simultaneously drilled at the same locations to determine the diffusive flux of NO2-, NO3-, NH4+ and PO43- and to estimate diagenetic mechanisms occurring below the sediment-water interface. Photosynthesis was not sufficiently high during the day, and the oxygen consumption at sediment-water interface was about 1.7 to 10mmol/m²/day, essentially controlled by the degradation of organic matter and oxidation of reduced elements. Nitrate contents are relatively high in the sediment (above 140μM for NO3-)and their production is not always in conformity with the general scheme of early diagenesis, moreover, benthic flux between water and sediment are not clearly established. The diffusive flux of NH4+ and PO43- are always directed to the water column, at averages of 1.27μmol/m²/day for PO43- and 96.5μmol/m²/day for NH4+, complying with those measured by benthic chambers, but representing less than 30% of benthic fluxes for NH4+ and less than 5% for PO43-.

Dissolved Inorganic Nitrogen Fluxes at Sediment-Water Interface in Yangtze Estuarine Tidal Flat

2013 ◽  
Vol 726-731 ◽  
pp. 288-295 ◽  
Author(s):  
Huan Guang Deng ◽  
Dong Qi Wang ◽  
Zhen Lou Chen
Keyword(s):  
Tidal Flat ◽  
Environmental Gradients ◽  
Inorganic Nitrogen ◽  
Yangtze Estuary ◽  
Water Interface ◽  
Dissolved Inorganic Nitrogen ◽  
Overlying Water ◽  
Spatial Differences ◽  
Estuary Sediment ◽  
Temporal And Spatial

Yangtze estuary data, collected over three years, indicates that the temporal and spatial distributions of the environmental gradients reflect complicated seasonal changes and spatial differences in the exchange flux of the dissolved inorganic nitrogen (DIN= NH4++ NO3-+ NO2-) across the sediment-water interface. Overall in northern sites of Yangtze estuary, sediment was a source of ammonium (NH4+) (-3.67~10.65 mmol·m-2·d-1) probably because of higher salinities. Sediment was a sink for NH4+ in southern sites (-18.45~3.33 mmol·m-2·d-1) during most years. The exchange behavior of nitrate (NO3-) showed temporal and spatial variation from the upper to lower estuary and ranged from-32.8 mmol·m-2·d-1 to 35.8 mmol·m-2·d-1. The interface exchange direction of ammonium was affected by NH4+ concentration, but the relationship between NO3- concentration and the direction of flux was not obvious. The concentration of nitrite (NO2-) was very low and its interface flux was not related to DIN concentration. Overall, the sediment of Yangtze Estuarine tidal flat was a source of DIN to overlying water in the spring, but a sink for DIN during the other three seasons of the year.

Nutrient fluxes across sediment-water interface in Bohai Bay Coastal Zone, China

2017 ◽  
Vol 114 (2) ◽  
pp. 705-714 ◽  
Author(s):  
Di Mu ◽  
Dekui Yuan ◽  
Huan Feng ◽  
Fangwei Xing ◽  
Fang Yenn Teo ◽  
...  
Keyword(s):  
Coastal Zone ◽  
Nutrient Fluxes ◽  
Bohai Bay ◽  
Water Interface

Le banc des Hermelles de la baie du Mont-Saint-Michel, bioherme a annelides; sedimentologie, structure et genese

1967 ◽  
Vol S7-IX (1) ◽  
pp. 68-78 ◽  
Author(s):  
R. Mathieu
Keyword(s):  
Surface Area ◽  
Environmental Conditions ◽  
Intertidal Zone ◽  
Hydrodynamic Regime ◽  
English Channel ◽  
Reef Complex ◽  
Precise Analysis

Abstract The Hermelles bank is a bioherm built by sedentary polychaete annelids along the coast of the English Channel (Bay of Saint-Michel). Situated in the lower part of the intertidal zone, the bank forms a mass over 400 hectares in surface area. Compilation of a detailed map has permitted a precise analysis of the 'reef' constructions and the associated sediments (biogenic sands, fine sands, calcareous mud) and the proposal of a hypothesis concerning the genesis and evolution of the bank. The faunal association encountered is not characteristic of the bank; the bioherm is characterized by the favorable environmental conditions found there by the organisms. The hydrodynamic regime dominant in this part of the Bay of Saint-Michel is responsible for the establishment and development of the reef complex.

Spatial distribution of the intertidal snail Ilyanassa obsoleta in relation to parasitism by two species of trematodes

2000 ◽  
Vol 78 (7) ◽  
pp. 1137-1143 ◽  
Author(s):  
Dean G McCurdy ◽  
J Sherman Boates ◽  
Mark R Forbes
Keyword(s):  
Spatial Distribution ◽  
Intertidal Zone ◽  
Bay Of Fundy ◽  
Spatial Distributions ◽  
Ilyanassa Obsoleta ◽  
Intermediate Hosts ◽  
Corophium Volutator ◽  
Vertical Distributions ◽  
Second Intermediate Host ◽  
Intertidal Snail

We studied the spatial distributions of mud snails (Ilyanassa obsoleta) infected by two trematodes, Lepocreadium setiferoides and Gynaecotyla adunca, on a macrotidal mudflat in the Minas Basin, Bay of Fundy. Snails, as first intermediate hosts, were castrated by both parasites, and we found no evidence of sex differences in parasitism. Similar to previous work, prevalence of L. setiferoides in I. obsoleta increased exponentially with host size (and age). Unexpectedly, prevalence of G. adunca decreased over the largest size classes of snails, a result that may be due to several causes. Distributions of both parasites across the intertidal zone differed from previous accounts in that snails infected with L. setiferoides were found only in the middle of the intertidal zone, whereas prevalence of G. adunca increased exponentially moving seaward. Several species of polychaetes could be infected by L. setiferoides in the laboratory and may act as appropriate second intermediate hosts, whereas only the amphipod Corophium volutator served as a second intermediate host for G. adunca. Finally, the vertical distributions of I. obsoleta infected by either species of trematode overlap with distributions of apparent or known second intermediate hosts.

Response of diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT) trace metal profiles in sediments to phytodetritus mineralisation

2012 ◽  
Vol 9 (1) ◽  
pp. 41 ◽  
Author(s):  
Yue Gao ◽  
Martine Leermakers ◽  
Annelies Pede ◽  
Aurelie Magnier ◽  
Koen Sabbe ◽  
...  
Keyword(s):  
Thin Films ◽  
Trace Metals ◽  
Trace Metal ◽  
Phytoplankton Bloom ◽  
Marine Ecosystem ◽  
Trace Metal Concentration ◽  
Water Interface ◽  
Overlying Water ◽  
Study Laboratory ◽  
Diffusive Gradients

Environmental contextContaminated sediments can have a large and lasting effect on marine ecosystems. It was discovered that significant amounts of pollutants, especially arsenic, were released from contaminated sediments during a phytoplankton bloom in the Belgian Continental Zone. Once released to the water column, these pollutants can accumulate up marine food chains and be a source of contaminants to humans. AbstractField data from the Belgian Continental Zone showed elevated trace metal concentrations at the sediment–water interface after the occurrence of a phytoplankton bloom. In the present study, laboratory incubation experiments were used to investigate the effect of the phytodetritus remineralisation process on the release of trace metals from contaminated muddy sediments. This remineralisation process was followed by the measurement of chlorophyll-a and dissolved organic carbon levels in the top sediment layers. Two gel techniques, diffusive equilibrium in thin films (DET) and diffusive gradients in thin films (DGT), were used to assess vertical metal profiles in the sediment pore waters and to calculate the metal effluxes. These metal effluxes compared very well with the trace metal concentration variations in the overlying water of the sediment. Much higher effluxes of Mn, Co and As were observed after 2 days of incubation in the microcosms which received additions of phytodetritus. This trend gradually decreased after 7 days of incubation, suggesting that the elevated efflux of trace metals was proportional to the quantity of phytodetritus mineralised at the sediment–water interface. The release of large amounts of toxic elements from the sediments after phytoplankton blooms can therefore potentially affect the marine ecosystem in the Belgian Continental Zone.

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