Depth profiles of volatile iodine and bromine-containing halocarbons in coastal Antarctic waters   总被引：1，自引：0，他引：1  

L.J. Carpenter  D.J. Wevill  C.J. Palmer  J. Michels 《Marine Chemistry》2007,103(3-4):227-236

Measurements of bromoform (CHBr₃), diiodomethane (CH₂I₂), chloroiodomethane (CH₂ICl) and bromoiodomethane (CH₂IBr) were made in the water column (5–100 m depth) of the Southern Ocean within 0–40 km of the Antarctic sea ice during the ANTXX1/2 transect of the German R/V Polarstern, at five locations between 70–72°S and 9–11°W in the Antarctic spring/summer of 2003–2004. Some of the profiles exhibited a very pronounced layer of surface sea-ice meltwater, as evidenced by salinity minima and temperature maxima, along with surface maxima in concentrations of CHBr₃, CH₂I₂, CH₂ICl and CH₂IBr. These results are consistent with in situ surface halocarbon production by ice algae liberated from the sea ice, although production within the sea ice followed by transport cannot be entirely ruled out. Additional sub-surface maxima in halocarbons occurred between 20 and 80 m. At a station further from shore and not affected by surface sea-ice meltwater, surface concentrations of CH₂I₂ were decreased whereas CH₂ICl concentrations were increased compared to the stations influenced by meltwater, consistent with photochemical conversion of CH₂I₂ to CH₂ICl, perhaps during upward mixing from a layer at  70 m enhanced in iodocarbons. Mean surface (5–10 m) water concentrations of halocarbons in these coastal Antarctic waters were 57 pmol l^− 1 CHBr₃ (range 44–78 pmol l^− 1), 4.2 pmol l^− 1 CH₂I₂ (range 1.7–8.2 pmol l^− 1), 0.8 pmol l^− 1 CH₂IBr (range 0.2–1.4 pmol l^− 1), and 0.7 pmol l^− 1 CH₂ICl (range 0.2–2.4 pmol l^− 1). Concurrent measurements in air suggested a sea-air flux of bromoform near the Antarctic coast of between 1 and 100 (mean 32.3, median 10.4) nmol m^− 2 day^− 1 and saturation anomalies of 557–1082% (mean 783%, median 733%), similar in magnitude to global shelf values. In surface samples affected by meltwater, CH₂I₂ fluxes ranged from 0.02 to 6.1 nmol m^− 2 day^− 1, with mean and median values of 1.9 and 1.1 nmol m^− 2 day^− 1, respectively.  相似文献   

Comparison of β-dimethylsulfoniopropionate (DMSP) levels in two mediterranean ecosystems with different trophic levels     

Natacha Jean  Grard Boge  Jean-Louis Jamet  Dominique Jamet 《Marine Chemistry》2006,101(3-4):190-202

β-dimethylsulfoniopropionate (DMSP) and dimethylsulfide (DMS) concentrations were recorded from September 1999 to September 2000 in two geographically close ecosystems, differently affected by eutrophication: the Little Bay of Toulon and the Niel Bay (N.W. Mediterranean Sea, France). Little Bay had higher nutrient levels ([NO₃⁻]_max. = 30.3 μM; [PO₄³⁻]_max. = 0.46 μM) and higher chlorophyll a concentrations ([chl a]_mean = 2.4 μg/L) compared to Niel Bay ([NO₃⁻]_max. = 19.7 μM; [PO₄³⁻]_max. = 0.17 μM; [chl a]_mean = 0.4 μg/L). In the two sites, we measured dissolved (DMSP_d < 0.2 μm) and particulate DMSP (DMSP_p > 0.2 μm) concentrations. The DMSP_p was particularly analysed in the 0.2–5, 5–90 and > 90 μm fractions. In the eutrophicated Little Bay, DMSP_d concentrations showed a clear seasonality with high values from January to March (124–148 nM). The temporal profile of the DMSP_p concentrations was similar, peaking in February–March (38–59 nM). In the less eutrophic Niel Bay, DMSP_p concentrations were much lower (6–9 nM in March–April), whereas DMSP_d concentrations were relatively high (110–92 nM in February–March). DMS concentrations were elevated from the end of the winter to the spring in Little Bay, ranging from 3 nM in October to 134 nM in March. In the less eutrophic Niel Bay, lower DMS levels were observed, generally not exceeding 20 nM. Each particulate fraction (0.2–5; 5–90; > 90 μm) contained less DMSP in Niel Bay than in Little Bay. At both sites, the 5–90 μm fraction made up most of the DMSP_p. This 5–90 μm fraction consisted of microphytoplankton, principally Dinophyceae and Bacillariophyceae. The 5–90 μm biomass calculated from cell biovolumes, was more abundant in Little Bay where the bloom at the end of the winter (165 μg/L in March) occurred at the same time as the DMSP peaks. The estimated DMSP_p to biomass ratio for the 5–90 μm fraction was always higher in Little Bay than in Niel Bay. This suggests that the high DMSP levels recorded in Little Bay were not only due to a large Dinophyceae presence in this ecosystem. Indeed, the peak of DMSP_p to biomass ratio obtained from cell biovolumes (0.23 nmol/μg in March) was consistent with the proliferation of Alexandrium minutum. This Dinophyceae species may account for between 50% (2894 cells/L) and 63% (4914 cells/L) of the total phytoplankton abundance in the Little Bay of Toulon.  相似文献   

On the relevance of iron adsorption to container materials in small-volume experiments on iron marine chemistry: Fe-aided assessment of capacity, affinity and kinetics     

A.C. Fischer  J.J. Kroon  T.G. Verburg  T. Teunissen  H.Th. Wolterbeek 《Marine Chemistry》2007,107(4):533-546

Iron chemistry in seawater has been extensively studied in the laboratory, mostly in small-volume sample bottles. However, little has been reported about iron wall sorption in these bottles. In this paper, radio-iron ⁵⁵Fe was used to assess iron wall adsorption, both in terms of capacity, affinity and kinetics. Various bottle materials were tested. Iron sorption increased from polyethylene/polycarbonate to polymethylmetacrylate (PMMA)/high-density polyethylene/polytetrafluoroethylene to glass/quartz, reaching equilibrium in a 25–70 h period. PMMA was studied in more detail: ferric iron (Fe(III)) adsorbed on the walls of the bottles, whereas ferrous iron (Fe(II)) did not. Considering that in seawater the inorganic iron pool mostly consists of ferric iron, the wall will be a factor that needs to be considered in bottle experiments.The present data indicate that for PMMA with specific surface (S)-to-volume (V) ratio S/V, both iron capacity (42 ± 16 × 10^− 9 mol/m² or 1.7 × 10^− 9 mol/L recalculated for the S/V-specific PMMA bottles used) and affinity (log K_Fe'W = 11.0 ± 0.3 m²/mol or 12.4 ± 0.3 L/mol, recalculated for the S/V-specific PMMA bottles used) are of similar magnitude as the iron capacity and -affinity of the natural ligands in the presently used seawater and thus cannot be ignored.Calculation of rate constants for association and dissociation of both Fe'L (iron bound to natural occurring organic ligands) and Fe'W (iron adsorbed on the wall of vessels) suggests that the two iron complexes are also of rather similar kinetics, with rate constants for dissociation in the order of 10 ⁻⁴–10^− 5 L/s and rate constants for association in the order of 10⁸ L/(mol s). This makes that iron wall sorption should be seriously considered in small-volume experiments, both in assessments of shorter-term dynamics and in end-point observations in equilibrium conditions. Therefore, the present data strongly advocate making use of iron mass balances throughout in experiments in smaller volume set-ups on marine iron (bio) chemistry.  相似文献   

Seasonal survey of copper-complexing ligands and thiol compounds in a heavily utilized, urban estuary: Elizabeth River, Virginia   总被引：1，自引：1，他引：0  

Christina L. Dryden  Andrew S. Gordon  John R. Donat   《Marine Chemistry》2007,103(3-4):276-288

Concentrations of thiol compounds, copper-complexing ligands, and total dissolved copper were followed over the course of 1 year (October 2002 until September 2003) in the Elizabeth River, Virginia to evaluate seasonality. Copper-complexing ligand concentrations were determined by competitive ligand equilibration-adsorptive cathodic stripping voltammetry (CLE/ACSV). Thiol detection was carried out by high performance liquid chromatography (HPLC) and calibration using a suite of nine thiol compounds (cysteine, glutathione, mercaptoacetic acid, 2-mercaptoethanesulfonic acid, 2-mercaptoethanol, 2-mercaptopropionic acid, 3-mercaptopropionic acid, mercaptosuccinic acid, and monothioglycerol). Total dissolved copper concentrations reached a January low of 13.1 nM to a June high of 24.7 nM and were found to vary seasonally with higher concentrations occurring from June to September. With a low of 26 nM during April to a high of 56 nM in October, copper-complexing ligand (average log K′_CuL of 12.0 ± 0.2) concentrations displayed a similar seasonal pattern to that of total dissolved copper. Free cupric ion concentrations remained below 1.5 pM for a majority of the year except during March, April, and December when values reached pM levels greater than 1.5. Six of the nine thiol compounds surveyed were detected in the Elizabeth River samples and ranged in concentration from below detectable concentrations (< 5 nM) to individual highs ranging from 25.3 to168.5 nM. The thiol compound concentrations displayed a clear seasonality fluctuating at below detection limits during November to February then increasing with increasing surface water temperatures from March to July. CLE/ACSV was used to assess whether or not the suite of thiol compounds detected by HPLC could contribute to the copper-complexing ligand pool. Conditional stability constants for each one of six thiol standards (average log K′_CuL  12.1 ± 0.5) were found to be statistically equivalent to the naturally occurring copper-complexing ligands (average log K′_CuL  12.0 ± 0.2). This suggests that these thiol compounds could act as copper-complexing ligands in natural samples and could contribute to the copper-complexing ligand pool detected by CLE/ACSV. This study involving seasonality of copper-complexing ligands and thiols in an industrialized, urban estuary underscored several points that have to be substantiated in future research efforts including copper-complexing ligands sources and the role that thiol compounds as well as other unidentified organic compounds play in the copper-complexing ligand pool.  相似文献   

The impact of groundwater discharges on mercury partitioning, speciation and bioavailability to mussels in a coastal zone     

F.J.G. Laurier  D. Cossa  C. Beucher  E. Brvire 《Marine Chemistry》2007,104(3-4):143-155

The Mussel Watch program conducted along the French coasts for the last 20 years indicates that the highest mercury concentrations in the soft tissue of the blue mussel (Mytilus edulis) occur in animals from the eastern part of Seine Bay on the south coast of the English Channel, the “Pays de Caux”. This region is characterized by the presence of intertidal and submarine groundwater discharges, and no particular mercury effluent has been reported in its vicinity. Two groundwater emergence systems in the karstic coastal zone of the Pays de Caux (Etretat and Yport with slow and fast water percolation pathways respectively) were seasonally sampled to study mercury distribution, partitioning and speciation in water. Samples were also collected in the freshwater–seawater mixing zones in order to compare mercury concentrations and speciation between these “subterranean” or “groundwater” estuaries and the adjacent macrotidal Seine estuary, characterized by a high turbidity zone (HTZ). The mercury concentrations in the soft tissue of mussels from the same areas were monitored at the same time.The means of the “dissolved” (< 0.45 μm) mercury concentrations (HgT_D) in the groundwater springs were 0.99 ± 0.15 ng l^− 1 (n = 18) and 0.44 ± 0.17 ng l^− 1 (n = 17) at Etretat and Yport respectively. High HgT_D concentrations were associated with strong runoff over short water pathways during storm periods, while low concentrations were associated with long groundwater pathways. Mean particulate mercury concentrations were 0.22 ± 0.05 ng mg^− 1 (n = 16) and 0.16 ± 0.10 ng mg^− 1 (n = 17) at Etretat and Yport respectively, and decreased with increasing particle concentration probably as a result of dilution by particles from soil erosion. Groundwater mercury speciation was characterized by high reactive-to-total mercury ratios in the dissolved phase (HgR_D/HgT_D: 44–95%), and very low total monomethylmercury concentrations (MMHg < 8 pg l^− 1). The HgT_D distributions in the Yport and Etretat mixing zones were similar (overall mean concentration of 0.73 ± 0.21 ng l^− 1, n = 43), but higher than those measured in the adjacent industrialized Seine estuary (mean: 0.31 ± 0.11 ng l^− 1, n = 67). In the coastal waters along the Pays de Caux dissolved monomethylmercury (MMHg_D) concentrations varied from 9.5 to 13.5 pg l^− 1 (2 to 8% of the HgT_D). Comparable levels were measured in the Seine estuary (range: 12.2– 21.1 pg l⁻¹; 6–12% of the HgT_D). These groundwater karstic estuaries seem to be mostly characterized by the higher HgT_D and HgR_D concentrations than in the adjacent HTZ Seine estuary. While the HTZ of the Seine estuary acts as a dissolved mercury removal system, the low turbid mixing zone of the Pays de Caux receives the dissolved mercury inputs from the groundwater seepage with an apparent Hg transfer from the particulate phase to the “dissolved” phase (< 0.45 μm). In parallel, the soft tissue of mussels collected near the groundwater discharges, at Etretat and Yport, exhibited significantly higher values than those found in the mussel from the mouth of the Seine estuary. We observe that this difference mimics the differences found in the mercury distribution in the water, and argue that the dissolved phase of the groundwater estuaries and coastal particles are significant sources of bioavailable mercury for mussels.  相似文献   

Water mass ages of coastal ponds estimated using Ra and Ra as tracers     

A.L. Hougham  S.B. Moran 《Marine Chemistry》2007,105(3-4):194-207

Measurements of the naturally occurring radioisotopes ²²³Ra (t_1/2 = 11.4 days) and ²²⁴Ra (t_1/2 = 3.66 days) in southern Rhode Island salt ponds were combined with a simple model to obtain independent estimates of the age of these coastal waters. Surface water and porewater samples were collected quarterly in Winnapaug, Quonochontaug, Ninigret, Green Hill, and Pt. Judith-Potter Ponds, as well as nearly monthly in the surface water of Rhode Island Sound, beginning January 2002 through August 2003. Surface water activities ranged from 1–78 dpm 100 L^− 1 and 5–885 dpm 100 L^− 1 for ²²³Ra and ²²⁴Ra, respectively. Porewater radium activities ranged from 3 to 715 dpm 100 L^− 1 for ²²³Ra, and 57–4926 dpm 100 L^− 1 for ²²⁴Ra. Results indicate seasonally varying water mass ages for Ninigret (5–12 days), Winnapaug (2–6 days) and Pt. Judith-Potter Ponds (1–9 days) and, in contrast, relatively constant ages for Green Hill (5–7 days) and Quonochontaug Ponds (3–6 days).  相似文献   

Seasonal changes in submarine groundwater discharge to coastal salt ponds estimated using Ra and Ra as tracers     

A.L. Hougham  S.B. Moran  J.P. Masterson  R.P. Kelly 《Marine Chemistry》2008,109(3-4):268

Submarine groundwater discharge (SGD) to coastal southern Rhode Island was estimated from measurements of the naturally-occurring radioisotopes ²²⁶Ra (t_1/2 = 1600 y) and ²²⁸Ra (t_1/2 = 5.75 y). Surface water and porewater samples were collected quarterly in Winnapaug, Quonochontaug, Ninigret, Green Hill, and Pt. Judith–Potter Ponds, as well as nearly monthly in the surface water of Rhode Island Sound, from January 2002 to August 2003; additional porewater samples were collected in August 2005. Surface water activities ranged from 12–83 dpm 100 L^− 1 (60 dpm = 1 Bq) and 21–256 dpm 100 L^− 1 for ²²⁶Ra and ²²⁸Ra, respectively. Porewater ²²⁶Ra activities ranged from 16–736 dpm 100 L^− 1 (2002–2003) and 95–815 dpm 100 L^− 1 (2005), while porewater ²²⁸Ra activities ranged from 23–1265 dpm 100 L^− 1. Combining these data with a simple box model provided average ²²⁶Ra-based submarine groundwater fluxes ranging from 11–159 L m^− 2 d^− 1 and average ²²⁸Ra-derived fluxes of 15–259 L m^− 2 d^− 1. Seasonal changes in Ra-derived SGD were apparent in all ponds as well as between ponds, with SGD values of 30–472 L m^− 2 d^− 1 (Winnapaug Pond), 6–20 L m^− 2 d^− 1 (Quonochontaug Pond), 36–273 L m^− 2 d^− 1 (Ninigret Pond), 29–76 L m^− 2 d^− 1 (Green Hill Pond), and 19–83 L m^− 2 d^− 1 (Pt. Judith–Potter Pond). These Ra-derived fluxes are up to two orders of magnitude higher than results predicted by a numerical model of groundwater flow, estimates of aquifer recharge for the study period, and values published in previous Ra-based SGD studies in Rhode Island. This disparity may result from differences in the type of flow (recirculated seawater versus fresh groundwater) determined using each technique, as well as variability in porewater Ra activity.  相似文献   

Uncoupled distributions of transparent exopolymer particles (TEP) and dissolved carbohydrates in the Southern Ocean     

E. Ortega-Retuerta  I. Reche  E. Pulido-Villena  S. Agustí  C.M. Duarte   《Marine Chemistry》2009,115(1-2):59-65

Transparent exopolymer particles (TEP) are formed by the assembly of dissolved precursors, mainly mono and polysaccharides (DMCHO and DPCHO) that are released by microorganisms. Although TEP formation plays a significant role in carbon export to deep waters and can affect gas exchange at the sea surface, simultaneous measurements of TEP and their precursors in natural waters have been scantly reported. In this study, we described the spatial (vertical and regional) distribution of TEP, DMCHO and DPCHO in a region located around the Antarctic Peninsula, assessed their contribution to the total organic carbon pool, and explored their relationships with phytoplankton (with chlorophyll a (chl a) as a proxy) and bacteria. TEP concentration ranged from undetectable values to 48.9 µg XG eq L^− 1 with a mean value of 15.4 µg XG eq L^− 1 (11.6 µg TEP-C L^− 1). DMCHO and DPCHO showed average values of 4.3 µmol C L^− 1 and 8.6 µmol C L^− 1, respectively. We did not find simple relationships between the concentrations of TEP and dissolved carbohydrates, but a negative correlation between DMCHO and DPCHO was observed. Chl a was the best regressor of TEP concentration in waters within the upper mixed layer, while bacterial production was the best regressor of TEP concentration below the mixed layer, underlining the direct link between these particles and bacterial activity in deep waters.  相似文献   

Population structure, size at maturity and condition of sardine, Sardina pilchardus (Walb., 1792), in the nursery ground of the eastern Adriatic Sea (Krka River Estuary, Croatia)     

Gorenka Sinov i&#x;  Vanja ike&#x; Ke   Barbara Zorica 《Estuarine, Coastal and Shelf Science》2008,76(4):739-744

A total of 1125 specimens of sardine, Sardina pilchardus, ranging in total length from 4.9 to 12.5 cm (mean 8.31 ± 1.41 cm) and in weights between 1.02 g and 11.18 g (mean 4.40 ± 1.87 g) were randomly sampled using a beach seine from the Krka River estuary. Samples were collected monthly according to their occurrence in this area from October to February during 2002/03, 2003/04 and 2004/05, which is during the spawning period of this species. Monthly fluctuations in the length frequency distributions of sardine were observed during that time. The length–weight relationship of all sardine specimens was described by the equation: W=0.007L^2.9587(r² = 0.9626); and the isometric nature of relative growth was established (t = −5.1495; p < 0.05). According to the allometric condition factor K_a, sardine specimens were in better somatic condition at the beginning of their appearance (spawning period) in the Krka River estuary. The length at which 50% of sardines were mature (L₅₀) was calculated to be 7.9 cm.  相似文献   

Dissociation constants of protonated methionine species in seawater media     

Virender K. Sharma  Frank J. Millero  Concetta De Stefano  Pasquale Crea 《Marine Chemistry》2007,106(3-4):463-470

The dissociation constants (pK₁ and pK₂) for methionine have been measured in artificial seawater as a function of salinity (S = 5 to 35) and temperature (5 to 45 °C). The seawater pK₂ values were lower than the values in NaCl at the same ionic strength while the pK₁ values in seawater were lower only at S = 35. In an attempt to understand these differences, we have made measurements of the constants in Na–Mg–Cl solutions at 25 °C. The measured values have been used to determine the formation of Mg²⁺ complexes and Pitzer interaction parameters for Mg²⁺ with methionine. The seawater model with the interaction parameters accounts for the differences between the value of pK₁ and pK₂ between NaCl and seawater. This study demonstrates that it is important to consider all of the ionic interactions in natural waters when examining the dissociation of organic acids.  相似文献   

Time-series of surface water CO₂ and oxygen measurements on a platform in the central Arkona Sea (Baltic Sea): Seasonality of uptake and release   总被引：1，自引：1，他引：1  

Joachim Kuss  Wolfgang Roeder  K.-Peter Wlost  Michael D. DeGrandpre 《Marine Chemistry》2006,101(3-4):220-232

High resolution measurements of carbon dioxide and oxygen were made in surface waters of the central Arkona Sea (Baltic Sea) from May 2003 to September 2004. Sensors for CO₂ partial pressure (pCO₂^w) and oxygen (O₂) concentration were mounted in 7 m depth on a moored platform which is used for hydrographic and meteorological monitoring. The pCO₂^w data were obtained in half hour intervals and O₂ was measured each hour as an average of a 10 min measurement. To check the performance of the sensors, pCO₂^w and O₂ were determined by shipboard measurements on a research vessel which visited the site in 1–2 month intervals. In addition, pCO₂^w was measured on a “volunteer observing ship” (VOS) passing the platform each second day at a distance of about 25 km. Minima of 220 to 250 μatm of pCO₂^w were observed at the time of the spring bloom and a cyanobacteria bloom in mid-summer. During winter the pCO₂^w was mostly close to equilibrium with the atmosphere but maxima of 430 to 530 μatm were also observed. The seasonality of oxygen and pCO₂^w showed an opposing pattern. From a multiple regression analysis, we concluded that two processes primarily controlled pCO₂^w during our study: biological turnover and mixing. A parameterization, based on apparent oxygen utilisation (AOU) and salinity (S) only (pCO₂^w = 1.23 AOU + 43 S), reproduced the seasonality of pCO₂^w in surface water reasonably well. Based on our pCO₂, salinity, and temperature data set, we attempted to separate processes changing total inorganic carbon concentrations (C_T) by using an alkalinity–salinity relation for the area. The contribution of CO₂ gas exchange and mixing were calculated and from this the biological turnover was deduced to reveal the calculated C_T changes.The net annual uptake of CO₂ in the central Arkona Sea was estimated to be about 1.5 Tg (1.5·10¹² g) which was approximately balanced by a net oxygen release considering the uncertainties of the flux calculations. Near-coast CO₂ emission due to episodic upwelling partly compensated the uptake of the central part of the Arkona Sea reducing the overall magnitude of the CO₂ uptake.  相似文献   

Influence of salinity and humic substances on the uptake of trace metals by the marine macroalga, Ulva lactuca: Experimental observations and modelling using WHAM     

Andrew Turner  Silvia S. Pedroso  Murray T. Brown 《Marine Chemistry》2008,110(3-4):176-184

Uptake of the trace metals, Pd, Cd, Hg and Pb, by the marine macroalga, Ulva lactuca, has been studied along a salinity gradient (S = 15–35; pH ~ 8.3) created by batch mixing of synthetic sea water and pure water, both in the absence and presence of humic substances. Factors defining the concentration ratio of metal taken up (w/w) to metal remaining in solution ranged from about 10² mL g^− 1 for Cd to 10³ mL g^− 1 for Pd and Hg. Within experimental error, only the biouptake of Cd appeared to exhibit a dependence on salinity, while the addition of 3 mg L^− 1 of humics resulted in a small suppression of Pd and Hg uptake and a moderate enhancement of Pb uptake compared with the humic-free system. Metal internalisation, evaluated from an EDTA wash of the alga, followed the sequence: Hg > Pd > Cd > Pb; and was notably inhibited in the presence of humics for Pb. Metal uptake (as adsorption and internalisation) was modelled using the Windermere Humic Aqueous Model (WHAM, v6) by encoding the macroalga as a polyelectrolytic binding phase whose properties were defaulted to those of aqueous humics in the software database. By setting the “activity” of the binding phase to about 0.1 and systematically reducing the default constants for metal binding, the magnitude of metal uptake by U. lactuca was reproduced. However, for all metals the model predicted a reduction in algal uptake as a function of salinity that was not always observed experimentally. Moreover, calculations performed in the presence of aqueous humic substances and using the earlier fitted constants significantly underestimated metal uptake by U. lactuca. Discrepancies between experimental observations and model calculations, which are attributed to the formation of ternary complexes at the algal surface, suggest that conventional equilibrium speciation considerations alone are not applicable for modelling metal interactions with marine macroalgae.  相似文献   

Copper complexing ligands and organic matter characterization in the northern Adriatic Sea     

Marta Plav&#x;i&#x;  Blaenka Ga&#x;parovi&#x;  Sla&#x;ana Strme ki  Vjero ka Vojvodi&#x;  Nata&#x;a Tepi&#x; 《Estuarine, Coastal and Shelf Science》2009,85(2):299-306

The study on dissolved organic ligands capable to complex copper ions (L_T), surface-active substances (SAS) and dissolved organic carbon (DOC) in the Northern Adriatic Sea station (ST 101) under the influence of Po River was conducted in period from 2006–2008. The acidity of surface-active organic material (Ac_r) was followed as well. The results are compared to temperature and salinity distributions. On that way, the contribution of the different pools of ligands capable to complex Cu ions could be determined as well as the influence of aging and transformation of the organic matter. The L_T values in the investigated period were in the range of 40–300 nmol l⁻¹. The range of DOC values for surface and bottom samples were 0.84–1.87 mg l⁻¹ and 0.80–1.30 mg l⁻¹, respectively. Total SAS concentrations in the bottom layer were 0.045–0.098 mg l⁻¹ in equiv. of Triton-X-100 while those in the surface layer were 0.050–0.143 mg l⁻¹ in equiv. of Triton-X-100. The majority of organic ligands responsible for Cu binding in surface water originate from new phytoplankton production promoted by river borne nutrients. Older, transformed organic matter, possessing higher relative acidity, is the main contributor to the pool of organic ligands that bind copper in the bottom samples. It was estimated that 9% of DOC in surface samples and 12% of DOC in the bottom samples are present as ligands capable to complex copper ions.  相似文献   

Solvent extraction of copper acetylacetonate in studies of copper(II) speciation in seawater     

James W Moffett  Rod G Zika 《Marine Chemistry》1987,21(4)

A liquid-liquid partition, ligand exchange procedure involving the formation of copper(II) complexes with acetylacetone is presented for the determination of stability constants and concentrations of copper chelators in seawater. Acetylacetone competes with natural ligands for copper, and the equilibrium concentration of the copper acetylacetonate complex is used in speciation calculations. The concentration of the complex is calculated by partitioning a fraction of it into an organic phase and determining the total Cu concentration in that phase by back extracting with acid, and analyzing by flameless atomic absorption spectroscopy. The concentration of Cu acetylacetonate in seawater in equilibrium with the organic phase is calculated from the partition coefficient. The simple, thermodynamically well characterized procedure offers several advantages over previous techniques. Studies using organic free seawater and model ligands show good agreement between experimental and calculated conditional stability constants. Studies from seawater in Biscayne Bay, Florida, indicate two ligand types are present; type 1, K₁ = 1.2 × 10¹², C_L1 = 5.1 × 10⁻⁹ M; type 2, K₂ = 2.8 × 10¹⁰, C_L2 = 1.1 × 10⁻⁷ M. Speciation is dominated by ligand type 1. Depth profiles of [Cu(II)]_free/[Cu(II)]_total measured with the procedure at ambient copper concentrations show an increase from < 5 × 10⁻⁵ at 50–60 m to > 1 × 10⁻³ at the surface at two stations off the Florida coast.  相似文献   

Distributions and sources of bulk organic matter and aliphatic hydrocarbons in surface sediments of the Bohai Sea, China   总被引：11，自引：0，他引：11  

Limin Hu  Zhigang Guo  Jialiang Feng  Zuosheng Yang  Ming Fang 《Marine Chemistry》2009,113(3-4):197-211

Surface sediment samples from a matrix of fifty-five sites covering virtually the entire Bohai Sea (Bohai), China were analyzed for total organic carbon (TOC), total nitrogen (TN), n-alkanes, unresolved complex mixture (UCM), biomarkers and stable carbon isotopic composition (δ¹³C), and principal component analysis was performed for source identification of organic matter (OM). The distribution of organic carbon correlated well with sediment grain size with the finest sediments having the highest concentration, suggesting the influence of hydrodynamics on the accumulation of sedimentary organic matter (SOM). The corrected TOC/ON (organic nitrogen) ratios and δ¹³C indicated mixed marine and terrestrial sources of SOM. Results suggested that δ¹³C could be used as a potential indicator to observe the dispersion of Huanghe-derived sediments in Bohai. Total n-alkane concentrations varied over 10-fold from 0.39 to 4.94 μg g^− 1 (dry weight) with the maximum terrigenous/aquatic alkane ratio observed at the Huanghe River Estuary (HRE) due to more higher plant OM from riverine inputs. C₁₂–C₂₂ n-alkanes with even-to-odd predominance were observed in several central-eastern Bohai sites. The HRE and its adjacent area is the main sink for the Huanghe river-derived OC. The ubiquitous presence of UCM, biomarkers (hopanes and steranes) and PCA results indicated the presence of petroleum contamination in Bohai, mainly from offshore oil exploration, discharge of pollutants from rivers, shipping activities and atmospheric deposition.  相似文献   

Apparent copper complexation capacity and conditional stability constants in north atlantic waters     

Cees J.M Kramer 《Marine Chemistry》1986,18(2-4)

Surface water samples were collected in the north Atlantic Ocean in July–August 1983. Their apparent complexation capacity for copper (CC_Cu) was determined on board, using differential pulse anodic stripping voltammetry under clean room conditions. Measurements were carried out by direct titrations as well as after equilibration of copper spikes. CC_Cu and conditional stability constants (K′) were calculated, by means of three different methods, which are compared.On the basis of salinity, temperature, silicate and phosphate concentrations the following surface waters could be distinguished: North Atlantic Drift (I), East Greenland Current (II), Labrador Current (III) and Gulf Stream waters (IV, V). CC_Cu and K′ were found to differ between these waters. The range of values for CC_Cu and their mean values given in parentheses, as calculated from van den Berg plots for waters I–IV are: I, 53–65 (59); II, 47–66 (55); III, 37–53 (45); IV, 20–42 (33) nM Cu. The range and mean values for log K′ are: I, 8.23–8.33 (8.28); II, 7.89–8.11 (7.98); III, 8.40–8.41 (8.41); IV, 7.90–8.21 (8.06).Information on complexation kinetics extracted from the titration curve revealed that k_f^′ is area-specific. The complexation rate constant in the northern part (Area I) is about two times larger than that in the southern area IV, (3.6 ± 0.3) and (2.2 ± 0.2) × 10⁴s⁻¹M⁻¹ Cu, respectively.Preliminary results for deep water samples suggest smaller but still existent CC_Cu and higher K′ than those found for surface waters.  相似文献   

Bioavailability and bacterial degradation rates of dissolved organic matter in a temperate coastal area during an annual cycle   总被引：3，自引：0，他引：3  

Christian Lnborg  Keith Davidson  Xos A. lvarez&#x;Salgado  Axel E.J. Miller 《Marine Chemistry》2009,113(3-4):219-226

The bioavailability and bacterial degradation rates of dissolved organic matter (DOM) were determined over a seasonal cycle in Loch Creran (Scotland) by measuring the decrease in dissolved organic carbon (DOC), nitrogen (DON) and phosphorous (DOP) concentrations during long-term laboratory incubations (150 days) at a constant temperature of 14 °C. The experiments showed that bioavailable DOC (BDOC) accounted for 29 ± 11% of DOC (average ± SD), bioavailable DON (BDON) for 52 ± 11% of DON and bioavailable DOP (BDOP) for 88 ± 8% of DOP. The seasonal variations in DOM concentrations were mainly due to the bioavailable fraction. BDOP was degraded at a rate of 12 ± 4% d^– 1 (average ± SD) while the degradation rates of BDOC and BDON were 7 ± 2% d^– 1 and 9 ± 2% d^– 1 respectively, indicating a preferential mineralization of DOP relative to DON and of DON relative to DOC. Positive correlations between concentration and degradation rate of DOM suggested that the higher the concentration the faster DOM would be degraded. On average, 77 ± 9% of BDOP, 62 ± 14% of BDON and 49 ± 19% of BDOC were mineralized during the residence time of water in Loch Creran, showing that this coastal area exported C-rich DOM to the adjacent Firth of Lorne. Four additional degradation experiments testing the effect of varying temperature on bioavailability and degradation rates of DOM were also conducted throughout the seasonal cycle (summer, autumn, winter and spring). Apart from the standard incubations at 14 °C, additional studies at 8 °C and 18 °C were also conducted. Bioavailability did not change with temperature, but degradation rates were stimulated by increased temperature, with a Q₁₀ of 2.6 ± 1.1 for DOC and 2.5 ± 0.7 for DON (average ± SD).  相似文献   

Biogeochemical transport in the Loxahatchee River estuary, Florida: The role of submarine groundwater discharge   总被引：3，自引：1，他引：2  

Peter W. Swarzenski  William H. Orem  Benjamin F. McPherson  Mark Baskaran  Yongshan Wan 《Marine Chemistry》2006,101(3-4):248-265

The distributions of dissolved organic carbon (DOC), Ba, U, and a suite of naturally occurring radionuclides in the U/Th decay series (²²²Rn, ^{223,224,226,228}Ra) were studied during high- and low-discharge conditions in the Loxahatchee River estuary, Florida to examine the role of submarine groundwater discharge in estuarine transport. The fresh water endmember of this still relatively pristine estuary may reflect not only river-borne constituents, but also those advected during active groundwater/surface water (hyporheic) exchange. During both discharge conditions, Ba concentrations indicated slight non-conservative mixing. Such Ba excesses could be attributed either to submarine groundwater discharge or particle desorption processes. Estuarine dissolved organic carbon concentrations were highest at salinities closest to zero. Uranium distributions were lowest in the fresh water sites and mixed mostly conservatively with an increase in salinity. Suspended particulate matter (SPM) concentrations were generally lowest (< 5 mg L^− 1) close to zero salinity and increased several-fold ( 18 mg L^− 1; low discharge) toward the seaward endmember, which may be attributed to dynamic resuspension of bottom sediments within Jupiter Inlet.Surface water-column ²²²Rn activities were most elevated (> 28 dpm L^− 1) at the freshwater endmember of the estuary and appear to identify regions of the river most influenced by the discharge of fresh groundwater. Activities of four naturally occurring isotopes of Ra (^{223,224,226,228}Ra) in this estuary and select adjacent shallow groundwater wells yield mean estuarine water-mass transit times of less than 1 day; these values are in close agreement to those calculated by tidal prism and tidal frequency. Submarine groundwater discharge rates to the Loxahatchee River estuary were calculated using a tidal prism approach, an excess ²²⁶Ra mass balance, and an electromagnetic seepage meter. Average SGD rates ranged from 1.0 to 3.8 × 10⁵ m³ d^− 1 (20–74 L m^− 2 d^− 1), depending on river-discharge stage. Such calculated SGD estimates, which must include both a recirculated as well as fresh water component, are in close agreement with results obtained from a first-order watershed mass balance. Average submarine groundwater discharge rates yield NH₄⁺ and PO₄^− 3 flux estimates to the Loxahatchee River estuary that range from 62.7 to 1063.1 and 69.2 to 378.5 μmol m^− 2 d^− 1, respectively, depending on river stage. SGD-derived nutrient flux rates are compared to yearly computed riverine total N and total P load estimates.  相似文献   

Macrozoobenthic biomass in the Bay of Seine (eastern English Channel)   总被引：1，自引：0，他引：1  

Jean-Claude Dauvin  Thierry Ruellet 《Journal of Sea Research》2008,59(4):320-326

The benthic biomass values of various trophic groups were studied for the first time at the scale of the entire Bay of Seine (50 × 100 km) in the eastern English Channel. Sampling was carried out before and after the winter of 1999. In both cruises the suspension feeders dominated (66% of the 12 gAFDW m^− 2 in 1998 and 56% of the 10 gAFDW m^− 2 in 1999).The common European ophiuroid Ophiothrix fragilis was the most important contributor to total biomass. The repartition of its patches (sometimes > 20 gAFDW m^− 2) cannot be explained by the environmental parameters recorded (viz., granulometry, organic matter and pigment content).  相似文献   

Seasonal and interannual variability of the air–sea CO₂ flux in the Atlantic sector of the Barents Sea     

Abdirahman M. Omar  Truls Johannessen  Are Olsen  Staffan Kaltin  Francisco Rey 《Marine Chemistry》2007,104(3-4):203-213

The seasonal and interannual variability of the air–sea CO₂ flux (F) in the Atlantic sector of the Barents Sea have been investigated. Data for seawater fugacity of CO₂ (fCO₂^sw) acquired during five cruises in the region were used to identify and validate an empirical procedure to compute fCO₂^sw from phosphate (PO₄), seawater temperature (T), and salinity (S). This procedure was then applied to time series data of T, S, and PO₄ collected in the Barents Sea Opening during the period 1990–1999, and the resulting fCO₂^sw estimates were combined with data for the atmospheric mole fraction of CO₂, sea level pressure, and wind speed to evaluate F.The results show that the Atlantic sector of the Barents Sea is an annual sink of atmospheric CO₂. The monthly mean uptake increases nearly monotonically from 0.101 mol C m^− 2 in midwinter to 0.656 mol C m^− 2 in midfall before it gradually decreases to the winter value. Interannual variability in the monthly mean flux was evaluated for the winter, summer, and fall seasons and was found to be ± 0.071 mol C m^− 2 month^− 1. The variability is controlled mainly through combined variation of fCO₂^sw and wind speed. The annual mean uptake of atmospheric CO₂ in the region was estimated to 4.27 ± 0.68 mol C m^− 2.  相似文献