Studies of the behaviour of trace metals during mixing in some estuaries of the Solent region

Measurements have been made in the Beaulieu Estuary of dissolved nutrients, dissolved organic carbon (DOC) (1.2 pun and 1 nm cut offs), trace metals (0.4 /jm and lnm) with determinations also of fractions taken up on C18 Sep-Pak material, and trace metals in suspended particulate material (SPM), including acetic acid leachable and residual fractions. Apart from DOC and the truly dissolved fractions, the same parameters were measured on samples from the Southampton Water system. Analytical chemical investigations were undertaken, particularly to evaluate the performance of the cross-flow filtration and Sep-Pak separations used in these studies. Localized anthropogenic influences on the Beaulieu Estuary generally have minor effects, but a marked addition of Cu within the estuary is attributed to input from the use of antifouling paints. Catchment processes produce high concentrations of dissolved (0.4 pm) Fe (1710-2750 nM), Mn (1265-1750 nM) and Co (6.1-20 nM) and leachable Fe (11-15%) in SPM in the river waters. Behaviour during estuarine mixing approximated to conservative for dissolved Mn, Ni and probably Zn; addition of dissolved Cd and Co, and removal of microcolloidal Fe, occurred. A marked decrease in colloidal Fe in the lower salinity (&lt;5) region was broadly paralleled by the behaviour of Pb. The colloidal Mn and Ni were much less important than the truly dissolved fraction within the system. Colloidal fractions of Cd (52-46%), Co (43-51%) and Cu (32-46%) were significant in the river water; these fractions decreased for Cd and Co with increasing salinity but for Cu changes within the estuary were temporally variable. Significant proportions of dissolved (0.4 ^m) Cu (17-55%) and Zn (1-40%) were organically associated as defined by the Sep-Pak separation; for Cu these fractions were similar for the truly dissolved metal. Compositions of SPM in the Beaulieu Estuary were strongly influenced by the presence of iron-rich riverine material, with strong correlations between leachable Fe and other metals. Ratios of trace metals to Al in SPM, especially for Fe, Mn, Zn and Cd decreased markedly within the lower salinity region. Overall, changes in composition of estuarine SPM were probably largely attributable to physical mixing of riverine and marine materials. In Southampton Water and the Test and Itchen Estuaries the dissolved trace metals showed non-conservative behaviour, with evidence of inputs from benthic sources and waste effluents. The range of percentages of organically associated Cu (17-53%) was similar to that in the Beaulieu Estuary. Correlations between concentrations of leachable Fe and the other metals in SPM were weak but ocasional strong correlations were found between Mn and other metals. Results were broadly consistent with a primary control on composition of SPM by mixing of riverine and marine material, but with considerable variability in composition locally, attributed to in situ scavanging and localized direct input. The KD values for metals found in the Beaulieu river were similar to those from the Test river, but those for Co and Mn were slightly lower in the former. With the exception of Cd, Mn and probably Co, there were no systematic variations of the KD values with changes in salinity in the Beaulieu Estuary and Southampton Water system. The KD values for Cd showed a decrease with salinity in both systems, while those for Mn increased with increasing salinity, especially at high salinity. The KD values for Co showed a slight increase at high salinity but not as clearly as for Mn. Fisrt-order estimates of fluxes of metals from the Beaulieu Estuary were derived using extropolated zero salinity end member concentrations derived from concentration/salinity relationships. The factors identified made this approach of limited applicability to Southampton Water.</p

Different Mercury Species Partitioning and Distribution in the Water and Sediment of a Eutrophic Estuary in Northern Taiwan

The total Hg and methyl Hg in waters and sediments, as well as particulate total Hg (PTHg), were analyzed to study their distribution and partitioning in the Danshuei River Estuary (DRE), northern Taiwan. TOC and grain size were also determined in the sediment samples. The dissolved total Hg (DTHg) in waters ranged from 24.0 to 45.8 ng/L. The dissolved methyl Hg (DMeHg) concentrations contributed 0.6–30.4% of the DTHg pool, with the higher percentage appearing in the upper estuary. The DMeHg concentration positively correlated with the Chl.a within the estuary, suggesting that phytoplankton plays an important role in influencing the DMeHg concentration. The partitioning results indicated that DTHg chiefly dominates the THg (DTH + PTHg) pool, especially at a salinity of &gt;15 psu region. The value of partition coefficient, log(KD), was within a range of 3.54 to 4.68, and the value linearly decreased with increasing salinity. The sediment total Hg (STHg) concentrations ranged from 80 to 379 ng/g, and most data exceeded the NOAA guidelines value (ERL &lt; 150 ng/g), indicating that the DRE is contaminated with Hg. The STHg concentrations inversely and positively correlated with the grain size and TOC content, respectively, suggesting that sediment Hg distributions are strongly influenced by the both parameters

Distribution of Geochemical Species of P, Fe and Mn in Surface Sediments in the Eutrophic Estuary, Northern Taiwan

The Danshuei River Estuary (DRE) in northern Taiwan is a seriously eutrophic estuary due to the domestic effluent discharge. Surface sediment samples were collected from the DRE to study the concentrations and spatial distributions of different fractions of phosphorus through the five-step sequential extraction method which chemically divides the sedimentary P into five fractions: PSORB, PCDB, PCFA, PDET, and PORG. The Fe and Mn contents in the extracted solution were also determined. The total organic carbon (TOC) and grain size in sediment samples were analyzed as well. The sedimentary total P (TP) concentrations ranged within 537–1310 mg/kg and mostly exceeded 800 mg/kg, suggesting that the DRE sediments were moderately polluted by phosphorus. The PCDB was the dominant fraction of P, averagely contributing 58% of TP, followed by PDET 31%. The contributions of the PSORB and PCFA fractions to the TP were relatively minor. Two fractions, FeCDB and FeORG, of sedimentary Fe equally shared approximately 70% of total Fe, followed by FeDET with 22%. The contribution of different fractions of sedimentary Mn followed the sequence: MnCDB (36%) &gt; MnCFA (29%) &gt; MnORG (14.7%) &gt; MnDET (14.5%) &gt; MnSORB (5.3%). The sedimentary P, Fe, and Mn within the DRE are easily mobilized because they were mainly present in the reducible fraction. The concentrations of sedimentary TP positively correlated with the TOC contents and inversely negatively correlated with grain size, suggesting that the TOC and grain size play the crucial roles in influencing the distribution of sedimentary P within the DRE. Finally, the Fe(III) (hydro)oxides seems to play an important carriers to adsorb dissolved P because PCDB positively correlated with FeCDB

The Geochemical and Environmental Characteristics of Trace Metals in Coastal Sediment Discharge off the Mailiao Industrial Zone of Central Western Taiwan

The geochemical fractions of trace metals in the coastal sediments of the central western Taiwan were examined, employing the Tessier sequential extraction method, and the metals contamination status of the analyzed sediments were also evaluated in the present study. Based on the metal fraction present in sediments, trace metals can be divided into three groups: (1) Al, Cr, Fe, Ni and Zn; (2) Cu and Pb and (3) Mn. In group (1) metal, the metals’ total concentrations were chiefly dominated by the residual fraction, exceeding 80% of the total concentration pool. In group (2) metal, the metals’ total concentrations were dominated by three labile fractions, carbonate, Fe-Mn oxides and organic, accounting for nearly 65% of the total pool, and the residual fraction contributed 35% of the total concentrations. Over 90% of Mn total concentrations were shared by three fractions, carbonate, Fe-Mn oxides and the residual fraction. The statistic results indicated that the total organic carbon contents in sediments played a more important role in influencing the metals contents in sediments. The contamination assessment results suggested that the Mailiao coastal sediments were minorly contaminated by trace metals. Lead should be paid more concerns because Pb total concentrations at some sediments exceeded the value (46.7 mg/kg) of effect range low, USA, and Pb was mainly present in the labile fraction

Interplay between Asian Monsoon and Tides Affects the Plume Dispersal of the New Hu-Wei River off the Coast of Midwest Taiwan

In the coupled estuary–shelf system, plumes originating from the New Hu-Wei and Choshui rivers, consisting of many terrestrial materials, could contaminate the water of the Mailiao industrial harbor. To determine the contribution of the two rivers to pollution, the interaction between river-forced, tide-generating, and monsoon-driven water motions in and around the Mailiao industrial zone harbor was examined by performing a series of numerical model experiments. We used a three-dimensional general circulation model to examine the interplay between Asian monsoon-driven, river-forced, and tide-induced water motions, one of which could primarily affect the plume. The model-derived results for different river discharges revealed that almost all of the ammonium entering the harbor had a slope-positive trend, with oscillations in response to flood–ebb tidal cycles. The ammonium increased with time and flux, except for the 10 m3/s flux. Although the river discharge flux exceeded 200 m3/s, the ammonium entering the harbor was the same as that of the 200 m3/s flux; the ammonium concentration did not increase significantly with time after the flux exceeded 200 m3/s. In addition, irrespective of flood or ebb tidal currents being suppressed by strong Asian monsoons, this mechanism avoided contaminating the water quality of the harbor while northeasterly winds prevailed. By contrast, the southwesterly monsoon drove the geostrophic current northward along the coast; concurrently, the coastal sea level increased to form the surface isobar slope up toward the coast, producing a secondary flow to accelerate geostrophic alongshore currents. The northward geostrophic currents compressed the plumes shoreward, forming a relatively narrow-band plume; the coupling model demonstrated that the southwesterly monsoon-driven current pushed plumes favorably along the west pier into the harbor

Interplay between Asian Monsoon and Tides Affects the Plume Dispersal of the New Hu-Wei River off the Coast of Midwest Taiwan

In the coupled estuary&ndash;shelf system, plumes originating from the New Hu-Wei and Choshui rivers, consisting of many terrestrial materials, could contaminate the water of the Mailiao industrial harbor. To determine the contribution of the two rivers to pollution, the interaction between river-forced, tide-generating, and monsoon-driven water motions in and around the Mailiao industrial zone harbor was examined by performing a series of numerical model experiments. We used a three-dimensional general circulation model to examine the interplay between Asian monsoon-driven, river-forced, and tide-induced water motions, one of which could primarily affect the plume. The model-derived results for different river discharges revealed that almost all of the ammonium entering the harbor had a slope-positive trend, with oscillations in response to flood&ndash;ebb tidal cycles. The ammonium increased with time and flux, except for the 10 m3/s flux. Although the river discharge flux exceeded 200 m3/s, the ammonium entering the harbor was the same as that of the 200 m3/s flux; the ammonium concentration did not increase significantly with time after the flux exceeded 200 m3/s. In addition, irrespective of flood or ebb tidal currents being suppressed by strong Asian monsoons, this mechanism avoided contaminating the water quality of the harbor while northeasterly winds prevailed. By contrast, the southwesterly monsoon drove the geostrophic current northward along the coast; concurrently, the coastal sea level increased to form the surface isobar slope up toward the coast, producing a secondary flow to accelerate geostrophic alongshore currents. The northward geostrophic currents compressed the plumes shoreward, forming a relatively narrow-band plume; the coupling model demonstrated that the southwesterly monsoon-driven current pushed plumes favorably along the west pier into the harbor

Phytoplankton Communities Impacted by Thermal Effluents Off Two Coastal Nuclear Power Plants in Subtropical Areas of Northern Taiwan

This study investigates the seasonal and spatial differences in phytoplankton communities in the coastal waters off two nuclear power plants in northern Taiwan in 2009. We identified 144 phytoplankton taxa in our samples, including 127 diatoms, 16 dinoflagellates, and one cyanobacteria. Four diatoms, namely, Thalassionema nitzschioides (T. nitzschioides), Pseudo-nitzschia delicatissima (P. delicatissima), Paralia sulcate (P. sulcata), and Chaetoceros curvisetus (C. curvisetus) and one dinoflagellate Prorocentrum micans (P. micans) were predominant during the study period. Clear seasonal and spatial differences in phytoplankton abundance and species composition were evident in the study area. Generally, a higher mean phytoplankton abundance was observed in the waters off the First Nuclear Power Plant (NPP I) than at the Second Nuclear Power Plant (NPP II). The phytoplankton abundance was usually high in the coastal waters during warm periods and in the offshore waters in winter. The phytoplankton species composition was different in the NPP intake and outlet. An abundant phytoplankton increase in the outlet was frequently detected, probably due to the difference in phytoplankton species suitability to thermal stress. Our results suggest that thermal discharge may affect the phytoplankton communities by altering its species composition within a restricted area close to the NPP. This study provides basic knowledge on phytoplankton distribution patterns, essential information required to further understand the ecological impact caused by thermal effluents

Comparison Between Pancreaticojejunostomy and Pancreaticogastrostomy After Pancreaticoduodenectomy

Pancreatic leakage is a leading cause of morbidity and mortality after pancreaticoduodenectomy (PD). Pancreaticogastrostomy (PG) has been reported to be associated with a lower pancreatic leakage rate and morbidity rate than pancreaticojejunostomy (PJ). This study compared the preoperative characteristics, surgical risk factors, intraoperative parameters, and postoperative outcome between PJ and PG. Methods: From March 1992 to March 2005, a comparative study between PJ and PG for patients with periampullary lesions undergoing PD was conducted. A total of 377 consecutive patients underwent PD. Among them, 188 patients underwent PJ and 189 underwent PG. Results: The overall mortality, morbidity and pancreatic leakage following PD were 5%, 45.1% and 10.6%, respectively. The mortality, morbidity and pancreatic leakage were 8.9%, 56.4% and 17.6% in the PJ group, and 2.1%, 33.9% and 3.7% in the PG group (p 65 years) were identified as risk factors for pancreatic leakage, while PJ, soft pancreas, pancreatic duct stenting and low surgical volume ( 65 years) were identified to be surgical risk factors for mortality. Conclusion: PG is a safer method than PJ following PD as a significantly lower rate of pancreatic leakage, surgical morbidity and mortality, shorter operation time, and shorter postoperative hospital stay are reported

Millennial-scale ocean dynamics controlled export productivity in the subtropical North Pacific

The integrated effects of ocean-climate dynamics on export production in the North Pacific have remained elusive. We present a 91 k.y. export productivity (EP) record based on sedimentary reactive phosphorus from the western subtropical North Pacific. On a millennial time scale, EP decreased during Northern Hemisphere cold events when atmospheric dust loading was high, and increased during warm episodes. The inferred antiphase relation between dust and EP suggests that the supply of macronutrients to the sunlit surface ocean, modulated by the penetration depth of North Pacific Intermediate Water and not eolian Fe, exerted a major control on EP in the subtropical North Pacific. A compilation of global EP records suggests that eolian Fe most likely played a role in stimulating EP regionally only in the Subantarctic zone of the Southern Ocean. Over the past 91 k.y., during the cold-south–warm-north phase of the bipolar seesaw, the biological pump in both hemispheres was enhanced synchronously, yet by different drivers; atmospheric Fe input for the Subantarctic and subsurface macronutrient supply for the North Pacific, including the tropical and/ or subtropical Pacific, and the Antarctic zone of the Southern Ocean