Seasonal, neap-spring variation of sediment concentration in the joint area between Yangtze Estuary and Hangzhou Bay

An analysis of variations in suspended sediment concentration (SSC) over one year is presented for the joint area between the Yangtze Estuary and the Hangzhou Bay. Results suggest that daily SSC presents periodic variations, which correspond with seasonal and neap-spring tidal cycle. SSCs are higher during the winter season and during spring tides when compared with summer and neap-tide conditions. Furthermore, data indicate that wave and tidal currents are the two dominant factors affecting SSC. Although the Yangtze River discharges abundant sediments to the study area, it does not directly affect concentration variations. But the changing path of the Yangtze River plume plays a certain role in the seasonal variations of SSC. Finally, the calculation of bottom stresses suggests that SSC is a function of both wave and tide-induced resuspension.     

Seasonal,neap-spring variation of sediment concentration in the joint area between Yangtze Estuary and Hangzhou Bay

An analysis of variations in suspended sediment concentration (SSC) over one year is presented for the joint area between the Yangtze Estuary and the Hangzhou Bay. Results suggest that daily SSC presents periodic variations, which correspond with seasonal and neap-spring tidal cycle. SSCs are higher during the winter season and during spring tides when compared with summer and neap-tide conditions. Furthermore, data indicate that wave and tidal currents are the two dominant factors affecting SSC. Although the Yangtze River discharges abundant sediments to the study area, it does not directly affect concentration variations. But the changing path of the Yangtze River plume plays a certain role in the seasonal variations of SSC. Finally, the calculation of bottom stresses suggests that SSC is a function of both wave and tide-induced resuspension.     

动力和盐度影响下长江口近岸沉积物中汞的再悬浮行为

利用PES(particle entrainment simulator)装置, 实验测定了不同的扰动强度和盐度条件下长江口近岸沉积物中Hg的再悬浮迁移和释放过程. 在盐度再悬浮试验中, 上覆水中HgD(溶解态Hg)和HgP(颗粒态Hg)含量分别在0.06~0.176 μg/L和0.033~0.723 μg/g之间变化, 在盐度×动力耦合再悬浮试验中, 上覆水中HgD和HgP含量分别在0.024~0.112 μg/L和0.05~0.958 μg/g之间变化. 在盐度较低(< 1‰)的水环境中, 动力条件是影响上覆水中Hg行为的重要因子, 动力条件改变后, 沉积物中的部分HgD和HgP存在短期释放行为, 但随扰动时间延长, 被扰动起来的悬浮颗粒对上覆水中的Hg起了较强的吸附作用. 当盐度在1‰以上时, 上覆水中的HgP出现解吸行为, 动力条件的耦合影响促进了Hg的解吸作用, 当动力条件达到250 r/min以上时, Hg的解吸作用增强, 上覆水中的HgD出现正通量, 表现为向上覆水的释放. 此外, 在较强动力条件下, 孔隙水中大量HgD的扩散释放也增加了其释放通量.     

Natural radionuclides and 137Cs activity concentration in the bottom sediment cores from Kuwait Bay

Summary The activity concentration of natural radionuclides and ¹³⁷Cs in the bottom sediments cores from Kuwait Bay have been determined by γ-ray spectrometry. Particular attention was devoted to the exact determination of two uranium isotopes: ²³⁵U and ²³⁸U in order to find any presence of depleted uranium dispersed during the 1991 Gulf War. The calculated ²³⁸U/²³⁵U activity ratios for all the surface (15 cm) as well as the core profile (up to 70 cm in depth) samples were within the limit of one standard deviation close to the value of 21.5 for natural uranium. Simultaneous instrumental determination of the unsupported ²¹⁰Pb and ²²⁶Ra in a few sediment core profiles was used for quantification of sediment accumulation rates. The calculated sedimentation rates (for the constant atmospheric ²¹⁰Pb flux rate - CRS model) ranged from 0.2 to 0.6 cm ^. y^-1 and were close to the data calculated by the Weibull distribution of ¹³⁷Cs in undisturbed sediment cores.     

Seasonal variation of Pb concentration in airborne particles at several sites of debrecen city

Lead concentrations of atmospheric particulate matter were measured systematically by X-ray fluorescence method at three sites of Debrecen city over long periods. The time dependence of Pb concentration level in air was investigated and compared with literature data. High variation was found in lead concentration values with respect to place and time.     

Behavior of Zn, Cu, Pb and Cd in biota of Yangtze Estuary

The contents of zinc, copper, lead and cadmium were measured in the dominant species (plants: Scripus triquetor and Phrgrmites australis, macrobenthos: llyoplax deschampsin, Helice tridens tientsinensis, Bullacta exarata and Corbicula fluminea, and migrating waders: Calidris ruficollis and C. alpina) of the ecosystem of Yangtze Estuary, China, from 1995-1998. Results show that:     

Behavior of Zn,Cu, Pb and Cd in biota of Yangtze Estuary

The contents of zinc, copper, lead and cadmium were measured in the dominant species (plants:Scripus triquetor andPhrgrmites australis, macrobenthos:Ilyoplax deschampsin, Helice tridens tientsinensis, Bullacta exarata and Corbicula fluminea, and migrating waders: Calidris ruficollis and C. alpina) of the ecosystem of Yangtze Estuary, China, from 1995–1998. Results show that:

1. (1)

   Since the heavy metals stored in plants during growth seasons will be released into the environment in winter, plants are temporary stocks for metals. For the aboveground parts of reeds, about 156.6 kg·ha^-1·a^-1 of zinc, 369.9 kg·ha^-1·a^-10 of copper, 32.9 kg·ha^-·a^-1 of lead and 6.5 kg·ha^-1·a^-1 of cadmium were released.

2. (2)

   The mollusca, especially C.fluminea, are the key species storing and transporting heavy metals on the food chain.

3. (3)

   The temporal change in the highest trophic level was studied and found that it was significantly related with metabolic rates. The contents of heavy metals in Dunlin reach the peaks in January and October, which are wintering season and migratory season, respectively, of the bird.

4. (4)

   Organisms often show regulation/accumulation mechanisms to different elements of heavy metals. The elements that are widely required, such as zinc and copper, are accumulated at the metabolically active parts. It is quite another thing for the other two elements. Lead was regulated well and scarcely accumulated in the bodies of macrobenthos, but cadmium was absolutely accumulated in the animals.

5. (5)

   Heavy metals were found accumulated in some parts of the bodies of these organisms, such as shells and skeletons of macrobenthos and lives and muscles of waders.

6. (6)

   All these four elements were accumulated higher in the bodies of waders than in the plants and macrobenthos, which showed a bio-magnification function of the food chain. Overall, besides the physical and chemical processes, biological processes of heavy metal elements in Yangtze Estuarine ecosystem play a very important role in self-purification function of the ecosystem. Measurement of heavy metal contents in plants and animals in the estuarine ecosystem is an efficient technology for monitoring the environmental quality of the estuary.

     

Element geochemistry of Holocene sediment and paleoenvironmental change in the Changjiang Estuary

Analyses of 41 elements reveal that Holocene sediments In the Changjiang Estuary bear regular elemental compositions in different sedimentary environments, and Holocene sediments came mainly from the Changjiang River based on compositions of REEs and most trace elements. Some heavy metals are more enriched in the surface sediment than in the deltaic sediments, reflecting human impact. Elemental compositions of the river channel sediment are related to the influence of proximal sediments. Sedimentary environments exert some influences on elemental compositions. Some chemical indices can be used to record chemical weathering undergone by the Changjiang sediment and environmental change.     

Element geochemistry of Holocene sediment and paleoenvironmental change in the Changjiang Estuary

Analyses of 41 elements reveal that Holocene sediments in the Changjiang Estuary bear regular elemental compositions in different sedimentary environments, and Holocene sediments came mainly from the Changjiang River based on compositions of REEs and most trace elements. Some heavy metals are more enriched in the surface sediment than in the deltaic sediments, reflecting human impact. Elemental compositions of the river channel sediment are related to the influence of proximal sediments. Sedimentary environments exert some influences on elemental compositions. Some chemical indices can be used to record chemical weathering undergone by the Changjiang sediment and environmental change.     

Measurement of butyltin contamination of water and sediment in Osaka Bay,Japan

The concentration of tributyltin (TBT) in surface water from Osaka Bay ranged from 0.023 to 0.061 µg l⁻¹ in 1989 and from not detected (ND) to 0.059 µg l⁻¹ in 1990 while the proportion of TBT as a percentage of the total butyltins (BTs) was more than 40%. The concentration of TBT was also surveyed in the Port of Osaka and the Yodo River basin. TBT levels were highest in the estuary (the Port of Osaka), followed by sea areas (Osaka Bay) and rivers (Yodo River basin). A fairly high correlation coefficient between TBT concentration and salinity in water from the estuary and the sea areas was observed. This result shows that the TBT in the estuary water is diluted by seawater. Generally, the TBT concentrations in the water columns were distributed uniformly and the composition of the BTs was also constant. TBT was detected in sediment from Osaka Bay in the range from ND to 0.023 mg kg⁻¹ dry weight with a high ratio of monobutyltin (MBT) to the total BTs. TBT in sediment core was also measured; its concentration decreased with core depth. It was estimated from these measurements that the release of TBT into Osaka Bay began in the 1960s. Copyright © 1998 John Wiley & Sons, Ltd.     

Field measurements of bottom boundary layer processes and sediment resuspension in the Changjiang Estuary

A field observation of the hydrodynamics and the sediment resuspension in a bottom boundary layer was carried out in the Changjiang Estuary, during July-August 1997. Using bottom field research facilities, detailed measurements of near-bottom currents and suspended sediment concentration distribution within 1.0 m above bed have been obtained in the Changjiang Estuary——a high concentration estuary. An Acoustic Suspended Sediment Monitor (ASSM) wasused to observe near bed sediment resuspension processes. In addition, the log-profile method was applied to estimating hydraulic roughness Z0 and bottom shear stress values (or friction velocities u). Further understanding of sediment suspension mechanics and hydrodynamic characteristics will require the long-term measurements of near bed processes.     

Seasonal variation in the isotopic contents of precipitation in Korea

Tritium and other stable isotopes in precipitation were analyzed on a monthly based on Jeju Island and in Daejeon Korea and variations between the island and continent were compared. The tritium concentration in Daejeon ranged from 2.27 to 15.71 TU and on Jeju from <0.5 to 5.4 TU. The maximum value of the tritium content was in March and the minimum in July and August due to the dilution effect of heavy rain. The tritium content in precipitation on Jeju Island was lower than in Daejeon and the results reflected the general tritium content value in the Northern Hemisphere. The stable isotope analysis results showed that the mean value of δ ¹⁸O (‰) was ?6.28 and ranged from ?11.70 to ?1.67. Further the mean δD (‰) value was ?36.33 and ranged from ?85.56 to 4.27. The mean deuterium excess value (d-value) was 13.89  ‰ and ranged from 3.33 to 33.61 ‰.     

Field measurements of bottom boundary layer processes and sediment resuspension in the Changjiang Estuary

2,4-Bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine(bpt) has been synthesized by using a new, simple and general method with high yields. Reactions of bpt with Ni(ClO₄)₂·6H₂O and Zn(ClO₄)₂·6H₂O in methanol gave mononuclear complex [Ni(bpt)₂]· (ClO₄)₂·H₂O and ternary complex [Zn(mpt)₂(dmp)](ClO₄)₂ respectively, where mpt (2,4-dimethoxy-6-(3,5-dimethyl- pyrazol-1-yl)-1,3,5-triazine) and dmp(3,5-dimethylpyrazole) are the alcoholysis products of bpt in the presence of Zn²⁺ ion. A possible mechanism for this catalytic reaction was proposed. X-ray crystal structure for ligand bpt, Ni and Zn complexes are reported. The protonated form of the ligand bpt crystallizes as its perchlorate salt including one molecule of water, [Hbpt·H₂O·ClO₄]. The proton is located on one pyrazole N-atom. [Hbpt·H₂O·ClO₄], in which [Hbpt]⁺ is in cis-cis conformation, are packed in slipped stacks of approximately parallel layers. The Π -Π overlap interactions between the non-protonized pyrazoles of the adjacent layers give a zigzag arrangement of the planar aromatic [Hbpt]⁺ molecules. In [Ni(bpt)₂](ClO₄)₂·H₂O, bpt are meridionally three-coordinated with Ni²⁺. The coordination sphere around Ni²⁺ is a slightly distorted square bipyramid, where four pyrazole nitrogen atoms occupy the basal positions and two triazine nitrogen atoms the apical one. In [Zn(mpt)₂(dmp)](ClO₄)₂, the Zn atom is coordinated with a pair of bidentate mpt ligands and one monodentate dmp ligand, forming a distorted trigonal bipyramid, where the two triazine nitrogen atoms of mpt and one nitrogen atom of dmp occupy the basal positions, and the two pyrazole nitrogen atoms of mpt the apical one.     

Distribution and forms of phosphorus in tidal flat sediments of the Yangtze Estuary and coast

The distribution and forms of phosphorus (P) were investigated in the tidal flat sediments of the Yangtze Estuary and coast. The total P contents in surface sediments range from 18.0 to 31.4 μmol·g^-1 along the southern coast. The spatial and temporal distribution of P in tidal flats is closely related to the location and pollution resources, especially in association with the variation of hydrodynamic conditions. Significant variations in the forms of P in different sites were observed. P bonded with Ca(Ca-P) is the dominant mineral form in all surface sediments, organic P(Org-P) is lower. Most P is of unstable form, suggesting that P has larger potential activity. P accumulation is the main behavior process between water and sediment in the coastal environment of the Yangtze Estuary.

     

Distribution and forms of phosphorus in tidal flat sediments of the Yangtze Estuary and coast

The distribution and forms of phosphorus (P) were investigated in the tidal flat sediments of the Yangtze Estuary and coast. The total P contents in surface sediments range from 18.0 to 31.4 μmol · g-1 along the southern coast. The spatial and temporal distribution of P in tidal flats is closely related to the location and pollution resources, especially in association with the variation of hydrodynamic conditions. Significant variations in the forms of P in different sites were observed. P bonded with Ca(Ca-P) is the dominant mineral form in all surface sediments, organic P(Org-P) is lower. Most P is of unstable form, suggesting that P has larger potential activity. P accumulation is the main behavior process between water and sediment in the coastal environment of the Yangtze Estuary.     

Seasonal variation of 129I species in the Baltic Proper

Iodine speciation plays a significant role in iodine volatilizing into atmosphere from the seas, as well as serving as a biological indicator. Despite this importance, the data on iodine species revealed inconclusive evidence of what factors controlling speciation transformation. We here present new data on profiles of ¹²⁹I speciation in the Baltic Proper during November 2009. Along with the two earlier investigations (August 2006 and April 2007), an assessment of seasonal variation of ¹²⁹I species is presented. The results show that, due to the anoxic nature of Baltic Proper, presence of ¹²⁹IO₃ ^? in the Baltic Proper does not follow an obvious seasonal cycle, as the case with ¹²⁹I^?. Concentrations of ¹²⁹I^? in the Baltic Proper exhibit higher values in summer than the other two seasons (spring and winter), which might be associated with degrading of organic matter and release from sediment to water column that is more pronounced during summer. ¹²⁹I^? in surface water from the three seasons does not reflect the release function from the reprocessing facilities during the period April 2007 to November 2009. Consequently variability of ¹²⁹I^? in surface seawater of the Baltic Proper depends, to some extent, on local physical as well as biochemical conditions.     

Seasonal variation, chemical behavior and kinetics of uranium in an unconfined groundwater system

The seasonal changes in the concentration of uranium in an unconfined groundwater system in Cyprus have been investigated and compared to corresponding changes of boron and salinity, to better understand the chemical behavior of uranium in the respective system. Uranium concentration measurements were performed by alpha spectroscopy after selective pre-concentration, whereas boron concentration analysis and electrical conductivity measurements were carried out by photometry using azomethine-H and an electrical conductivity electrode, respectively. The experimental data show that seasonal variations are mainly related to rainwater infiltration and the specific chemical behavior of a species. Increased levels of uranium and boron in natural water systems are attributed to the increased stability of the uranium(VI)-carbonato complexes and the boric acid, which are in natural waters the predominant chemical species for uranium and boron, respectively. Dilution/dissolution processes govern the seasonal concentration changes of uranium and boron in a groundwater system, however redox-reactions resulting in the reduction of U(VI) to U(IV) affect significantly the concentration of uranium in the respective system, particularly under suboxic conditions.     

Levels and patterns of polychlorinated biphenyls in water collected from the San Francisco Bay and Estuary, 1993–95

Levels of polychlorinated biphenyls (PCBs) were measured in water (particulate and dissolved fractions) from various locations in the San Francisco Estuary over the years 1993–1995 during six cruises. Geometric mean levels of ΣPCBs (sum of 58 congeners) in the combined dissolved and particulate fractions for the six cruises ranged from 340?ng/L to 1600?ng/L. Comparing this data to previous data from 1975 and 1980 does not reveal any significant temporal trends. The partitioning of PCBs into the dissolved/particulate fraction were correlated with total suspended solids. Using the novel chemometric technique of polytopic vector analysis (PVA) on the data from cruise 8 (April 1995), five separate PCB congener fingerprints were identified in the data. Fingerprint 1 (or end-member 1) represents a slightly degraded source of Aroclor^® 1260 in the northern part of the South Bay; the end-member (EM) 2 fingerprint is related to a predominantly Aroclor^® 1260 source that has been moderately-severely degraded present in the highest proportions in the Pacific Ocean sample; EM-3 is interpreted as a slightly degraded Aroclor^® 1242:1254:1260 mixture in southern San Pablo Bay; end-member 4 is interpreted as a moderately degraded source of multiple Aroclors^® and is present in the river samples; EM-5 is interpreted as a slightly degraded Aroclor^® 1254/1260 mixture present in northern San Pablo Bay and the South Bay.     

Levels and patterns of polychlorinated biphenyls in water collected from the San Francisco Bay and Estuary, 1993–95

Levels of polychlorinated biphenyls (PCBs) were measured in water (particulate and dissolved fractions) from various locations in the San Francisco Estuary over the years 1993–1995 during six cruises. Geometric mean levels of ΣPCBs (sum of 58 congeners) in the combined dissolved and particulate fractions for the six cruises ranged from 340 ng/L to 1600 ng/L. Comparing this data to previous data from 1975 and 1980 does not reveal any significant temporal trends. The partitioning of PCBs into the dissolved/particulate fraction were correlated with total suspended solids. Using the novel chemometric technique of polytopic vector analysis (PVA) on the data from cruise 8 (April 1995), five separate PCB congener fingerprints were identified in the data. Fingerprint 1 (or end-member 1) represents a slightly degraded source of Aroclor^? 1260 in the northern part of the South Bay; the end-member (EM) 2 fingerprint is related to a predominantly Aroclor^? 1260 source that has been moderately-severely degraded present in the highest proportions in the Pacific Ocean sample; EM-3 is interpreted as a slightly degraded Aroclor^? 1242:1254:1260 mixture in southern San Pablo Bay; end-member 4 is interpreted as a moderately degraded source of multiple Aroclors^? and is present in the river samples; EM-5 is interpreted as a slightly degraded Aroclor^? 1254/1260 mixture present in northern San Pablo Bay and the South Bay. Received: 21 March 1997 / Revised: 23 May 1997 / Accepted: 28 May 1997     

Metal levels and foraminifera occurrence in sediment cores from Guanabara Bay,Rio de Janeiro,Brazil

Summary Guanabara Bay, located at Rio de Janeiro, is an example of an impacted coastal environment due to the high influx of industrial and domestic effluents. Four sediment cores were sampled in areas with different levels of pollution and were analyzed for trace elements and foraminifera for abundance. Instrumental neutron activation analysis (INAA) was used to determine As, Ba, Co, Cr, Fe, Sb, Sc, and Zn. The effects of metal concentrations in the benthic foraminifera were studied. The low concentrations of the benthic foraminifera and the dominance of opportunistic species in coastal regions such as Ammonia may be correlated to natural stress or anthropogenic impact.