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.     

Denitrification in tidal flat sediment, Yangtze estuary

Sediment denitrification rates at six Yangtze River estuary tidal flat locations (mudflats and salt marshes) were measured from July 2003 to October 2004. In winter and summer, spatial distribution of denitrification rates was not great in the Yangtze estuary, while in spring and autumn, denitrification rates had a great spatial distribution because of the human activity effect. The temporal change of denitrification rates was greater. They ranged from 0.2 to 36.4 μmolN·m⁻²·h⁻¹, and were higher in the summertime. The annual average of sediment denitrification rate was 18.2±12.3 μmolN·m⁻²·h⁻¹ in the middle tidal flat and 15.1±9.45 μmolN·m⁻²·h⁻¹ in the low tidal flat in the Yangtze estuary. Data analysis indicated that the temperature was the primary factor controlling the process of denitrification (significant positive correlation, P<0.01); at the same time, the content of sediment total nitrogen (TN) and the molar ratio of sediment carbon and nitrogen (C/N) had significant positive correlation (P<0.05) and negative correlation (P<0.05) with denitrification rates, respectively. In the Yangtze estuary, increasing of water salinity had no significant inhibition of denitrification because of the wide change range of water salinity. Supported by the National Natural Science Foundation of China (Grant Nos. 40173030, 40571006 and 40131020), the Science & Technology Department of Shanghai (Grant Nos. 05DZ120007 and 05JC14059) and China Postdoctoral Science Foundation.     

Spatial distribution and accumulation of heavy metals in tidal flat sediments of Shanghai coastal zone

Surface and core sediments from the high, middle and low tidal flats of Shanghai coastal zone were analyzed for heavy metal (e.g. Cu, Pb, Zn, Cr, Cd, Fe, Mn) concentrations. Besides Cd, the concentrations of Cu, Zn, Cr and Pb are 2–5 times higher than their background values and show serious pollution trend due to the direct discharge of industrial and municipal sewage along the Shanghai tidal flat, as well as the wet and dry depositions of industrial dusts. It seems that heavy metals prefer to accumulate and be enriched in the sediments near large sewage outlets, high flats, and the subsurface layer at the depth of 10–30 cm. Several main factors, which include the direct sewage discharge along the tidal flat, tidal hydrodynamic action, large engineering activity, early diagenesis and windstorm tide, are considered to be responsible for influencing spatial distribution patterns of heavy metals in the Shanghai tidal flat.

     

Spatial distribution and accumulation of heavy metals in tidal flat sediments of Shanghai coastal zone

Surface and core sediments from the high, middle and low tidal flats of Shanghai coastal zone were analyzed for heavy metal (e.g. Cu, Pb, Zn, Cr, Cd, Fe, Mn) concentrations. Besides Cd, the concentrations of Cu, Zn, Cr and Pb are 2-5 times higher than their background values and show serious pollution trend due to the direct discharge of industrial and municipal sewage along the Shanghai tidal flat, as well as the wet and dry depositions of industrial dusts. It seems that heavy metals prefer to accumulate and be enriched in the sediments near large sewage outlets, high flats, and the subsurface layer at the depth of 10-30 cm. Several main factors, which include the direct sewage discharge along the tidal flat, tidal hydrodynamic action, large engineering activity, early diagenesis and windstorm tide, are considered to be responsible for influencing spatial distribution patterns of heavy metals in the Shanghai tidal flat.     

Distribution and environmental impact of radionuclides in marine sediments along the Venezuelan coast

The activity concentrations of ¹³⁷Cs, ⁴⁰K, ²²⁶Ra and ²³²Th in Bq/kg from 42 marine sediment samples collected at nine sampling sites were determined in order to establish a radiological baseline along the Venezuelan coast. The radioactivity levels were determined by means of a gamma-ray spectroscopy system using a hyper-pure germanium detector in a low-background configuration. Particle size distribution and total organic matter content were also determined. Activity concentrations of ¹³⁷Cs were lower than the detection limit of the analytical technique (0.9 Bq/kg) in all studied sites. The results suggest that the variation of grain-size distribution is one of the most important factors influencing the spatial variations of ⁴⁰K, ²²⁶Ra and ²³²Th in sediments along the Venezuelan coasts. In all sampling sites, average concentrations of ⁴⁰K, ²²⁶Ra and ²³²Th were lower than the world average values. Activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in coastal marine sediments along the Venezuelan coast could be considered to be low when compared with global average values, indicating that they are not apparently above of the range that might be considered normal or background. These results suggest that the studied sites do not pose any significant radiological threat to the population. The results attained in this study should be of considerable value as baseline data and background reference levels for Venezuelan coastlines.     

Distribution of total carbohydrates in surface sediments of the Egyptian Mediterranean coast,in relation to some inorganic factors

The interrelation between calcium, magnesium, carbonate, fluoride and total carbohydrates (THCO) distribution was investigated for surface sediments collected from three sectors (A–C) along the Egyptian Mediterranean coast during the summer of 2008. The recent ultrasound-acetic acid technique was used for the simultaneous extraction and hydrolysis of total carbohydrates. Based on the average values, the sandy sediments of sector (C) exhibited the highest THCO levels (163.78 ± 53.28 μg/g). In contrast, the silty sand sediments of sector (A) had the lowest average THCO level (8.56 ± 2.60 μg/g). Linear regression model with one predictor showed that there are significant correlations between total carbohydrates, carbonate and fluoride suggesting the common origin of these components. Neither calcium nor magnesium has correlation with THCO. This study revealed that carbonate is the dominant factor affecting the distribution of carbohydrates in the sediments. The spatial distribution of THCO was not affected by the potential sources of runoff, but varied according to the sediments mineralogy.     

Solid-phase-spectrophotometric and test determination of simultaneously present phosphorus forms (phosphorus speciation) in water

Solid-phase-spectrophotometric and test procedures are proposed to determine phosphorus as its ion associate with a quaternary ammonium salt and molybdoantimonophosphoric acid immobilized on silica gel in the concentration range 1.9–124 μg P/L. The determination of 4 μmol of phosphorus is not affected by (in μmol) alkali and alkaline-earth metals (≤2 × 10⁴), NH ₄ ⁺ (≤1 × 10³), Co²⁺ (≤1.0), Cu²⁺ (≤100), Mn²⁺ (≤10), Fe³⁺ (≤300), NO ₃ ^? and SO ₄ ^2? (≤2 × 10⁴), CO ₃ ^2? (≤1 × 10⁴), As (≤20), and Si (≤1 × 10³). The procedure was tested in the determination of various phosphorus forms in natural waters.     

中国煤中磷的分布特征

以“中国煤种资源数据库”为基础,结合新采集煤样,对中国不同煤田1117个煤层煤样的磷含量数据进行了统计分析.结果表明,中国煤中磷可采储量加权平均质量分数为224x10-6,大约90％的煤中磷质量分数低于500x10-6,为特低磷煤或低磷煤,全国总体上呈“北低南高”的趋势.按不同聚煤区、不同成煤时代和不同煤炭类别讨论了中...     

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.

     

Anomalously high237Np in intertidal sediments from the Ribble Estuary in the Irish Sea

Depth profiles and inventories of²³⁷Np in sediment cores from the Ribble Estuary in the Irish Sea have been studied along with those of Pu isotopes,²⁴¹Am and¹³⁷Cs, to allow a more detailed look of anomalously high²³⁷Np content observed in this estuary previously. The comprehensive data obtained showed that the depth profiles of both²³⁷Np contents and²³⁷Np/^239,240Pu activity ratios were clearly different from those of^239,240Pu,²⁴¹Am, and¹³⁷Cs and their activity ratios. As much as 80–90% of²³⁷Np inventories (0.32–1.06 kBq/m²), found in three cores, were estimated to be derived from a source other than Sellafield, on the basis of comparison of the²³⁷Np/^239,240Pu inventory ratio (0.65–1.74%) found in the Ribble Estuary cores with those (0.10–0.16%) in the Ravenglass Estuary cores.     

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:     

Methylation of inorganic lead by Tamar Estuary (UK) sediments

Tetramethyllead (TML) has been produced from inorganic lead salts using biologically active sediments and waters from the Tamar Estuary, S. W. England. The TML production was a two-stage process involving an initial lag phase of about 100 hours followed by the exponential appearance of TML, which amounted to about 0.03% of total added lead. The methylation process is discussed in the context of lead transport in estuaries.     

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.     

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.

     

Artificial radioactive contamination of sediments along the Romanian sector of the Danube river and the Black Sea coast

The concentrations of⁹⁰Sr,²³⁸Pu,^239,240Pu and²⁴¹Am were determined in 12 sediment samples, collected from the bed of the Romanian sector of the Danube river and the Black Sea coast during 1996–1997. The samples were dissolved using a microwave digestion technique which left the refractory part of the samples undissolved. Part of the samples were also dissolved totally by alkaline fusion. The results obtained after radiochemical separations and measurement of the radionuclides by the two dissolution methods were compared recommending the optimum method. The radioactive contamination of the investigated sector in 1996–1997 is compared with the results obtained for the same locations in 1994–1995 reported in previous papers.     

Comparison of digestion methods for determination of total phosphorus in river sediments

In this study, four digestion methods used to determine total phosphorus in river sediments, including Na₂CO₃ fusion, the H₂SO₄ and H₂SO₄ + H₂O₂ methods and the SMT protocol were investigated. Interference effects of iron, calcium and organic matter in river sediments, and the substances contained in the digestion agents on the photometric determination of the phosphates were analysed. The digestion methods were tested on ten river sediment samples. Statistical analysis of the results showed significant differences between sample treatments relating to the mean total phosphorus concentration.     

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.     

The distribution and behaviour of artificial radionuclides in sediments of the north Wales coast,U.K.

The distribution of¹³⁴Cs,¹³⁷Cs and²¹⁴Am in surface and core sediments from areas in north Wales has been investigated. Coastal sites show a predominance of Sellafield-derived material for all three radionuclides whereas estuarine sites show an increased proportion of Chemobyl-derived caesium present. By the use of the¹³⁴Cs/¹³⁷Cs ratio, a mean proportion of Chemobyl-derived¹³⁷Cs in surface sediments collected in 1991 fell from 34% at an estuarine site to 11% at a coastal site. In deeper sections of cores representing sedimentation dates near the Chemobyl accident, up to 90% of¹³⁷Cs at the estuarine site and 26% at the coastal site can be attributed to Chemobyl. By using the position of the Chemobyl¹³⁴Cs and¹³⁷Cs peak in the cores, sedimentation rates of 0.7 mm·a^–1 were calculated.