人类活动影响下福建三都澳近百年来重金属沉积记录及其对生态环境的影响

因重金属难以被生物降解,易形成毒害环境因子,沉积物中的重金属污染演变是工业化以来全球共同面临的生态环境问题。为揭示福建三都澳地区人类活动与重金属沉积的关系,对采集自三都澳海域的6根岩心柱进行了系统的粒度分析、²¹⁰Pb测年以及重金属元素测试。研究结果表明：（1）近百年来,三都澳海域沉积物重金属含量呈现显著增加趋势,顶部比底部增加1.01~2.8倍,并表现出3个明显演变阶段：1900-1950年,沉积物中的重金属含量相对稳定;1950-2000年,重金属含量开始缓慢增加;2000年以来,远岸区重金属含量急剧增加。这种变化趋势与人口、经济发展密切相关。（2）三都澳近岸区沉积物重金属含量总体大于远岸区,自2000年以来,近岸区和远岸区沉积物重金属含量的演变趋势呈现差异性,表现为近岸区重金属含量有所降低,远岸区重金属含量急剧升高,这种时空差异与沉积物粒度变化及地区产业分布有密切关系。（3）重金属对三都澳海洋生态环境影响较大,在湾内渔业养殖强度越来越高的背景之下,应对近期以来湾内重金属含量的快速升高给予足够重视,提高保护和修复治理力度,避免海洋生态破坏。     

Radioelemental study of Kolaghat,thermal power plant,West Bengal,India: possible environmental hazards.

Coal combustion in power plants in India produces large quantities of coal-related wastes, e.g. fly ash and bottom ash. Indian coals used in power stations are of high ash content, thus resulting in the generation of large amounts of fly ash (~100 million tons/year). Combustion of coal results in enhanced concentration of most radionuclides found in waste materials. In the present work, an attempt has been made to assess the radiological impact of the Kolaghat thermal power plant in West Bengal, India. The fly ashes and coal from the power plant were analysed for ²³⁸U, ²³²Th and ⁴⁰K by a NaI (Tl)-based gamma-ray spectrometer. The results show that ²²⁶Ra and ²³²Th range from 81.9-126 and 132-169 Bq/kg in fly ash and 25-50 and 39-55 Bq/kg in coal. These results are high compared to those of other thermal power plants of India. Hence, the Kolaghat fly ash has a significant amount of radioactivity which, if not properly disposed, will be a serious threat to the ambient environment.     

Sources and history of heavy metal contamination and sediment deposition in Tivoli South Bay, Hudson River, New York

Persistent inorganic constitutents preserved in sediments of aquatic ecosystems record temporal variability of biogeochemical functioning and anthropogenic impacts.²¹⁰Pb and¹³⁷Cs dating techniques were used to study the past variations of heavy metals (Pb, Cu, and Zn) and accumulation rates of sediments for Tivoli South Bay, in the Hudson River National Estuarine Research Reserve ecosystem. South Bay, a tidal freshwater embayment of the Hudson, may play an important role in the sediment dynamics of this important river. The measured sedimentation rate range of 0.59 to 2.92 cm yr⁻¹ suggests that rapid accumulation occurred during the time period represented by the length of the cores (approximately the past 50 yr). Direct measurements of sediment exchange with the Hudson River reveal high variability in the sediment flux from one tidal cycle to the next. Net exchange does not seem to be adequate to explain sediment accumulation rates in the bay as measured by²¹⁰Pb and¹³⁷Cs. The difference may be supplied from upland streams or the Hudson River during storm events. Concentrations of the metals Pb, Cu and Zn were found to be well correlated with each other within individual cores at five of six sites tested. This suggests a common proximate source for the three metals at a specific site. The evidence is consistent with mixing in some environmental compartment before delivery to the bay. While metals self-correlate within individual cores, absolute concentrations, depth distribution patterns, and ratios of the metals to each other vary among the cores collected at different locations within the bay. Organic matter, Fe content, and particle size distribution of sediments do not account for the intercore variations in metal concentration. It is likely that cores collected from different sites may have derived metals from different sources, such as watershed streams and tidal exchange with the Hudson River.     

Heavy metal distribution in the Godavari River basin

Suspended and bed sediments collected from the entire region of the Godavari River basin were analyzed for Fe, Mn, Cr, Cu, Ni, and Zn. There are pronounced temporal and spatial variations in the heavy metal distributions. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments.Throughout the basin heavy metals are enriched in the finer fractions (<2 µm) of the bed sediments. The average heavymetal composition of the sediments is higher when compared to the average Indian river sediments. Heavy-metal concentration in the two shallow cores collected shows, to some extent, the influence of urbanization. When compared to the other tropical Indian rivers such as the Krishna, the Godavari appears to be a significant contributor of heavy metals to the Bay of Bengal. Considering the enormous sediment load of the Godavari River—170 million tons/yr, the heavy metal fluxes to the Bay of Bengal is very significant. Except for the Pranhita, other tributaries of the Godavari do not contribute significant loads of heavy metals. All the metals show high correlation among themselves and the correlation is more pronounced in suspended sediments than in the bed sediments. The heavy-metal distribution, fractionation, and its relationship with total suspended sediments and depth in various parts of the basin are discussed in detail.     

Historical record of heavy metal pollution deduced by lead isotope ratios in core sediments from the Osaka Bay,Japan

Three marine sediment cores from Osaka Bay were analyzed for ²¹⁰Pb geochronology, heavy metal concentrations (Zn, Cu, and Pb) and stable lead isotope ratios (²⁰⁶Pb/²⁰⁷Pb) in order to reconstruct high-resolution heavy metal pollution history from 1900–2006. Anthropogenic metal accumulation in sediments peaked in 1970 in agreement with the high economic growth period in Japan. The comparison of temporal patterns of ²⁰⁶Pb/²⁰⁷Pb ratio with other areas of Japan suggested that the heavy metals, imported from several different countries during the periods of economic growth (1955 to 1973), are the main pollution source for the country. For the period 1970–2006, the sediment data reflect the result of stricter environmental regulations applied after the late 1960s. However, heavy metal concentrations in the surface sediments are still elevated to levels several times higher than the levels at the bottoms of the cores. Additionally, the lead isotope ratio does not show significant change after the 1980s. Secondary heavy metal pollution through the mixing of deeper polluted sediment appears to be the likely reason for the deterioration of present time submarine sediment environments. In conclusion, this study has demonstrated that it is difficult to recover over a period of several years the benthic quality of a bay, once it is heavily polluted.     

Radiological hazards of coal and ash samples collected from Xi’an coal-fired power plants of China

The natural radiological characteristics and their respective annual effective dose (AED) rates, produced by ²²⁶Ra, ²³²Th and ⁴⁰K in coal, fly ash and bottom ash from two large coal-fired power plants (CFPPs) of Xi’an were determined by means of γ-ray spectrometry. The average activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in all ash samples (fly ash and bottom ash samples) from the two CFPPs were 67.6, 74.3 and 225.3 Bq kg⁻¹, respectively. The results are compared with data from other locations. To evaluate the radiological hazards of the natural radioactivity, the radium equivalent activity (Ra_eq), air absorbed dose rate (D), AED and external hazard index (H _ex) are compared with internationally accepted values. Ra_eq and H _ex of all samples except three fly ash samples were less than the limits of 370 Bq kg⁻¹ and unity, respectively. The average D and AED for ash samples were 86.8 nGy h⁻¹ and 0.11 mSv y⁻¹, respectively, which exceed the world average and Xi’an average values.     

The relative importance of terrestrial versus marine sediment sources to the Nueces-Corpus Christi Estuary, Texas: An isotopic approach

Determining sources of sediment to coastal systems is an important and complex problem that figures prominently in a myriad of geological, geomorphological, geochemical, and biological processes. Lithogenic (²²⁶Ra,²²⁸Ra,²²⁸Th,²³⁰Th,²³²Th) and fallout (¹³⁷Cs,²¹⁰Pb) isotopes were employed in conjunction with sedimentological methods to determine rates of sedimentation in the Nueces Delta and Nueces-Corpus Christi Estuary and to assess the relative importance of marine versus terrestrial sediment sources to the estuary. Similarity of lithogenic isotope ratios in surface sediments throughout the system precluded a numeric approach to discerning the importance of each of the two large scale sediment sources (terrestrial and marine). A stepwise, graphical examination of discrete lithogenic isotope activity concentrations shows more promise. Terrestrial, marine, and bay sediment means for²²⁶Ra versus²³²Th,²²⁶Ra versus²³⁰Th, and²²⁸Ra versus²³²Th show that terrestrial and marine sediment sources have different signatures, despite having similar grain size distributions (sands), and that sediment deposited in Nueces and Corpus Christi Bays are indistinguishable from the terrestrial component. Supporting evidence is provided by thorium isotopes,²³⁰Th versus²³²Th,²²⁸Th versus²³²Th, and²²⁸Th versus²³⁰Th. Nueces Delta sedimentation (0.09–0.53 g cm⁻² yr⁻¹) shows a subtle gradient, with rates generally lower in the west and progressively higher moving east, likely reflecting contrasts in land use and topography. Nueces Bay cores differ from those in Corpus Christi Bay in that sands comprise a larger percentage of their composition, and they are mixed over greater depth, most likely due to geographic and physiographic effects. Sediment accumulation rates consistently decrease over the first 20 km from the Nueces River and become constant after that, implying that the river is the most significant source of sediment to the estuary. The interpretation of sediment supply to this estuary as dominated by terrestrial inputs is based on three complimentary sets of data: sediment grain size distributions, discrete lithogenic isotope data (Ra versus Th and Th versus Th), and sediment accumulation rates for both Nueces and Corpus Christi Bays.     

Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta

Six sediment cores were taken in sedimentation zones of the Volga river (located in the southern part of the Russian Federation) and, additionally, 6 sediment cores were taken in several lakes (sedimentation zones) in the central and western part of the Danube delta in Romania. Priority pollutants (8 metals, 7 polychlorinated biphenyls and 10 polycyclic aromatic hydrocarbons) were determined in all samples of all cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers (¹³⁷Cs, ¹³⁴Cs). For the persistent metals and polycyclic aromatic hydrocarbons, trends in the concentration profiles during the last 5 decades are described. Low and hardly changing concentrations of As, Cu, Zn and all studied PAHs were observed during the last five decades in the sediments of the Volga river. Recently deposited sediments show slightly increasing levels for the heavy metals Zn and Cr and As in the Volga delta. For the studied metals and PAHs, maximum concentrations were found around 1987 in the sediments of the Danube delta. Sediments deposited around 1940 and recently deposited sediments in the Danube delta showed lower pollutant levels. If the contents of heavy metals, PAHs and PCBs in the aquatic sediments in the deltas of the rivers Rhine, Danube and Volga are compared, it is clear that the Volga delta is and was the cleanest delta during the last 5 decades. Nowadays the contents of heavy metals (except Cu and Ni), PAHs and PCBs in the aquatic sediments of the river Rhine are still highest compared to the other two rivers. The recent load of heavy metals (except Cd and Zn) in the sediments of the river Danube is the highest compared to the other two rivers.     

Industrialization affects heavy metal and carbon isotope concentrations in recent Baltic Sea sediments

Recent sediment cores of the western Baltic Sea were analyzed for heavy metal and carbon isotope contents. The sedimentation rate was determined from radiocarbon dates to be 1.4 mm/yr. The ‘recent age’ of the sediment was about 850 yr. Within the upper 20 cm of sediment, certain heavy metals became increasingly enriched towards the surface; Cd, Pb, Zn and Cu increased 7-, 4-, 3- and 2-fold, respectively, whereas Fe, Mn, Ni and Co remained unchanged. Simultaneously, the radiocarbon content decreased by about 14 per cent. The enrichment in heavy metals as well as the decrease in the ¹⁴C-concentration during the last 130 ± 30yr parallels industrial growth as reflected in European fossil fuel consumption within that same period of time. The near-surface sediments are affected by residues released from fossil fuels at the rate of about 30 g/m² yr for the past two decades. The residues have a pronounced effect on the heavy metal and carbon isotope composition of the most Recent sediments allowing estimates to be made for sedimentation, erosion and heavy metal pollution.     

Natural radioactivity levels and evaluation of radiological hazards from Beni Haroun dam sediment samples,northeast Algeria

Levels of naturally occurring radioactivity in sediment samples of Beni Haroun dam have been investigated. The activity concentrations of ²³⁸U and ²³²Th decay chains and ⁴⁰K primordial radionuclide have been measured using high-resolution HPGe detector. Activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K radionuclides were found in the ranges 9–66, 14–37, and 177–288 Bq/kg with the mean values 24.67, 25.98, and 208.10 Bq/kg, respectively. Radiological hazard parameters were estimated based on the activity concentrations for ²²⁶Ra, ²³²Th, and ⁴⁰K to find out any radiation hazard associated with the sediments. Correlation studies between pairs of radionuclides were performed and discussed, and the obtained results are compared with international recommended values.     

Evaluation of the anthropogenic influx of metallic pollutants into Puck Bay,southern Baltic

Distributions of 15 elements with depth in two sediment cores from Puck Bay in the Gulf of Gdansk show that Ag, Cd, Pb, Zn and possibly Cu and Ni are anthropogenically enriched in the sediments there. The concentrations of these elements decrease sharply with depth in the sediment column and the elements are preferentially enriched in the <2 μm size fraction of the sediment. The sequence of element enrichment depends on whether the enrichment factor (EF) and the anthropogenic factor (AF) are used to calculate the element enrichment. By contrast, the anthropogenic elements show no systematic decrease in concentration with depth in a sediment core taken from near the mouth of the Vistula River. This reflects the higher sedimentation rate there such that the entire upper 20 cm of the core was deposited during the major, post-war period of industrialization in Poland. In addition, these elements are enriched in the 2–63 μm fraction compared to the <2 μm fraction in these sediments. This suggests that the heavy metals are mainly adsorbed on Fe oxyhydroxide particles with diameters greater than 2 μm at the hydrological front where Vistula river water mixes with brackish Baltic water. It appears that heavy-metal pollution of sediments in parts of Puck Bay may be greater than that near the mouth of the Vistula River which may reflect, in part, the higher sedimentation rate near the mouth of the Vistula River. The mode of incorporation of heavy-metals into the sediments in the two areas may also be different.     

Dynamics of sediment and contaminant transport in the Hudson River estuary: Evidence from sediment distributions of naturally occurring radionuclides

Near surface (<10 cm) sediment distributions of²³⁴Th sampled multiple times at five locations along the axis of the Hudson Estuary from the Upper Bay of New York to Haverstraw Bay are compared with²¹⁰Pb data from longer cores at the same locations. The comparison indicates that while there is little net sediment accumulation anywhere except at one location in the Upper Bay, near surface sediment in this reach of the estuary is mobile on short (months) time scales. The sediment appears to be physically mixed rather than bioturbated. Comparison of the sediment inventories of²³⁴Th with calculated water column production indicates short time scale (months) variability in²³⁴Th deposition. Some parts of the bottom have²³⁴Th inventories in excess of local production but these appear to be balanced by²³⁴Th deficient areas, resulting in a general equilibrium. Sediment inventories of Pb, Cu, and Zn normalized to²¹⁰Pb show no evidence of a uniquely urban source of these metals to the lower estuary. Silver distributions in sediment indicate a possible source of silver from New York City, probably related to sewage inputs.     

Correlations of natural radionuclides in sediment from Danube

The correlation between specific activities of some natural radionuclides (²³⁸U, ²²⁶Ra, ²³²Th, ⁴⁰K) measured in sediment taken from river bottom was studied. The sediment was taken from the Serbian part of the Danube River. Good correlation between some of the isotopes is observed, so that their specific activity ratios are spread over a lower range than specific activities themselves. This suggests that evaluation of specific activity ratios of some natural radionuclides could be a more sensitive method for the determination of increased levels of some of them than the straightforward analysis of specific activities.     

Trace metals and radionuclides reveal sediment sources and accumulation rates in Jordan Cove, Connecticut

Many small estuaries are influenced by flow restrictions resulting from transportation rights-of-way and other causes. The biogeochemical functioning and history of such systems can be evaluated through study of their sediments. Ten long and six short cores were collected from the length of Jordan Cove, Connecticut, a Long Island Sound subestuary, and analyzed for stratigraphy, radionuclides (¹⁴C, ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs, and ⁶⁰Co), and metals (Ag, Cd, Cu, Pb, Zn, Fe, and Al). For at least 3,800 yr, rising sea level has gradually inundated Jordan Cove, filling it with mud similar to that currently being deposited there. Long-term sediment accumulation in the cove averaged close to 0.1 cm yr⁻¹ over the last three millennia. Recent sediment accumulation rates decrease inland from 0.84 cm yr⁻¹ to 0.40 cm yr⁻¹, and are slightly faster than relative sea-level rise at this site (0.3 cm yr⁻¹). Similarity of depth distributions of trace metals was used to confirm relative sediment accumulation rates. ⁶⁰Co and Ag are derived from sources outside the cove and its watershed, presumably the Millstone nuclear power plant and regional contaminated sediments, respectively. The combined data suggest that Long Island Sound is an important source of sediment to the cove; a minor part of total sediment is supplied from the local watershed. Trace metal levels are strongly correlated with Fe but not with either organic matter or Al. Sediment quality has declined in the cove over the past 60 yr, but only slightly. Cu, Pb, and Zn data correlate strongly with Fe but not with either organic matter or aluminum. Ratios of Ag to Fe and to trace metals suggest that Ag in the cove is derived almost entirely from Long Island Sound. This result supports the notion that Fenormalized Ag can serve as a better tracer of some kinds of contamination than more common and abundant metals, like Cu, Pb, and Zn. *** DIRECT SUPPORT *** A01BY085 00008     

渤海沉积物中放射性核素分布及其对沉积环境变化的响应

为了探讨近百年来,人类活动背景下近海沉积物中放射性核素的沉积记录及其对物质输入与埋藏等沉积环境变化的响应,利用γ能谱法对渤海表层和柱状沉积物中的放射性核素238U、226Ra、232Th、210Pb、40K和137Cs进行分析.结果显示,渤海沉积物中放射性核素水平和垂直分布特征明显,铀衰变系核素238U、226Ra和210Pb不平衡,232Th和210Pb受沉积物粒度和有机碳影响显著,238U与226Ra、232Th、40K存在显著相关性.226Ra/238U、232Th/238U和40K/238U比值时空差异显著,渤海沉积物陆源输入影响由西南向东北方向延伸,受河流影响,渤海北部和南部的沉积物输入不稳定,近几十年波动显著.利用210Pb_ex和137Cs法的测年结果计算获得的渤海近百年来沉积速率在中国近海沉积速率研究背景值范围内;空间上,渤海北部、中部和南部沉积速率处于同一水平,其中北部偏高;时间上,近百年来渤海沉积速率随时间波动,整体上呈现增加趋势,尤其是1980年之后,人类活动影响下渤海沉积速率增加幅度显著,与沉积物输入的波动变化相对应.      

The mobility of radium-226 and trace metals in pre-oxidized subaqueous uranium mill tailings

The exchange of ²²⁶Ra and trace metals across the tailings-water interface and the mechanisms governing their mobility were assessed via sub-centimetre resolution profiling of dissolved constituents across the tailings–water interface in Cell 14 of the Quirke Waste Management Area at Rio Algom's Quirke Mine, near Elliot Lake, Ontario, Canada. Shallow zones (<1.5 m water depth) are characterized by sparse filamentous vegetation, well-mixed water columns and fully oxygenated bottom waters. Profiles of dissolved O₂, Fe and Mn indicate that the tailings deposits in these areas are sub-oxic below tailings depths of ∼3 cm. These zones exhibit minor remobilization of Ra in the upper 5 cm of the tailings deposit; ²²⁶Ra fluxes at these sites are relatively small, and contribute negligibly to the water column activity of ²²⁶Ra. The shallow areas also exhibit minor remobilization of Ni, As, Mo and U. The release of these elements to the water cover is, however, limited by scavenging mechanisms in the interfacial oxic horizons. The presence of thick vegetation (Chara sp.) in the deeper areas (>2 m water depth) fosters stagnant bottom waters and permits the development of anoxia above the benthic boundary. These anoxic tailings are characterized by substantial remobilization of ²²⁶Ra, resulting in a relatively large flux of ²²⁶Ra from the tailings to the water column. The strong correlation between the porewater profiles of ²²⁶Ra and Ba (r²=0.99), as well as solubility calculations, indicate that the mobility of Ra is controlled by saturation with respect to a poorly ordered and/or impure barite phase [(Ra,Ba)SO₄]. In the anoxic zones, severe undersaturation with respect to barite is sustained by microbial SO₄ reduction. Flux calculations suggest that the increase in ²²⁶Ra activity in the water cover since 1995 (from <0.5 to 2.5 Bq l⁻¹) can be attributed to an increase in the spatial distribution of anoxic bottom waters caused by increased density of benthic flora. The anoxic, vegetated areas also exhibit minor remobilization with respect to dissolved As, Ni and Zn. The removal of trace metals in the anoxic bottom waters appears to be limited by the availability of free sulphide. Collectively, the data demonstrate that while the water cover over the U mill tailings minimizes sulphide oxidation and metal mobility, anoxic conditions which have developed in deeper areas have led to increased mobility of ²²⁶Ra.     

Geochemistry of radium in soils of the Eastern United States

The abundance and chemical/mineralogical form of ²²⁶Ra, ²³⁸U and ²³²Th were determined on samples of soil and associated vegetation at 12 sites in the eastern United States. Progressive, selective chemical extraction plus size fractionation determined the abundance and radiometric equilibrium condition of these nuclides in 6 operationally defined soil fractions: exchangeable cations, organic matter, “free” Fe-oxides, sand, silt, and clay.In soils, profile-averaged ²²⁶Ra/²³⁸U activity ratios (AR) are within 10% of unity for most sites, implying little fractionation of U and Ra when the entire soil profile is considered. However, ²²⁶Ra greatly exceeds ²³⁸U activity in most surface soil (AR up to 1.8, av 1.22), in vegetation (AR up to 65, av. 2.8), in the exchangeable+organic fraction (AR up to 30, av. 13), in some soil Fe oxides (AR up to 3.5, av. 0.83) and in the C horizons of deeply weathered soils (AR up to 1.5).A major factor in Ra behavior is uptake by vegetation, which concentrates Ra>U and moves Ra from deeper soil to surface soil. Vegetation is capable of creating the observed Ra excess in typical surface soil horizons (AR up to 1.8, av. 1.22) in about 1000 a. Of the total Ra in an average A horizon, 42% occurs as exchangeable ions and in organic matter, but only 6–8% of the parent U and Th occur in these soil forms. In contrast, U is slightly enriched relative to Ra in Fe-oxides of A horizons, implying rapid chemical partition of vegetation-cycled U and Ra.In deeper horizons, transfer by vegetation and/or direct chemical partitioning of Ra into organic and exchangeable forms provides a source for unsupported ²²⁶Ra in Ra-rich organic matter, and leaves all soil minerals Ra-poor (AR=0.73). Organic matter evidently has a strong affinity for Ra.The phenomena discussed above are relevant to evaluation of indoor Rn hazard, and behavior of Ra at sites affected by radioactive waste disposal, phosphate tailings, Ra-rich brine, and uraniferous fertilizer.     

Elemental composition of sediment cores from a mangrove environment using neutron activation analysis

The geochemistry of Sepetiba Bay was studied in four sediment cores using a multi-element approach. Two cores were sampled in the more contaminated eastern part of the bay and two cores were sampled in the western region. The aim was to determine whether less common elements like the rare earths or the actinides are associated with contaminant metals like zinc in the Bay. Samples were analysed by instrumental neutron activation analysis that permits the quantification of total concentrations of metals (Ba, Co, Cr, Cs, Fe, Hf, Rb, Sc, Zn), rare earth elements (Ce, Eu, La, Lu, Sm and Yb), actinides (Th, U), non-metals and semi-metals (As, Br). Organic carbon and total sulphur were also analysed. The results show very strong zinc contamination in the top layers (more than 1000 μg g⁻¹) and background concentrations in the bottom (15 μg g⁻¹). Elements like chromium which would be expected to be released by the heavy industries of Sepetiba Bay, did not show a contamination profile, and concentrations remained close to those of natural environments. No evidence of any association between the zinc and other potential contaminant elements could be identified in this work.     

The role of zooplankton fecal pellets in the sedimentation of polycyclic aromatic hydrocarbons in Dabob Bay,Washington

Polycyclic aromatic hydrocarbon (PAH) compositions were determined in plankton, sediment-trap-collected particulate material and sediment cores from Dabob Bay using a high performance liquid Chromatographie (HPLC)/fluorescence technique. The annual flux of individual PAH measured in a series of sediment traps was compared with the flux of corresponding compounds determined from ²¹⁰Pb dated bottom sediments. Systematic seasonal variations in the fluxes and concentrations of PAH, Al and organic carbon in the trap-collected particulates and seasonally collected plankton were also investigated to determine whether or not PAH are associated with either terrestrial or marine-derived materials.Concentrations of all PAH studied increased tenfold within the last 80–100 yr of sediment deposition, except for perylene which displayed a reasonably constant concentration profile. This suggests at least two sources contribute to the observed sedimentary PAH compositions in Dabob Bay, i.e., anthropogenic combustion and a natural source. Plankton and sediment trap-collected particulates contained PAH mixtures qualitatively similar to underlying surface sediments. Microscopic examination indicated fecal pellets were the major form of particulate material in the sediment traps. The fecal pellets collected in the sediment trap time series quantitatively account for essentially 100% of the PAH fluxes measured in the ²¹⁰Pb dated sediments, implying Zooplankton fecal pellets control the removal of PAH to Dabob Bay sediments. These measurements provide clear evidence that the PAH studied are not produced after sediment deposition. The observed seasonal covariations of PAH and Al in both sediment trap and plankton samples further indicate that PAH originate from terrestrially-based sources, are introduced into the marine environment by runoff and erosion or atmospheric deposition and are not produced by marine plankton.     

Retention of fly ash-derived copper in sediments of the Pandu River near Kanpur,India

A coal-based thermal power plant is situated on the bank of the Pandu River, which is a tributary to the Ganges near Kanpur. River sediments downstream from the ash pond outfall are contaminated by fly ash. In order to establish the role of soils and sediments in retaining fly ash-derived heavy metals, copper was investigated as a model metal. A maximum concentration of 70 ppm Cu could be leached from the fly ash, confirming that it is a major source of this metal. Soil samples and river sediments were examined for Cu adsorption in the natural state as well as after treatment with H₂O₂, EDTA, and H₂O₂ followed by EDTA. The organic fraction of the samples was determined, and it had a major control on removal of Cu from a solution with 10^–4 M initial concentration. Further characterization of organic matter indicated that with reference to natural samples, the humic acid fraction had a copper enrichment factor in the range 9.1–15.1. The factor for fulvic acids, in contrast, was between 3.5 and 5.5. This leads to the conclusion that river deposits rich in humic acids would withstand relatively high metal loads. Only when the metal input exceeds the maximum retention potential, would the metal be fractionated into the aqueous phase and act as a potential biocide.