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1.
《Marine pollution bulletin》2009,58(6-12):403-408
Laboratory experiments were carried out to investigate the adsorption behaviour of dibutyl phthalate (DBP) on marine sediments collected from five different sites in Victoria Harbour, Hong Kong. DBP adsorption can be well described by the Langmuir isotherm. The maximum DBP adsorption capacity (Qmax) of the marine sediments ranges from 53 to 79 mg g−1, which has a positive correlation with their organic content. Around 90% of the organic can be removed from the sediments with treatment by H2O2 oxidation, and the Qmax then decreases to a range between 13 and 22 mg g−1. The black carbon content of the sediments has a much greater DBP adsorption capacity than does the natural organic matter of the sediments. The amount of DBP adsorbed on the sediments increases as the salinity of the marine water increases.  相似文献   

2.
A laboratory incubation experiment was conducted using replicate cores collected from a muddy-sand sediment facies offshore Sydney, Australia to determine what components and processes would be affected by the addition of sewage organic matter. Sewage effluent has a solid phase composition of 40% carbon (35% organic carbon), 5% nitrogen, 1% phosphorus and 5% silicate. The molecular C:N:P ratio is 92:10:1, compared to the Redfield ratio of 106:16:1 in marine phytoplankton. Sediment cores were incubated at in situ temperature in a darkened room for periods up to 95 days. Sewage organic matter was added to the cores at three different loads equivalent to 0 (T0), 65 (T1) and 130 (T2) g m−2 of sediment. Following the addition of sewage organic matter, fluxes of oxygen (into the sediments), ammonia and phosphate (from the sediments) increased, reflecting an enhanced organic carbon supply to the sediments. Oxygen penetrated to a depth of 6 mm in the ambient cores, but the sediment oxygen content was severely depleted following the addition of the sewage-derived organic matter. Sediment porewater data, together with nutrient flux data indicate that oxygen reduction, nitrate reduction and sulphate reduction occurs within these sediments. Following the addition of sewage organic matter, increases in total nitrogen, total phosphate and total organic carbon were measured to depths of 5 cm in the sediments, suggesting that bioturbation influences nutrient and organic carbon distributions. Additionally, irrigation of the surficial sediments may play an important role in the metabolism of organic matter. These results indicate that oxygen penetration, oxygen fluxes, nitrate concentrations within porewaters, ammonia flux rates, and solid phase concentrations of total organic carbon and nutrients may be useful indicators of sediments affected by high rates of organic matter deposition onto Sydney's offshore sediments. The EPA has recently predicted maximum deposition rates of sewage particulate matter to be approximately 1 g m−2 day−1. Because of the similarities in CNP ratios of sewage organic matter and marine organic matter, the effects of sewage organic matter and marine organic matter inputs to coastal sediments may not be easily distinguishable.  相似文献   

3.
章奇  居琪  李健欣  曹驰程  江和龙  张晖 《湖泊科学》2020,32(4):1041-1049
为探究富营养化湖泊中自生源可溶有机质(DOM)在泥水界面的吸附行为,以马来眼子菜(Potamogeton malaianus)和铜绿微囊藻(Microcystis aeruginosa)释放的DOM为代表,考察针铁矿对草、藻源DOM中不同组分的吸附特征.三维荧光平行因子分析表明类富里酸组分C1和类胡敏酸组分C4的含量很低,而类蛋白物质(类酪氨酸组分C2和类色氨酸组分C3)分别占草、藻源DOM荧光组成的70%和93%. 2种DOM均可被针铁矿吸附,吸附过程符合伪一级动力学.通过等温线拟合发现针铁矿吸附藻源DOM的非线性更强,饱和吸附量(23.77 mg/g)高于草源DOM(19.10 mg/g).特别地,类蛋白组分呈现非线性吸附,而类腐殖物质的吸附近似线性,且针铁矿对于DOM各荧光组分的吸附量顺序为:C3C2 C4 C1,此非均质吸附特征与DOM组分的初始含量、分子大小、芳香性及有效吸附位点有关.红外光谱证实氨基、羧基和羟基是吸附过程中的重要官能团.因此,草、藻源DOM显著改变了针铁矿表面的有机物质组成,影响湖泊沉积物的生物地球化学行为.  相似文献   

4.
The adsorption of cobalt ions was evaluated using sediment samples from water bodies to investigate the adsorption properties of sediment and the behavior of these natural materials in the presence of nuclear and industrial waste.The two sediments(S1 and S2)were treated to eliminate humic and fulvic acids and then they were characterized by several techniques.The minerals found in both the sediments(X-ray diffraction)were quartz and albite;plus,goethite and muscovite in S1,and kaolinite and montmorillonite in S2.Point of zero charge(PZC)of S1 and S2 was 6.00 and 5.22,respectively.The specific area of S1(63.3 m2/g)is higher than S2(1.5 m2/g).Adsorption kinetics data for S1 and S2 were best fitted to the pseudo second-order model.The removal efficiency of S1 for cobalt was 96%with an adsorption capacity(qe)of 0.93 mg/g,and for S2 was 45%with a qeof 0.40 mg/g.The experimental data of the adsorption isotherms were adjusted to Langmuir and Freundlich models for S1 and S2,respectively.The thermodynamic parameters(enthalpy,entropy,and Gibb’s free energy)indicated that the adsorption processes were endothermic,spontaneous,and chemisorption mechanism.The results show that the adsorption capacities of the sediments depend on their composition.These water sediments have important adsorption properties for cobalt,and they can be used in the treatment of nuclear and industrial aqueous wastes.  相似文献   

5.
有机质对城市污染河道沉积物铵态氮吸附-解吸的影响   总被引：2，自引：0，他引：2  
采集污染程度不同的城市河道沉积物(通吕运河、濠河和通甲河),在分析H2O2对沉积物有机质和铵态氮影响的基础上,分析沉积物在去除有机质前后铵态氮释放动力学和吸附热力学过程,研究城市污染河道沉积物有机质对铵态氮吸附-解吸的影响.结果表明:单位体积H2O2对有机质去除率随H2O2使用量增多而降低;去除有机质后,沉积物铵态氮含量显著增加,通吕运河、濠河和通甲河铵态氮最大含量分别是有机质去除前的4.16、3.55和2.85倍;沉积物对铵态氮的饱和吸附量随有机质含量减少而下降;沉积物铵态氮释放过程均表现为先快速释放,后减缓至平衡过程;去除有机质后,随着有机质含量的减少,沉积物铵态氮的最大释放量呈增大趋势;沉积物有机质和铵态氮含量是影响沉积物铵态氮释放的主要因素.  相似文献   

6.
The influence of the sediment’s physico-chemical properties and black carbon content, on the distribution of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in benthic sediments of the Gulf of Gdansk (Baltic Sea) was determined. Sediments from port, marine dump site of dredged spoils, the Vistula river mouth, Gdansk Deep were selected.The concentrations of ∑PAHs (fluoranthene, pyrene, benzo(a)anthracene, benzo(k)fluoranthene, benzo(a)pyrene, dibenzo(ah)anthracene, benzo(ghi)perylene) were 294-2200 ng/g d.w. and for ∑PCBs (28, 52, 101, 118, 138, 153, 180) were 2.4-11.3 ng/g d.w.The sediments content of loss on ignition was 1.13-16.15%, total organic carbon was 0.89-7.15%, black carbon was 0.20-1.15%. The highest correlation coefficient values (r = 0.76-0.92, p < 0.05) for a relationship between the concentrations of organic pollutants, and organic matter, organic and black carbon contents were obtained in harbor sediments with low content of organic matter (<5%) and high share of black carbon in total carbon (up to 40%).  相似文献   

7.
This study examined the phosphorus retention and release characteristics of sediments in the eutrophic Mai Po Marshes in Hong Kong. Results of chemical fractionation show that the sum of inorganic P pools exceeded 50% of the total sediment P content, with the redox-sensitive iron-bound P (Fe(OOH) approximately P) being the dominant P fraction. Given the considerable average Fe(OOH) approximately P concentration of 912 microg g(-1), Mai Po sediments demonstrated a great potential to release bioavailable P under low sediment redox potentials. This was further supported by the high mean anaerobic P flux of 31.8 mg m(-2)d(-1) recorded in Mai Po sediment cores, indicating the role of bottom sediments as a net P source. Although sediments in Mai Po had appreciable Langmuir adsorption maxima (1642-3582 mg kg(-1)), the high zero equilibrium P concentrations (0.02-0.51 mg L(-1)) obtained suggest that sediment sorption processes would contribute to sustaining the eutrophic conditions in overlying water column even with a further reduction in external P load. Concerted efforts should be made to reduce internal loading of P, especially under reducing conditions, to complement the implementation of zero discharge policy for Deep Bay for effective eutrophication abatement and long-term water quality improvement in the Mai Po Marshes.  相似文献   

8.
Fei YH  Li XD  Li XY 《Marine pollution bulletin》2011,63(5-12):578-582
Hydrophobic organic contaminants in marine water are mostly adsorbed onto (partitioned into) sediment organic matter (SOM). To study the impact of SOM diagenesis on sediment adsorption properties, artificial sediment with rich SOM content was incubated for more than 120 days. The sediment was sampled every week, and batch sediment adsorption tests were conducted with bisphenol A (BPA) and nonylphenol (NP) as the model pollutants. The results show that the amount of organic matter loaded in the sediment decreased by nearly 80% during incubation. For the incubated sediment, the BPA partition coefficient, Kd, decreased whereas the organic normalized partition coefficient, Koc, more than doubled. The experiments with NP show an even greater increase in Koc. Organic matter diagenesis shows a profound effect on the adsorption behavior of sediment, as the SOM residue has an increasing affinity and partition capacity for organic contaminants.  相似文献   

9.
Accumulation rates of marine and terrigenous organic carbon in the continental margin sediments off southwestern Taiwan were estimated from the measured concentrations and isotopic compositions of total organic carbon (TOC) and previously reported sedimentation rates. Surficial sediments were collected from the study area spanning from the narrow shelf near the Kaoping River mouth to the deep slope with depths reaching almost 3000 m. The average sediment loading of Kaoping River is 17 Mt/yr, which yields high sediment accumulation rates ranging from 0.08 to 1.44 g cm−2 yr−1 in the continental margin. About half of the discharged sediments were deposited on the margin within 120 km of the river mouth. Carbon isotopic compositions of terrestrial and marine end-members of organic matter were determined, respectively, based on suspended particulate matter (SPM) collected from three major rivers in the southwestern Taiwan and from an offshore station. All samples were analyzed for the TOC content and its isotopic composition (δ13Corg). The SPM samples were also analyzed for the total nitrogen (TN) content. TOC content in marine sediments ranges from 0.45% to 1.35% with the highest values on the upper slope near the Kaoping River mouth. The TOC/TN ratio of the SPM samples from the offshore station is 6.8±0.6, almost identical to the Redfield ratio, indicating their predominantly marine origin; their δ13Corg values are also typically marine with a mean of −21.5±0.3‰. The riverine SPM samples exhibit typical terrestrial δ13Corg values around −25‰. The δ13Corg values of surficial sediments range from −24.8‰ to −21.2‰, showing a distribution pattern influenced by inputs from the Kaoping River. The relative contributions from marine and terrestrial sources to sedimentary organic carbon were determined by the isotope mixing model with end-member compositions derived from the riverine and marine SPM. High fluvial sediment inputs lead to efficient trapping of organic carbon over a wide range of water depth in this continental margin. The marine organic accumulation rate ranges from 1.6 to 70 g C m−2 yr−1 with an area weighted mean of 4.2 g C m−2 yr−1, which is on a par with the mean terrestrial contribution and accounts for 2.3% of mean primary production. The depth-dependent accumulation rate of marine organic carbon can be simulated with a function involving primary productivity and mineral accumulation rate, which may be applicable to other continental margins with high sedimentation rates. Away from the nearshore area, the content of terrigenous organic carbon in surficial sediments decreases with distance from the river mouth, indicating its degradation in marine environments.  相似文献   

10.
Batch and continuous flow adsorption experiments are carried out and the design of a full‐scale facility for removing dissolved natural organic matter (DNOM) from Catalan Lakewater is demonstrated. The adsorption efficiency is proportional to the temperature and the amount of adsorbent unlike pH increase. The highest DNOM removal rate is obtained at 35 °C, pH 4, and an adsorbent amount of 0.8 g L?1. Optimum contact time for batch studies is 60 min at equilibrium. Correlation constants (r) of Langmuir and Freundlich isotherms are 0.8905 and 0.9739, respectively. Based on the Freundlich isotherm, the highest adsorption capacity (qmax) obtained is 2.44 and 6.01 mg DNOM/g granulated activated carbon (GAC) for raw and enriched water, respectively. Consequently, the effects of adsorbent amount, bed depth, empty bed contact time, and organic loading on removal performance are investigated in the rapid small‐scale column test (RSSCT) columns. The targeted effluent concentration of 1 mg DNOM/L can easily be achieved in the columns. At the design capacity of the facility, 15 adsorption columns with dimensions of 7 m height, 4.33 m diameter, and 22 days of operation cycle are required to remove DNOM from raw water.  相似文献   

11.
A laboratory study was carried out to investigate the influence of the biomass content in the sediment on the rate of diagenesis of particulate organic materials (POM) and the consequent sediment oxygen demand (SOD) and nutrient fluxes. Fish food pellets were loaded into the sediment to simulate a sudden POM input. Three types of sediments with different biomass contents were tested, including a raw marine sediment, the marine sediment after one month of cultivation and an artificial sediment of sand and clay without any biomass. There was little difference in organic flux from the three different sediments. However, compared to the artificial sediment, the marine sediments had much higher SOD and ammonia flux. A mathematical model also has been developed for the SOD dynamics and nutrient fluxes. Both the experimental and simulation results indicate the important role of the biomass in the sediment in POM diagenesis, SOD and nutrient fluxes.  相似文献   

12.
The attenuation of compressional and shear waves ( Q p and Q s) has been studied by several authors but most of these investigations were performed on deep buried reservoir sandstones in order to distinguish between gas and condensate reservoirs and water-saturated sandstones. We present a preliminary investigation into the use of seismic wave attenuation as a measure of the geotechnical parameters of the near-surface marine sediments, a little-studied geological setting. A 6.9 m-long gravity core was taken from the continental slope of the Barents Sea at a water depth of 2227 m. The core was primarily composed of brown to olive-grey clayey mud, having a high content of foraminifers and being locally bioturbated. The values of Q p and Q s were determined using the rise-time method at 19 and 18 different points of the core, respectively, and they were correlated with geotechnical parameters such as wet bulk density, porosity, water content, shear strength and C/P ratio (the ratio of shear strength to overburden pressure). The calculated correlation coefficients for all correlations ranged from −0.39 to 0.41, suggesting that the attenuation characteristics of seismic waves could not be used to derive geotechnical parameters of marine sediments. However, with such a small data set it is difficult to determine clearly whether attenuation is primarily a frequency-dependent parameter and consequently not related to sediment properties, or whether the limited number of data points is the main factor responsible for the low correlation coefficients observed. Moreover, several different methods are available for the computation of the quality factor Q , and the rise-time method may not be the most appropriate means of determining the attenuation on near-surface marine sediments.  相似文献   

13.
A nomogram is developed to show that pH, redox potentials (EhNHE) and measures of dissolved sulfides (H2S + HS− + S2−)(total free S2−) can be used to classify organic enrichment impacts in marine sediments. The biogeochemical cycle of sulfur in marine sediments is described to show that changes in macrobenthic infauna community structure associated with high levels of organic matter supply result from stress due to oxygen deficiency (hypoxia and anoxia) and toxic effects of S2−. The changes reflect enhancement of microbial sulfate reduction under conditions of high organic matter sedimentation and the progressive formation of hypoxic–anoxic conditions measured by decreased EhNHE and increased concentrations of S2−. The nomogram provides a basis for classification of the oxic status of marine sediments based on changes in inter-related biological and biogeochemical variables along an organic enrichment gradient.  相似文献   

14.
Total organic carbon (TOC), total nitrogen (TN) and their δ(13)C and δ(15)N values were determined for 42 surface sediments from coastal Bohai Bay in order to determine the concentration and identify the source of organic matter. The sampling sites covered both the marine region of coastal Bohai Bay and the major rivers it connects with. More abundant TOC and TN in sediments from rivers than from the marine region reflect the situation that most of the terrestrial organic matter is deposited before it meets the sea. The spatial variation in δ(13)C and δ(15)N signatures implies that the input of organic matter from anthropogenic activities has a more significant influence on its distribution than that from natural processes. Taking the area as a whole, surface sediments in the marine region of coastal Bohai Bay are dominated by marine derived organic carbon, which on average accounts for 62±11% of TOC.  相似文献   

15.
《Marine pollution bulletin》2009,58(6-12):681-688
A laboratory study was carried out to investigate the influence of the biomass content in the sediment on the rate of diagenesis of particulate organic materials (POM) and the consequent sediment oxygen demand (SOD) and nutrient fluxes. Fish food pellets were loaded into the sediment to simulate a sudden POM input. Three types of sediments with different biomass contents were tested, including a raw marine sediment, the marine sediment after one month of cultivation and an artificial sediment of sand and clay without any biomass. There was little difference in organic flux from the three different sediments. However, compared to the artificial sediment, the marine sediments had much higher SOD and ammonia flux. A mathematical model also has been developed for the SOD dynamics and nutrient fluxes. Both the experimental and simulation results indicate the important role of the biomass in the sediment in POM diagenesis, SOD and nutrient fluxes.  相似文献   

16.
Radiocesium reaction with illite and organic matter in marine sediment   总被引：1，自引：0，他引：1  
The mineralogical effect on the (137)Cs reaction with marine sediment has not been systematically studied yet, even though illite has been known to adsorb Cs preferentially on its frayed edge sites in a low Cs concentration. Ninety-three marine sediment samples were collected near Yangnam, Korea for quantitative X-ray-diffraction (XRD), gamma-ray, and total organic carbon (TOC) analysis. Illite content was in the range of 0-23 wt.% and those of (137)Cs and TOC were minimum detectable activity (MDA) approximately 7.19 Bq/kg-dry and approximately 3.32%, respectively. The illite content in the marine sediment showed a good relationship with the (137)Cs content (R(2)=0.69), but with an increase in the illite content, the relationship became less linear. This trend can be clearly shown in two groups of samples with different size fractions (< and >5Mdvarphi). For the samples of larger particle sizes (low contents of illite), the relationship is linear, but for the samples of the smaller particle sizes (high illite content) it is less linear with a decreased slope, indicating that increase in illite content does not significantly contribute to the fixation of (137)Cs in marine sediment. Rather, the TOC has a more linear relationship with (137)Cs content with no slope change in all particle size ranges. This may indicate that humic materials in marine sediment block the access of (137)Cs to the frayed edge site and reduces the adsorption of (137)Cs on illite and that the organic materials in marine sediment play more important roles in adsorbing Cs than illite.  相似文献   

17.
Petroleum hydrocarbons persist in salt marsh sediments in Winsor Cove (Buzzards Bay, Massachusetts) impacted from the 1974 spill of No. 2 fuel oil by the barge Bouchard 65. Intertidal sediment cores were collected from 2001 to 2005 and analyzed for total petroleum hydrocarbons (TPHs). TPHs content was greatest (as high as 8.7 mg g(-1) dry weight) in the surface sediments and decreased with distance landward. Select samples were analyzed for polycyclic aromatic hydrocarbons (PAHs) with values as high as 16.7 microg g(-1) for total naphthalenes and phenanthrenes/anthracenes. These remaining PAHs are mainly C(4)-naphthalenes and C(1)-, C(2)-, and C(3)-phenanthrenes/anthracenes revealing preferential loss of almost all of the naphthalenes and the parent compound phenanthrene. Inspection of the data indicates that biodegradation, water-washing and evaporation were major removal processes for many of the petroleum hydrocarbons in the marsh sediments. In addition, historical data and photographs combined with their recent counterparts indicate that erosion has physically removed these contaminants from this site.  相似文献   

18.
Local marine environments in China's Pearl River Delta (PRD), the most rapidly developing region in one of the world's fastest growing economies, have been experiencing significant environmental stress during the past decades. This investigation was conducted to determine the status and trends of persistence organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs), petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-related compounds in marine sediments collected from sixteen coastal stations in the Pearl River Delta (PRD) in March 2003. Elevated concentrations of PAHs (94-4300 ng/g), PCBs (6.0-290 ng/g), PHCs (14-150 microg/g), and DDTs (1.4-600 ng/g) were detected in sediment samples. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activities in the sediment samples were estimated to range from 0.3 to 440 pg TCDD-EQ/g. Sediments collected from Xiashan contained the greatest concentrations of trace organic contaminations amongst all the sampling stations in the present study. The degree of trace organic contamination was, in general, more severe at stations situated along the west shores of the PRD than their counterparts in the east. A preliminary assessment was performed to examine the probable risks to the marine ecosystem due to POPs. The results showed that OC pesticide contamination in the PRD was particularly serious and might pose a threat to the health of the marine inhabitants.  相似文献   

19.
Distribution of metals, PAH's and PCB's in lobsters, mussels, and sediments were used to assess marine environmental quality of the Bay of Fundy. This study demonstrates that the lobster (Homarus americanus) is a better bioindicator for monitoring contaminants in the marine environment and has a greater capacity for the uptake and accumulation of contaminants than the mussel (Mytilus edulis) and sediments. A definite pattern in the spatial distribution of lobster Cu, Cd, and Ag was evident. The distribution of organic contaminants for both mussels and lobsters in the Bay of Fundy lacked a spatial trend, and organic contaminants were undetectable in sediments from all sites. The Gulf Watch Programme, which monitors chemicals in mussels in the Bay of Fundy, did not indicate a problem with high levels of Cu, Cd, and Zn in the ecosystem. Analytes below the detection limit, such as in mussels and sediments, increase the difficulties of chemical analysis and detection for environmental monitoring. Deficiencies of mussels in monitoring the Bay of Fundy were discussed.  相似文献   

20.
Variations in porosity of surface sediments are often the major cause of sediment loss during gravity and box coring. Sediments with a high content of organic matter usually have higher porosity, and thus, lower resistance (strain) towards mechanical disturbance. Here, we demonstrate that box coring artifacts (i.e. sediment loss and core shortening) can be produced in sediments from the Palos Verdes (PV) shelf, which in the past had received relatively high loads of organic carbon (OC) enriched particulate matter originating from the Whites Point outfall that had created a high porosity layer at depth. This has been overlooked as a possibility for obtaining low estimates of sediment and pollutant accumulation rates. Since any such sediment loss during coring can lead to serious underestimates of sedimentation rates, our results here may have important implications for any attempts at reconstructing pollutant fluxes and histories in these coastal marine sediments.  相似文献   

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