Matter Content Of Sediment Research Articles

Distribution and bioaccumulation of organochlorine pesticides in surface sediments and benthic organisms from Taihu Lake, China

The spatial distribution and bioaccumulation of organochlorine pesticides (OCPs) in surface sediments and benthic organisms from Taihu Lake were studied. OCPs were detected in all sediment samples with total concentrations ranging from 4.22 to 461 ng g −1 dry weight (dw). The ratios of certain metabolites to their parent compounds indicated there are still new inputs of parent DDT (dichlorodiphenyltrichloroethane) to Taihu Lake, while the highest residues of HCHs (hexachlorocyclohexanes) mainly came from earlier usage and fresh γ-HCH (lindane). No positive correlation was found between the distribution of OCPs and organic matter contents in sediments. Concentrations of OCPs and lipids in typical large benthic organisms, Bellamya aeruginosa ( B. aeruginosa) and Corbicula fluminea ( C. fluminea) , increased with body weight. HCHs, DDTs, chlordanes and heptachlors were the dominant compounds detected in organisms and C. fluminea accumulated much more OCP than B. aeruginosa. Higher values of biota-sediment accumulation factor (BSAF) were detected in C. fluminea, which was both affected by biological characteristics of the organisms and physicochemical properties of the compounds.

Butyltin compounds and their relation with organic matter in marine sediments from San Vicente Bay—Chile

Tributyltin and its degradation products, mono-and dibutyltin have been determined in sediments collected in some representative sites in San Vicente Bay, Chile. The organic matter contents of sediments and water collected simultaneously from the same sampling sites were also determined. High levels of total organic carbon were found in sediments, especially in those from the northern part of the bay (1.80-8.87%). Good correlations were found between total organic carbon and the oxidizable and refractory carbon fractions. Among the butyltin species determined, TBT presented the highest levels, ranging from 14 to 1,560 ng Sn g(-1) dry weight. Concentration ratios of TBT to DBT ranged between 1.33 and 3.10, showing a high degree of contamination in sediments of this Chilean bay. All data obtained were analysed by the chemometric method of principal components analysis. A strong correlation was found between TBT and DBT concentrations in sediments, the different organic matter contents in sediments and water. In marine organisms only TBT was detected, containing the filterer organism Semele solida higher level than Perumytilus purpuratus and Pyura chilensis (220, 150 and 120 ng Sn g(-1) dry weight, respectively). For the alga Rodoficea iridae the TBT concentration was 60 ng Sn g(-1) dw. Comparatively, these values are higher than those reported for the same kind of marine organisms worldwide. The different samples from San Vicente Bay were found to be contaminated by TBT. This contamination can be attributed to the different anthropogenic activities taking place in the bay.

Total and Methyl Hg in Sediment Adjacent to Offshore Platforms of the Gulf of Mexico

Distribution of total Hg and methyl Hg in surface sediment with distance from the three legs of two offshore oil production platforms was studied. Concentration of both total Hg and methyl Hg decreased with distance (0 to 800 m) from two platforms. Average methyl Hg content in sediment near the platform was 1.15 ppb, decreasing to 0.44 at 800 m. Average total Hg content in surface sediment measured at the two platforms was 63.40 ppb, decreasing to 29.45 at 800 m. The mercury level paralleled decrease in sediment organic matter with distance from the platform. Results of this study showed low levels of mercury in vicinity of the platform. Increased methyl Hg was likely associated with the higher organic matter content of sediment near the platform rather than mercury levels in sediment.

Nitrogen and phosphorus forms and release risks of lake sediments from the middle and lower reaches of the Yangtze River

运用聚类分析、主成分分析和相关矩阵的统计分析手段,对长江中下游湖群共18个湖泊的沉积物氮磷释放风险以及湖泊沉积物、间隙水和上覆水中氮磷形态以及其他相关地球化学参数进行分析.草型和藻型湖泊的环境差异是造成氮磷释放风险的主要原因.氮磷释放风险与铁磷、藻类可利用磷、总氮、总磷、上覆水氮磷含量、间隙水氮含量、孔隙度和有机质含量间的关系最为密切.决定磷酸盐释放风险的主要形态磷是藻类可利用磷和铁磷,其他形态磷或者含量较低或者不易被转化释放,对磷酸盐释放风险影响较小.有机磷含量对磷的释放风险没有直接决定作用,但它与有机质含量间呈显著正相关.;Cluster analysis, principal component analysis and correlation matrix analysis were used to analysis the nitrogen and phosphorus release risks from sediments in 18 lakes located in the middle and lower reaches of the Yangtze River, as well as the nitrogen and phosphorus forms and related geochemical parameters from sediments, pore waters and overlying waters. The ecological difference of macrophyte and algae dominated lakes was the main reason of the difference of nitrogen and phosphorus release. The release risks were well correlated with the iron-bound phosphorus (FeP), algae available phosphorus (AAP), total nitrogen (TN), total phosphorus (TP) in sediment, the content of nitrogen and phosphorus in overlying and pore waters, porosity and organic matter content of surficial sediment. The AAP and FeP was the main phosphorus forms deciding the phosphorus release risk and other forms were in less effect on it due to the lower contents or lower transformation ability. The sediment organic phosphorus was not directly related to the phosphorus release risks but remarkably positively correlated to organic matter contents in sediment.

The phosphorous chemical behavior in water-sediment polluted by sewage of manure and aquiculture

通过受猪场污水影响的池塘和鱼塘水生生态系统中表层水-沉积物的磷含量、磷吸附能力比较,了解猪场污水、鱼塘养殖对表层水-沉积物系统磷行为的影响.结果表明,猪场污水排放和鱼塘养殖都会明显增加水体中溶解性反应磷(DRP)和溶解性有机磷(DOP)的含量,从DRP、DOP、PP3种形态磷在总磷中所占的比例来看,DRP是水体中主要增加的磷含量.猪场污水排放对水体中磷的增加作用比鱼塘养殖更剧烈一些,猪粪是水体中磷的主要来源.但是猪场污水排放对沉积物中不同形态磷含量的影响不明显,这可能与水体中磷的存在形态和转化时间有关.鱼塘养殖增加了沉积物中有机质、Fe-P、Al-P和总无机磷含量,增加了沉积物对磷的最大吸附容量,但是对磷的吸附能力却有所降低,进而增加了沉积物中磷向上覆水释放的可能.;According to compare the content of phosphorus (P) fraction, P sorption ability of water-sediment in ponds polluted by sewage from a hoggery and a rearing-pond, the influences of sewage from hoggery and fishery on P behavior in water-sediment system were studied. The results indicated that sewage from hoggery and fishery could significantly increase P contents in water, and sewage from hoggery increased more significantly dissolved P in water than fishery. Sewage from hoggery had no significant influence on sediment P concentration and P sorption properties, whereas fishery could significantly increase total inorganic P, Fe bound P (Fe-P) in sediment and maximum P sorption capacity and decrease P absorptive capability of sediment. The P sorption properties of sediment had some relationship with organic matter content in sediment.

Is Arenicola marina a suitable test organism to evaluate the bioaccumulation potential of Hg, PAHs and PCBs from dredged sediments?

This paper presents the results of investigations on the suitability of lugworms ( Arenicola marina) to study the bioaccumulation potential of Hg, PCB and PAH compounds from dredged sediments upon laboratory exposure. The results of tissue concentrations for several sediments from Spanish ports showed that it is possible to identify increased levels of contaminants in lugworms just after 10 days of exposure although different bioaccumulation trends were shown amongst compounds and sediments. Total and organic Hg compounds were accumulated following a non-linear trend, with a sharp increase of tissue concentrations in lugworms exposed to levels of contamination associated to a significant increase in mortality. Interestingly organic Hg compounds accounted for an average of 40% of the total Hg in lugworms exposed to sediments presenting sublethal concentrations while, when exposed to sediments presenting lethal concentrations, organic Hg compounds only accounted for 4% of the total Hg accumulated in lugworms. While lugworms seem to readily accumulate Hg and PCB compounds, with some variability explained by the organic matter content in sediments or other factor for which it accounts for, the results for PAHs suggest a more complex process of bioaccumulation as no relationship was observed between the measured concentrations in sediments and in lugworms, not even after correcting the results for this factor. Besides, the differences in the calculated BSAFs for each compound and for each sediment supported the use of bioassays for evaluating the bioaccumulation potential of sediment-bound contaminants as part of the assessment framework required in pre-dredging investigations, as they still offer unique information about the bioavailability of sediment-bound contaminants.

Relationships between deep-water polychaete fauna and environmental factors in the southeastern Gulf of California, Mexico

Polychaetes inhabiting deep-sea soft bottoms in the southeastern Gulf of California were collected during four oceanographic cruises in 2000 and 2001 at a depth range of 732-2110 m. A total of 84 taxa, representing 32 families, were collected. The relationships between density, species number and diversity and depth, dissolved oxygen, temperature, granulometry and organic matter content in sediments were analysed. Cluster analyses and MDS plots based on density allowed faunal assemblages to be established for each environmental variable: 700-1100 m, 1100-1600 m, 1900-2100 m and 2100-2200 m (depth); 0.00-1.20 ml/L, 1.20-2.00 ml/L and 2.00-2.40 ml/L (oxygen); 2.0-2.5°C, 2.5-4.0°C, 4.0-6.0°C and 6-6.5°C (temperature); 8-16%, 16%-18% and 18-20% (organic matter), 20-30%, 60-70% and 80-100% (mud). Polychaetes were not distributed according to gradients of any of these environmental variables. The dominant and frequent species of each group were not restricted to unique assemblages. Results of a canonical correspondence analysis indicated that depth, oxygen and temperature were the main environmental variables responsible for polychaete distribution. The dominance of muddy sediments with high organic matter content (8.26 to 18.78%) throughout the study area reduces the importance of these parameters for polychaete distribution, since the dominant and frequent species belong to the detritivore families Ampharetidae, Maldanidae and Cirratulidae.

Physiological responses of the seagrass Posidonia oceanica to elevated organic matter content in sediments: An experimental assessment

Here we studied the effects of adding organic carbon and nutrients to sediment on the physiology and survival of the seagrass Posidonia oceanica in a field experiment in the Medes Islands (NE Spain). Nine randomly selected plots were established at a depth of 10 m; three were enriched with organic carbon (OM treatment), three with organic carbon and nutrients (OMN treatment), and three were kept as controls (CON). The experiment was performed over 5 months and sampling of plants and sediments was done in March, May and July 2002. Sediment sulfide pools and pore water ammonium concentrations increased significantly in OM and OMN plots, both treatments showing increased reducing conditions in the sediment. Plants in these two treatments showed higher mortality and lower biomass compared to plants from CON plots. The greatest effects on seagrass occurred in the OMN plots, indicating a synergistic effect of organic carbon and nutrient additions. Treatments had significant effects on plant nitrogen (N) and phosphorous (P) metabolism, shown by an increase in free amino acid (FAA) content, a change in FAA composition and a lack of increase in N and P tissue content. Treated plants showed higher g-aminobutyric acid (GABA) and malate concentrations and lower concentrations of non-structural carbohydrates compared to CON, indicating that anaerobic respiration in below-ground tissues occurred. Several of the physiological changes shown by P. oceanica can be interpreted as adaptations to anoxia exposure. However, the increased mortality in treated plots demonstrates that this seagrass does not tolerate highly reduced sediments.

Effect of organic matter on the sorption of dissolved organic and inorganic phosphorus in lake sediments

The sorption of phosphate on lake sediments has a major influence on transport, degradation, and ultimate fate of phosphorus (P) in lake ecosystem. Organic P is abundant in sediments and is an important P speciation for primary productivity. Organic P can also be transferred from sediments into the overlying water and supplies nutrition for aquatic organisms. Despite the importance of organic P, it remains poorly understood, especially the organic P sorption on sediments. This study evaluated dissolved organic phosphorus (DOP) and PO 4 3− sorption on sediments, effect of organic matter on the sorption of DOP and PO 4 3−, and differences of the sorption characteristics of DOP versus PO 4 3− and dissolved organic carbon (DOC) versus DOP. The results show that DOP and PO 4 3− sorption kinetics can be satisfactorily fitted by the modified Langmuir model and linear model, respectively, organic matter did not significantly affect their general trend. For inorganic P, with the increasing of organic matter content, sediments had lower sorption efficiency (m), higher amount of P naturally sorbed and higher risk of P release. While for organic P, with the increasing of organic matter content, sediments had weaker binding strength, stronger ability of dissolved organic matter (DOM) release and higher sorption capacity. The results also show that the DOP and PO 4 3− sorption process was composed of quick and slow sorption, the quick sorption mainly occurred within 0.5 h. The DOP and PO 4 3− sorption kinetics can be best fitted by both power function and simple Elovich models. Organic matter in sediments had a remarkable effect on DOP and PO 4 3− sorption rates. But it did not affect the DOP and PO 4 3−sorption trend, and the effect of organic matter on PO 4 3− sorption rate was more obvious than that on DOP. DOP was preferentially sorbed over PO 4 3− in sediments and the DOP sorption increased more strongly with the increasing of organic matter content in sediments than the PO 4 3− sorption. The sorption of DOP and DOC increased similarly with the increasing of organic matter content in sediments, and DOC was preferentially absorbed. The rank order of sorption strength of sediments was as follows: DOC < PO 4 3− < DOP. This study has significant implication for the understanding of P biogeochemical cycling and its role in affecting eutrophication in lake ecosystem.

Denitrification in bottom sediment near oil production facilities off the Louisiana Gulf Coast

There is little information on denitrification in Gulf of Mexico bottom sediment. Potential denitrification rates in surface sediment were measured along transects legs extending 0–800 m from two offshore oil production platforms. The average potential denitrification ranged from approximately 50 mg N m−2 d−1 in surface sediment near the platforms to 15 mg N m−2 d−1 in sediment 800 m from the platforms. Measured denitrification rates were correlated to a higher organic matter content in sediment nearer the platforms. This research examined only a small component of nitrogen processing in Gulf of Mexico sediment. Additional research should examine the effect of nitrogen loading and temporal and spatial variability on denitrification rate.

Behavior of arsenic and geochemical modeling of arsenic enrichment in aqueous environments

Arsenic is present in aqueous environments in +III and +V oxidation states. In oxidizing environments, the principle attenuation mechanism of As migration is its adsorption on Fe(III) oxide and hydroxides. The adsorption affinity is higher for As(V) under lower pH conditions and for As(III) under higher pH conditions. Ferric oxide and hydroxides can dissolve under low Eh and pH conditions releasing adsorbed As. Oxidation-reduction processes often involve high organic matter content in sediments and also contamination by organics such as BTEX. Arsenic may desorb under high pH conditions. Changes of pH can be related to some redox reactions, cation exchange reactions driving dissolution of carbonates, and dissolution of silicates. In very reducing environments, where SO 4 reduction takes place, secondary sulfide minerals like As-bearing pyrite and orpiment, As 2S 3, can incorporate As. Geochemical modeling can be divided into two principal categories: (a) forward modeling and (b) inverse modeling. Forward modeling is used to predict water chemistry after completion of predetermined reactions. Inverse modeling is used to suggest which processes take place along a flowpath. Complex coupled transport and geochemistry programs, which allow for simulation of As adsorption, are becoming available. A common modeling approach is based on forward modeling with surface complexation modeling (SCM) of As adsorption, which can incorporate the effect of different adsorbent/As ratios, adsorption sites density, area available for adsorption, pH changes and competition of As for adsorption sites with other dissolved species such as phosphate. The adsorption modeling can be performed in both batch and transport modes in codes such as PHREEQC. Inverse modeling is generally used to verify hypotheses on the origin of As. Basic prerequisites of inverse modeling are the knowledge of flow pattern (sampling points used in model have to be hydraulically connected) and information about mineralogy including As mineral phases. Case studies of geochemical modeling including modeling of As adsorption are presented.

Effects of leaping grey mullet Liza saliens (Osteichthyes, Mugilidae) in the macrophyte beds of oligohaline Mediterranean coastal lagoons

Some mugilid fish are known to enhance small phytoplankton in freshwater macrophyte-free environments due to zooplankton depletion. This suggests that they may have negative effects on natural macrophyte beds of freshwater and oligohaline lagoons due to phytoplantkon enhancement. To test this hypothesis, we compared the ecosystems of control enclosures that contained no fish with those of enclosures stocked with Liza saliens at two different densities. The occurrence of L. saliens at a density of 321±92.42 kg ha−1 reduced cladoceran density, depleted epiphytic chironomid larvae, enhanced mayfly nymphs and cyclopoid copepods and reduced the organic matter content of sediment, all in comparison with control enclosures. At a density of 673±42.04 kg ha−1, L. saliens reduced total zooplankton density, depleted epiphytic and sediment dwelling chironomid larvae and enhanced mayfly nymphs. The organic matter contents of sediment was not affected. These results showed that L. saliens was very effective in reducing zooplankton density even when macrophyte biomass was high. However, these effects do not affect phytoplankton density, probably because zooplankton was dominated by species with low filter-feeding rates and macrophytes depleted nutrients.

Uranium and thorium isotopes in some red sea sediments

Alpha-emitting isotopes of uranium and thorium in surface marine sediments collected from the harbours at Port Sudan and Sawakin on the Sudanese coast of the Red Sea have been studied using radiochemical separation procedures and alpha-particle spectrometry. Activity concentrations of 238U, 235U, 234U, 232Th, 230Th and 228Th were measured. The ranges of activities observed for 238U and 232Th were 2.71-13.42 Bq/kg and 3.62-18.73 Bq/kg from Port Sudan and 3.87-24.79 Bq/kg and 1.13-10.04 Bq/kg dry weight from Sawakin, respectively. The behaviour of these decay-series nuclides was examined using daughter/parent and non-isotopic specific activity ratios in sediments. Simple regression analysis showed insignificant correlation between uranium and thorium activities and the organic matter content in sediments. The results are compared with those from coastal waters of other oceans.

Spatial changes in sublittoral soft-bottom polychaete assemblages due to river inputs and sewage discharges

Spatial changes in species composition and structure of sublittoral soft-bottom polychaete assemblages along a transect parallel to the shoreline off the Barcelonès and Maresme regions on the Spanish Catalan coast (NW Mediterranean sea) are described. The transect (20 m mean depth) covers 30 km through an area affected by both water sewage discharges and river outflow. These effluents generate a spatial gradient of both silt and organic enrichment, according to the prevailing southerly currents in the zone. South of the effluents, eutrophized sediments supported a macrofaunal assemblage which was typical of polluted bottoms, characterized by the massive presence of Capitella capitata and Malacoceros fuliginosus, high abundance and biomass, low values of species richness, and a simplified trophic structure dominated by surface and subsurface-deposit feeders. North of the effluents, both the mud and organic matter content in sediment decreased drastically and the polychaete assemblages described were progressively less affected with distance. Thus, a clear change in species composition, as well as low values of abundance and biomass, increases in species richness, and a more complex trophic structure on the polychaete assemblages was observed north rather than south of the effluents.

Sediment oxygen demand in Hiroshima Bay

Effects of environmental factors, depth and layer thickness of sediment, organic matter, reducing substance, oxygen concentration and temperature, on sediment oxygen demand (SOD) were examined by laboratory experiments. Apparent effects on the SOD rates were recognized from each factor, except for the layer thickness and organic matter content in sediment. The SOD rates varied with sediment depths, which was attributed to the reducing substances in sediments. Temperature (T) revealed the most marked effect among these factors, and SOD rates increased linearly with temperature in the range of 10–30°C. Oxygen concentration in overlying water did not influence the SOD rate when it was over 2–3 mg/l, but influenced below this concentration.The SOD rates in Hiroshima Bay, measured by both an in situ chamber (bell jar) and a laboratory method with intact cores, agreed well with each other and ranged from 0.10 to 0.61 g O2/m2/d, with a mean of 0.3–0.4 g O2/m2/d on an annual basis. The rates in summer and autumn were twice those in winter. It also became evident in this study that SOD rates in Hiroshima Bay were mainly controlled by biological consumptions from summer to autumn and by chemical consumption of the reducing substances during winter and spring.

Ecological assessment of semi-enclosed marine water bodies of the Archipelago Sabana-Camaguey (Cuba) prior to tourism development projects

The semienclosed marine water bodies of the Sabana-Camaguey Archipelago (N of Cuba) are the locations of extensive tourism development projects. Highways and bridges across these water bodies are being planned and constructed for the purpose of reaching and interconnecting outer bordering keys. In order to evaluate any possible ecological impact and to elaborate recommendations to avoid or minimize it, a multidisciplinary research was carried out. In some places, high organic matter contents in sediments due to the weak circulation regime which enhances accumulation processes, and high microbial mineralization rates, impoverish benthic assemblages. In some cases, salinity reaches very high values, sediments are dominated by silt or both conditions are met, situation that also lead to ecosystem constraints. Phyto and zooplankton show lower concentrations than expected in supposedly fertile semienclosed water bodies. Precipitation deficit during many years combined with damming for fresh water storage, and natural limited exchange between inshore and oceanic water are responsible for the observed ecological features.

Organic Matter Content in Sediments of Three Navigation Pools along the Upper Mississippi River

ABSTRACT Organic matter content was measured in 84 sediment profiles collected in navigation Pools 7, 8, and 9 along the upper Mississippi River. Organic matter content ranged from 0.25 to 22.80% with a mean content of 3.53 ± 2.06% but did not vary significantly (p = 0.05) with depth. Organic matter content in Pool 7 was significantly (p = 0.05) higher (4.81%) than that measured in Pool 8 (3.09%) or Pool 9 (3.20%). Organic matter content of sediment deposited between 1964–1977 was generally less than that in sediments deposited between 1954–1964 which was usually less than that in sediments deposited prior to 1954. Based on measured sediment accumulation rates in Pools 7, 8, and 9, the average influxes of organic matter for the period between 1954 and 1977 were 421, 265, and 328 g m−2 yr−1, respectively.

Geochemistry of Bottom Sediments, Conception Bay, Southeastern Newfoundland

Analysts of texture, mineralogy, and chemistry of bottom sediments in Conception Bay, southeastern Newfoundland has shown: (1) Sediment texture is related to water depth, (2) water depth, CaCO3 content, organic-C content, and feldspar/quartz peak area ratios are all related to sediment mean grain size, (3) concentrations of major elements are related to clay, organic-C, and CaCO3 contents and feldspar/quartz peak area ratios of sediments, (4) concentrations of trace elements are related to clay and organic-C contents, (5) sediment pH is related to Organic-C and CaCO3 contents, and (6) sediment temperature is related to water depth. These relationships indicate that four interrelated factors regulate sedimentary geochemical variables: Source and depositional environment are primary factors that regulate the type of solid components comprising sediments and sediment grain size, respectively; grain size is a secondary factor that regulates mineral and organic matter content of sediments; solids composition (quartz, feldspar, clay minerals, CaCO3, and organic matter) is a tertiary factor that regulates sediment chemistry. Sediment pH is regulated mainly by CaCO3 content and temperature is regulated by depositional environment. Particular attention should be paid to these factors when conducting sedimentary geochemical investigations.A surface layer of brick-red, iron-enriched sediment around Bell Island, which is the waste product of former mining activities, provides the only evidence of man's alteration of the Conception Bay bottom environment. Therefore, trace and major element concentrations in bottom sediments described in this paper are natural background levels which can be utilized for a future comparative study in the event of increased urbanization and/or industrialization of the Conception Bay area.Results of echosounder profiling have shown that the physiography of Conception Bay has been glacially modified. Four sets of marine terraces have been identified at water depths of 110–120, 90, 70–75, and 20 m. These terraces are correlative with others found elsewhere in Atlantic Canada.