Influence Of Suspended Sediment Research Articles

Bioavailability of citalopram to Daphnia magna in the presence of suspended sediments with various properties

The influence of suspended sediment (SPS) properties on the biological effects of antidepressant citalopram (CIT) was investigated in our study. For CIT exposure alone, the feeding behavior, energy available, glutathione-S-transferase (GST) activity of D. magna were vitally induced at 10 μg/L. In the presence of SPS, significant dose-dependent reduction in the ingestion and filtration rates were observed with the increase of SPS concentration, while SPS organic content (foc) of 1% exhibited the most serious aggravation. The protein was the main contributor to detoxification and cellular protection under the stress of CIT and SPS. Obvious disturbance effects on the malonaldehyde content, catalase and GST activities were observed for SPS of 0.1 g/L, 60–90 μm and foc of 2%. Overall, the important role of SPS properties on the biological effects of CIT should be taken into consideration for the accurate risk assessment of pollutants.

Northwest monsoon upwelling within the Indonesian seas

ABSTRACT The previous studies of upwelling within the Indonesian seas only focused on the Southeast Monsoon (SEM) season. The western coast of Sumatra Island; the southern coast of Java Island, Sunda Islands, and Sulawesi Island; the Banda Sea, the Maluku Sea, and the Arafura Sea are well-known SEM upwelling areas. However, the upwelling events during Northwest monsoon (NWM) have never been investigated. The investigation of NWM upwelling is challenging due to the broad cloud coverage, limiting the observation of infrared and visible sensors of the satellites. This study used the blended products of the satellite-based sea surface temperature (SST), chlorophyll-a (chl-a), sea level anomaly (SLA), surface wind, and rainfall to identify the NWM upwelling occurrences. Remote sensing reflectances 443 nm and 555 nm were also used to examine the influence of suspended sediment and organic matter which may bias the chl-a concentration. Along the northern coast of the Lesser Sunda Islands, the north coast of Papua Island and the Malacca Strait are the areas of NWM upwelling as denoted by the positive anomaly of chl-a, the negative anomaly of SST, and the negative anomaly of SLA. Focusing on the area along the northern coast of the Lesser Sunda Islands, the NWM upwelling is generated by offshore Ekman Mass Transport that reduces SST and increases chl-a. From 2010 onwards, El Niňo Southern Oscillation has a more consistent effect on the NWM upwelling than Indian Ocean Dipole. El Niňo (La Niňa) tends to weaken (strengthen) upwelling. The magnitude of NWM upwelling is weaker than SEM upwelling.

Influence of suspended sediment on the bioavailability of benzophenone-3: Focus on accumulation and multi-biological effects in Daphnia magna

The UV-filter benzophenone-3 (BP3) tends to associate with suspended sediment (SPS) due to hydrophobicity, which could alter its toxicological effects on non-target aquatic organisms. In this study, the freshwater cladoceran Daphnia magna (D. magna) was selected as a model organism to investigate the impacts of the source and composition of SPS on the accumulation and multiple toxicological effects (from the molecular level to individual level) of BP3. Among the three components of SPS, amorphous organic carbon (AOC) and minerals promoted the body burden of BP3, while black carbon (BC) inhibited the bioaccumulation. The inhibition effects of BP3 on swimming and feeding behaviors of D. magna were also enhanced due to the presence of AOC and BC. Compared with BP3 exposure alone, higher oxidative stress and neurotoxicity were observed in the presence of SPS containing AOC, BC and minerals, corresponding to that superoxide dismutase, catalase and glutathione-S-transferase activities were further induced, and acetylcholinesterase activity was inhibited. Furthermore, BP3 induced mRNA expression levels of the endocrine system (ecdysone receptor, cytochrome P450 CYP314) and metabolic system (toxicant nuclear receptor HR96, P-glycoprotein), and the presence of SPS containing AOC, BC and minerals exhibited an enhanced effect. Combined with all endpoints, evident relationship was observed between the bioaccumulation level and the response of individual behavior and molecular biomarkers. The results demonstrated that the effects of SPS compositions on bioaccumulation and toxicological effects of organic UV-filters should be considered in aquatic environments.

悬浮物对造礁石珊瑚营养方式的影响及其适应性研究进展

营养方式是造礁石珊瑚获取能量与营养物质的基础，影响其生长与分布。近年来珊瑚礁区悬浮物含量与组分结构发生显著变化，其对造礁石珊瑚营养方式的诸多影响正成为当前研究热点。研究系统综述了珊瑚礁区悬浮物变化特征、悬浮物对造礁石珊瑚营养方式的影响及其适应性研究现状。发现近年来人类活动加剧与强降雨事件频发是驱动珊瑚礁，尤其是近岸珊瑚礁区悬浮物含量递增、组分改变与变频加剧的主因；悬浮物变化对造礁石珊瑚光合自养与异养营养的影响存在显著的种间差异，这主要与悬浮物消光效应、生物可利用性及造礁石珊瑚种类密切相关。虽然少数种类造礁石珊瑚具光合可塑性或异养可塑性，能在高含量悬浮物存在的弱光环境中较好生长。然而对绝大多数造礁石珊瑚而言，其营养方式适应性较差，无法在悬浮物影响下较好地获取生命活动所需的能量与营养物质，进而难以生存。总体来说，悬浮物被认为是近年来影响造礁石珊瑚生长与分布的重要环境因子之一，而关于造礁石珊瑚营养方式对悬浮物变化的响应及其适应机制，当前研究仍较薄弱，需要进一步加强相关研究。;The nutritional mode is the basis for scleractinian corals to obtain energy and nutrients, which affects their growth and distribution. In recent years, the content and composition of suspended sediment in coral reefs have changed significantly, and many effects on the nutritional mode of scleractinian corals are becoming the focus of current research. This article reviewed the characteristics of the suspended sediment changes in coral reefs, the effects of suspended sediment on the nutritional mode of scleractinian corals and their adaptability. The results show that the intensification of human activities and the frequent occurrence of heavy rainfall events in recent years are the main reasons driving the increase in suspended sediment concentration, composition changes and frequency conversion in coral reefs, especially in fringing reefs. The influences of suspended sediment on autotrophy and heterotrophy of scleractinian corals are significantly different, which are mainly related to the extinction effect and bioavailability of suspended sediment, and the species of scleractinian corals. Although some species of scleractinian corals have photosynthetic plasticity or heterotrophic plasticity, they can grow well in low-light environments where high levels of suspended sediment exist. However, for the majority of scleractinian corals, the adaptability of nutritional mode is poor, so they can't obtain the energy and nutrients needed for living better under the influence of suspended sediment, which makes them difficult to survive. Overall, suspended sediment is considered to be one of the important environmental factors affecting the growth and distribution of scleractinian corals in recent years. However, the present studies on the response and adaptability mechanism of the nutritional mode of scleractinian corals to the change of suspended sediment are still rare, and further research is needed.

The Connection between a Suspended Sediments and Reservoir Siltation: Empirical Analysis in the Maziarnia Reservoir, Poland

This paper presents research on the influence of suspended sediments on selected aspects of a reservoir’s functioning. As the amount of sediment suspended in water (SS) there was found to correlate significantly with sedimentation rate (Us), it was possible to develop a function allowing the rate of accumulation of sediments to be predicted by reference to known amounts of suspended sediment. The latter factor was also shown to correlate significantly with the content of organic matter in suspension (OMSS), in sediment captured in a sediment trap (OMS), and of bottom sediment (OMSB). Analysis of amounts of suspended sediment can provide for estimates of total loads of organic pollutants deposited in the sediments of a reservoir. A further significant correlation with SS was noted for the concentration of total phosphorus in water (TPW), confirming the importance of internal production where the circulation of this biogenic substance in a reservoir ecosystem is concerned. Analysis of stable carbon isotopes in turn showed that entrapped sediments were depleted of—or enriched in—13C, in line with whether concentrations of total P in those sediments (TPS) were at their highest or lowest levels. This dependent relationship may thus be of key importance in assessing sources of phosphorus, as well as in forecasting concentrations present in reservoir sediments. The results obtained make it clear that sediments suspended in the water of a reservoir unify phenomena and processes ongoing there, between elements of the water-sediment system.

The influence of suspended sediment on the transport and survival of E. coli in the Tagus estuary

The influence of suspended sediment on the transport and survival of E. coli in the Tagus estuary

The fluid dynamics of river dunes: A review and some future research directions

Dunes are present in nearly all fluvial channels and are vital in predicting flow resistance, sediment transport, and deposition within many rivers. Progress in understanding the fluid dynamics associated with alluvial dunes has been significant in the last 15 years and has witnessed huge advances in field, laboratory, and numerical investigations. Progress has been made in detailing the principal features of mean and turbulent flow over asymmetric dunes that possess flow separation in their leesides and how these forms affect both downstream boundary layer structure and stress partitioning over the dune. Additionally, the links between sediment transport over dunes and instantaneous coherent flow structures are being increasingly understood, with the feedback of dune three‐dimensionality upon flow and sediment dynamics over these bed forms beginning to be recognized as vital. Such research now provides an outstanding background for beginning to address areas of greater complexity that will enable a fuller understanding of these important natural features. This review paper summarizes the principal features of mean and turbulent flow over alluvial sand dunes. Five areas are then highlighted and discussed as a possible focus for future research: (1) the influence of dune leeside angle upon flow processes in the dune wake and downstream flow field, (2) the influence of three‐dimensionality in dune shape upon the generation of turbulence and distribution of bed shear stress, (3) flow field modification resulting from bed form superimposition and amalgamation, (4) the scale and topology of dune‐related turbulence and its interactions with sediment transport and the flow surface, and (5) the influence of suspended sediment on the dune flow field and dune morphology.

Influence of Coherent Flow Structures on the Dynamics of Suspended Sediment Transport in Open-Channel Flow

The influence of suspended sediments on coherent flow structures has been studied by simultaneously measuring the longitudinal and vertical components of the instantaneous velocity vector and the instantaneous suspended particle concentration with an acoustic particle flux profiler. The measurements were carried out in clear water and in particle-laden open-channel flows. In both cases, they clearly show the predominance of ejection and sweep phases that are part of a burst cycle. The analysis further demonstrates the importance of the ejection and sweep phases in sediment resuspension and transport. Ejections pick up the sediment at the bed and carry it up through the water column close to the surface. It is shown that ejections and sweeps are in near equality in the near-bottom layer, whereas ejections clearly dominate in the remaining water column. The implications of these results for sediment transport dynamics are discussed.

Influence of suspended sediment on the transport processes of nonlinear reactive substances in turbulent streams

The fluid dynamic behaviour of a reactive chemical in a stream can be greatly influenced by the presence of sorbing suspended particles. In this case, a kinetically controlled mass transfer is established between sorbed and dissolved phases and complex interactions emerge between fluid dynamical transport processes, sorption–desorption kinetics and chemical reactions. These conditions often occur in rivers, where both suspended sediment and reactive substances are frequently present. This paper deals with the important case in which the chemical reactions are nonlinear decay phenomena that often affect chemical or biological substances. A vertical two-dimensional mathematical model is formulated to take into account advection, turbulent diffusion, particle sedimentation, exchange kinetics between sorbed and dissolved phases, and decay. The decay is modelled for the case in which two different nonlinear decay reactions affect the dissolved and sorbed phases. The main result of the work is to obtain analytically a one-dimensional differential model of the vertically averaged concentration of the dissolved phase, this being conceptually similar to the classical advection–dispersion–decay equation. However, in this case we include the effects of (i) the kinetics with the phase sorbed by suspended particles and (ii) the influence of the two different decay processes. For this purpose, the multiple-scale method of homogenization is applied to the two-dimensional model. The resultant one-dimensional differential model shows how suspended load and decay phenomena affect the pollutant transport mechanisms to a great extent in a non-intuitive way and that the links are nonlinear. Some quantitative results show that these influences are, in general, not negligible.

Influences of suspended sediments on the ecosystem in Lake Michigan: a 3-D coupled bio-physical modeling experiment

The influence of suspended sediments on the Lake Michigan ecosystem was examined using a 3-dimensional (3-D) coupled biological and physical model developed by Chen et al. (part I). The model was driven by the realistic meteorological forces observed in March 1998, with daily inputs of suspended sediment concentration that were derived from temporally and spatially interpolated satellite imagery. The model results show the significant impact of a seasonally recurring coastal resuspension plume on the spatial and temporal variation of the nutrients and plankton in southern Lake Michigan. The plume-released nutrients played an essential role in maintaining the nutrient level in the lake. Although the growth of phytoplankton in the plume depended on the availability of nutrients and light, the offshore decrease in phytoplankton biomass still satisfied the Sverdrup's relationship. Cross-shore fluxes of nutrients and phytoplankton were controlled by episodic wind events with a period of ≈5–7 days: offshore during southward winds and onshore during northward winds. The flux estimates for biological variables suggest that the microbial food web is a key contributor to secondary production in southern Lake Michigan and the lower trophic level food web system could be dynamically divided into two decoupled loops: (1) detritus–bacteria–microzooplankton–large zooplankton; and (2) nutrient–phytoplankton–detritus. The model-predicted spatial distributions of nutrients and phytoplankton were in reasonable agreement with observations taken during the 1998 EEGLE interdisciplinary cruises, suggesting that the model was sufficiently robust to capture the basic characteristics of the Lake Michigan ecosystem during the plume event.

Growth and mortality rates of the zebra mussel,Dreissena polymorpha, in the Lower Mississippi River

We investigated seasonal growth and mortality of a population of zebra mussels, Dreissena polymorpha, near the extreme southern limit of their current North American distribution. Dreissena in the Lower Mississippi River experience seasonal regimes of temperature and suspended sediment that are distinctly different from those found in northern lentic environments. Shell growth and mortality were determined biweekly using marked animals in caged environments. Tissue condition was also estimated biweekly using mussels from caged and wild environments. Our results demonstrate that, although annual growth is comparable with that reported for more temperate environments, the seasonal pattern of increase is different. Shell growth and tissue condition were highest during the early spring. Tissue condition declined and shell growth ceased during the summer, when temperatures remained at 29-30°C for 3 months. This midsummer depression was accompanied by increased mortality, particularly for mussels greater than 15 mm. Condition improved for all sizes in fall and winter. These patterns of growth and mortality appear to be primarily driven by fluctuations in seasonal temperature and spawning condition with some influence of suspended sediment. Our observations indicate that periodic summer mortality events will occur, and the extent of this mortality will depend primarily on temperature, population size structure, and spring tissue condition.

Patchiness in dissolved metals (Al, Cd, Co, Cu, Mn, Ni) in North Sea surface waters: seasonal differences and influence of suspended sediment

In February 1988, 60 near surface samples were taken on a track between 2°W in the English Channel, the Pentland Firth and the inner German Bight. Determinations were made on filtered and unfiltered samples. Concentrations of dissolved metals in the North Sea normalized to a salinity of 34.5 were Al 31, Cd 0.13, Co 0.13, Cu 3.4, Mn 6.2 and Ni 3.9 nM. In July 1984 the equivalent concentrations were Al 11, Cd 0.15, Co 0.15, Cu 4.3, Mn 12 and Ni 3.6 nM. Distinct regional differences were detectable which can be related to the origin of the water, differing river inputs, and solution-solid phase exchange reactions. The degree of the influence of exchange reactions was investigated through the concept of Kd, the distribution coefficient. A Kd of 10 5 ml g −1 for Al is consistent with other observations and explains the relatively high concentrations of dissolved Al detected in the English Channel on this cruise. The data suggest a higher Kd for Mn approaching 10 6 ml g −1. The high Mn Kd coupled to higher suspended sediment loads in winter may be sufficient to explain the lower concentration of dissolved Mn in winter. Comparison of concentrations across the shelf break suggests that for all the metals studied, the European Shelf is a source of dissolved metals to the deep sea. Calculations based on the limited available data indicate that this export is of similar magnitude to the fresh water input of dissolved metals.

Influence of suspended sediment on the biodegradation of chlorinated dibenzo- p-dioxins

Little is known of how the uptake and degradation of highly hydrophobic compounds, such as polychlorinated dibenzo- p-dioxins (PCDDs), by microorganisms is influenced by sorption of these compounds to sediment. In this study aqueous solutions of a mixture of 2-chloro-, 1,3-dichloro-, 2,8-dichloro- and 1,2,4-trichlorodibenzo- p-dioxins were first incubated for 24 days with 100 mg/l suspended sediment. Subsequently, the degradation of the PCDDs in these sediment suspensions by Alcaligenes sp. strain JB1 was compared to that in solutions which did not contain sediment. The amounts of all four compounds degraded in the sediment suspensions after 168 h were greater than those initially present in the dissolved phase, based on their calculated sediment-water partition coefficients. The sorbed fractions were therefore sufficiently readily desorbed to be partly degraded. However, the biodegradation rates were lower in the sediment suspensions than in the solutions.

Influence of suspended sediment on the biodegradation of alkyl esters ofp-aminobenzoic acid

Influence of suspended sediment on the biodegradation of alkyl esters ofp-aminobenzoic acid

Preliminary investigations on the influence of suspended sediments on the bioaccumulation of two chlorobenzenes by the guppy (Poecilia reticulata)

In this study the uptake by guppies (Poecilia reticulata) of 1,2,3-trichlorobenzene (TCB) and hexachlorobenzene (HCB) from sediment-free water was compared with uptake in the presence of suspended sediment. The results show that the influence of suspended sediment on the uptake of chlorobenzenes varies with test compound. For TCB uptake was not influenced by the presence of suspended sediment. This is probably due to the large amount of the chemical which is dissolved relative to the amount which is present in the sorbed state. For the more hydrophobic HCB, the concentration found in the fish from the system with suspended sediment was significantly higher than in fish from the control experiment.

Influence of suspended sediment on the temperatures of surface waters of reservoirs

(1975). Influence of suspended sediment on the temperatures of surface waters of reservoirs. SIL Proceedings, 1922-2010: Vol. 19, No. 1, pp. 133-136.

The influence of suspended sediment on the reaeration of uniform streams

The influence of suspended sediment on the reaeration of uniform streams