Suspended sediment and fisheries: An exploration of empirical relationships

The accurate measurement of suspended sediment (<200 μm) in aquatic environments is essential to understand and effectively manage changes to sediment, nutrient, and contaminant concentrations on both temporal and spatial scales. Commonly used sampling techniques for suspended sediment either lack the ability to accurately measure sediment concentration (e.g., passive sediment samplers) or are too expensive to deploy in sufficient number to provide landscape‐scale information (e.g., automated discrete samplers). Here, we evaluate a time‐integrated suspended sediment sampling technique, the pumped active suspended sediment (PASS) sampler, which collects a sample that can be used for the accurate measurement of time‐weighted average (TWA) suspended sediment concentration and sediment particle size distribution. The sampler was evaluated against an established passive time‐integrated suspended sediment sampling technique (i.e., Phillips sampler) and the standard discrete sampling method (i.e., manual discrete sampling). The PASS sampler collected a sample representative of TWA suspended sediment concentration and particle size distribution of a control sediment under laboratory conditions. Field application of the PASS sampler showed that it collected a representative TWA suspended sediment concentration and particle size distribution during high flow events in an urban stream. The particle size distribution of sediment collected by the PASS and Phillips samplers were comparable and the TWA suspended sediment concentration of the samples collected using the PASS and discrete sampling techniques agreed well, differing by only 4% and 6% for two different high flow events. We should note that the current configuration of the PASS sampler does not provide a flow‐weighted measurement and, therefore, is not suitable for the determination of sediment loads. The PASS sampler is a simple, inexpensive, and robust in situ sampling technique for the accurate measurement of TWA suspended sediment concentration and particle size distribution.

The aim of the current study is to investigate the spread of the COVID-19 pandemic as a multiphase percolation process. Mathematical equations have been developed to describe the time dependence of the number of cumulative infected individuals, , and the velocity of the pandemic, , as well as to calculate epidemiological characteristics. The study focuses on the use of sigmoidal growth models to investigate multiwave COVID-19. Hill, logistic dose response and sigmoid Boltzmann models fitted successfully a pandemic wave. The sigmoid Boltzmann model and the dose response model were found to be effective in fitting the cumulative number of COVID-19 cases over time 2 waves spread (N = 2). However, for multiwave spread (N > 2), the dose response model was found to be more suitable due to its ability to overcome convergence issues. The spread of N successive waves has also been described as multiphase percolation with a period of pandemic relaxation between two successive waves.

A Decade of Prospective SBRT Protocols For Prostate: Dose Response Models of Late Effects For The Emulating HDR Study

Characterizing dose–responses of catalase to nitrofurazone exposure in model ciliated protozoan Euplotes vannus for ecotoxicity assessment: Enzyme activity and mRNA expression

Suspended sediment releases in rivers: Toward establishing a safe sediment dose for construction projects

Spatial and temporal variation of stream chemistry associated with contrasting geology and land-use patterns in the Chesapeake Bay watershed—Summary of results from Smith Creek, Virginia; Upper Chester River, Maryland; Conewago Creek, Pennsylvania; and Difficult Run, Virginia, 2010–2013

Development of a microbial dose response visualization and modelling application for QMRA modelers and educators

Our meta-analysis of 80 published and adequately documented reports on fish responses to suspended sediment in streams and estuaries has yielded six empirical equations that relate biological response to duration of exposure and suspended sediment concentration. These equations answer an important need in fisheries management: quantifying the response of fishes to suspended sediment pollution of streams and estuaries has been difficult historically, and the lack of a reliable metric has hindered assessment for risk and impact for fishes subjected to excess sedimentation. The six equations address various taxonomic groups of lotic, lentic, and estuarine fishes, life stages of species within those groups, and particle sizes of suspended sediments. The equations all have the form z = a + b (log ex) + c(log ey); z is severity of ill effect, x is duration of exposure (h), y is concentration of suspended sediment (mg SS/L), a is the intercept, and b and c are slope coefficients. The severity of ill eff...

High turbidity in rivers, intensified by extreme rainfall associated with climate change, poses a great challenge to water resource management globally. To manage and control turbidity events, prediction models have been developed utilizing suspended sediment (SS) data. However, traditional methods for measuring SS data, such as water sampling and laboratory analysis, are time-consuming and impractical for real-time applications. Although the turbidity–SS relationship is widely used, its accuracy depends on sediment particle size distribution. To address this limitation, we developed turbidity–SS equations adaptive to various SS fractions, using data from controlled circulating flume experiments designed to reflect sediment characteristics of a natural river. The results showed significant improvements in the linear turbidity–SS relationship, with R2 values ranging from 0.60 to 0.99, depending on sediment fractions. These equations were applied to field data from the area upstream of Soyanggang Dam in South Korea, yielding error rates of 1–18%. This study highlights the importance of incorporating sediment fraction variability into turbidity–SS models, which significantly improves their accuracy and reliability. The proposed approach offers a practical and scalable solution for real-time and large-scale SS monitoring, contributing to improved water quality management in various riverine conditions.

Performance based building (PBB) and design is closely connected to various needs and requirements: Performance levels need to be defined, test methods for verification of performance need to be developed, and reliable performance data are needed for materials, products, constructions, and different design solutions. In contrast to other building materials, PBB and thus service life prediction of timber and wood-based products requires particular consideration of wood-degrading organisms and their physiological needs. For the most relevant group of wood-destroying organisms, which are the different decay fungi and bacteria, wood moisture content and temperature need to be considered as key factors. This study aimed on the development of performance models on the basis of hard data obtained in field trials performed under most realistic conditions. Dose–response relationships, which can serve as essential parts of a performance based design model, were derived from material climatic data and corresponding decay development in the field. Different dose–response models are proposed and evaluated for predicting onset (and progress) of decay when wood is exposed to a dynamic and arbitrary climate exposure described in terms of time series of coupled temperature and moisture content. A logistic dose–response model was primarily focused on describing the relation between exposure and decay rating for moisture traps with long periods of high moisture contents. A two-step linear engineering model was more focused on predicting the behavior in a wider, more simplified, sense where periods of high moisture content are interrupted by periods of drier and/or colder climate.

Suspended sediment load to water bodies is governed by climate change and human activities. Fluctuation in water temperature due to climate change affects the suspended sediment deposition. In this study, laboratory experiments are conducted to understand the influence of water temperature on suspended sediment concentration and its particle size in ionized water. Experiments are conducted in an annular flume with kaolin (d50 = 6.9 μm) and ionized water by changing water temperature (30, 40, and 50 °C), bed shear stress (0.01, 0.05, 0.10, and 0.20 N/m2), and initial suspended sediment concentration (1, 2, and 4 g/L). Results show that rise in water temperature causes decrease in both settling flux and degree of deposition, but particle size increases. Variation in initial suspended sediment concentration has an inverse effect on settling flux and has minimum influence on degree of deposition. Size of suspended sediments showed direct relation with initial suspended sediment concentration.

<p>Manual and unattended sampling in the field and laboratory analysis are common practices to measure suspended sediment (SS) carbon content and particle size. However, one of the major drawbacks of these ex-situ methods is that they make high frequency measurements challenging. This includes restricted data collection due to limited access to the sampling locations during turbulent conditions or high flows, when the largest amount of sediments is transported downstream, introducing uncertainty in quantification of SS properties (particle size and carbon content) and sediment loads. Knowledge on SS carbon content and particle size is also important to better understand the multi-component form of suspended sediments (i.e. flocs) that directly affect sediment transport and other sediment properties (e.g. settling velocity and density). Moreover, SS carbon content and particle size exert an impact on the optical sensor readings that are traditionally used to measure turbidity. In that respect, high frequency measurements of SS carbon content and particle size could eventually help us to move from ‘local’ calibrations towards ‘global’ dependencies based on in-situ SS characterization.</p><p>In this study, we propose to use a submerged UV-VIS spectrometer to infer SS carbon content and particle size. The sensor measures the entire light absorption spectrum of water between 200 nm and 750 nm at sampling intervals as short as 2-minutes. To this end, we first test our approach under controlled conditions with an experimental laboratory setup consisting of a cylindrical tank (40-L) with an open top. An UV-VIS spectrometer and a LISST-200X sensor (to measure particle size distribution) are installed horizontally. A stirrer facilitates the homogeneous mixing of SS and prevents the settling of heavy particles at the bottom. We use the sediments sampled from 6 sites in Luxembourg with contrasting composition and representing different land use types and geological settings. The sampled sediments were wet sieved into 3 size classes to clearly recognize the effect of particle size on absorption. In our investigation, we use specific wavelengths, chemometric techniques and carbon content specific absorbance indices to infer SS composition and particle size from the absorption spectrum. Results are then validated using in-situ field data from two instrumented field sites in Luxembourg. Amid the challenge of associating laboratory and field results, the preliminary results indicate that the absorption spectrum measured with a submerged UV-VIS spectrometer can be used to estimate SS particle size and carbon content.</p>

Information on the distribution of species richness, faunal density, biomass and estimated productivity of benthic invertebrates in Tasmanian estuaries was quantified at a variety of spatial and temporal scales to assess general hypothesis relating community metrics to such environmental variables as salinity, seagrass biomass and sediment particle size. An associated aim was to assess appropriate scales of investigation for soft-sediment biota distributed in estuaries, including whether patterns identified at individual sites, estuaries, tidal levels or times are likely to have more general relevance. Faunal biomass and productivity varied principally at between-estuary (10 to 1000 km) and replicate-sample (1 m) scales, indicating that these two community metrics were largely responding to estuary-wide effects, such as nutrient loading, and to microhabitat features, rather than to locality characteristics at intermediate scales such as salinity, anoxia or sediment particle size. By contrast, faunal density showed greater response to tidal height (1 to 100 m) and to factors distributed at the locality scale within estuary (10 km) than to factors between estuary. Both faunal density and species richness in estuaries declined over three- and fivefold ranges down the shore from high water mark to the shallow sublittoral, while estimated productivity and biomass showed highest overall levels at low water mark. The greatest component of variance in species richness was associated with tidal height, with variance then distributed approximately evenly between other spatial scales examined. At the low-tide and shallow subtidal levels, species richness, faunal biomass and estimated productivity were all highly correlated with salinity and biomass of macrophytes, whereas faunal density was highly correlated with biomass of macrophytes only. Relationships between environmental and biological variables examined were poorly defined at high tidal levels. Seasonal plus interannual variance was much lower than spatial variance—a clear indication that sampling effort in studies would generally be better directed across a range of localities than for a single locality to be repeatedly investigated over time.

Effect of particle size and composition of suspended sediment on denitrification in river water

氮是影响和控制水体富营养化的重要因素，不同形态的氮对水体富营养化贡献不同.使用连续提取法对东苕溪干流悬浮物、表层沉积物样品中各形态氮含量进行测定，探讨各形态氮的分布特征及其影响因素.结果表明，东苕溪水体氮污染严重，总氮浓度均值为4.48 mg/L.悬浮物中各形态氮含量均高于沉积物，其中悬浮物中铁锰氧化态氮（IMOF-N）含量所占比例最大，均值为1506.94 mg/kg；沉积物中有机硫化物结合态氮（OSF-N）含量最高，均值为625.31 mg/kg.IMOF-N、OSF-N含量受阳离子交换量、粒径影响显著，均与总氮浓度显著相关.相关性分析表明水体的性质对IMOF-N及OSF-N含量影响较显著，并且总体上对悬浮物的影响强于沉积物.另外，悬浮物有助于水体中的氮发生硝化反应向硝态氮转化，沉积物则有助于水体的氮发生还原作用向氨氮转化.在一定程度上，水体中的悬浮物对藻类具有抑制作用.;Nitrogen is a dominant nutrient influencing and controlling eutrophication, and different nitrogen forms can make diverse contributions to water quality. The contents of different nitrogen forms in suspended sediments and surface sediment of East Tiaoxi River were determined by sequential extraction procedure. In addition,their distribution characteristics and influence factors were discussed. The results showed that the nitrogen pollution in East Tiaoxi River were serious with an average concentration of 4.48 mg/L, and the water quality in the middle reach of East Tiaoxi River was better than that in the upper and lower reaches. The amounts of four nitrogen forms in suspended sediments were significantly higher than those in surface sediment, in addition, the percentage of iron-manganese oxides bound nitrogen (IMOF-N) with the mean concentration of 1506.94 mg/kg were higher than that of other three nitrogen forms in suspended sediment. The percentage of organic matter-sulfide bound nitrogen (OSF-N) with the mean of 625.31 mg/kg was highest in surface sediment. IMOF-N and OSF-N contents were significantly affected by cation exchange capacity and particle size in both suspended sediments and surface sediments, and they were also significantly correlated with total nitrogen(TN),indicating that IMOF-N and OSF-N were the main fractions of TN. The correlation results showed that the water quality had significant influence on IMOF-N and OSF-N,and the influence of water on suspended sediments was stronger than that on surface sediments. Furthermore, suspended particulates were beneficial to produce nitrate nitrogen in water. In contrast, sediments were available for generating ammonia nitrogen in water, and to some extent, suspended sediments has inhibitory effect on algae.