Concentrations Of Inorganic Suspended Solids Research Articles

Developmental Strategies for a Water Quality Assessment Model with Limited Datasets – A Case Study from River Bhavani, India

Understanding the significance of rational attributes for a water quality model depends largely on the availability and reliability of virgin datasets pertaining to their spatial-temporal variations and interactions. Present study aims to identify certain crucial attributes for deriving a water quality model for a selected reach of River Bhavani in Tamil Nadu, India using the results of the QUAL2K model based on a limited dataset. The spatial variations in the concentrations of inorganic suspended solids (ISS) and carbonaceous biochemical oxygen demand (cBOD) were studied in detail corresponding to the possible variations in other model parameters (pertaining to the hydraulic, environmental and climatic conditions). The results indicate that the cBOD has a significant dependency on temperature, dissolved oxygen and pH, while the ISS has shown more dependency on alkalinity, conductivity and bottom algae. It is further inferred that variations in pH and dissolved oxygen can impose triggering effects when external pollution loads (point and nonpoint sources) are introduced while generating the corresponding profiles of ISS and cBOD. Based on the results, the conceptual strategies for developing a data-limited model is presented, which can be further developed to simulate water quality profiles for similar data-limited scenario.

Effects of the chemical characteristics and concentration of inorganic suspended solids on nitrification in freshwater.

The effect of inorganic suspended solids (ISS) on nitrification in freshwater samples has been described inconsistently and remains unclear. This study therefore investigated the effects of the chemical characteristics and concentration of ISS on the nitrification rate by focusing on Nitrosomonas europaea and Nitrobacter winogradskyi as the two most dominant nitrification species in freshwater. Batch-wise experiments were conducted using three chemically well-characterized ISS (i.e. the clay minerals montmorillonite, sericite, and kaolinite in the concentration range 0-1,000 mg L-1). The results show that the ammonium oxidation rate constant (kNH4) was significantly affected by the ISS type, whereas changes in the ISS concentration had an insignificant effect on kNH4, except for kaolinite. The highest kNH4 was observed in samples containing sericite (kNH4, 0.067 L mg-1 day-1), followed by samples containing montmorillonite (kNH4, 0.044 L mg-1 day-1). The ammonium oxidation rate was low in the control and kaolinite samples. Nitrite oxidation was enhanced in the presence of all types of ISS. The rate constants of ISS-mediated nitrite oxidation (kNO2, 0.13-0.21 L mg-1 day-1) were not significantly different among the three types of ISS, but kNO2 was significantly affected by ISS concentration. Overall, our study indicated various effects of the ISS type and concentration on nitrification and, in particular, a notable positive effect of sericite.

Multiple extreme environmental conditions of intermittent soda pans in the Carpathian Basin (Central Europe).

Soda lakes and pans represent saline ecosystems with unique chemical composition, occurring on all continents. The purpose of this study was to identify and characterise the main environmental gradients and trophic state that prevail in the soda pans (n=84) of the Carpathian Basin in Central Europe. Underwater light conditions, dissolved organic matter, phosphorus and chlorophyll a were investigated in 84 pans during 2009-2010. Besides, water temperature was measured hourly with an automatic sensor throughout one year in a selected pan. The pans were very shallow (median depth: 15 cm), and their extremely high turbidity (Secchi depth median: 3 cm, min: 0.5 cm) was caused by high concentrations of inorganic suspended solids (median: 0.4 g L-1, max: 16 g L-1), which was the dominant (>50%) contributing factor to the vertical attenuation coefficient in 67 pans (80%). All pans were polyhumic (median DOC: 47 mg L-1), and total phosphorus concentration was also extremely high (median: 2 mg L-1, max: 32 mg L-1). The daily water temperature maximum (44 °C) and fluctuation maximum (28 °C) were extremely high during summertime. The combination of environmental boundaries: shallowness, daily water temperature fluctuation, intermittent hydroperiod, high turbidity, polyhumic organic carbon concentration, high alkalinity and hypertrophy represent a unique extreme aquatic ecosystem.

Effects of small-sized crucian carp (Carassius carassius) on the growth of submerged macrophytes: Implications for shallow lake restoration

Reestablishment of submerged macrophytes is considered important when restoring shallow eutrophic lakes. To improve water clarity and consequently the growth conditions of macrophytes, removal of plankti-benthivorous fish has been used. In sub-tropical shallow lakes, however, rapid recruitment of small fish, especially benthivores during restoration, may hamper early reestablishment of submerged macrophytes. Crucian carp (Carassius carassius) and Vallisneria natans are common species dominated in sub-tropical shallow lakes. To investigate the effect of small benthivorous fish on the growth of Vallisneria natans, a 28-day outdoor controlled experiment was undertaken in 12 mesocosms with three densities of Carassius carassius − low (10gm−2), high (40gm−2) and no fish (all in four replicates). The results showed that the fish significantly increased chlorophyll-a concentrations and periphyton biomass in both fish treatments, most significantly at high density for Chl a. This concurs with an increase in nutrient concentrations, likely mediated by fish sediment disturbance and excretion, and a reduction of zooplankton biomass (less algal grazing). Increased concentrations of inorganic suspended solids with increasing fish density further enhanced turbidity, causing shading of the macrophytes. Accordingly, the relative growth rate, ramet number and root/leaf ratio of V. natans decreased significantly at low and high fish density compared with the controls, but the effects did not depend on fish density. However, mean leaf length rose with increasing fish density, likely to allow the plants to obtain more light. Overall, our results show that not only large-bodied carp, as demonstrated frequently, but also small-sized crucian carp posed a constraint on submerged macrophyte reestablishment, and we conclude that crucian carp may hamper restoration efforts in sub-tropical shallow lakes. Restoration by biomanipulation should therefore target also small-sized crucian carp.

Contrasts between channels and backwaters in a large, floodplain river: testing our understanding of nutrient cycling, phytoplankton abundance, and suspended solids dynamics

In floodplain rivers, variability in hydraulic connectivity interacts with biogeochemistry to determine the distribution of suspended and dissolved substances. Nutrient, chlorophyll a, and suspended solids data spanning longitudinal (5 study reaches across 1300 river km), lateral (main channel and backwaters), and temporal (1994–2011) gradients in the Upper Mississippi River (UMR) were used to examine the extent to which observed differences between the main channel and backwaters were consistent with expectations based on current understanding of biogeochemical processes in large rivers. For N and P, the results largely conformed to expectations. N concentrations were greater in the main channel than in the backwaters in 82 to 96% of the observations across river reaches. Maximum TP concentrations generally occurred in backwaters during summer, when backwater TP often exceeded that of the main channel. Flux of P from sediments may be a substantial source of water-column P in UMR backwaters in summer. The data for suspended solids and chlorophyll a suggest that some refinements are needed of our understanding of ecosystem processes in large rivers. During low-discharge conditions, concentrations of inorganic suspended solids often were greater in backwaters than in the main channel, suggesting the importance of sediment resuspension. Chlorophyll a concentrations were usually greater in backwaters than in the main channel, but exceptions indicate that phytoplankton abundance in the main channel of the UMR can sometimes be greater than is typically expected for large rivers.

Drought-induced water-level reduction favors cyanobacteria blooms in tropical shallow lakes

Many arid and semiarid regions are likely to become warmer and drier by the end of this century, due to human-induced climate change. We hypothesize that a reduction in water level caused by droughts will aggravate eutrophication, leading to higher cyanobacteria biomass and dominance in tropical regions. To test this hypothesis, we analyzed physical and chemical variables and plankton communities of 40 man-made lakes in warm semiarid northeastern Brazil at the end of the wet and dry seasons. We also constructed a predictive model of cyanobacteria biovolume in these lakes. The lakes had significantly lower water volume, transparency, and CO2 concentrations but higher water temperature, water column stability, electrical conductivity, pH, suspended solids, ammonium, total nitrogen concentrations, bacteria biomass, phytoplankton biomass, and cyanobacteria biomass and dominance in the dry than in the wet season. Our regression model suggested that cyanobacteria biovolume was positively related to water column stability, pH, and total nitrogen and negatively related to water transparency and concentrations of inorganic suspended solids. These results suggest that the projected warmer and drier climate in the future will reduce water quantity and quality of man-made lakes in the region, increasing the risks of salinization, anoxia, eutrophication, and cyanobacteria blooms.

Using modified multiple phosphorus sensitivity indices for mitigation and management of phosphorus loads on a catchment level

The relationships between river and lake phosphorus sensitivity, environmental drivers and catchment characteristics within the upper Olifants River and Lake Loskop were studied over a period of four years to come up with mitigation and management strategies. Using modified indices it was evident that the best strategy for improving the trophic state of Lake Loskop was to drastically reduce the external nutrient loading coming from the upper Olifants River catchment. According to the lake phosphorus sensitivity index (LPSI) developed, Lake Loskop was phosphorus sensitive and will possibly respond to phosphorus reduction in its upper catchment. The river phosphorus sensitivity index (RPSI) developed showed that certain rivers and streams in the upper catchment of Lake Loskop were particularly sensitive to increases in phosphorus (P) loads. The substrate of these rivers and streams consisted of approximately 90 % cobbles or bedrock and showed eutrophic conditions during low flow regimes. The increase in P loads in these streams stimulates the productivity and growth of periphyton dominated by filamentous green algae mats. On the other hand, a restriction of light penetration into the water column by high concentrations of inorganic suspended solids limited the growth of both benthic and planktonic algae in > 3 order streams dominated by sand or mud bottom substrates, thus making these streams less sensitive to high P loads. Rivers and streams in the upper catchment that required mitigation of P loads were identified according to the RPSI and different P load management practices were outlined. The findings of this study are important for restoration and management purposes of increased P loads in conjunction with river characteristics and phytoplankton occurrence. The modified indices developed for P management can be a useful tool in river basins in other parts of the world with the similar environmental drivers and catchment characteristics.

Reference spectra to classify Amazon water types

Reference spectra extracted from spectral libraries can distinguish different water types in images when associated with limnological information. In this study, we compiled available databases into a single spectral library, using field water reflectance spectra and limnological data collected by different researchers and campaigns in the Amazonian region. By using an iterative clustering procedure based on the combination of reflectance and optically active components (OACs), reference spectra representative of the major Amazonian water types were defined from this library. Differences between the resultant limnological classes were also evaluated by paired t-tests at significance level 0.05. Finally, reference spectra were tested for Spectral Angle Mapper (SAM) classification of waters in Hyperion/Earth Observing-One (EO-1) and Medium Resolution Imaging Spectrometer (MERIS)/Environment Satellite (Envisat) images acquired simultaneously as the field campaigns. Results showed highly variable concentrations of OACs due to the complexity of the Amazonian aquatic environments. Ten classes were defined to represent this complexity, broadly grouped into four limnological characteristics: clear waters with low concentrations of OACs (class 1); black waters rich in dissolved organic carbon (DOC) (class 2); waters with large concentrations of inorganic suspended solids (ISSs) (classes 3–7); and waters dominated by chlorophyll-a (chl-a) (classes 8–10). Using the ten reference spectra, SAM classification of the field water curves produced an overall accuracy of 86% with the highest values observed for classes 3, 4, 6 and 7 and the lowest accuracy for classes 1 and 2. The results of paired t-tests confirmed the class differences based on the concentrations of OACs. SAM classification of the Hyperion and MERIS images using ground truth information resulted in overall classification accuracies of 48% and 67%, respectively, with the highest errors associated with specific portions of the scenes that were not adequately represented in the spectral library.

Optical properties of inorganic suspended solids and their influence on ocean colour remote sensing in highly turbid coastal waters

The influence of the optical properties of inorganic suspended solids (ISS) on in-water algorithms was evaluated using an optical model in highly turbid coastal water, whose ISS concentration reached several hundred grams per cubic metre. The measurements were conducted in the upper Gulf of Thailand. The backscattering coefficient of the ISS was calculated using the Lorenz–Mie scattering theory. On the basis of the measurement, the ISS size distribution was parameterized as a function of ISS concentration, and both the spherical and non-spherical particle shape models were evaluated. For ISS concentrations of 10 g m−3, an estimate of the chlorophyll-a (chl-a) concentration within a factor of 2 on a logarithmic scale is possible in a [chl-a] range of 4–30 mg m−3. The differential coefficient of remote sensing reflectance was calculated to evaluate its respective sensitivities for chl-a and ISS concentrations. The use of radiometric data at 670 nm (700–900 nm) is valid for in-water algorithms used to estimate chl-a (ISS) concentration in highly turbid coastal waters.

Scattering characteristics and relevant factors in autumn Lake Taihu

水体散射特性的研究是水色遥感和水生态学研究中重要的组成部分.通过对2007-11-08至2007-11-21在太湖获取的水体固有光学属性和室内水样分析数据的分析,研究太湖水体散射特性及其相关因素.结果表明,太湖水体散射系数与波长之间存在幂函数递减规律,平均幂指数为-0.82±0.21,变异系数为25.39%;粒径分布斜率与幂指数以及散射系数ln(550nm)/ln(756nm)之间存在线性相关,R²分别为0.894和0.783;后向散射率与无机悬浮物浓度之间指数负相关R²=0.854;折射指数与无机悬浮物浓度和无机物与有机物的比例之间指数负相关,R2分别为0.851和0.781.;Characteristic of water scattering is very important for researches on water color remote sensing and aquatic ecology. The inherent optical properties of water samples collected in Lake Taihu from Nov. 8 to Nov. 21 in 2007 were analyzed, and the scattering characteristics and relative factors were researched. The results showed that, the scattering coefficient was reduced with increasing wavelength according to power function. The average power index is -0.82±0.21, and the variation coefficient is 25.39%. Both slope and power of the particle size distribution function are linearly correlated with the scattering coefficient of ln(550nm)/ln(756nm). The correlation coefficients (R²) are 0.894 and 0.783 respectively. Negative correlation between the backscattering rate and the concentration of inorganic suspended was found and R² was 0.854. Correlations between refractive index and the inorganic suspended solids concentration and between the ratio of inorganic and organic were negative, and the coefficients (R²) were 0.851 and 0.781 respectively.

A predictive model for the reactor inorganic suspended solids concentration in activated sludge systems

A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration (excluding that from chemical precipitant dosing) is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mg OHO organic (volatile) suspended solids (VSS) and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). Organism ISS content is conceptualized as the uptake of dissolved inorganic solids by active organisms, which when dried in the total suspended solids (TSS) test procedure, precipitate and manifest as ISS. The model is validated with data from 22 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification-denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater, and operated from 3 to 20 days sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. To use the model for design, two parameters need to be known: (1) the influent ISS concentration, which is not commonly measured in wastewater characterization analyses and (2) the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on the measurement of influent ISS concentration and selection of the PAO P content to calculate the mixed liquor VSS/TSS ratio for design is given.

Modelling inorganic material in activated sludge systems

A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mgOHOVSS and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). The model is validated with data from 21 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater and operated from 3 to 20 d sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. For effective use of the model for design, two significant issues require attention: measurement of the influent ISS concentration, which is not commonly done in wastewater characterisation analyses; and estimating a priori the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on selection of the mixed liquor VSS/TSS ratio for design is given. WaterSA Vol.30 (2) 2004: 153-174

Eutrophication of freshwater and coastal marine ecosystems: a global problem.

Humans now strongly influence almost every major aquatic ecosystem, and their activities have dramatically altered the fluxes of growth-limiting nutrients from the landscape to receiving waters. Unfortunately, these nutrient inputs have had profound negative effects upon the quality of surface waters worldwide. This review examines how eutrophication influences the biomass and species composition of algae in both freshwater and costal marine systems. An overview of recent advances in algae-related eutrophication research is presented. In freshwater systems, a summary is presented for lakes and reservoirs; streams and rivers; and wetlands. A brief summary is also presented for estuarine and coastal marine ecosystems. Eutrophication causes predictable increases in the biomass of algae in lakes and reservoirs; streams and rivers; wetlands; and coastal marine ecosystems. As in lakes, the response of suspended algae in large rivers to changes in nutrient loading may be hysteretic in some cases. The inhibitory effects of high concentrations of inorganic suspended solids on algal growth, which can be very evident in many reservoirs receiving high inputs of suspended soils, also potentially may occur in turbid rivers. Consistent and predictable eutrophication-caused increases in cyanobacterial dominance of phytoplankton have been reported worldwide for natural lakes, and similar trends are reported here both for phytoplankton in turbid reservoirs, and for suspended algae in a large river A remarkable unity is evident in the global response of algal biomass to nitrogen and phosphorus availability in lakes and reservoirs; wetlands; streams and rivers; and coastal marine waters. The species composition of algal communities inhabiting the water column appears to respond similarly to nutrient loading, whether in lakes, reservoirs, or rivers. As is true of freshwater ecosystems, the recent literature suggests that coastal marine ecosystems will respond positively to nutrient loading control efforts. Our understanding of freshwater eutrophication and its effects on algal-related water quality is strong and is advancing rapidly. However, our understanding of the effects of eutrophication on estuarine and coastal marine ecosystems is much more limited, and this gap represents an important future research need. Although coastal systems can be hydrologically complex, the biomass of marine phytoplankton nonetheless appears to respond sensitively and predictably to changes in the external supplies of nitrogen and phosphorus. These responses suggest that efforts to manage nutrient inputs to the seas will result in significant improvements in coastal zone water quality. Additional new efforts should be made to develop models that quantitatively link ecosystem-level responses to nutrient loading in both freshwater and marine systems.

Lake age and water level affect the turbidity of floodplain lakes along the lower Rhine

SUMMARY 1. We sampled a set of 93 lakes situated in the floodplains of the lower River Rhine in search for morphometric and other factors that explain their variation in clarity.2. Lakes with a drop in summer water level were less turbid at the time of sampling, mainly because of a lower concentration of inorganic suspended solids (ISS).3. We also found that older lakes were more turbid than younger lakes and that this was largely because of an increase in phytoplankton.4. Water clarity was positively related to lake depth and the presence of vegetation.5. Model calculations indicated that the underwater light climate was strongly affected by chlorophyll and ISS, the latter being the dominant factor affecting Secchi depth. Dissolved organic carbon (DOC) was less important.6. The high concentration of ISS suggests that intensive resuspension occurs in most of the lakes. Using a simple wave model, and assuming that vegetation protects sediments against resuspension, we could eliminate wind resuspension as an important process in 90% of the lakes, leaving resuspension by benthivorous fish as probably the most important factor determining transparency.7. Chlorophyll a concentration showed a strong positive correlation to ISS concentration, suggesting that resuspension may also have a positive effect on phytoplankton biomass in these lakes.8. In conclusion, in‐lake processes, rather than river dynamics, seem to be driving the turbidity of floodplain lakes along the lower River Rhine.

Mechanisms of Viral Capture by Microfiltration

The male-specific bacterial virus MS2 is being used in this study to investigate the mechanisms of virus capture from aqueous suspension by a polypropylene microfilter. Mechanisms being studied include 1) adsorption of viruses to clean, unused filters; 2) adsorption of viruses to used filters; 3) capture of particulates formed from virus complexation with organic or inorganic materials; and 4) entrapment of viruses by a barrier layer generated by these materials on the outer surface of the filter. Batch studies were conducted using chopped filter material to quantify virus adsorption to unused filters. Identical studies are planned to examine used filters. Constant pressure studies using manufactured filter modules will be performed to assess the importance of complexation and barrier layer formation. Ranges of values of solution pH and ionic strength are to be examined in combination with varied concentrations of inorganic suspended solids, organic suspended solids and dissolved organic material to determine method and extent of virus capture. Initial data show adsorption directiy to an unused filter surface to be negligible between pH3 and pH10. Data is being collected to quantify the relative contribution of each of the other three mechanisms.

The cumulative effect of wetlands on stream water quality and quantity. A landscape approach

A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis—St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4 flow-weighted total P, and a decreased proportion of phosphorus in dissolved form(p < 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.