Inorganic Suspended Matter Research Articles

Residual Fluxes in a Cross-section of the Valdivia River Estuary, Chile

The circulation dynamics, the transport of suspended sediment and salt as well as the residual flow of water, salt and particulated matter in suspension during a tidal cycle in the mouth of the Valdivia River Estuary, southern coast of Chile, are analysed. Results show a marked saline and thermic stratification during the low tide with differences of up to 20%, and 7 °C between surface and bottom. Maximum speed of the currents was 0·9 m s -1 on the ebb direction. Concentrations of inorganic suspended and combustible matter (organic carbon) were variable with maxima of up to 7 and 15 mg l -1, respectively. Residual transport computations show that Stokes drift and tidal pumping are important features in the net inward transport of water, salt and suspended matter. In the cases of salt and organic seston, it cannot be compensated by the Lagrangian transport through the section. Also the results confirm the fact that the behaviour of the Valdivia Estuary is of the partially mixed type. Previously, this had been deduced from longitudinal profiles of salinity and temperature.

Lake Patzcuaro, Mexico: Watershed and Water Quality Deterioration in a Tropical High-altitude Latin American Lake

ABSTRACT Lake Patzcuaro is a tropical, high-altitude, freshwater lake (130 km2 surface area) located on the Mexican plateau. The lake originated from tecto-volcanic processes associated with the Mexican Neovolcanic Axis. Maximum depth (12 m) occurs in the northern part of the lake, whereas shallow areas are developing in the south. Its indigenous fish fauna and the presence of P'urhepecha Indian settlements around its shoreline identify Lake Patzcuaro as a unique natural resource having ecological, historical, and cultural value. The lake is endorheic and the annual water balance is controlled by differences among rainfall, seepage, watershed runoff, and evaporation. A mass-balance model indicates that hydrologic inputs from the watershed are being reduced as a result of watershed deterioration. High turbidities result from volcanic silt, raw sewage, and increasing erosion loads to the lake. Lake Patzcuaro is light-limited due to scattering and attenuation from suspended inorganic materials. The lake has ...

Macroinvertebrate responses along the recovery gradient of a regulated river (Spain) receiving an industrial effluent

Macroinvertebrate responses were examined along the recovery gradient of the regulated Rio Duraton (northern Spain) receiving an industrial effluent. Hypolimnial releases from Burgomillodo Dam caused short-term flow fluctuations and low concentrations of dissolved oxygen at S-2, S-3, S-4, and S-5 sampling sites (0.2, 0.4, 2.5, and 7.6 km below the dam, respectively) compared with the upstream reference station (S-1). The industrial effluent caused a significant (P<0.05) increase in the fluoride concentration at S-3, S-4, and S-5 stations. Moreover, because of the differential discharge of hypolimnial waters from the dam, fluoride concentrations experienced a temporal variation over a one-day period at S-3, S-4, and S-5. The suspended inorganic matter (SIM) only increased significantly (P<0.05) just below the effluent (S-3), settling on the stream bottom of this sampling site. Tricladida, Amphipoda, Plecoptera and Coleoptera were the major macroinvertebrate groups most adversely affected. Total density (N), total biomass (B) and family diversity (D′) were higher at S-1 than at downstream sampling sites, their values being lowest at S-3. The family uniformity (U′) had its highest value at S-3. The family dominance (d′) exhibited lower values at S-2, S-3, and S-4 than at S-1 and S-5. Shredders and collector-gatherers were the functional feeding groups most adversely affected, predators and filter-feeders increasing their abundances downstream from the dam. According to the River Continuum Concept, these changes in functional feeding groups reflect a potamonization (enhancement of potamic conditions) in the trophic structure of the macrobenthic community. The highest values of environmental impact (EI) were estimated at S-3 and the lowest values at S-5. The lowest value of percentage similarity (PS) was estimated between S-1 and S-3 and the highest value between S-4 and S-5. It is concluded that the major abiotic factors responsible for macroinvertebrate responses were short-term flow fluctuations and dissolved O2 deficit at S-2, S-4, and S-5 sampling sites, and the siltation of SIM just below the industrial effluent (S-3). The fluoride pollution was a minor factor. In this sense, reductions in hypolimnial release and improvements in waste treatment are recommended in order to mitigate the adverse effects of the industrial effluent and Burgomillodo Dam on the structure of the macrobenthic community.

Tank depth determination for water radiometric measurements

Abstract To determine the optimum tank depth for the assessment of spectral reflectance from suspended inorganic matter (SIM), a 1·10 m × 0.90 m × 0·67 m black-coated tank was used. A plate with the same coating was constructed to simulate various depths. Different concentrations of bentonite and red silt suspensions were produced and radiometric measurements were performed in the 400-900 nm spectral range. The results showed close relationships between optimum depth and suspension characteristics, e.g., at 5mg/l of bentonite the optimum depth was around 0·63 m and at 140 mg/l it was 0·41 m. For red sill, at 140 mg/1 the optimum tank depth was greater than 0·41 m too. Before each experiment the optimum tank depth must be assessed to produce spectral reflectance of SIM.

Effect of kaolinite clay on the feeding activity of the eastern oyster Crassostrea virginica (Gmelin)

Estuarine bivalve molluscs live and grow in the presence of substantial concentrations of suspended inorganic material. These organisms have adapted to tolerate and even benefit their turbid environment. We carried out several experiments to determine if suspended kaolinite clay particles affect the amount of food cleared, rejected in pseudofeces, and/or ingested by a common estuarine bivalve, the eastern oyster Crassostrea virginica (Gmelin). Juvenile oysters were fed a diet consisting of 14C-labelled algae ( Isochrysis galbana Parke) and 3H-labelled rice starch, with or without kaolinite. Starch was selectively rejected in oyster pseudofeces, compared with algae. Oysters were able to sort algal cells from starch particles more efficiently with no kaolinite in the water than when kaolinite was added to the chambers. This disruption of selection by kaolinite caused oysters to ingest more starch under certain conditions. Kaolinite did not significantly affect the amount of algae cleared or rejected. Kaolinite particles adsorbed a small but statistically significant amount of dissolved organic material from the food.

Biomass, carrageenan yield and reproductive state of Hypnea musciformis (Rhodophyta: Gigartinales) under natural and experimental cultivated condition

Cultivation of the macroalga Hypnea musciformis (Wulfen) Lamouroux was conducted from April 1987 to January 1988 at Praia do Forte (State of Bahia, Brazil), utilizing floating racks, Biomass, reproductive state, carrageenan yield and viscosity of algae artificially grown in situ were compared with those from natural populations. Temperature, salinity, pH, dissolved oxygen, organic and inorganic suspended matter and phosphate in surface waters were similar in all experimental phases. Algae growing on the racks exhibited significantly higher daily biomass increase (0·94-9·69g/m2day dw) than plants from natural reefs (1·39-1·74g/m2/day dw). Cultivated algae presented a dominance of tetrasporic stages, while algae from the reefs had a high occurrence of vegetative stages. Both cultivated and natural plants showed higher numbers of cystocarpic specimens during the summer. Carrageenan yield of cultivated plants was significantly higher than those growing under natural conditions only during summer-time experiments, presenting values of 3972% and 38-28% for experiments and a range of 22·7-34·88% for the reef plants. However, carrageenan viscosity of cultivated algae was always higher (40·33 ± 4·62 centipoise) and less variable than that found for the reef growing algae (35·71 ± 19·92 centipoise).

Ecotoxicological study of the influence of an industrial effluent on a net-spinning caddisfly assemblage in a regulated river

The influence of an industrial effluent on the spatial distribution of net-spinning caddisflies (Trichoptera, Insecta) in the regulated Rio Duraton (northern Spain) was studied using field and laboratory methods. The effluent caused an increase in the fluoride concentration at three downstream sampling sites (mean values 6.8, 2.7 and 1.3 mg F-L−1 at S-3, S-4 and S-5) compared with control stations (0.1 mg F-L−1 at S-1 and S-2). The suspended inorganic matter (SIM) only increased just below the effluent (S-3), settling on the stream bottom at this sampling station. In addition, discharge fluctuations of hypolimnial waters with a significant OZ deficit, < 5 mg L−1 just below the reservoir (S-2), were produced daily by the dam, causing an hourly variation of fluoride concentrations at S-3, S-4 and S-5. The 48 and 72 hr LC50s (mg F-L−1) calculated from fluoride toxicity bioassays in soft water were 79.2 and 44.9 for Hydropsyche bulbifera, 86.6 and 43.7 for H. exocellata, 112 and 59.1 for H. pellucidula, 78.2 (72 hr) for H. lobata, and 120 and 79.7 for Chimarra marginata. H. siltalai, H. bulbifera, H. exocellata and Polycentropus flavomaculatus increased their abundances at S-4 and S-5 with regard to the upstream control station (S-1). Densities of Hydropsyche sp., H. lobata, H. pellucidula, Chimarra marginata and Cheumatopsyche lepida decreased or were absent downstream from the dam. No caddisfly species was collected at S-3 during sampling surveys. It is concluded that the main physicochemical factors responsible for changes in structure and composition of the net-spinning caddisfly assemblage along the study area were short-term flow fluctuations, dissolved O2 deficit and siltation of SIM. The increased fluoride concentration was a minor factor.

Ecotoxicological analysis of the influence of an industrial effluent on fish populations in a regulated stream

Abstract. The influence of an industrial effluent on the spatial distribution of fish populations in the regulated Río Duratón (northern Spain) was examined by field and laboratory studies. The effluent caused an increase in the fluoride ion concentration at three downstream sampling sites (mean values 6·8, 2·7 and 1·3mg/l) compared with reference stations (0·1 mg/l). The suspended inorganic matter (SIM) only increased immediately below the effluent, settling on the stream bottom of this sampling station. In addition, hypolimnial waters with low concentrations of dissolved oxygen (<5 mg/l) were released daily by the dam. Rainbow trout, Oncorhynchus mykiss (Walbaum), and brown trout, Salmo trutta L., disappeared downstream of the impoundment. The 72 and 96h LC50s (mgF-/1) calculated from fluoride toxicity tests in soft water were 138·5 and 107·5 for rainbow trout, and 223·0 and 164·5 for brown trout. Fish (Barbus bocagei Steindachner, Rutilus arcasii (Steindachner) and Gobio gobio (L.)) were collected at all sampling stations. The benthic fish species Cobitis maroccana Pellegrin was also collected downstream of the impoundment but was absent just below the industrial effluent. It is concluded that the main physicochemical factors responsible for the spatial distribution of fish populations were low concentrations of dissolved oxygen for trout and the siltation of SIM for cobitids, the increased fluoride concentration being a minor factor.

Estimation of Organic and Inorganic Matter in Inland Waters: Optical Cross Sections of Lakes Ontario and Ladoga

The high degree of optical complexity of inland water masses necessitates the development of models which consider the optical competitiveness of several co-existing aquatic components. A model is described which was developed to simultaneously estimate chlorophyll a, suspended mineral, and dissolved organic carbon concentrations from a single measurement of the subsurface volume reflectance spectrum in the optically complex waters of Lake Ontario. To estimate such aquatic concentrations requires a quantification, as a function of wavelength, of the amount of scattering and absorption that may be ascribed to a unit concentration of each aquatic component (i.e., the pertinent optical cross sections). Cross section spectra are presented for Lake Ontario and it is illustrated how such cross sections may be utilized in conjunction with directly-measured subsurface volume reflectance spectra and optimization analyses to extract the organic and inorganic components. Cross section spectra obtained in a similar manner for Lake Ladoga are also presented and compared to those of Lake Ontario. Similarities in absorption, but differences in backscattering cross section spectra for suspended inorganic matter were observed for the two lakes. Near-identical absorption and very similar backscattering cross section spectra suggest that Lakes Ontario and Ladoga are characterized by optically-comparable populations of chlorophyll-bearing biota.

The downstream impacts of the burgomillodo reservoir, Spain

AbstractThe Burgomillodo Dam, located in the middle Rio Duraton (north Spain, Duero Basin), has created a small eutrophic reservoir with a capacity of 15 × 106 m 3 and a maximum depth of 40m. Burgomillodo Reservoir is solely used for producing hydroelectric power. The regulated flow pattern of hypolimnial waters is characterized by higher daytime flows than those by night, with low flows at weekends all the year round. The environmental impact generated by this hydropower scheme on the river downstream was assessed by comparing physiochemical characteristics and aquatic communities of an upstream site (reference station) with those of three downstream stations, which were located 0–2, 2–5, and 7–6 km below the dam.Water temperature, pH and dissolved oxygen were significantly lower downstream from the reservoir. Hardness, alkalinity, suspended inorganic matter, and conductivity had reduced annual variability below the dam. Photosynthetic activity was directly involved in the recovery of dissolved oxygen and pH values.Species richness and abundance of macrophytes increased just below the dam. Macrobenthic and fish communities were composed of higher numbers of potamic species. Number of taxa, density, biomass, and diversity were higher at the reference site, recovering their values as the distance below the reservoir increased. Macrobenthic trophic structure was changed by an increase in predators and filter feeders and a decrease in shredders. Environmental impact values for the macrobenthic community living just below the dam were higher than those for the fish community.It is concluded that the main physiochemical factors involved in environmental impacts were dissolved oxygen deficit and short‐term flow fluctuations for the macrobenthic community, and oxygen deficit for the fish fauna. Benthic macroinvertebrates appear to be the best aquatic organisms for detecting changes and for reflecting the spatial recovery of environmental conditions.

Some limnological observations on two Ethiopian hydroelectric reservoirs: Koka (Shewa administrative district) and Finchaa (Welega administrative district)

Koka Reservoir in the Ethiopian Rift Valley (altitude about 1600 m) appears to be similar to natural lakes in the region. Its water is turbid because of suspended inorganic material. At the time of measurement it was supersaturated with oxygen to a depth of about 8 m, and displayed a pronounced conductivity stratification, due probably to the incomplete mixing of two inflows. The phytoplankton was dominated by Microcystis. The zooplankton was of low diversity but abundant. There was a large population of benthic invertebrates.

Composition and distribution of suspended sediments in Lake Michigan during summer stratification

A quantitative description of the composition and distribution of suspended sediments is a necessary prerequisite to the determination of the transport and fate of those particles and of the chemical substances associated with them. This report is the first to make such a description for materials in the Great Lakes. Suspended sediment samples were collected from Lake Michigan during August from several depths at six locations between Grand Haven, Michigan, and Milwaukee, Wisconsin. Concentrations of total suspended material range from 1.05–2.40 mg/l. Diatoms comprise nearly all of the biogenic fraction and approximately 60% of the total. Quartz plus feldspar (25%) is usually more abundant than carbonate minerals (13%), and clays are a minor component. Abundances of all constituents were higher near the shore where shoreline input provides both nutrients and minerals. Suspended materials were concentrated at the base of the thermocline and in a bottom nepheloid layer of resuspended sediment. Mineral ratios in the nepheloid layer were similar to those in the surface centimeter of bottom sediment but diatom abundance decreased markedly below the sediment-water interface. The residence time of suspended inorganic materials in Lake Michigan is about 1.8 yrs, ample time for suspended sediment grains to be distributed throughout the lake.

Turbidity and its causes in a narrow glacial lake with winter ice cover1

Results from a field investigation of seasonal variations in turbidity are presented for a narrow (≈12 × ≈1 km) glacial Finger Lake south of Rochester, N.Y. The turbidity structure is primarily vertical in summer and under winter ice cover; during spring and fall mixing horizontal gradients dominate. Inflows from the large drainage area at the southern end of the lake show a Coriolis influence. Vertical mixing of this inflow correlates well with density. During most of the year turbidity seems to be associated principally with suspended inorganic material.

Particulate matter grain‐size characteristics and flocculation in a partially mixed estuary

ABSTRACTThe concentration and grain size of the natural and deflocculated inorganic suspended particulate matter were measured along the length of the Miramichi Estuary and interpreted with respect to flocculation and transport properties. Changes in particulate matter concentration are associated with regular changes in grain‐size characteristics. In the turbidity maximum region of the estuary the suspended matter occurs mostly as large flocculated particles whereas, in the waters with lower particle concentrations, a larger proportion of the material occurs as fine material. At higher concentrations natural floc modes and inorganic grain modes vary simultaneously but at low concentrations the two modes vary inversely. This modal relationship and the variation in organic matter within the estuary is proposed to result from variation in inorganic—organic composition of flocs. Increase in settling rates due to flocculation is believed to increase the trapping effect of the estuarine circulation that produces the turbidity maximum.

Glaciomarine Sediments and Suspended Particulate Matter, Weddell sea, Antarctica (Abstract only)

Samples of glaciomarine sediments and suspended particulate matter filtered from sea-water were collected in the Weddell Sea during the Norwegian Antarctic Research Expedition (NARE) in 1978–79. Analyses have provided information on the textural and mineralogical composition of shelf sediments, on the nature of biogenic and inorganic suspended particulate matter, and on the total sediment transport to the shelf areas and further into the deeper waters (Orheim and Elverhøi 1981).The shelf waters contain 0.1 to 1.2 g m–3 of suspended particulate matter, which is close to the range of 0.5 to 1.5 g m–3 reported for suspension concentrations in the oceans, but considerably lower than that found for some other glaciomarine environments such as the Bering Sea {up to 13-15 g m–3 (Lisitzin 1972)) and off Kongsbreen, Spitsbergen {up to 500 g m–3 (Elverhøi and others 1980)).Suspended particles from the Weddell Sea have maximum sizes of 50 to 70 µm and mean diameters in the range of 10 to 20 µm. In contrast, the bottom sediments on the outer shelf are deficient in the corresponding fractions. This reflects that when floating Antarctic ice supplies material to the Weddell Sea, the coarser fragments (&gt;20-70 µm) are deposited, while the medium silt and finer fractions go into suspension. Considering the suspended-load data and the bottom-current measurements on the shelf break, it is evident that in January 1979 an average of 8.6 × 104tonnes d–1 (or 32 × 106 tonnes a–l) of particulate matter was transported by the current from the central Weddell Sea to the South Atlantic deep water. Morphological (scanning electron microscopy) and chemical analyses show the suspended material to be dominated by silica organisms (diatoms), and also to contain clastic grains of phyllosilicates, feldspar, quartz, zircon, in a few cases Al- and Fe-hydroxides/oxides also; authigenic “Fe-sepiolite” and secondary gypsum.Mineralogical analyses (X-ray diffraction) of the bottom sediments show the fine sand silt fractions to contain mainly clastic materials like illite, smectite-vermiculite, and quartz. Biogenic silica (cristobalite) and carbonate (Mg-calcite) as well as authigenic Fe-silicates (“Fe-sepiolite”) are also present.

Chemical tracers for particle transport in the Chesapeake Bay

Particulate material from the Susquehanna River is enriched in Fe (5–7%),allowing it to be distinguished from other sources of particles in surface waters of the Chesapeake Bay. Although the turbidity maximum removes most of the river-borne detritus, chemical composition of particles (SPM) indicates that Susquehanna River materials dominate the inorganic suspended matter in surface waters of the Bay at least 20–40 km further. Fe concentrations, Fe/Ti, and Fe/Zn ratios in surface water SPM still farther down the Bay indicate that those particles are a mixture of river derived and biological material and that shore erosion is not normally a source of surface water suspended sediments as far as the mouth of the Potomac. Seasonal variations 1 of elemental ratios such as Fe/Zn can also be used to demonstrate scavenging of soluble trace elements by particles during summer conditions.

Silica in the sea — its forms and dissolution rate

Reactive, particulate, and total silica were investigated in seawater samples collected in the Oyashio and Kuroshio areas of the western North Pacific and Funka Bay near Hokkaido Island. The concentrations of particulate silica and suspended inorganic matter in the Japan Sea were also determined. A vertical diffusion model was first applied to the profiles of particulate silica to estimate the rate of dissolution of particulate silica in the intermediate water of the Japan Sea. The dissolution rate, which corresponds to the rate of increase of reactive silica, was estimated to be 0·04–0·4 μg-atoms Si 1 −1 γr −1, providing the vertical eddy diffusivity is 1–10 cm 2 s −1 and the settling velocity of particulate matter is (1·16–11·6) × 10 −4 cm s −1. Reactive silica is the dominant species of silica in seawater. No colloidal silica is detectable in samples taken either near shore or in open seas, in any of the whole water column from the surface to near the deep-sea bed. Particulate silica concentrations varied from 0·1 to 2·0 μM Si in the open seas and from 0·5 to 11 μM Si in Funka Bay. Higher values were observed in the surface and subsurface waters in the Oyashio area and the bottom waters in the coastal region.

Latitudinal distribution and origin of particulate silica in the surface water of the North Pacific

The concentrations of particulate silica and inorganic suspended matter in the surface water of the North Pacific were determined. The concentration of particulate silica depends on latitude, and increases with increasing degree of the north latitude. The concentration of inorganic suspended matter shows a similar distribution pattern, but it is of much smaller magnitude. There exists a high positive correlation between the concentrations of particulate silica and nutrients. On the other hand, a weak negative correlation is found between the concentrations in surface seawater of particulate silica and radioactive 210Pb which originate chiefly from precipitation and dry fallout. This evidence suggests that the particulate silica in the sea is mainly of biogenic origin and the contribution of nonbiogenic silica, i.e., of terrestrial origin, is small.

Limnological Studies of Western Lake Erie: II. Light Penetration and Its Relation to Turbidity

Changes in transparency of natural waters may be far more important in determining the quantity of light at a given depth than seasonal changes in the illumination reaching the surface of the water. Clarke ('38) has shown that in certain Atlantic coastal waters the seasonal variation in illumination at the surface resulted in a 2-fold difference in intensity of submarine light at 30 m., while a seasonal change in transparency caused a 1000-fold change at the same depth. If variations in transparency of water produce tremendous differences in the quantity of light reaching a given depth it is important that the causes and effects of these variations in transparency be investigated. This information is of particular value for bodies of water in which yearround ecological studies are being made, because a slight change in transparency may conceivably alter the depth of the photic zone and affect the activities of microcrustacea, fish and other aquatic organisms. The fact that the shallow water of western Lake Erie undergoes sudden and extreme changes in turbidity makes this particular study of considerable interest. The present report is concerned with variations in turbidity of the water of western Lake Erie and the effect of these variations on the depth to which one per cent of the surface light penetrates. In this investigation year-round observations were made of: (1) turbidity, (2) light penetration, (3) amount of organic and inorganic suspended matter, and (4) quantity of phytoplankton. The study extended from Sept., 1939, through Oct., 1940, during which time several observations were made each month. The writer is indebted to Leonard J. Bodenlos for field assistance and for the quantitative data pertaining to suspended materials, and to other associates who assisted from time to time.