Total phosphorus determination in eutrophic tropical river sediments by laser-induced breakdown spectroscopy techniques

Total phosphorus (TP) in sediments is an important chemical variable in the study of the extent of eutrophication in water bodies.

Generalized effective stress concept for saturated active clays

Experimental evidence shows that changes in pore water chemistry can significantly affect the mechanical behavior of saturated active clays. Despite this evidence, how the chemical composition of the pore water can be considered in effective stress definition is questionable. This paper develops the concept of generalized effective stress for active clays. To this end, physicochemical studies on water–clay mineral interactions are used to clearly define the different types of ions and water present in an active clay. In particular, the presence of both movable and non-movable ions within the liquid water is highlighted. Taking this into account, thermodynamic and geochemistry principles are applied to the representative elementary volume scale for determining the pore water pressure and redefine the effective stress accordingly. The theoretical development results in the dependence of the effective stress on the pore water chemistry through the effective solute suction variable. Equations for the determination of this chemical variable are developed. The implications of the use of the proposed effective stress concept are investigated using experimental results taken from the literature. The results show advantages both in the interpretation of shear strength and volumetric data, and all support the theoretical explanation underlying the proposed concept.

ANALISIS KUALITAS KIMIA AIR SUNGAI RIUAPA DAN DAMPAKNYA TERHADAP LINGKUNGAN

Riuapa river is an integrated part of Waeriuapa Watershed that usefull for people around the area as agriculture irrigation, livestock, fresh water fish pond, and other domestic use for people activities. As an open watershed ecosystem, that flow into the sea, the river of Watershed was received various input from outside, either from upland to the estuary. Those input were domestic household waste, farming activities waste, and input from land erosion and land slide. The study was conducted to identify water quality through polutant level measurement, in the river and in the flood plain, especially for Chemical polutant element. Red waste, farming activities waste, and input from land erosion and land slide. The study was conducted to identify water quality through polutant level measurement, in the river and in the flood plain, especially for Chemical polutant element. Result of analisys using Statistical Analisys, namely, Factorial Design in Randomized Completly Design (3x2x3), as follows: Location of station in the river and Season factor was significant influence the chemical variable of BOD, COD, Nitrite, and Chlor in the river, and shallow well as well, at the level of beyond National Water Quality Standard, and affected environmental around the area. Changging of upper land cover of Waeriuapa Watershed was significant effected to water debit, fluctuation of rainfall and effected to liquidity process of water quality, that increase of BOD from 2.9 mg/l in dry season to 4.6 mg/l in rainy season; COD from 2.9 in dry season to 21.3 mg/l in rainy season; Nitrite content of 0.0001 mg/l in dry season to 0.0022 mg/l in rainy season.

Effect of Free Fatty Acid Content on the Digestible Energy Value of Soyabean Oil and Tallow Fed to Growing / Finishing Pigs.

In addition to the degree of saturation, the second major chemical variable that influences the dietary energy value of fats is the free fatty acid (FFA) content. Whilst it is appreciated that the digestible energy (DE) value of a hydrolysed fat (i.e. with a high FFA content) is lower than that of the same fat prior to hydrolysis, quantifying the response remains to be studied. Previous attempts to evaluate the effect of increasing FFA content have often been confounded with variability in degree of saturation. Accordingly it was the objective of the current study to examine the DE value of fats of varying FFA content but of constant degree of saturation.

Effects of elevated hydrogen ion and aluminum concentrations on the survival of amphibian embryos and larvae

Egg hatching success was measured for three amphibian species (Bufo americanus, Rana sylvatica, and Ambystoma maculatum) exposed to varying hydrogen ion, aluminum, and dissolved organic carbon (DOC) concentrations. In the first experiment, hatching success in six stream pools was negatively correlated with Al and DOC and positively correlated with pH. Effects of any one chemical variable, however, could not be separated from the others. In a second experiment, to separate effects of pH and Al from DOC, eggs and larvae were exposed to simulated stream pools in which pH was reduced. At pH 4.8 and 37 μg/L inorganic monomeric Al, only eggs of A. maculatum were affected. At pH 4.3, 46 μg/L inorganic monomeric Al was more toxic (compared with 34–35 μg/L at pH 4.8 and 4.3) to B. americanus and R. sylvatica embryos. Bufo americanus was more sensitive to low pH and elevated Al than R. sylvatica. Mortality of eggs of both species mainly occurred within 1 day of exposure but continued until hatching. Mortality of A. maculatum eggs, however, did not occur during the 4 days of acidification, but 2–3 weeks later, at the time of hatching. Larval survival in general was not affected by reduced pH (pH 4.3) and (or) elevated Al (up to 46 μg/L inorganic monomeric Al).

Physicochemical Typologies of South-Central Ontario Lakes

We present basic physicochemical data and principal component analyses (PCA) of both morphometric and chemical variables for 37 Ontario lakes. Multivariately derived composite variables were substituted for more conventional independent variables in several regression models. These composite variables always explained a greater percentage of variance than the standard morphometric variables. A typology derived in part from the PCA was useful in identifying groups of lakes for which the Ragotzkie model predicting maximum depth of the summer thermocline was appropriate and other groups of lakes that appear to be outliers on the basis of insufficient volume. In addition, variables important in defining the typology, particularly [Formula: see text] ratio and lake volume, were shown to be among the most important in a stepwise, multiple linear regression explaining 91% of the variance in nannoplankton to filter-feeding zooplankton ratios in the lakes. This represents a 47% improvement over previously reported results. Total phosphorus still explained more variance in several measures of phytoplankton biomass than did a multivariately derived composite chemical variable, but there were significant explanatory improvements in phosphorus–phytoplankton regressions within lake groups derived from a typology based on a speciated chemical matrix. There appears to be some overlap in biological patterns from morphometrically and chemically defined lake types. We suggest that these may represent ends of a continuum of differing density regulation responses by the biological communities.

Spectral and Biochemical Characteristics of the Particulate Matter in Bedford Basin

A survey of the distribution, nature, and biochemical composition of particulate matter (less than 153 μm diam) showed that small particles (< 18 μm) made up the bulk of the particulate matter during most of the summer. Relatively large amounts of microzooplankton (tintinnids) were also recorded during the period of stable hydrographic conditions. Diatoms and dinoflagellates were abundant only in early fall prior to the fall bloom. All cell counts were transformed into parts per million on a volume basis to compare with Coulter Counter data. Cell counts on preserved samples strongly underestimated the number and volume of small particles and did not take into account the detritus. Considerations of the ATP content strongly suggested that for naturally occurring particulate matter there is not a constant ATP to carbon ratio but rather an upper and lower limit. Small particles were the main repository for protein whereas phytoplankton was the repository for carbohydrates. The high variability of both quality and quantity of particles in the neritic habitat suggests that a single chemical variable cannot describe fully the nutritive value of naturally occurring suspended matter. Key words: particulate matter, phytoplankton, microzooplankton, flagellates, protein, carbohydrates, ATP, carbon