A WATER POLICY-LAND USE COMPUTER SIMULATION MODEL1

ABSTRACT: This paper describes the philosophy, algorithms, and implementation of a computer-oriented land use forecasting-water policy simulation model. The model is applicable to SMSA's organized on a census tract basis by counties. The forecasts are macro to the census tract level for industrial, residential, commercial and public land uses, and are dynamically altered by hypothesized water management policies. Modeling is based on an economic data base of the region, and is extremely flexible for the user. An example set of simulations is included for illustrative purposes.     

Relationship between water solubility of chlorobenzenes and their effects on a freshwater green alga

The effective concentrations of benzene and 12 chlorobenzenes that reduced 50% of the primary productivity (EC₅₀) of a freshwater green alga, $\text{Ankistrodesmus falcatus}$, were determined. Benzene was the least toxic chemical and the toxicity increased as the degree of chlorine substitution in the aromatic ring increased. No EC₅₀ value could be obtained for HCB. A quantitative relationship was found to exist between water solubility, lipophilicity and the EC₅₀. A good correlation was also observed between the EC₅₀ for this alga and other toxicity data for various aquatic biota.     

Sorption and enhanced biodegradation of trace organics in a groundwater reclamation scheme— gloucester site, Ottawa, Canada

An inexpensive scheme to reclaim groundwaters contaminated by volatile organics at the Gloucester landfill site, near Ottawa, Canada, involved pumping of contaminated water into an conducted to evaluate the possible enhancement of biodegradation to improve this remedial measure.Batch experiments revealed that toluene (0.8–1.5 mg L⁻¹) was rapidly degraded aerobically while chloroform (1.2–1.0 mg L⁻¹) was recalcitrant under aerobic or anaerobic (denitrifying) conditions. Dynamic column experiments confirmed these findings. In column experiments, both chloroform and toluene were retarded relative to the pore water velocity, but to a far lesser extent than predicted by hydrophobic sorption theory. This discrepancy is attributed to the large particulate nature of the sorbent (sawdust) which prevented rapidly migrating organics from attaining an equilibrium partitioning with the bulk of this organic matter. Addition of acetate and nitrate at 20 mg L⁻¹ stimulated aerobic activity, but was inhibitory to toluene degradation. However, when nutrient addition ceased, enhanced toluene degradation was produced by the larger microbial population.In the field experiment, addition of acetate and nitrate to groundwater influent into the sawdust/sand pit may have stimulated benzene biodegradation, but had no apparent influence on volatile chlorinated hydrocarbon biodegradation. As in the column experiments, sorptive retardation was considerably less than predicted, due to a lack of equilibrium partitioning of organic solutes within the sawdust.Enhancing biodegradation in this remedial scheme was unsuccessful for a broad range of volatile organic compound types. Periodic nutrient addition to create variable environments for microbes appears to hold more promise for remediation than the continuous nutrient input scheme. This experience demonstrates the need for realistic field-scale experiments before translating laboratory studies into full-scale remedial operations.     

Finished leather waste chromium acid extraction and anaerobic biodegradation of the products

Due to the amounts of chromium in the leachate resulting from leather leaching tests, chromium sulfate tanned leather wastes are very often considered hazardous wastes. To overcome this problem, one option could be recovering the chromium and, consequently, lowering its content in the leather scrap. With this objective, chromium leather scrap was leached with sulfuric acid solutions at low temperature also aiming at maximizing chromium removal with minimum attack of the leather matrix. The effects of leather scrap dimension, sulfuric acid and sodium sulfate concentration in the solutions, as well as extraction time and temperature on chromium recovery were studied, and, additionally, organic matrix degradation was evaluated. The best conditions found for chromium recovery were leather scrap conditioning using 25 mL of concentrated H₂SO₄/L solution at 293 or 313 K during 3 or 6 days. Under such conditions, 30–60 ± 5% of chromium was recovered and as low as 3–6 ± 1% of the leather total organic carbon (TOC) was dissolved. Using such treatment, the leather scrap area and volume are reduced and the residue is a more brittle material showing enhanced anaerobic biodegradability. Although good recovery results were achieved, due to the fact that the amount of chromium in eluate exceeded the threshold value this waste was still hazardous. Thus, it needs to be methodically washed in order to remove all the chromium de-linked from collagen.     

Biological Control of Water Hyacinth Under Conditions of Maintenance Management: Can Herbicides and Insects Be Integrated?

Neochetina eichhorniae and N. bruchi. We therefore sampled water hyacinth and weevil populations at 54 sites distributed statewide. Half were under maintenance control, half were not treated with herbicides. General site conditions were assessed, demographic data were collected on weevil and plant populations, the reproductive condition of the weevils was determined, and plant nutrient and proximate composition of water hyacinth leaves were analyzed. Water hyacinth infestations under maintenance control were minimal when compared to unmanaged sites. Likewise, on a population basis, all weevil cohorts were much lower due to the paucity of plants. Plants at unmanaged sites, where weevil intensities were much higher, suffered high levels of stress and showed low growth potential. Lower percentages of the female weevils were reproductive at unmanaged sites when compared to managed sites, so densities of reproductives and immatures were similar at both site types. Reproductive status of the weevils improved with increased plant quality. Plant quality, in turn, declined as stresses arising from weevil feeding increased. Plant quality was positively correlated with plant growth potential and flower production. Thus, maintenance control improved plant nutritive quality thereby inducing reproductive vigor of the weevils, but ensuring plant regrowth and the need for future control. This suggests that biological and herbicidal controls should be integrated, using herbicides to maintain water hyacinth infestations below management thresholds but in a manner that conserves biological control agent populations. This approach would lead to improved plant nutritional quality that would, in turn, stimulate reproduction in biological control agent populations.     

Sexual selection on mature male parr of masu salmon (Oncorhynchus masou): does sneaking behavior favor small body size and less-developed sexual characters?

In many salmonid species, males exhibit morphological dimorphism associated with alternative mating behaviors. ”Precocious males” have a small body size with little or no development of sexual characters and adopt sneaking to gain access to females, while ”migratory males” of large body size and well-developed secondary sexual characters fight. We quantified selection on precocious male parr of masu salmon (Oncorhynchus masou) under simulated natural conditions to examine the contribution of morphology to sneaking success. In contrast to the prediction that sneaking behavior favors small body size, we detected selection favoring relatively large body size for sneaking success. This selection pressure was caused by the dominance hierarchy within parr and may have been facilitated by indifference of dominant migratory males to parr. Unlike the secondary sexual characters exhibited by migratory male salmon, such as the hooked snout and humped back, no morphological characters other than body size contributed to the reproductive success of masu salmon parr. This non-contribution may have been responsible for the lack of development of sexual characters in precocious males. Received: 15 November 1999 / Accepted: 20 May 2000     

Changes in the levels of aspartate and alanine aminotransferase activities of Anabastestudineus (Bloch) exposed to disyston

In $\text{Anabas}$$\text{testudineus}$, the per cent changes noted in the aspartate aminotransferase (AAT) activities of gill, brain, intestine, liver, muscle and kidney until 6 hr of exposure to lethal concentration (10.5 mg/L disyston) were relatively much less when compared to those of sublethal concentration (4.0 mg/L disyston). But in the case of alanine aminotransferase (AIAT) activity, the tissues which showed such effect (paradoxical effect) were gill, brain and liver.