MANGANESE IN LACUSTRINE ECOSYSTEMS: A REVIEW1

This paper serves as a literature review of manganese in fresh water. The major aspects of manganese occurrence discussed are: (1) sources, (2) geochemistry, (3) manganese-iron relationships, (4) effects on the fauna and flora and (5) detection.     

Fish bioassay monitoring of waste effluents

Spills of toxic materials into bodies of water receiving industrial waste discharges can be prevented only if frequent or continuous assessments of effluent quality can be made. Currently available methods can automatically measure individual physical or chemical waste components but cannot assess toxicity caused by the interaction of components or the presence of an unsuspected material. Aquatic organisms, in contrast, respond to their total environment and in this way integrate the effects of all the various chemical and physical waste parameters.This study evaluates the possibility of using the continuously and automatically recorded responses of fish to monitor the toxicity of industrial waste effluents. A review of previously developed toxicity monitoring systems is followed by a field evaluation of a method that uses the computer-monitored ventilatory patterns of 12 bluegills (Lepomis macrochirus Rafinesque) to monitor the toxicity of an industrial waste effluent as it flows into a river. No known toxic spills occurred in the effluent during the operation of this system, but acetone added to the effluent waste caused responses from the fish at concentrations which peaked near the 96-hr LC₅₀ level. Some responses were also noted when no known toxicant was present; these were related to environmental disturbances and system design problems. Recommendations are made for the design of future biologic monitoring units.     

WATER HARVESTING TREATMENT EVALUATION AT GRANITE REEF1

ABSTRACT: Yearly runoff efficiencies (total runoff/total precipitation), threshold retentions (precipitation needed to initiate runoff), and runoff-efficiencies-after-thresholds were determined for several water-harvesting catchment treatments at the Granite Reef test site. This information was found to be useful for showing (1) overall performance of catchments with time; (2) the distribution of the precipitation among runoff, surface retention, and infiltration; (3) why, how, and when certain treatments weathered and failed; (4) when to repair treatments; and (5) how to design catchments (size, site preparation, material selection, etc.). New impermeable membranes with smooth surfaces yielded nearly 100% of the precipitation. An asphalt-fiberglass treatment continues this high efficiency after 10 years of weathering – polyethylene after 8; efficiency of butyl sheeting was high initially but decreased rapidly after 9 years weathering. A standard roofing treatment retained up to 30% of the precipitation in the gravel covering. A concrete catchment lost as much as 50% of the total precipitation through micropores and surface cracks. Silicone treatments rapidly lost repellancy and efficiency, while paraffin treatments have weathered 5 years with little loss of efficiency.     

PHREATOPHYTE EVAPOTRANSPIRATION AND ITS POTENTIAL REDUCTION WITHOUT ERADICATION1

ABSTRACT: The continuous availability of ground water to riparian phreatophytic vegetation results in large evapotranspiration (ET) losses in summer. Chemical or physical eradication of this vegetation can have undesirable environmental side effects. Spraying phreatophyte foliage with a nontoxic antitranspirant (AT) may reduce transpiration without eradication. Transpiration rate per unit leaf area was similar for several phreatophyte species, but ET per unit land area of phreatophytes depneds more on stand density than species. The mean ET for saltcedar in June was 8.1 mm/day measured by Bowen ratio, compared with 7.9 mm by lysimeters. ATs and growth-retardants reduced transpiration by over 50 percent in laboratory tests where foliage was thoroughly sprayed. In the field AT sprayed by a back-pack mistblower reduced ET by 20–35 percent initially and 10 percent after a month. No ET reduction occurred when AT was sprayed by helicopter on saltcedar, because excessive droplet size and heavy salt deposits on the foliage resulted in poor spray adherence. Wax-based AT was relatively nontoxic to fish and wildlife. Dissolved oxygen could be reduced for aquatic life, but further AT dilution in streams and ponds would minimize this. Helicopter spraying may affect bird nests and egg hatchability. Although ATs significantly reduce ET, their high cost and spraying difficulties preclude current use on phreatophytes. With improvement they may economically help to conserve water in riparian areas in future years.     

COMPARATIVE EVALUATION OF THREE URBAN RUNOFF MODELS1

ABSTRACT: Three urban runoff models, namely, the Road Research Laboratory Model (RRLM), the Storm Water Management Model (SWMM) and the University of Cincinnati Urban Runoff Model (UCURM), were examined by comparing the model simulated hydrographs with the hydrographs measured on several instrumented urban watersheds. This comparison was done for the hydrograph peak points as well as for the entire hydrographs using such statistical measures as the correlation coefficient, the special correlation coefficient and the integral square error. The results of the study indicated that, when applying the three selected non-calibrated models on small urban catchments, the SWM model performed marginally better than the RRL model and both these models were more accurate than the UCUR model. On larger watersheds, the comparisons between the SWM model and the other two models would be likely even more favourable for the SWM model, because it has the most advanced flow routing scheme among the studied models.     

Statistical estimation of global mineral resources

The concentration of minerals in the crust forms a continuous distribution between the higher grade reserves mined as ore and the low-grade background mineralization of waste rock. A lognormal distribution could be generated by a mineralization process compatible with the theory of plate tectonics. A computer model of this process is demonstrated. The discussion is extended to other base metals and in particular to the distribution of reduced carbon. Neither base metals nor fossil fuels are ever likely to be exhausted, but they may rise in cost and be superseded by cheaper substitutes.     

HYDROLOGIC EFFECTS OF THE TONKAWA CREEK FLOOD ABATEMENT PROGRAM1

ABSTRACT: Floodwater-retarding impoundments, controlling 68 percent of the drainage area of Tonkawa Creek, a Washita River tributary in southwestern Oklahoma, have reduced the total flow volume about 36 percent over a 5-year period. Analyses showed the reduction occurred primarily in the less-than-2.5-cfs flow range, indicating the base flow regime has been altered. However, channelizing the downstream, mild-sloped, 3.6 miles of Tonkawa Creek that flows across a Washita River terrace increased the flow volume fourfold at the outlet. A double-masscurve analysis of water yield from a 1,127-square-mile Washita basin segment versus an untreated tributary showed the yield has not changed after 25 percent of the tributary area had been treated. Therefore, the flow reduction caused by structures is being offset by increased yields from channelization.     

CHANNELIZATION AND INVERTEBRATE DRIFT IN SOME IOWA STREAMS1

ABSTRACT: Habitat diversity and invertebrate drift were studied in a group of natural and channelized tributaries of the upper Des Moines River during 1974 and 1975. Channelized streams in this region had lower sinuosity index values than natural channel segments. There were significant (P=O.05) positive correlations between channel sinuosity and the variability of water depth and current velocity. Invertebrate drift density, expressed as biomass and total numbers, also was correlated with channel sinuosity. Channelization has decreased habitat variability and invertebrate drift density in streams of the upper Des Moines River Basin and probably has reduced the quantity of water stored in streams during periods of low flow.