GOLD-MINING EFFECTS ON HEAVY METALS IN STREAMS,CIRCLE QUADRANGLE,ALASKA1

Placer gold mining, which extracts gold from buried or exposed alluvia, is often conducted on or near streams. Such mining has the potential to adversely affect water quality. Other heavy metals associated with the gold (such as arsenic, cadmium, lead, zinc, and copper) may be freed to enter streams. Mercury may also enter streams if miners are using it to recover fine particles of gold. These heavy metals are toxic and thus may be harmful to the aquatic life of the streams receiving effluent or runoff from placer mines. In 1982 we sampled two streams intensively - one heavily mined and one unmined - for total recoverable arsenic, mercury, lead, zinc, and copper. Only mercury was not significantly higher in concentration in the mined streams. In 1983 we sampled two stream pairs three times, and 10 other sites at least once, for total and dissolved arsenic, cadmium, mercury, lead, zinc, and copper. Mercury and cadmium were not significantly elevated in mined streams, but the concentrations of total arsenic, lead, zinc, and copper, and dissolved arsenic and zinc were significantly higher in streams below active placer mining sites than in these that were not being mined or those that had never been mined. Additionally, total arsenic, lead, zinc, and copper and dissolved arsenic and copper became elevated after mining began in 1983 on a previously unmined stream.     

Spatial and Temporal Variations in the Sediment Habitat of Ranunculus spp. in Lowland Chalk Streams – Implications for Ecological Status?

Ranunculus spp. are the dominant plants of lowland chalk stream habitats in England. The spatial variability of sediment characteristics (silt–clay, organic matter, total phosphorus and total nitrogen content) within stands of Ranunculus spp. was investigated in 12 rivers in lowland England. Variability was found to be high and there were no discernible differences between samples taken from within Ranunculus and a limited number of samples from bare substrate. For two of these rivers, comparisons were also made between reaches upstream and downstream of waste water treatment works outfalls in terms of the characteristics of the sediments within Ranunculus stands. In one river a clear increase in sediment nutrient, fine and organic material content was observed downstream but in the other there was no consistent difference. Temporal variability was considered for two rivers in the Frome catchment, Dorset, by analysing the monthly variability in sediment organic matter and silt–clay content beneath Ranunculus stands over an annual cycle of growth and die-back. Whilst a clear pattern of fine and organic material retention consistent with seasonal plant growth patterns was evident at one site, the three sites displayed different temporal patterns. This inconsistency is believed to reflect differences in sediment supply at the three sites.     

A LONG‐TERM,WATERSHED‐SCALE,EVALUATION OF THE IMPACTS OF ANIMAL WASTE BMPs ON INDICATOR BACTERIA CONCENTRATIONS1

ABSTRACT: Driven by increasing concerns about bacterial pollution from agricultural sources, states such as Virginia have initiated cost sharing programs that encourage the use of animal waste best management practices (BMPs) to control this pollution. Although a few studies have shown that waste management BMPs are effective at the field scale, their effectiveness at the watershed scale and over the long term is unknown. The focus of this research was to evaluate the effectiveness of BMPs in reducing bacterial pollution at the watershed scale and over the long term. To accomplish this goal, a 1,163 ha watershed located in the Piedmont region of Virginia was monitored over a ten‐year period. Fecal coliforms (FC) and fecal streptococci (FS) were measured as indicators of bacterial pollution. A pre‐BMP versus post‐BMP design was adopted. Major BMPs implemented were manure storage facilities, stream fencing, water troughs, and nutrient management. Seasonal Kendall trend analysis revealed a significant decreasing trend during the post‐BMP period for FC concentrations at the watershed outlet, but not at the subwatershed level. Implementation of BMPs also resulted in a significant reduction in the geometric mean of FS concentrations. FC concentrations in streamflow at the watershed outlet exceeded the Virginia primary standard 86 and 74 percent of the time during pre‐BMP and post‐BMP periods, respectively. Corresponding exceedances for the secondary standard were 50 and 41 percent. Violations decreased only slightly during the post‐BMP period. The findings of this study suggest that although BMP implementation can be expected to accomplish some improvement in water quality, BMP implementation alone may not ensure compliance with current water quality standards.     

Operating Experience with the Alcoa 398 Process for Fluoride Recovery

During the 1940’s, aluminum smelting installations were increased in size to provide aluminum necessary for World War II. Increased evolution of fluorides made necessary the capture and treatment of pot gases. Following the application of water scrubbers, cyclones, and electrostatic precipitators, Alcoa Research Laboratories at New Kensington, Pa., discovered that small quantities of HF gas would react at low temperature with alumina. Following a series of design efforts, the Alcoa 398 Process was developed, incorporating a fluidizedbed reactor to contact pot gases with incoming feed alumina. Bag filters are used to separate entrained solid materials from pot gases. Ninety-five percent interception of pot gases is reported with 99% recovery of fluorides from gases treated. No significant effect is observed on purity of metal produced.

Installation costs are in the range of $>28-$37 per annual ton for new installations and about 50% more for conversion of old plants. These are somewhat less than the conventional electrostatic precipitators and water scrubbers at today’s prices. Direct operating costs for the Alcoa 398 Process range from $2.90 to $4.70/ton of aluminum and recover $8 worth of fluorine, giving a net credit. This contrasts with $3.93/ton of aluminum to operate existing precipitator scrubber combinations. The Alcoa 398 Process is being rapidly extended throughout the Alcoa system.     

Economic assessment of dredging operations in Mobile Bay,USA and some additional notes on sustainable management of dredged material

This paper describes a study that was performed to determine the cost-effective method of dredging in Mobile Bay in the United States and to explore the possibility of utilizing the dredged materials in an environmentally sustainable way. An analysis of the historical cost and working time data for hopper dredging and pipeline dredging for Mobile Bay showed that there was not a substantial difference in unit costs between the two methods. However, while the disposal methods for dredged materials were taken into consideration, the pipeline dredging seemed to be a more desirable and environmentally friendly option for dredging in Mobile Bay. In addition to cost analysis, the paper discusses several possible ways of sustainable management of dredged materials. The paper also indicates that if the sediment in Mobile Bay is found to be contaminated by the Deepwater Horizon oil spill, the pipeline dredging will become a more desirable dredging alternative.     

Fate of 17β-estradiol in terrestrial model ecosystems amended with contaminated composted biosolids

Biosolids spread onto agricultural soils are potential sources of steroidal hormones that are able to adversely affect the soil ecosystem. Here we studied the fate of the [4-¹⁴C]-17-β-estradiol hormone in laboratory experiments. First, our results show that only 2.9% of the hormone was mineralized in the soil from a French vineyard. By contrast, the mineralization increased to 7.1% when the hormone was provided in composted biosolids. Second, we found that only a minor part of the estradiol-derived ¹⁴C was mobile and partly transferred to soil leachates. Indeed, the hormone was mainly stabilized in the soil as non-extractable residues. Overall, our findings show that estradiol undergoes two main processes, complete degradation and stabilisation. We therefore conclude that the environmental risk of hormones provided to the soil through composted biosolids is negligible under the conditions of our experiments.     

Bio-Based Polymers and End-of-Life Vehicles

As new materials, such as bio-based plastics and composites, are introduced in vehicles for their improved environmental performance, it is necessary to understand how to efficiently recover these biodegradable materials. This paper provides an overview of the end-of-life phase for automobiles, focusing on the dismantling and shredding processes, and the recovery of materials. Targeted unit operations, such as dismantling of components from vehicles and pretreatment prior to shredding, along with design-for-environment principles, should enable the efficient recovery of materials at the end-of-life phase compared with popularly conceived all-in-one-approaches because of the diverse arrangement of material components.     

Living with disasters: social capital for disaster governance

This paper explores how social networks and bonds within and across organisations shape disaster operations and strategies. Local government disaster training exercises serve as a window through which to view these relations, and ‘social capital’ is used as an analytic for making sense of the human relations at the core of disaster management operations. These elements help to expose and substantiate the often intangible relations that compose the culture that exists, and that is shaped by preparations for disasters. The study reveals how this social capital has been generated through personal interactions, which are shared among disaster managers across different organisations and across ‘levels’ within those organisations. Recognition of these ‘group resources’ has significant implications for disaster management in which conducive social relations have become paramount. The paper concludes that socio‐cultural relations, as well as a people‐centred approach to preparations, appear to be effective means of readying for, and ultimately responding to, disasters.     

Crossing the frontier: vertical transit rates of deep diving cormorants reveal depth zone of neutral buoyancy

Knowing the depth zone of neutral buoyancy of divers is important because buoyancy can determine how animals manage their energy budget. In this study, we estimate the depth zone of neutral buoyancy of free-ranging cormorants for the first time, using time-depth recorders. We discovered that vertical ascent rates of 12 Crozet and 15 Kerguelen diving blue-eyed shags (respectively Phalacrocorax melanogenis and P. verrucosus) slowed down considerably at the 50–60 m depth zone. We suggest this was due to birds trying to reach the surface from that point upwards using reduced locomotor activity because the force of buoyancy becomes greater than the force of gravity at that depth. The results show a shift of this depth zone in relation to maximum targeted dive depth, suggesting cormorants may control buoyancy through respiratory air volume adjustment. Interestingly, 60 m is close to the maximum depth zone reached by these two species during dives lasting 4 min, their estimated behavioural aerobic dive limit. This suggests that the decision to swim deeper has a direct consequence on the energy budget, with time spent recovering at the surface (time thus lost to foraging) strongly increasing relative to the preceding time of submergence. Resources found in deeper waters must be of sufficient quantity or quality to justify crossing the frontier of physical neutral buoyancy.