Uncontaminated Stream Research Articles

Improving Dairy Farm Sustainability II: Environmental Losses and Nutrient Flows

This paper continues tbe analysis of nutrient management on a case study dairy farm in New York State. In Part I, it was found that 60 to 70% of the imported N and P were not accounted for in the exported milk, crops, and animals. The purpose of this paper is to present a process for accounting for the fate of the excess nutrients and to determine the extent to which they were contributing to air and water pollution from the farm. Environmental losses of N and net excess of P in different subsections of the farm were estimated. Losses of N from volatilization on the barn floor and in storage were estimated to be 16% of excreted N. As a partial check on these results, manure nutrient composition for lactating cows was analyzed at excretion, entering storage, and leaving storage. Soil leaching losses from the farm were calculated using the LEACHN model, and were 9% of total N inflows to the farm. Predicted nitrate N concentrations in the leachate were 10.6 ppm. Results from monitoring a stream originating from the farm gave an annual average of 14.4 ppm of nitrate N. About 80% of the total N inflows were accounted for as milk sold (25%), animals sold (2%), leaching losses (9%), and volatilization/denitrification losses (46%). Environmental losses accounted for 75% of the excess N. Projected scenarios for increased use of farm-produced forages, reduction in fertilizers, and increased feed conversion to milk resulted in only minor improvements in the nutrient imbalance on this farm.

Evidence of Damage to Pink Salmon Populations Inhabiting Prince William Sound, Alaska, Two Generations after theExxon ValdezOil Spill

Our investigations into the effects of the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, suggest that chronic damage occurred to some populations of pink salmon Oncorhynchus gorbuscha. Significantly elevated embryo mortalities were observed from 1989 through 1993 in populations inhabiting streams previously contaminated by oil. No statistically detectable difference in embryo mortality was observed in 1994 and 1995. We assessed the possible influence of the natural environment on these findings by collecting gametes from adults returning to contaminated and to uncontaminated streams, transporting the gametes to a hatchery where intrastream crosses were made, and incubating the resulting embryos under identical environmental conditions. Significantly increased embryo mortality was detected for embryos originating from the oil-contaminated lineages in 1993 but not in 1994, which indicated that the significant differences detected in the field in 1989–1993 were not induced by naturally occurring environmental variables.

Comparative sub-lethal and lethal acute toxicity of copper to the freshwater crayfish, Cambarus robustus (Cambaridae, Decapoda, Crustacea) from an acidic metal-contaminated lake and a circumneutral uncontaminated stream

Comparative toxicological responses to Cu concentrations ranging from 0.61 to 24.06 mg 1 −1 by Cambarus robustus (Girard) intermoult adult males, trapped from Wavy Lake, an acid-stressed (pH 4.6) metal-contaminated freshwater reservoir near Sudbury, Ontario [Cu, Ni, Pb and Cd body burden in whole crayfish (mean x ± SD) 89.94 ± 30.69, 2.60 ± 2.07, 42.82 ± 8.08, 4.08 ± 0.60 μg g −1 dry wt] and Pike Creek, a circumneutral (pH 6.2) uncontaminated fast-flowing stream [Cu, Ni, Pb and Cd body burden in whole crayfish (mean x ± SD) 43.68 ± 24.98, 1.76 ± 1.42, 13.53 ± 8.52, 11.40 ± 0.91 μg g −1 dry wt, respectively] in northeastern Ontario, were quantified using replicate standard 96-h static acute toxicity tests. In EC 50 comparisons, crayfish from the contaminated Wavy Lake were significantly more tolerant to all Cu concentrations during 24-h exposures than were those from Pike Creek; no significant differences ( P > 0.05) in the response between the two populations were observed with increases in exposure periods beyond 24 h. In LC 50 comparisons, Pike Creek crayfish had a significantly lower mortality rate in 48-h exposure than did decapods from Wavy Lake; no significant differences ( P > 0.05) in the response between the two populations were observed with increases in exposure periods beyond 48 h. The two populations, on the whole, did not show significant differences in their EC 50-LC 50 values at various periods they were exposed to the toxicant. However, there were significant differences ( P < 0.05) in Cu concentrations that caused behavioural impairment and mortality in animals from the two sites. In general, individuals from the contaminated Wavy Lake were better suited to resist short-term (≤ 24 h) behavioural impairment than were crayfish from the uncontaminated Pike Creek, possibly because of the ability of the former to detoxify Cu at a comparatively quicker rate than the latter. However, once their behaviour was impaired, the crayfish from the contaminated lake were unable to withstand further Cu intake. The reason for the phenomenon may lie in the early saturation and subsequent failure of their copper regulatory mechanism because of comparatively high Cu body burdens associated with living in a metal-contaminated environment.

Epilithic extracellular-enzyme activity in a zinc-contaminated stream

Most dissolved organic material in natural waters exist as high-molecular-weight, polymeric compounds, representing a potential source of organic matter for catabolism and growth and of essential inorganic nutrients but they are not immediately available to microorganisms because only low-molecular-weight compounds can be conveyed into microbial cells. The problem is resolved by extracellular enzymatic hydrolysis of the polymers to oligomeric and monomeric molecules. The extracellular enzymes involved are produced by heterotrophic microorganisms and microalgae. They function in periplasmic spaces, and bound to cell walls or non-living surfaces, and free in the surrounding water. Substantial extracellular-enzyme activity is associated with epilithic biofilms in streams. Evidently, the breakdown of epilithic extracellular-enzyme function, in response to toxic pollution, would adversely affect the epilithic microbiota. In the present paper we report extracellular-enzyme activity on stones from a long-term zinc-contaminated stream in Northeast England, and contrast this with activity on stones from a neighboring uncontaminated stream. The area was mined for mineral ores in the nineteenth century and abandoned zinc-rich spoil heaps are a feature of the West Allen catchment. There is much reduced abundance and diversity of invertebrates in the West Allen, where zinc concentrations were up to ten times greater than in the Eastmore » Allen. Other chemical variables, including pH and conductivity, were similar in both streams; potentially-toxic heavy metals other than zinc (Cu, Cd, Pb, Ni, Co) were not detectable. 14 refs., 1 fig., 1 tab.« less

Impact of farm waste on freshwater invertebrate abundance and the feeding rate of Gammarus pulex L.

Farm slurry is an important contaminant of rural catchments in the U.K., causing both major pollution incidents and more subtle chronic effects. An ecological and ecotoxicological assessment of contaminated (Clarbeston Stream) and uncontaminated (Deepford Brook) river stations revealed significant differences in the abundance of invertebrate taxa and sublethal effects on the amphipod Gammarus pulex. Fewer Leuctridae, Rhyacophilidae, Limnephilidae, Limnius volckmari, Elmis aenaea, Potamopyrgus jenkinsi and G. pulex were found in the contaminated stream and the feeding rate of caged G. pulex was also reduced. There was no significant reduction in either macroinvertebrate abundance or G. pulex feeding rate below the confluence of the contaminated and uncontaminated streams.

Chloride loading in the South Fork of the Shenandoah River, Virginia, U.S.A.

Loading trends and sources of CI− in the South Fork of the Shenandoah River, Virginia were analyzed for the period 1929–1982. CI− has increased from approximately 2 mg/L (2,776 tons/yr) to over 10 mg/L (14,256 tons/yr). Natural CI− is estimated to be 1.01 mg/L (1,388 tons/yr) with precipitation providing 0.99 mg/L and rocks 0.02 mg/L. From 1929 to 1949 CI− concentrations were relatively constant and independent of discharge, conforming to the Type II curve of Davis and Zobrist (1978), indicative of natural or relatively uncontaminated streams. Since 1952 CI− concentrations increased exponentially as river discharge decreases conforming to the Type I curve of Davis and Zobrist for polluted streams. Since 1965 anthropogenic CI− loading at 12,868 tons/yr has remained relatively constant. Four major sources contribute 92.2 percent (11,871 tons/yr) of the anthropogenic CI−: (1) deicing salts—4,149 tons/yr, (2) domestic sewage—3,015 tons/yr, (3) livestock and poultry wastes—2,458 tons/yr, and (4) commercial fertilizers—2,249 tons/yr.

Bone Development in Creek Chub from a Stream Chronically Polluted with Heavy Metals

Creek chub Semotilus atromaculatus from Rocky Fork, a metal-contaminated stream in north-central Ohio, and Clear Fork, a nearby uncontaminated stream, were studied to determine the effects of chronic heavy metal contamination from industrial and municipal sources on bone development. We examined bone development offish from two contaminated sites in Rocky Fork and from four reference sites – three in Clear Fork and one in Rocky Fork – to evaluate variability among reference sites, and to determine if the clean-water headwater site on Rocky Fork was a suitable reference site for the two downstream contaminated sites. Collagen composition, density, strength, and energy-absorbing capacity of bone were significantly higher in fish from the headwater site on Clear Fork (upstream from an impoundment) than in fish at the other three reference sites. In bones of creek chub from sites in Rocky Fork where the water contained high total concentrations of chromium, copper, iron, nickel, and zinc, the collagen content of bone was lower but density and strength were higher than in bone of fish from the reference site, Some fish also had deformed vertebrae in the caudal peduncle region of the spinal column, which is a condition characteristic of neuromuscular overload of vertebrae, The high concentrations of chromium and zinc in fish from the contaminated sites probably interfered with collagen metabolism and altered the density and mechanical properties of bone, Creek chub at the contaminated sites seem to be tolerant of heavy metal contamination and may be adapting physiologically to the chronic metal stress in their environment.

Changes in water and sediment bacterial community structure in a lake receiving acid mine drainage

Water and sediment bacterial communities in a freshwater impoundment were studied over a 13-month period for stress-related responses to a point source of acid mine drainage (AMD). Comparisons of community structure were made on collections taken at the mouth of the acid stream, at a point 2 km downstream, and at the mouth of an uncontaminated stream. Monthly measurements of pH and specific conductance indicated the expected decrease in the AMD pollution with increasing distance from the source. Acridine orange direct counts did not differ significantly among the sites; however significantly fewer viable heterotrophs were observed by plate counts at the acid impacted station relative to the uncontaminated site. The diversity of the communities was significantly lower at the sites receiving mine drainage as compared with the unaffected station, and comparisons of community similarity showed that collections from the impacted sites were more like each other than like the control site. The assemblage at the latter site contained many bacterial guilds not found at the contaminated sites. The guilds unique to the control site showed a reduced in vitro ability to tolerate heavy metals as compared with the general community.

In situ persistence of indicator bacteria in streams polluted with acid mine drainage

Persistence of indicator organisms (total coliforms, fecal coliforms, and fecal streptococci) associated with natural samples of raw sewage was studied following in situ exposure to five aquatic environments. Three of these streams contained significant amounts of acid mine water (AMW) while the other two were relatively uncontaminated. Indicator organisms were rapidly killed upon exposure to the acid mine systems, whereas little reduction in numbers was observed in the uncontaminated streams. Seasonal changes affected survival of indicators as reflected by prolonged persistence at colder in situ water temperatures. The fecal coliform group was most susceptible to the AMW stress, while the fecal streptococci were most persistent. An enrichment technique resulted in substantially enhanced recovery of certain species of sublethally injured survivors of acid stress. Enrichment was particularly beneficial for recovery of AMW-injured fecal coliforms. Relatively little improvement in recovery of fecal streptococci was afforded by the enrichment technique.

Microbial Transformation of Polycyclic Aromatic Hydrocarbons in Pristine and Petroleum-Contaminated Sediments

To determine rates of microbial transformation of polycyclic aromatic hydrocarbons (PAH) in freshwater sediments, C-labeled PAH were incubated with samples from both pristine and petroleum-contaminated streams. Evolved CO(2) was trapped in KOH, unaltered PAH and polar metabolic intermediate fractions were quantitated after sediment extraction and column chromatography, and bound cellular C was measured in sediment residues. Large fractions of C were incorporated into microbial cellular material; therefore, measurement of rates of CO(2) evolution alone would seriously underestimate transformation rates of [C]naphthalene and [C]anthracene. PAH compound turnover times in petroleum-contaminated sediment increased from 7.1 h for naphthalene to 400 h for anthracene, 10,000 h for benz(a)anthracene, and more than 30,000 h for benz(a)pyrene. Turnover times in uncontaminated stream sediment were 10 to 400 times greater than in contaminated samples, while absolute rates of PAH transformation (micrograms of PAH per gram of sediment per hour) were 3,000 to 125,000 times greater in contaminated sediment. The data indicate that four- and five-ring PAH compounds, several of which are carcinogenic, may persist even in sediments that have received chronic PAH inputs and that support microbial populations capable of transforming two- and three-ring PAH compounds.