Benthic algal biomass and productivity in high subarctic streams,Alaska

Year-round measurements of the standing crop of epilithic algae (as chlorophyll a concentration) in two streams — one second and one fourth order (map scale 1:63 360) — in interior Alaska (64°–65° N) were only about one tenth that reported from streams of temperate North America. Cell densities in these streams, however, were similar to those in comparable temperate streams. Year-round domination of the benthic flora by very tiny diatoms (Achnanthes spp.) may explain the apparent disparity between low chlorophyll a content and nearly average cell densities. Chlorophyll a standing crop in a more alkaline groundwater-fed stream, however, was higher and within the range of similarly sized temperate streams. Maximum chlorophyll a standing crop varied positively with alkalinity in 5 clear-water streams where standing crop was measured on natural or artificial substrates. Seasonal mean concentrations of sestonic chlorophyll a (used as estimates of benthic algal chlorophyll a standing crop) varied directly and significantly with alkalinity among ten clear-water streams; and, with total phosphorus among 8 of 10 clear-water and 5 brown-water streams studied. During the summer, when there is little darkness, gross primary productivity (as estimated by the diurnal dissolved-oxygen method) was similar to that of northern temperate streams. Gross primary productivity was also seen to vary directly with alkalinity in 5 clear-water streams of this region.U.S. Fish and Wildlife Service     

Nutrient budgets in a dry heathland watershed in northeastern Spain

Dissolved nutrient inputs in bulk precipitation and outputs in streamwater were measured during 3 years of contrasting hydrological conditions in a 6.3-ha, grazed heathland watershed on schists in the Montseny mountains (NE Spain), drained by an intermittent stream. On average, 39% of the precipitation became streamflow. Bulk precipitation delivered positive net alkalinity (mean 0.22 keq/ha/yr), sulphate input was moderate (9.0 kg SO₄-S/ha/yr), and the mean input of inorganic N was not exceptionally high (6.6 kg/ha/yr). Ion concentrations were relatively low in streamwater; SO₄ ^2- was the dominant anion. Most concentrations in streamwater varied seasonally, with maxima in late summer or early autumn and minima in spring. This pattern probably resulted from increased availability of ions for leaching due to decomposition of organic matter and chemical weathering during the warm period. Nitrate concentrations were relatively high in winter and dropped sharply in early spring, probably because of biological uptake. Annual element outputs in streamwater varied between years and seemed to be controlled by both the amount of annual streamflow and its seasonal distribution. Annual inputs exceeded outputs for dissolved inorganic N. The watershed accumulated H⁺ and Ca²⁺, had net losses of Na⁺ and Mg²⁺, and was close to steady state for K⁺, SO₄ ^2-, Cl^- and alkalinity. The chloride budgets gave no evidence of substantial dry deposition in this system. The cationic denudation rate was negative (-0.14 keq/ha/yr) because Ca²⁺ retention was higher than net exports of Na⁺ and Mg²⁺ from silicate weathering. Low nutrient export and little production of alkalinity suggest that this watershed has a low buffering capacity.     

Incorporation of 35SO 4 2− into sediments of three New York lakes

Intact sediment cores were obtained from three New York lakes in May, July, and October 1981. Radioactive S (as ³⁵SO ₄ ²⁻ ) was added to the overlying water and cores were incubated without atmospheric exchange for one week near lake bottom temperatures. Headspace flux of 0₂ as an index of sediment respiration rates varied among lakes and seasonally within lakes. Acidic South Lake had the lowest respiration rate at all seasons and also the smallest net incorporation of the ³⁵SO ₄ ²⁻ . Summer net isotope transformation into ester sulfate and non-HI reducible S (pyrite and C-bonded S) constituents was 88.6%, 89.4%, and 59.7% of total sediment isotope for Oneida, Deer, and South, respectively. Seasonal variation of net isotope incorporation was observed in each lake as were differences in ³⁵SO ₄ ²⁻ partitioning into major S pools. Of the S constituents analyzed, HCl digestible S (volatile sulfides) was the smallest pool, while ester sulfate and non-HI reducible S together accounted for greater than 50% of S isotope transformation in all lakes. In addition, ester sulfate is the major product of dissolved SO ₄ ²⁻ transformation and its formation results in less alkalinity generation than the formation of non-HI reducible S constituents. Thus ester sulfate transformation processes must be considered in calculating alkalinity generation by lake sediments. Financial support provided by Office of Water Research Technology (Project No. 13-096-NY). Financial support provided by Office of Water Research Technology (Project No. 13-096-NY).     

Sulphate reduction in oxic and sub-oxic North-East Atlantic sediments

Abstract Oxic and sub-oxic N.-E. Atlantic sediments were examined for sulphate-reducing activity. Oxygen and/or nitrate reduction are probably the dominant mineralisation processes in the abyssal plain sediment studied. A low rate of sulphate reduction (0.1 nmol SO²⁻₄/ml/day) was recorded in the surface 5 cm of the continental slope sediment, together with the presence of a range of sulphate-reducing bacteria (SRB). A higher activity of sulphate reduction (2.2 nmol SO²⁻₄/ml/day) occurred in the continental shelf sediment which led to a small decrease in pore water sulphate and an increase in titration alkalinity. This sediment contained approx. 10²–10³ acetate, lactate and propionate oxidising SRB/ml. No low- M _r organic acids were detected in these sediments. However, amendment with 75 μM acetate stimulated sulphate-reducing activity in the shelf sediment.     

The anaerobic filtration of dairy waste: Results of a pilot trial

Results are presented from a pilot scale (4·3 m³) upflow anaerobic filter for the treatment of the wastewater from ice-cream manufacture. The reactor was completely mixed by gas production but the solids or sludge held within the reactor were shown to be affected by the liquid velocities. The reactor was subject to a number of organic and hydraulic shocks and this reduced the consistency of COD removal. Daily loading rates varied from 0 to 18 kg COD/m³/day but with an average load of 5·5 kg/m³/day the mean COD removal was 70%. This was compared with previous work and shown to be a typical performance for an anaerobic filter. Alkalinity and carboxylic acid data are also presented and were within the normal, stable, operating range. Previous research on the anaerobic treatment of industrial effluents has shown alkalinity to be the most important factor controlling reliability.     

Increase of atmospheric CO2 promotes phytoplankton productivity

It is usually thought that unlike terrestrial plants, phytoplankton will not show a significant response to an increase of atmospheric CO₂. Here we suggest that this view may be biased by a neglect of the effects of carbon (C) assimilation on the pH and the dissociation of the C species. We show that under eutrophic conditions, productivity may double as a result of doubling of the atmospheric CO₂ concentration. Although in practice productivity increase will usually be less, we still predict a productivity increase of up to 40% in marine species with a low affinity for bicarbonate. In eutrophic freshwater systems doubling of atmospheric CO₂ may result in an increase of the productivity of more than 50%. Freshwaters with low alkalinity appeared to be very sensitive to atmospheric CO₂ elevation. Our results suggest that the aquatic C sink may increase more than expected, and that nuisance phytoplankton blooms may be aggravated at elevated atmospheric CO₂ concentrations.     

Spatial and temporal patterns of temperature,alkalinity, dissolved oxygen and conductivity in an oligo-mesotrophic,deep-storage reservoir in central Texas

Impoundment behavior was determined for alkalinity, temperature, dissolved oxygen, and conductivity from stations located along the length of a bottom-draining, oligo-mesotrophic, hardwater, deep-storage reservoir located in central Texas. The epilimnion deepened the length of the reservoir throughout the summer as a result of drawdown. Bicarbonate alkalinity and conductivity exhibited both longitudinal and vertical stratification. Alkalinity and conductivity in the epilimnion decreased from the riverine reach downreservoir to the dam. This longitudinal progression was attributed to inflow and photosynthetically induced epilimnetic decalcification.Hypolimnetic anoxic conditions first occurred in the sedimentation zone in the upreservoir and riverine reaches and then developed in a downreservoir pattern as summer progressed as a result of drawdown. Alkalinity and conductivity in the hypolimnion increased during anoxic conditions and consequently increased in a downreservoir progression.     

耐盐碱促生菌的筛选及性能

盐分是影响作物生长最重要的因素,使用能促进植物生长的耐盐碱促生菌减轻盐胁迫引起的损害是一种农业上的有效方法。文中从盐碱地筛选得到7株耐盐细菌,并考察筛选菌株的产胞外聚合物(EPS)能力、降碱能力和产吲哚-3-乙酸(IAA)能力。经综合评价选出1株优势菌株DB01,菌株DB01产EPS能力为0.21 g/g,降碱能力为8.7%,产IAA的能力为8.97 mg/L。菌株经16S rRNA鉴定为海水盐单胞菌Halomonas aquamarina,并且有抑制香蕉枯萎病、番茄早疫病、大豆疫霉病、小麦纹枯病病原菌的能力,同时能够在盐胁迫下促进小麦幼苗的发芽率和根长。海水盐单胞菌Halomonas aquamarina DB01可为土壤微生物资源开发利用和盐碱地改良提供理论依据。     

THE USE OF SMALL FARM DAMS IN THE TRANSKEI AND CISKEI FOR THE PRODUCTION OF TABLE-FISH USING AISCHGRUND CARP

SUMMARY

Small stockwatering dams are usually ignored in the Transkei and Ciskei in fishfarming ventures. This paper reports on experimental results in fish production studies, using Aischgrund carp, which were obtained in the Ciskei and which indicate that economically worthwhile fish production can be achieved in such dams.