Responses of microbial populations in the rhizosphere to deposition of simulated acidic rain onto foliage and/or soil

Air pollutants or some chemicals applied to plant foliage can alter the ecology of the rhizosphere. Experiments were conducted to distinguish among possible foliage-mediated versus soil- or root-mediated effects of acid deposition on microorganism in the rhizosphere. Seedlings of a sorghum x sudangrass hybrid in pots of non-sterile soil-sand mix in a greenhouse were exposed to simulated rain solution adjusted with H2SO4 + HNO3 to pH 4.9, 4.2, 3.5 or 2.8. Solutions were applied as simulated rain to foliage and soil, foliage only (soil covered by plastic, and deionized water applied directly to the soil), or soil only (solution applied directly to the soil). Solutions were applied on 16 days during a 6-week period (1.5 cm deposition in 1 h per application). Plant shoot and root dry weights and population densities of selected types of bacteria, filamentous actinomycetes and fungi in the rhizosphere were quantified after exposures were completed. Deposition of simulated acidic rain onto foliage alone had no effect on plant biomass or microbial population densities in the rhizosphere (colony-forming units per gram of rhizosphere soil). However, plant growth was stimulated and all microbial populations in the rhizosphere increased 3- to 8-fold with increased solution acidity (relative to pH 4.9 solution) when solution penetrated the soil. Statistical analyses indicated that the acid dose-population response relationships for soil-only and foliage-and-soil applications were not different. Thus, no foliage-mediated effect of simulated acidic rain on rhizosphere ecology was detected.     

Response of the Plastic Lake catchment, Ontario, to reduced sulphur deposition

As a consequence of decreases in the emission rate of sulphur in eastern North America in the late 1970s and early 1980s, sulphate deposition in central Ontario declined by about 40%, but has remained constant for about six years. Plastic Lake, a small, dilute lake on the Precambrian shield that the authors have studied since 1979, acidified between the start of the study and about 1986, but since then has not changed. The authors also monitored the chemistry of streamwater draining the Plastic Lake catchment. Water quality of runoff from an upland site improved rapidly (pH and alkalinity increased, SO4(2-) and Al decreased), but two factors offset these improvements. A small wetland area downstream reversed most of these changes, resulting in a constant output of strong acid from the catchment. In addition, in extremely dry years (1983, 1987, 1989) there were very high concentrations of SO4(2-) in the streamwater, suggesting substantial re-oxidation of reduced S in the catchment.     

Hunger, poverty and food aid in Sub-Saharan Africa: Retrospect and potential

Frustrations and failures will continue to mount if we do not immediately summon the courage to revise the ways we think and take action-as well as maintaining essential services to support life and health … Saving hundreds of thousands … who are at risk of dying from malnutrition or infection is an immediate imperative. But it must be only one stage in the progress toward other activities, and one element in the truly comprehensive approach… The main intent of this paper is to explore aspects of the nature and evolution of poverty in Sub-Saharan Africa with special reference to food and hunger and their interaction with macro-economic policy. An attempt is made to outline the overall context within which food aid needs to be used in order to have a greater developmental impact. Following an Introductory Section I, Section II provides a sketch map of how recession and lagging food production - with cyclical weather crises superimposed - affect the human condition of poor people. Section III reviews die interaction between "standard" IMF stabilization and World Bank structural adjustment strategies and poverty/hunger. Improvements in the design of stabilization and adjustment programmes, and of the inter-relationship with them of emergency programmes, can be identified. A number turn on the broadened and more innovative or catalytic use of food aid. Section IV reviews aspects of facing a continuing series of emergencies and of designing life support programmes to facilitate rehabilitation of the households directly affected as well as of the national economies. From this base it explores a series of elements in achieving renewed development. The concluding Section seeks to explore the strengths, limitations and potentials of food aid in the context set by the previous sections. The standard criticisms of food aid appear to be overstated and/or to relate to particular modalities or approaches rather than to anything intrinsic. A number of criteria for improving the effectiveness of food aid - especially in respect to rehabilitation, recovery and renewed development - are set out.     

Death and injury in earthquakes

The assumption that the ratio of mortality to morbidity will approximate 1:3 in earthquake disasters is investigated. When it occurs, a 1:3 ratio is most likely to coincide with a Richter magnitude in the range 6.5–7.4, but many other ratios of death to injuries may instead be probable. For each individual disaster the pattern of casualties is likely to be very heterogeneous, but it would be easier to discover regularities if a more standardized definition of 'injury' could be found.     

Evaluation and selection strategy for green supply chain using interval-valued q-rung orthopair fuzzy combinative distance-based assessment

Environment, Development and Sustainability - Environmental deterioration and global warming has created a substantial impact on international companies to incorporate eco-friendly, green supply...     

SWOT analysis of renewable energy sector in Mazowieckie Voivodeship (Poland): current progress,prospects and policy implications

Environment, Development and Sustainability - Renewable energy (RE) plays an increasingly important role in the economy of almost every country in the world. In order to examine the state of...     

Reproductive Success of Marginal Populations of Dactylorhiza maculata (L.) Soó (Orchidaceae)

Russian Journal of Ecology - Populations at the border of ranges are considered more vulnerable than those in the center. However, some recent reviews contradict this hypothesis. We have studied...     

The Arbuscules Formation Intensity Decreased in Mycorrhizal Alien Plants of Belarusian Polesia

Russian Journal of Ecology - Abstract—We tested a hypothesis about the different abilities of alien and native plants to form arbuscular mycorrhizae. The studies were carried out in the...