Long-Term Effectiveness of Restoration Treatments on Closed Wilderness Campsites

This study assessed long-term recovery of vegetation on six wilderness campsites in subalpine forests in Oregon that were closed to use and that received common restoration treatments (scarification, soil amendments, mulch, transplanting, and seeding). Vegetation cover was assessed every year for the first 7 years following treatment, as well as 10 and 15 years after treatment. This made it possible to compare long-term treatment effectiveness to short-term efficacy. Plots that were closed and not scarified had virtually no vegetation cover even after 15 years without use. If long-used campsites in these subalpine forests are simply closed and allowed to recover on their own, restoration of undisturbed conditions will require hundreds if not thousands of years. Study results show, however, that simple treatments can accelerate recovery rates substantially. Scarification and transplanting were highly effective treatments, with seeding and soil amendment with organic matter and compost also contributing to success, but to a lesser degree. The use of a mulch mat, in contrast, had no effect, either positive or negative. Assessments of success conducted within the first few years of treatment overestimate treatment efficacy, particularly the effectiveness of soil amendments and seeding.     

Artificial Groundwater Recharge Zones Mapping Using Remote Sensing and GIS: A Case Study in Indian Punjab

Artificial groundwater recharge plays a vital role in sustainable management of groundwater resources. The present study was carried out to identify the artificial groundwater recharge zones in Bist Doab basin of Indian Punjab using remote sensing and geographical information system (GIS) for augmenting groundwater resources. The study area has been facing severe water scarcity due to intensive agriculture for the past few years. The thematic layers considered in the present study are: geomorphology (2004), geology (2004), land use/land cover (2008), drainage density, slope, soil texture (2000), aquifer transmissivity, and specific yield. Different themes and related features were assigned proper weights based on their relative contribution to groundwater recharge. Normalized weights were computed using the Saaty’s analytic hierarchy process. Thematic layers were integrated in ArcGIS for delineation of artificial groundwater recharge zones. The recharge map thus obtained was divided into four zones (poor, moderate, good, and very good) based on their influence to groundwater recharge. Results indicate that 15, 18, 37, and 30 % of the study area falls under “poor,” “moderate,” “good,” and “very good” groundwater recharge zones, respectively. The highest recharge potential area is located towards western and parts of middle region because of high infiltration rates caused due to the distribution of flood plains, alluvial plain, and agricultural land. The least effective recharge potential is in the eastern and middle parts of the study area due to low infiltration rate. The results of the study can be used to formulate an efficient groundwater management plan for sustainable utilization of limited groundwater resources.     

Neurophysiological Effects Induced in the Nervous Tissue by Low-Frequency, Pulsed Magnetic Fields

Summary The influence of pulsed magnetic fields (PMF) on the properties of nervous tissue was investigated. Hippocampal slices or synaptosomes obtained from hippocampal tissue were used as model systems. The amplitude of potentials recorded in vitro from one of the hippocampal pathways (Schaffer collaterals that use glutamate as a neurotransmitter) was employed as a measure of the influence of magnetic fields on synaptic efficiency. The synaptic glutamate turnover and radioactive calcium accumulation were used as markers of the PMF influence on biochemistry of synaptic mechanisms. The exposure of hippocampal slices for 30 min to PMF amplified evoked potentials. While the frequency of 0.16 Hz exerted the strongest effect, lower (0.01, 0.07, 0.03 Hz) and higher (0.5 Hz) frequencies were much less effective. The enhancement of the neuronal excitability was correlated with significant increase in the neuronal spontaneous activity mediated by electrical synapses. The PMF-induced changes in the excitability of the tissue were accompanied by an increase in the synaptic turnover of glutamate. The release of radioactive D-Aspartate (a glutamate analog used as a marker for glutamate turnover) from the slices, and its uptake by synaptosomes were enhanced, and reduced respectively, following the stimulation with pulsed magnetic fields. The frequency which was the most efficient in amplification of evoked potentials (0.16 Hz) was also the most effective in the modulation of the release and uptake processes. The PMF-induced changes in neurotransmitter turnover coincided with an increase in ⁴⁵Ca²⁺ accumulation observed in hippocampal slices exposed to PMF.     

Cattle feedlot soil moisture and manure content: II. Impact on Escherichia coli O157

The moisture and manure contents of soils at cattle feedlot surfaces vary spatiotemporally and likely are important factors in the persistence of Escherichia coli O157 in these soils. The impacts of water content (0.11-1.50 g H2O g(-1) dry feedlot surface material [FSM]) and manure level (5, 25, and 75% dry manure in dry FSM) on E. coli O157:H7 in feedlot soils were evaluated. Generally, E. coli O157:H7 numbers either persisted or increased at all but the lowest moisture levels examined. Manure content modulated the effect of water on E. coli growth; for example, at water content of 0.43 g H2O g(-1) dry FSM and 25% manure, E. coli O157:H7 increased by 2 log10 colony forming units (CFU) g(-1) dry FSM in 3 d, while at 0.43 g H2O g(-1) dry FSM and 75% manure, populations remained stable over 14 d. Escherichia coli and coliform populations responded similarly. In a second study, the impacts of cycling moisture levels and different drying rates on naturally occurring E. coli O157 in feedlot soils were examined. Low initial levels of E. coli O157 were reduced to below enumerable levels by 21 d, but indigenous E. coli populations persisted at >2.50 log10 CFU g(-1) dry FSM up to 133 d. We conclude that E. coli O157 can persist and may even grow in feedlot soils, over a wide range of water and manure contents. Further investigations are needed to determine if these variables can be manipulated to reduce this pathogen in cattle and the feedlot environment.     

ACCURACY OF LAKE AND STREAM TEMPERATURES ESTIMATED FROM THERMAL INFRARED IMAGES1

Emitted thermal infrared radiation (TIR, λ= 8 to 14 μm) can be used to measure surface water temperatures (top approximately 100 μm). This study evaluates the accuracy of stream (50 to 500 m wide) and lake (300 to 5,000 m wide) radiant temperatures (15 to 22°C) derived from airborne (MASTER, 5 to 15 m) and satellite (ASTER 90 m, Landsat ETM+ 60 m) TIR images. Applied atmospheric compensations changed water temperatures by ?0.2 to +2.0°C. Atmospheric compensation depended primarily on atmospheric water vapor and temperature, sensor viewing geometry, and water temperature. Agreement between multiple TIR bands (MASTER ‐ 10 bands, ASTER ‐ 5 bands) provided an independent check on recovered temperatures. Compensations improved agreement between image and in situ surface temperatures (from 2.0 to 1.1°C average deviation); however, compensations did not improve agreement between river image temperatures and loggers installed at the stream bed (from 0.6 to 1.6°C average deviation). Analysis of field temperatures suggests that vertical thermal stratification may have caused a systematic difference between instream gage temperatures and corrected image temperatures. As a result, agreement between image temperatures and instream temperatures did not imply that accurate TIR temperatures were recovered. Based on these analyses, practical accuracies for corrected TIR lake and stream surface temperatures are around 1°C.     

Cumulative silvicultural impacts on watersheds: A hydrologic and regulatory dilemma

Because of the nature of watersheds, the hydrologic and erosional impacts of logging and related road-building activities may move offsite, affecting areas downslope and downstream from the operation. The degree to which this occurs depends on the interaction of many variables, including soils, bedrock geology, vegetation, the timing and size of storm events, logging technology, and operator performance. In parts of northwestern California, these variables combine to produce significant water quality degradation, with resulting damage to anadromous fish habitat.Examination of recent aerial photographs, combined with a review of public records, shows that many timber harvest operations were concentrated in a single 83 km² watershed in the lower Klamath River Basin within the past decade. The resulting soil disturbance in this case seems likely to result in cumulative off-site water quality degradation in the lower portion of the Basin.In California, both state and federal laws require consideration of possible cumulative effects of multiple timber harvest operations. In spite of recent reforms that have given the state a larger role in regulating forest practices on private land, each timber harvest plan is still evaluated in isolation from other plans in the same watershed. A process of collaborative state-private watershed planning with increased input of geologic information offers the best long-term approach to the problem of assessing cumulative effects of multiple timber harvest operations. Such a reform could ultimately emerge from the ongoing water quality planning process under Section 208 of the amended Federal Water Pollution Control Act.     

DISTRIBUTED DISCHARGE OF COOLING WATER ALONG DIRECTION OF STREAM FLOW1

ABSTRACT. A multiple-outfall system for cooling water disposal which is distributed along the direction of stream flow is analyzed. The results provide a simple method of preliminary design of a cooling water discharge outfall system and for a quick extimate of water quality of a polluted stream. It is shown that a properly designed distributed discharge system is capable of preventing serious pollution due to localized discharge of wastes and waste heat; however, the final design of the discharge system should take into account alternative schemes of waste heat disposal and their economic consequences.     

High-affinity ouabain receptors: primary membrane sensors for ionizing radiation

Although the high sensitivity of the Na/K pump in cell membrane to ionizing radiation is well known in literature, the individual role of different isoforms of pump in determination of its radio-sensitivity is not clear yet. This is the subject of the present investigation. Using isotope, electro-physiological and enzymological methods, the effect of γ-ionizing radiation on cell membrane voltage-current characteristics, acetylcholine-induced membrane current, ²²Na⁺ and ⁴⁵Ca²⁺ exchange between cells and bathing solution, Na+K⁺-ATPase activity, dose-dependent ouabain binding with cell membrane, intracellular cAMP and membrane phosphorylation in snail neurons were studied. The changes in neurons as a result of 30-min γ-radiation exposure of snails to 5.16 Ci/kg at the end of the first 30 min of post-radiation period were as follows: the increase in membrane ionic conductance reversed the ouabain sensitivity of acetylcholine-induced currents, stimulation of ²²Na⁺ and ⁴⁵Ca²⁺ uptakes, inhibition of Na/K pump, activation Na/Ca exchange in reversed mode, increase in ouabain binding with high-affinity α₃ and decrease with α₂ middle-affinity receptors, decrease in intracellular cAMP content and membrane dephosphorylation. On the basis of the obtained data, it is suggested that both α₃ and α₂ catalytic subunits of Na⁺+K⁺-ATPase serve primary membrane sensors through the activation of which the biological effect of γ-radiation on neurons is realized. The IR has activation effects on α₃-dependent Na⁺/Ca²⁺ exchange in forward and its inactivation on α₂-dependent reverse modes.