Vertical wind shear and concentration gradients of viable, airborne bacteria were used to calculate the upward flux of viable cells above bare soil and canopies of several crops. Concentrations at soil or canopy height varied from 46 colony-forming units per m over young corn and wet soil to 663 colony-forming units per m over dry soil and 6,500 colony-forming units per m over a closed wheat ca...

The diurnal variations in soil-gas helium concentration have been monitored at depths of 0.5-2.0 m in three localities in Colorado, Wyoming, and C•lifornia.'Bar•metric p e•su TM, air temperature, wind speed, soil temperature and moisture, relative humidity, and precipitation were also measured. The helium variation below a 1-m sampling depth usually did not exceed the analytical sensitivity of ...

This study was initiated to explore the effects of ozone (O3) exposure on potted wheat roots and soil microbial community function. Three treatments were performed: (1) Air with daily averaged O3 concentration of 4–10 ppb (control situation, CK), (2) Air plus 8 h averaged O3 concentration of 76.1 ppb (O3-1), and (3) Air plus 8 h averaged O3 concentration of 118.8 ppb (O3-2). In treatments with ...

Snow cover is projected to decline during the next century in many ecosystems that currently experience a seasonal snowpack. Because snow insulates soils from frigid winter air temperatures, soils are expected to become colder and experience more winter soil freeze-thaw cycles as snow cover continues to decline. Tree roots are adversely affected by snowpack reduction, but whether loss of snow w...

Plants are the most common bioindicatorsused in air quality biomonitoring studies because they are immobile and they have more sensitive to the most prevalent air pollutants than humans and animals. To identify the concentrations and sources of heavy metals in ornamental plants of Isfahan landscape, samples of leaves and soil around Pinuseldarica and Nerium oleander were collected at different ...

abstract microbial contaminants transport to groundwater is a serious environmental problem that can result in large outbreaks of waterborne diseases. some of bacteria can travel from vadose zone and cause contamination of groundwater resources. thus, an accurate prediction of transport and fate of pathogenic microorganisms in unsaturated soil is needed to protect groundwater resources. the mai...

This study investigates the runoff-sediment relationship (RSR) of the Weihe River, a sandy waterway originating from the Loess Plateau, and considers the potential variations in RSR under an evolving environment. The double mass curve method was used to investigate RSR inflection points at six hydrologic stations located in the Weihe River basin (WRB) spanning the period from 1956 to 2010. Beca...

this experiment was conducted to study the effect of nozzle types and the time of herbicide incorporation in soil on weed control, using split plot design by randomized block design. the main plots were soil and herbicide mixing time and the subplots were nozzle types with three replications. this study was performed in karaj station of seed and plant improvement institute, located 25 km west o...

The ecological impacts of wildland fire-suppression activities can be significant and may surpass the impacts of the fire itself. A recent paradigm shift from fire control to fire management has resulted in increased attention to minimizing the negative effects of suppression. While the philosophy behind minimumimpact suppression tactics has provided a good first step in this direction, increas...