IMPLICATIONS OF ON‐GROUND NITROGEN LOADING AND SOIL TRANSFORMATIONS ON GROUND WATER QUALITY MANAGEMENT1

ABSTRACT: This paper presents a modeling approach based on a geographic information system (GIS) to estimate the variability of on‐ground nitrogen loading and the corresponding nitrate leaching to ground water. The methodology integrates all point and nonpoint sources of nitrogen, the national land cover database, soil nitrogen transformations, and the uncertainty of key soil and land use‐related parameters to predict the nitrate mass leaching to ground water. The analysis considered 21 different land use classes with information derived from nitrogen sources such as fertilizer and dairy manure applications, dairy lagoons, septic systems, and dry and wet depositions. Simulations were performed at a temporal resolution of one month to capture seasonal trends. The model was applied to a large aquifer of 376 square miles in Washington State that serves more than 100,000 residents with drinking water. The results showed that dairy manure is the main source of nitrogen in the area followed by fertilizers. It was also seen that nitrate leaching is controlled by the recharge rate, and there can be a substantial buildup of soil nitrogen over long periods of time. Uncertainty analysis showed that denitrification rate is the most influential parameter on nitrate leaching. The results showed that combining management alternatives is a successful strategy, especially with the use of nitrification inhibitors. Also, change in the land use pattern has a noticeable impact on nitrate leaching.     

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.     

Influence of canola and sunflower diet amendments on cattle feedlot manure

Cattle (Bos taurus) producers can replace a part of the traditional diet of barley (Hordeum vulgare L.) grain/silage with sunflower (Helianthus annus L.) seeds or canola meal (Brassica napus L.)/oil to enhance conjugated linoleic acids (CLA) content in milk and meat for its positive health benefits. The objective of this study is to investigate the effects of feeding sunflower or canola to finishing steers on cattle manure chemical properties and volatile fatty acid (VFA) content. The control diet contained 84% rolled barley and 15% barley silage, which provided only 2.6% lipid. The other six treatments had 6.6 to 8.6% lipid delivered from sources such as hay, sunflower seed (SS), canola meal/oil, and SS forage pellets. Manure samples (a mixture of cattle urine, feces, and woodchip bedding materials) were collected and analyzed after cattle had been on these diets for 113 d. The dietary source and level of lipid had no effect on organic N and nitrate N content in manure, but significantly affected ammonia N and VFA. Inclusion of SS forage pellets, hay, or canola meal/oil in cattle diets had no significant impact on manure characteristics, but SS significantly reduced the pH and increased propionic, isobutyric, and isovaleric content. In addition, N loss after excretion (mainly from urine N) increases with the pH and N levels in both feed and manure. The combination of SS with barley silage resulted in a lower VFA and NH3 content in manure and should be a more attractive option. To better manage N nutrient cycles and reduce NH3 related odor problems, feed and manure pH should be one of the factors to consider when determining feed mix rations.     

Wastewater treatment with multilayer media of waste and natural indigenous materials

Wastewater treatment using waste materials (refuse concrete, waste paper and charcoal) and natural indigenous rocks (andesite, limestone, granite and nitrolite) in the form of multilayer media was investigated. The removal of suspended solids (SS), phosphate ion, nitrate ion, ammonium ion, toxic metals and chemical oxygen demand (COD) were evaluated for the multilayer wastewater treatment system. Effective removal of heavy metals such as cadmium, chromium, mercury and lead was demonstrated. SS and phosphate ion were removed with relatively high efficiency and the COD after treatment was lessened using certain combinations of media. The present wastewater treatment system is simple, convenient and low cost. Therefore, this method can be applied in small scale plants for wastewater treatment in local and nonexclusive areas.     

Long-term microphytoplankton variability patterns using multivariate analyses: ecological and management implications

Microphytoplankton data along the southern Tunisian coasts have been monitored weekly since 1995. This study used the data collected during the period 2000–2007 to determine the temporal variability patterns and to characterize the geographical structures of microphytoplankton populations. The methodological approach consisted in isolating the temporal variability common to all sampled sites and in analyzing the “residual” site-specific component. Multivariate ordination methods were used to determine the seasonal and interannual variability. The temporal pattern shared by all sites was highlighted and the seasonal cycle of the most frequent phytoplankton communities contrasted the diatoms winter-spring species to the dinoflagellates summer-fall species. Multitable comparison allowed the identification of three areas exhibiting similar phytoplankton population variability. The results, despite the coastal location of sampling sites, indicated that hydrodynamic and geomorphologic properties of the different areas as well as anthropogenic activities play a key role in the structure of the phytoplankton communities.     

The interactions of Cr (VI) concentrations and amendments (biochar and manure) on growth and metal accumulation of two species of Salicornia in contaminated soil

Environmental Science and Pollution Research - Heavy metals are among the most dangerous contaminants in the environment. Organic components and plant species that can accumulate and stabilize...     

Facile Preparation of Chitosan Films for High Performance Removal of Reactive Blue 19 Dye from Aqueous Solution

This study aimed at finding effective strategies for high-performance removal of reactive blue 19 (RB19) dye from aqueous solution. Chitosan (CS) films had been prepared by using solvent casting with mild drying for this purpose. The CS films were characterized by X-ray diffraction, field-emission scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. The performance of RB19 removal using CS were evaluated by varying contact time, solution pH, initial dye concentration, and adsorbent dosage. Adsorption isotherms, kinetics, and desorption were investigated by batch experiments. Results showed that CS films exhibited the optimal adsorption performance for RB19 removal and high maximum adsorption capacities of RB19, which were 799 and 822.4 mg g^?1 at 20 and 40 °C, respectively. Adsorption kinetic data were well described by the pseudo-second-order kinetic model. FTIR analyses further indicated that interactions between RB19 and the CS film occurred during adsorption. The CS films also exhibited satisfactory desorption of RB19 at about 80 % after 30 min of desorption at pH 11. Our study demonstrated that the CS films can be easily prepared and applied for effective removal of RB19 in treatment of wastewater.