Foliar damage to ornamental trees sprinkler-irrigated with reuse water

The extent of foliar damage to ornamental trees irrigated with treated sewage effluent (reuse water) may be a significant factor dictating the extent of reuse water implementation on golf courses, schools and parks in the arid southwestern United States. An experiment was conducted on 20 tree species to determine the extent of foliar damage when sprinkler-irrigated with reuse water, municipal water or a synthesized saline water. Irrigations (168) were applied over a 16-month period via 183-cm raised sprinkler heads, to plots that contained the trees in a dual-pot system. Plant water status, growth, tissue ion concentrations and an index of visual damage (IVD) were assessed at different times throughout the experiment. A higher IVD (greater foliar damage) was reported for most species when sprinkler-irrigated with either reuse or synthesized saline water. However, six species showed significant foliar damage even when irrigated with municipal water. The accumulation of Cl in the tissue was shown to be a species-dependent response, with tissue Cl concentrations varying by as much as a factor of 5. When a backward stepwise multiple regression analysis was conducted on the normalized (reuse-municipal) IVD and tissue ion concentrations, all ions except Na were eliminated from the correlation (Index (reuse - municipal)=0.79+0.62Na (reuse - municipal), r=0.72***, n=20). Wax content on the leaves in the reuse (0.310 mg cm^-2) and saline treatments (0.546 mg cm^-2) and the increase in wax content with time (young leaves/May vs mature leaves/July) suggested a possible stress response. Based on the results of this experiment, we believe the number of woody ornamental trees that can tolerate spray irrigation of reuse water in the hot dry environment of southern Nevada to be limited.     

Effect of thyme essential oils (Thymus hyemalis and Thymus zygis) and monensin on in vitro ruminal degradation and volatile fatty acid production

The effect of the essential oils of thyme on the in vitro ruminal degradability of a barley seed/alfalfa hay substrate was studied. Two essential oils were used, one from Thymus hyemalis (TH), rich in carvacrol, and the other from Thymus zygis (TZ), rich in thymol. Four experimental treatments of in vitro degradability, using the Daisy II(200/220) incubator, were conducted including a negative control (CO), a positive control at 7.5 microg/mL of monensin (MO), and two treatments with essential oils (TH or TZ) at 1.35 microL/mL. The material was incubated at 39.5 degrees C for various lengths of time. At each time, the disappearance of dry matter, crude protein, and neutral detergent fiber was measured. Volatile fatty acids (VFAs) were determined after 48 h of incubation. CO and MO provided (p < 0.01) higher values of potential degradability (a + b) of DM than the TH and TZ treatments (72.6 and 70.8 vs 53.2 and 48.2%, respectively). Also, crude protein degradability was lowest in the essential oil treatments. The CO treatment showed the highest potential degradability of NDF. The values of VFA production obtained (p < 0.001) with CO and MO treatments were higher than those obtained with TH and TZ treatments (21.0 and 19.1 vs 11.2 and 10.1 mM). The essential oils decreased the molar proportion of propionate, increasing the acetate/propionate ratio. In conclusion, the effects of essential oils at assayed doses would not be nutritionally beneficial to the ruminal energetic metabolism.     

Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest. To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio calculations, we observed the formation of reduced and structurally distorted metal sites consistent with small polarons. Comparisons between different phases (hematite, maghemite, and ferrihydrite) revealed that short-range structural topology, not long-range order, dominates the electron-hopping rate.     

Within and between-field spatial variation in soil phosphorus in permanent grassland

Soil phosphorus (P) concentrations above certain critical thresholds are a problem in many areas leading to its transport into surface and ground waters. Site-specific nutrient applications and the development of nutrient management plans for farms would help to optimize nutrient applications, meet crop requirements and take into consideration current soil nutrient status. In Northern Ireland, high concentrations of soil P are common, whereas low concentrations of soil potassium (K) and sulphur (S) have been reported in many silage fields. This study used grid and transect soil sampling to measure within- and between-field spatial variation in soil Olsen-P status across a 50-ha permanent grassland site used for silage production. Soil phosphorus indices ranged from Index 1 to Index 4 within single fields. The spatial patterns of soil P across fields suggested that there was scope for site-specific P fertilizer applications, with variable quantities of P being applied to different fields and within individual fields. Site-specific nutrient management has the potential to reduce excess P applications in some areas and avoid deficiencies in others, thereby minimizing environmental problems and optimizing yield.     

Using patterns of reef fish assemblages to refine a Habitat Classification System for marine parks in NSW,Australia

• 1. The Solitary Islands Marine Park (SIMP) in New South Wales (NSW), Australia, is located in a tropical‐temperate biotone, with variable influence of the tropical East Australian Current (EAC) from inshore to offshore. Marine communities on the extensive, subtidal, rocky reefs are poorly described. As a result, the current Habitat Classification System (HCS) used as part of the process to determine the marine park zoning arrangements, which places all shallow reef (<25 m) in the same category, is unlikely to represent real biotic patterns.
• 2. To evaluate the influence of five key factors (distance from shore, reef type, dominant benthos, latitude, and depth range) fish assemblages were widely surveyed, using 30‐minute timed counts, at 68 sites across the extent of shallow reef within the park. Relationships between assemblage patterns and levels of the different factors were subsequently examined using multivariate analyses.
• 3. Patterns of reef fish assemblages were most strongly correlated with distance from shore. Three distinct assemblages occurred on inshore (<1.5 km), mid‐shelf (1.5–6 km), and offshore (>6 km) reefs. Differences in assemblage structure by reef type were also apparent on inshore and offshore reefs, but not on mid‐shelf reefs. Correlations with the other factors were weak. The cross‐shelf pattern was persistent over the scale of years.
• 4. The results of the study provide strong support for incorporating distance‐from‐shore categories into a refined HCS. This will improve its ability to represent biological diversity as reflected by patterns of reef fish assemblages. Further research is required to determine the wider application of the HCS to other marine parks in NSW and to determine if it also, effectively, represents other components of biodiversity. Copyright © 2009 John Wiley & Sons, Ltd.