Timing of phosphorus fertilizer application within an irrigation cycle for perennial pasture

Irrigated pastures are significant contributors of phosphorus (P) to inland watercourses, with much of the P coming from applied fertilizer. It was hypothesized that the timing of P fertilizer application relative to irrigation regulates P concentrations in runoff and infiltrating water. To test this hypothesis, a two-by-two factorial experiment was conducted on twelve 8- x 30-m border-irrigated bays growing perennial pasture. Phosphorus fertilizer in the form of single superphosphate (44 kg P ha(-1)) was surface-broadcast onto the bays when the nominal change in soil water deficit reached 0 or 50 mm (U.S. Class A pan evaporation minus rainfall). Following fertilizer application, the bays were again irrigated when the nominal soil water deficit between fertilizing and the subsequent irrigation reached either 0 or 50 mm. The volume of water applied, runoff volume, and changes in soil water content were recorded for the three irrigations following fertilizer application. Total phosphorus (TP) and filtrable reactive phosphorus (FRP, <0.45 microm) concentrations in runoff and at depths of 0.1, 0.3, and 0.6 m in the soil were also measured. Soil water content at fertilizer application had less effect on P concentrations in runoff and soil water than the additional time between fertilizing and irrigating. By allowing a deficit of 50 mm between fertilizer application and irrigation, the average concentration of P in runoff and moving below a soil depth of 0.1 m was approximately halved. To maximize fertilizer use efficiency and minimize environmental effects, a delay should occur between applying P fertilizer and irrigating perennial pasture.     

Cadmium availability from granulated and bulk-blended phosphate-potassium fertilizers

Recent field experiments have shown that high chloride (Cl) in irrigation waters can increase soil cadmium (Cd) uptake by crops because of the formation of soluble ion-pair complexes of Cd with Cl in soil solution. The present study was aimed at testing a hypothesis that KCl in granulated PK fertilizers may enhance Cd uptake by crops from Cd-containing P fertilizers because of close contact between Cd and Cl in the same granules. Less effect would be expected if the same granular PK fertilizers were bulk-blended because of separation of Cd and Cl in different granules. A single superphosphate (SSP) containing 32 mg Cd kg(-1) was granulated by the compaction process with KCl at a P to K ratio = 1:1. Granular KCl was also bulk-blended with granular SSP or Cd-free monocalcium phosphate (MCP) at the same P to K ratio. An acid Ultisol (pH 5.2) was treated with PK fertilizers at 400 mg kg(-1) each for P and K. Upland rice (Oryza sativa L.) and soybean [Glycine max (L.) Merr.] were grown to maturity, and signalgrass (Brachiaria decumbens Stapf.) was cut four times during the study. The results showed that the agronomic effectiveness in increasing crop yield was the same with SSP and MCP whether granulated or bulk-blended with KCl. Concentrations of Cd in plant tissue samples of all crops were much lower for MCP than for SSP. In all the plant tissue samples, except grain samples of upland rice, Cd concentrations obtained with granulated (SSP + KCl) were significantly higher than that with bulk-blended (SSP) + (KCl).     

Day-of-week patterns in toxic air contaminants in southern California

Day-of-week mean ambient concentrations were computed for six high-cancer-risk toxic air contaminants (TACs): 1,3-butadiene, benzene, acetaldehyde, formaldehyde, carbon tetrachloride (CCl4), and perchloroethylene. Data from six urban sites in southern California, from 1989 through 2001, were analyzed. Graphical displays were used to search for repeated patterns. Benzene and 1,3-butadiene, emitted mainly by mobile sources, exhibit distinctly lower concentrations on Sundays and slightly lower concentrations on Saturdays and Wednesdays. Acetaldehyde and formaldehyde show some trace of a weekly pattern similar to that of benzene and 1,3-butadiene, but the pattern is not strongly marked. Perchloroethylene, used primarily as a dry-cleaning solvent, is also distinctly lower on Sundays. CCl4 does not show a day-of-week pattern.     

(S)-2-Methyl-1-hexanol,characteristic mandibular gland substance of ants of theCataglyphis bicolor group

Summary In all the species of theCataglyphis bicolor group examined yet, i.e.C. bicolor, C. diehli, C. isis, C. nodus, andC. viaticus, 2-methyl-1-hexanol is the characteristic substance and almost the only substance found in the mandibular glands. Its chirality has been determined inC. bicolor and shown to be exclusively (S)-2-methyl-1-hexanol.     

The greater snow goose <Emphasis Type="Italic">Anser caerulescens atlanticus</Emphasis>: Managing an overabundant population

Between the early 1900s and the 1990s, the greater snow goose Anser caerulescens atlanticus population grew from 3000 individuals to more than 700 000. Because of concerns about Arctic degradation of natural habitats through overgrazing, a working group recommended the stabilization of the population. Declared overabundant in 1998, special management actions were then implemented in Canada and the United States. Meanwhile, a cost–benefit socioeconomic analysis was performed to set a target population size. Discussions aiming towards attaining a common vision were undertaken with stakeholders at multiple levels. The implemented measures have had varying success; but population size has been generally stable since 1999. To be effective and meet social acceptance, management actions must have a scientific basis, result from a consensus among stakeholders, and include an efficient monitoring programme. In this paper, historical changes in population size and management decisions along with past and current challenges encountered are discussed.     

Solid waste recycling within higher education in developing countries: a case study of the University of Lagos

To create a truly circular economy requires a shift from the traditional view of waste disposal to one of resource management. This is particularly important in developing countries, where municipal waste generation is increasing, and efficient recovery of economic value from waste is rarely achieved. Conducted in the University of Lagos (UoL), Nigeria, this study investigated the efficiency of a recycling scheme with the goal of making recommendations to improve the process. UoL’s recycling policy centers around source segregation of waste into color-coded bins. Waste audit was carried out using the output method and interviews were conducted with staff from the waste management team to understand practices on campus. Substantial contamination of colored bins with non-target material was observed. Organics (30%), mixed plastics (28%) and paper (24%) were the most abundant materials, hence have the greatest potential for recovery, and income generation, if segregation rates could be improved. Despite its recycling policy and infrastructure, 99% of UoL waste was going to landfill. Poor policy implementation results in low recovery rates. Targeted waste reduction and increased material recovery would enhance efficiency. Improved awareness of recycling benefits, in addition to policy enforcement, could serve as tools to increase stakeholder participation in recycling.

     

Contamination from historic metal mines and the need for non-invasive remediation techniques: a case study from Southwest England

The UK is legally required by the EU Water Framework Directive (WFD) to improve the environmental quality of inland and coastal waters in the coming years. Historic metal mine sites are recognised as an important source of some of the elements on the WFD priority chemicals list. Despite their contamination potential, such sites are valued for their heritage and for other cultural and scientific reasons. Remediating historic mining areas to control the contamination of stream waters, whilst also preserving the integrity of the mine site, is a challenge but might be achieved by novel forms of remediation. In this study, we have carried out environmental monitoring at a historic, and culturally-sensitive, lead-silver mine site in southwest England and have undertaken a pilot experiment to investigate the potential for a novel, non-invasive remediation method at the site. Concentrations of Pb and Zn in mine spoil were clearly elevated with geometric mean concentrations of 6,888 and 710 microg g(-1), respectively. Mean concentrations of Pb in stream waters were between 21 and 54 microg l(-1), in exceedance of the WFD environmental quality standard (EQS) of 7.2 microg l(-1) (annual average). Mean Zn concentrations in water were between 30 and 97 microg l(-1), compared to the UK EQS of 66.5 microg l(-1) (average). Stream sediments within, and downstream from, the mining site were similarly elevated, indicating transport of mine waste particles into and within the stream. We undertook a simple trial to investigate the potential of hydroxyapatite, in the form of bonemeal, to passively remove the Pb and Zn, from the stream waters. After percolating through bonemeal in a leaching column, 96-99% of the dissolved Pb and Zn in stream water samples was removed.     

Completely autotrophic nitrogen-removal over nitrite in lab-scale constructed wetlands: evidence from a mass balance study

A mass-balance study was carried out to investigate the transformation of nitrogenous pollutants in vertical flow wetlands. Landfill leachate containing low BOD, but a high concentration of ammonia, was treated in four wetland columns under predominately aerobic conditions. Influent total nitrogen in the leachate consisted mainly of ammonia with less than 1% nitrate and nitrite, and negligible organic nitrogen. There was a substantial loss of total nitrogen (52%) in one column, whereas other columns exhibited zero to minor losses (<12%). Net nitrogen loss under study conditions was unexpected. Correlations between pH, nitrite and nitrate concentrations indicated the removal of nitrogen under study conditions did not follow the conventional, simplistic, chemistry of autotrophic nitrification. Through mass-balance analysis, it was found that CANON (Completely Autotrophic Nitrogen-removal Over Nitrite) was responsible for the transformation of nitrogen into gaseous form, thereby causing the loss of nitrogen mass. The results show that CANON can be native to aerobic engineered wetland systems treating wastewater that contains high ammonia and low BOD.