Analysis of target and nontarget pollutants in aqueous leachates from the hazardous waste site Stringfellow, California, via ion chromatography - particle beam and inductively coupled plasma mass spectrometry

Liquid chromatography particle beam mass spectrometry (PB/MS is a powerful tool for the analysis of target pollutants but complementary methods are required for nontarget compounds. Preliminary data are presented on an anion exchange chromatography PB/MS based method for the detection of the target compound 4-chlorobenzene sulfonic acid (a contamlnant found in hazardous waste leachates) and also for nontarget pollutants in aqueous leachate samples from the Stringfellow hazardous waste site in California. Anion exchange chromatography coupled to inductively coupled plasma mass spectrometry yields qualitative and quantltative elemental analysis showing the presence or absence of key heteroatoms in organic pollutants including chlorine, other halogens, phosphorus and sulfur.     

Evaluation of the Design Features of Interactive Sea-Level Rise Viewers for Risk Communication

Interactive sea-level rise viewers (ISLRVs) are digital tools used to communicate about impacts of sea-level rise (SLR) and support decision-making. This study characterizes how ISLRVs communicate about SLR-related risks and provide decision-making support. It identifies key themes about fostering accurate mental models of SLR processes, informing about inundation likelihood, communicating about related social and ecological risks, and providing features users can apply to specific tasks. We present a framework for understanding this type of communication tool that designers can use to develop robust ISLRVs that can support audiences’ understanding and decision-making needs, and contribute to enhancement of coastal resiliency.     

Rate Constant Ratios During Nitrogen Dioxide Photolysis

Nitrogen dioxide is the light absorber in the hydrocarbon system leading to production of photochemical air pollution. Studies of the reactions involved are based on the kinetics of nitrogen dioxide photolysis and the values of the rate constants derived therefrom. The photolysis of nitrogen dioxide was investigated in the 2-20 ppm concentration range. The value of the bimolecular rate constant of the reaction between oxygen atoms and nitrogen dioxide was calculated to be 5.26 × 10⁹1 mole^–1 sec^–1, and thetermolecular rate constant of the reaction between oxygen atoms and nitrogen dioxide in presence of a third body is 4.24 × 10^–10 1²mole^–2 sec^–1. The rate constant for the reaction between oxygen atoms and nitric oxide in the presence of a third body was calculated to be 2.31 × 10¹⁰ 1²mole^–2 sec^–1. Nitrogen was used as the third body. In terms of order of magnitude these calculated rate constants are similar to previously reported values. However, in certain cases their use leads to an oxygen atom concentration which is 100% greater than previously calculated.     

Changes in the leachability of metals from dredged canal sediments during drying and oxidation

The behaviour of metals in canal sediments after their disposal to land has important implications for the environmental management of canal dredgings. The leaching behaviour of trace metals was investigated in a laboratory-based experiment using sediment from a canal in the UK (139 mg Zn kg-1dry sediment, 1.1 mg Cd, kg-1dry sediment 31.5 mg Cr kg-1dry sediment, 20.6 mg Cu kg-1dry sediment 48.4 mg Ni kg-1dry sediment, 43.4 mg Pb kg-1dry sediment and 7.6 mg As kg-1dry sediment). The sediment was allowed to dry. Cores (10 cm long) of the drying canal sediment were taken over a period of 12 weeks. A simple water extraction procedure was used to investigate changes in metal leachability at varying depths through the cores. Metal leachability increased over the first five weeks of drying and then subsequently decreased between weeks five and twelve, (e.g. Cd increased from approximately 0.006 to 0.018 mg/kgsediment then decreased to approximately 0.006 mg/kgsediment, Zn increased from approximately 1.5 to 3 mg/kgsediment and then decreased to approximately 1.5 mg/kgsediment). These results were combined with sulphide/sulphate ratios, which showed a decrease as the sediment dried (e.g. at 2-4 cm depth from approximately 1 to 0.49), and BCR sequential extraction data. Most metals (except Cd and As) showed a redistribution from the residual phase into more mobile phases as the sediment dried and oxidised. Metal leachability was strongly correlated with the sulphide/sulphate ratio with leachability normally increasing with decreasing sulphide/sulphate ratio. The combined results were used to infer the likely behaviour of dredged material upon disposal to land.     

Water supply,waste assimilation,and low-flow issues facing the Southeast Piedmont Interstate-85 urban archipelago

Rapidly growing cities along the Interstate-85 corridor from Atlanta, GA, to Raleigh, NC, rely on small rivers for water supply and waste assimilation. These rivers share commonalities including water supply stress during droughts, seasonally low flows for wastewater dilution, increasing drought and precipitation extremes, downstream eutrophication issues, and high regional aquatic diversity. Further challenges include rapid growth; sprawl that exacerbates water quality and infrastructure issues; water infrastructure that spans numerous counties and municipalities; and large numbers of septic systems. Holistic multi-jurisdiction cooperative water resource planning along with policy and infrastructure modifications is necessary to adapt to population growth and climate. We propose six actions to improve water infrastructure resilience: increase water-use efficiency by municipal, industrial, agricultural, and thermoelectric power sectors; adopt indirect potable reuse or closed loop systems; allow for water sharing during droughts but regulate inter-basin transfers to protect aquatic ecosystems; increase nutrient recovery and reduce discharges of carbon and nutrients in effluents; employ green infrastructure and better stormwater management to reduce nonpoint pollutant loadings and mitigate urban heat island effects; and apply the CRIDA framework to incorporate climate and hydrologic uncertainty into water planning.     

The illegal trading of high unit value minerals in developing countries

Attracted by the high unit value and low barriers to entry in terms of capital requirements, technology, infrastructure, minimum reserves and implementation time, the artisanal and small-scale mining of high unit value minerals, such as gemstones, diamonds and gold, has grown to significant proportions in developing countries. This is manifested by the value of output and large numbers of miners engaged in this activity. Despite the expansion of the subsector, its national economic role in many developing countries has largely been disappointing, primarily due to high levels of illegal trading activity. The objectives of this paper are to identify major factors responsible for the declaration problem. The economic impact of such activities is pointed out. To conclude the discussion, options are presented that provide a basis for eliminating illegal marketing practices and thereby strengthening the economic role of the subsector in meeting national development objectives of developing countries .     

Towards the characterisation of heavy metals in dredged canal sediments and an appreciation of 'availability': two examples from the UK.

Canal sediments can act as sinks for a wide range of contaminants including heavy metals from various sources (e.g. industrial and waste water discharges). Dredging of canals is required to maintain navigational depth and prevent flooding. The sediments removed from canals are often disposed of to land, being deposited either straight on to the banks of the canal or, in recent years, in licensed disposal sites. The aim of this work was to investigate the nature of dredged sediment-derived soils and the heavy metals present in them. Two disposal sites in the United Kingdom (UK) were investigated and soil samples taken. A variety of analytical techniques were used, including Aqua regia digestion and sequential extraction, in order to assess the concentrations and associations of metals present. Diethylene triaminepenta-acetic acid extracts, performed to illustrate plant-available metal concentrations, reveal that up to 40% of the total extracted metals were in an 'available' form. Variations in metal concentrations with depth in the soil cores show a significant correlation with total organic carbon content.     

Variability of spectral absorption efficiency within living cells of Pyrocystis lunula (Dinophyta)

This study examines variability in the spectral absorption efficiency in various parts of living Pyrocystis lunula cells. changes in spectral absorption efficiency measured within cells are attributed to light-induced chloroplast migration as well as reorganization of cellular material during the process of asexual reproduction. During the dark cycle, major pigment peaks were well resolved in those spectra measured in the distal cytoplasmic strands where chloroplasts were concentrated. In contrast, the absorption efficiencies measured in the granular central area that did not contain chloroplasts decreased gradually from the blue to the red portions of the spectrum and are similar to those published for detrital particles. When chloroplasts migrated toward the center of the cell in response to light, absorption efficiency curves for the granular central area were flatter than the curves measured in cytoplasmic strands containing chloroplasts. This was due to the combined absorption properties of the central area and the chloroplasts. Absorption efficiency spectra were also flattened in aplanospores within the parent vegetative cells because of the concentration of cellular material into smaller areas. These findings suggest that shapes of spectral absorption curves measured for the major phytoplankton groups cannot be assumed to remain constant over time. Furthermore, changes in cell structure may account for some of the reported diel changes in beam attenuation and stimulated fluorescence in natural waters.