Stage 1 of the Yueyang Urban Water System Project: Landscape planning and design of Wangjia River

Chinese landscape architects are largely focused on objective practical solutions to environmental problems. In the West, theoretical landscape knowledge is largely conceptual and abstract. This research debated how Australian ecological concepts could or should be transposed to Chinese landscapes. This project responded to severe water and soil pollution issues in the estuarine and riparian zones of rivers flowing into Dongting Lake, in Yueyang City, Hunan Province. This work proposed a range of waterfront design innovations that challenged the notion of corridor as habitat, filter, barrier and conduit in a Chinese riparian context.

Advances in heterogeneous photocatalytic degradation of phenols and dyes in wastewater : a review

The heterogeneous photocatalytic water purification process has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible light spectrum. This paper aims to review and summarize the recently published works in the field of photocatalytic oxidation of toxic organic compounds such as phenols and dyes, predominant in waste water effluent. In this review, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes are presented. Recent findings suggested that different parameters, such as type of photocatalyst and composition, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, mode of catalyst application, and calcinations temperature can play an important role on the photocatlytic degradation of organic compounds in water environment. Extensive research has focused on the enhancement of photocatalysis by modification of TiO2 employing metal, non-metal and ion doping. Recent advances in TiO2 photocatalysis for the degradation of various phenols and dyes are also highlighted in this review.

Microcosm study of ion mobilization and greenhouse gas evolution in soils of a plantation-forested subtropical coastal catchment

This study examined the potential for Fe mobilization and greenhouse gas (GHG, e.g. CO2, and CH4) evolution in SEQ soils associated with a range of plantation forestry practices and water-logged conditions. Intact, 30-cm-deep soil cores collected from representative sites were saturated and incubated for 35 days in the laboratory, with leachate and headspace gas samples periodically collected. Minimal Fe dissolution was observed in well-drained sand soils associated with mature, first-rotation Pinus and organic Fe complexation, whereas progressive Fe dissolution occurred over 14 days in clear-felled and replanted Pinus soils with low organic matter and non-crystalline Fe fractions. Both CO2 and CH4 effluxes were relatively lower in clear-felled and replanted soils compared with mature, first-rotation Pinus soils, despite the lack of statistically significant variations in total GHG effluxes associated with different forestry practices. Fe dissolution and GHG evolution in low-lying, water-logged soils adjacent to riparian and estuarine, native-vegetation buffer zones were impacted by mineral and physical soil properties. Highest levels of dissolved Fe and GHG effluxes resulted from saturation of riparian loam soils with high Fe and clay content, as well as abundant organic material and Fe-metabolizing bacteria. Results indicate Pinus forestry practices such as clear-felling and replanting may elevate Fe mobilization while decreasing CO2 and CH4 emissions from well-drained, SEQ plantation soils upon heavy flooding. Prolonged water-logging accelerates bacterially mediated Fe cycling in low-lying, clay-rich soils, leading to substantial Fe dissolution, organic matter mineralization, and CH4 production in riparian native-vegetation buffer zones.

A multivariate approach to the identification of surrogate parameters for heavy metals in stormwater

Stormwater is a potential and readily available alternative source for potable water in urban areas. However, its direct use is severely constrained by the presence of toxic pollutants, such as heavy metals (HMs). The presence of HMs in stormwater is of concern because of their chronic toxicity and persistent nature. In addition to human health impacts, metals can contribute to adverse ecosystem health impact on receiving waters. Therefore, the ability to predict the levels of HMs in stormwater is crucial for monitoring stormwater quality and for the design of effective treatment systems. Unfortunately, the current laboratory methods for determining HM concentrations are resource intensive and time consuming. In this paper, applications of multivariate data analysis techniques are presented to identify potential surrogate parameters which can be used to determine HM concentrations in stormwater. Accordingly, partial least squares was applied to identify a suite of physicochemical parameters which can serve as indicators of HMs. Datasets having varied characteristics, such as land use and particle size distribution of solids, were analyzed to validate the efficacy of the influencing parameters. Iron, manganese, total organic carbon, and inorganic carbon were identified as the predominant parameters that correlate with the HM concentrations. The practical extension of the study outcomes to urban stormwater management is also discussed.

DDT resistance and transformation by different microbial strains isolated from DDT-contaminated soils and compost materials

Bioremediation is a potential option to treat 1, 1, 1-trichloro-2, 2 bis (4-chlorophenyl) ethane (DDT) contaminated sites. In areas where suitable microbes are not present, the use of DDT resistant microbial inoculants may be necessary. It is vital that such inoculants do not produce recalcitrant breakdown products e.g. 1, 1-dichloro-2, 2-bis (4-chlorophenyl) ethylene (DDE). Therefore, this work aimed to screen DDT-contaminated soil and compost materials for the presence of DDT-resistant microbes for use as potential inoculants. Four compost amended soils, contaminated with different concentrations of DDT, were used to isolate DDT-resistant microbes in media containing 150 mg I -1 DDT at three temperatures (25, 37 and 55°C). In all soils, bacteria were more sensitive to DDT than actinomycetes and fungi. Bacteria isolated at 55°C from any source were the most DDT sensitive. However DDT-resistant bacterial strains showed more promise in degrading DDT than isolated fungal strains, as 1, 1-dichloro 2, 2-bis (4-chlorophenyl) ethane (DDD) was a major bacterial transformation product, while fungi tended to produce more DDE. Further studies on selected bacterial isolates found that the most promising bacterial strain (Bacillus sp. BHD-4) could remove 51% of DDT from liquid culture after 7 days growth. Of the amount transformed, 6% was found as DDD and 3% as DDE suggesting that further transformation of DDT and its metabolites occurred.

Fate and transport of nursery-box-applied tricyclazole and imidacloprid in paddy fields

The fate and transport of tricyclazole and imidacloprid in paddy plots after nursery-box application was monitored. Water and surface soil samples were collected over a period of 35 days. Rates of dissipation from paddy waters and soils were also measured. Dissipation of the two pesticides from paddy water can be described by first-order kinetics. In the soil, only the dissipation of imidacloprid fitted to the simple first-order kinetics, whereas tricyclazole concentrations fluctuated until the end of the monitoring period. Mean half-life (DT₅₀) values for tricyclazole were 11.8 and 305 days, respectively, in paddy water and surface soil. The corresponding values of imidacloprid were 2.0 and 12.5 days, respectively, in water and in surface soil. Less than 0.9% of tricyclazole and 0.1% of imidacloprid were lost through runoff during the monitoring period even under 6.3 cm of rainfall. The pesticide formulation seemed to affect the environmental fate of these pesticides when these results were compared to those of other studies.

Evaluating sewage associated JCV and BKV polyomaviruses for sourcing human fecal pollution in a coastal river in Southeast Queensland Australia

In this study, the host-sensitivity and -specificity of JCV and BKV polyomaviruses were evaluated by testing wastewater/fecal samples from nine host groups in Southeast Queensland, Australia. The JCV and BKV polyomaviruses were detected in 48 human wastewater samples collected from the primary and secondary effluent suggesting high sensitivity of these viruses in human wastewater. Of the 81 animal wastewater/fecal samples tested, 80 were PCR negative for this marker. Only one sample from pig wastewater was positive. Nonetheless, the overall host-specificity of these viruses to differentiate between human and animal wastewater/fecal samples was 0.99. To our knowledge, this is the first study in Australia that reports the high specificity of JCV and BKV polyomaviruses. To evaluate the field application of these viruses to detect human fecal pollution, 20 environmental samples were collected from a coastal river. Of the 20 samples tested, 15% and 70% samples exceeded the regulatory guidelines for E. coli and enterococci levels for marine waters. In all, 5 (25%) samples were PCR positive for JCV and BKV indicated the presence of human fecal pollution in the studied river. The results suggest that JCV and BKV detection using PCR could be a useful tool for the identification of human sourced fecal pollution in coastal waters.

Spatial variability of soil organic carbon in grasslands: implications for detecting change at different scales

Extensive data used to quantify broad soil C changes (without information about causation), coupled with intensive data used for attribution of changes to specific management practices, could form the basis of an efficient national grassland soil C monitoring network. Based on variability of extensive (USDA/NRCS pedon database) and intensive field-level soil C data, we evaluated the efficacy of future sample collection to detect changes in soil C in grasslands. Potential soil C changes at a range of spatial scales related to changes in grassland management can be verified (alpha=0.1) after 5 years with collection of 34, 224, 501 samples at the county, state, or national scales, respectively. Farm-level analysis indicates that equivalent numbers of cores and distinct groups of cores (microplots) results in lowest soil C coefficients of variation for a variety of ecosystems. Our results suggest that grassland soil C changes can be precisely quantified using current technology at scales ranging from farms to the entire nation. (C) 2001 Elsevier Science Ltd. All rights reserved.

Influence of hydrocarbon contamination on clay soil microstructure

Microstructural (fabric, forces and composition) changes due to hydrocarbon contamination in a clay soil were studied using Scanning Electron Microscope (micro-fabric analysis), Atomic Force Microscope (forces measurement) and sedimentation bench test (particle size measurements). The non-polluted and polluted glacial till from north-eastern Poland (area of a fuel terminal) were used for the study. Electrostatic repelling forces for the polluted sample were much lower than for the non-polluted sample. In comparison to non-polluted sample, the polluted sample exhibited lower electric charge, attractive forces on approach and strong adhesion on retrieve. The results of the sedimentation tests indicate that clay particles form larger aggregates and settle out of the suspension rapidly in diesel oil. In non-polluted soil, the fabric is strongly aggregated – densely packed, dominate the face-to-face and edge-to-edge types of contacts, clay film tightly adheres to the surface of larger grains and interparticle pores are more common. In polluted soil, the clay matrix is less aggregated – loosely packed, dominate the edge-to-face types of contacts and inter-micro-aggregate pores are more frequent. Substantial differences were observed in the morphometric and geometrical parameters of pore space. The polluted soil micro-fabric proved to be more isotropic and less oriented than in non-polluted soil. The polluted soil, in which electrostatic forces were suppressed by hydrocarbon interaction, displays more open porosity and larger voids than non-polluted soil, which is characterized by occurrence of the strong electrostatic interaction between clay particles.

Raman spectroscopy of some complex arsenate minerals—implications for soil remediation

The application of spectroscopy to the study of contaminants in soils is important. Among the many contaminants is arsenic, which is highly labile and may leach to non-contaminated areas. Minerals of arsenate may form depending upon the availability of specific cations for example calcium and iron. Such minerals include carminite, pharmacosiderite and talmessite. Each of these arsenate minerals can be identified by its characteristic Raman spectrum enabling identification.

Air pollution levels measured at traffic hot spots : Brisbane urban corridor study

Air pollution levels were monitored continuously over a period of 4 weeks at four sampling sites along a busy urban corridor in Brisbane. The selected sites were representative of industrial and residential types of urban environment affected by vehicular traffic emissions. The concentration levels of submicrometer particle number, PM2.5, PM10, CO, and NOx were measured 5-10 meters from the road. Meteorological parameters and traffic flow rates were also monitored. The data were analysed in terms of the relationship between monitored pollutants and existing ambient air quality standards. The results indicate that the concentration levels of all pollutants exceeded the ambient air background levels, in certain cases by up to an order of magnitude. While the 24-hr average concentration levels did not exceed the standard, estimates for the annual averages were close to, or even higher than the annual standard levels.