Rupak Aryal

Sewage pollution in urban stormwater runoff as evident from the widespread presence of multiple microbial and chemical source tracking markers.

The concurrence of human sewage contamination in urban stormwater runoff (n=23) from six urban catchments across Australia was assessed by using both microbial source tracking (MST) and chemical source tracking (CST) markers. Out of 23 stormwater samples human adenovirus (HAv), human polyomavirus (HPv) and the sewage-associated markers; Methanobrevibacter smithii nifH and Bacteroides HF183 were detected in 91%, 56%, 43% and 96% of samples, respectively. Similarly, CST markers paracetamol (87%), salicylic acid (78%) acesulfame (96%) and caffeine (91%) were frequently detected. Twenty one samples (91%) were positive for six to eight sewage related MST and CST markers and remaining two samples were positive for five and four markers, respectively. A very good consensus (>91%) observed between the concurrence of the HF183, HAv, acesulfame and caffeine suggests good predictability of the presence of HAv in samples positive for one of the three markers. High prevalence of HAv (91%) also suggests that other enteric viruses may also be present in the stormwater samples which may pose significant health risks. This study underscores the benefits of employing a set of MST and CST markers which could include monitoring for HF183, adenovirus, caffeine and paracetamol to accurately detect human sewage contamination along with credible information on the presence of human enteric viruses, which could be used for more reliable public health risk assessments. Based on the results obtained in this study, it is recommended that some degree of treatment of captured stormwater would be required if it were to be used for non-potable purposes.

Toxicity characterization of urban stormwater with bioanalytical tools.

Stormwater harvesting has become an attractive alternative strategy to address the rising demand for urban water supply due to limited water sources and population growth. Nevertheless, urban stormwater is also a major source of surface water pollution. Runoff from different urban catchments with source contributions from anthropogenic activities and various land uses causes variable contaminant profiles, thus posing a challenging task for environmental monitoring and risk assessment. A thorough understanding of raw stormwater quality is essential to develop appropriate treatment facilities for potential indirect potable reuse of stormwater. While some of the key chemical components have previously been characterized, only scarce data are available on stormwater toxicity. We benchmarked stormwater samples from urban, residential and industrial sites across various Australian capital cities against samples from the entire water cycle, from sewage to drinking water. Six biological endpoints, targeting groups of chemicals with modes of toxic action of particular relevance for human and environmental health, were investigated: non-specific toxicity (Microtox and combined algae test), the specific modes of action of phytotoxicity (combined algae test), dioxin-like activity (AhR-CAFLUX), and estrogenicity (E-SCREEN), as well as reactive toxicity encompassing genotoxicity (umuC) and oxidative stress (AREc32). Non-specific toxicity was highly variable across sites. The baseline toxicity equivalent concentrations of the most polluted samples were similar to secondary treated effluent from wastewater treatment plants. Phytotoxicity results correlated well with the measured herbicide concentrations at all sites. High estrogenicity was found in two sampling events and could be related to sewage overflow. Genotoxicity, dioxin-like activity, and oxidative stress response were evident in only three of the samples where the stormwater drain was beside a heavy traffic road, confirming that road runoff is the potential source of contaminants, while the bioanalytical equivalent concentrations (BEQ) of these samples were similar to those of raw sewage. This study demonstrates the benefit of bioanalytical tools for screening-level stormwater quality assessment, forming the basis for the evaluation of future stormwater treatment and reuse schemes.

Dynamics of PM2.5 concentrations in Kathmandu Valley, Nepal

This study analyzed daily patterns and dynamics of PM(2.5) concentrations in the Kathmandu Valley during three winters. The PM(2.5) data showed a daily repetitive cycle which represents influence of local air flow and dispersion and accumulation of air pollutants in the valley. Two concentration peaks were observed in the morning and in the evening periods, and they fell down during the daytime and the nighttime periods. This indicates local emission sources as major contributors in the valley. The more pronounced morning peak compared to the evening peak showed that the upslope wind in the morning helped to move the polluted inversion layer downward, subsequently adding to freshly emitted pollutants and causing a sharp pollutant concentration rise in the morning. Katabatic wind and rise of temperature in the basin during the day helped the pollutant upflow and dilution, resulting in a sharp PM(2.5) concentration decline. Through the afternoon, the decrease in air temperature followed by decrease in wind speed caused to lower PM(2.5) peaks in the evening. Also, higher morning peaks of PM(2.5) concentrations compared to the evening indicated pollution from the previous day is added to the fresh emission. The valley had increased PM(2.5) from the beginning of October which continued till the first week of February. The increase in PM(2.5) peak fit the logistic equation y=[k/(1+exp (p-qx)]+asin(bx) where k, p, q, a, and b are constants.

Urban stormwater harvesting and reuse: a probe into the chemical, toxicology and microbiological contaminants in water quality

Stormwater is one of the last major untapped urban water resources that can be exploited as an alternative water source in Australia. The information in the current Australian Guidelines for Water Recycling relating to stormwater harvesting and reuse only emphasises on a limited number of stormwater quality parameters. In order to supply stormwater as a source for higher value end-uses, a more comprehensive assessment on the potential public health risks has to be undertaken. Owing to the stochastic variations in rainfall, catchment hydrology and also the types of non-point pollution sources that can provide contaminants relating to different anthropogenic activities and catchment land uses, the characterisation of public health risks in stormwater is complex, tedious and not always possible through the conventional detection and analytical methods. In this study, a holistic approach was undertaken to assess the potential public health risks in urban stormwater samples from a medium-density residential catchment. A combined chemical–toxicological assessment was used to characterise the potential health risks arising from chemical contaminants, while a combination of standard culture methods and quantitative polymerase chain reaction (qPCR) methods was used for detection and quantification of faecal indicator bacteria (FIB) and pathogens in urban stormwater. Results showed that the concentration of chemical contaminants and associated toxicity were relatively low when benchmarked against other alternative water sources such as recycled wastewater. However, the concentrations of heavy metals particularly cadmium and lead have exceeded the Australian guideline values, indicating potential public health risks. Also, high numbers of FIB were detected in urban stormwater samples obtained from wet weather events. In addition, qPCR detection of human-related pathogens suggested there are frequent sewage ingressions into the urban stormwater runoff during wet weather events. Further water quality monitoring study will be conducted at different contrasting urban catchments in order to undertake a more comprehensive public health risk assessment for urban stormwater.

Unusual Sydney dust storm and its mineralogical and organic characteristics

Environmental context In 2009, at the end of the longest drought period ever recorded in Australia, a major dust storm blanketed the cities of Sydney and Brisbane for more than 24 h. The source of the dust was inner New South Wales and South Australia, where large scale open-cut mining occurs together with agricultural practices. We report results of extensive mineralogical and chemical analyses of the dust, and discuss their significance in terms of the dust origins and potential human health risks. Abstract In a 24-h period from 23 to 24 September 2009, a dust storm passed over Sydney, Australia that produced a red sky and reduced the visibility to a few metres. It was Sydney’s worst dust storm since 1942. During this period, the PM10 (particles measuring 10 μm or less) value jumped from 50 to 11 800 µg m–3. The dust storm was sampled and its mineralogical and organic contents were analysed. Four major particle sizes (0.6, 4.5, 9.3 and 20 µm) were observed in the dust. A multimodal particle distribution indicated a long range of dust transport. Mineralogical analysis showed that the particles were mainly composed of crustal elemental oxides of Al and Si. The ratio of Al/Si was 0.39 and the organic content was 10.6 %, which was found to be enriched with humic-type substances. The high Al/Si ratio (>0.3) indicated that the dust originated from desert land whereas the high organic content indicated that the particles were also derived from eroded agricultural land. A fluorescence spectroscopic study on the organic matter at excitation and emission wavelengths of 245–265 and 330–350 nm indicated that biohazardous substances were unlikely to be present in the dust.

Pesticide occurrence and spatio-temporal variability in urban run-off across Australia

Stormwater is a major driving factor of aquatic ecosystem degradation as well as one of the largest untapped urban freshwater resources. We present results from a long-term, multi-catchment study of urban stormwater pesticides across Australia that addresses this dichotomous identity (threat and resource), as well as dominant spatial and temporal patterns in stormwater pesticide composition. Of the 27 pesticides monitored, only 19 were detected in Australian stormwater, five of which (diuron, MCPA, 2,4-D, simazine, and triclopyr) were found in >50% of samples. Overall, stormwater pesticide concentrations were lower than reported in other countries (including the United States, Canada and Europe), and exceedances of public health and aquatic ecosystem standards were rare (<10% of samples). Spatio-temporal patterns were investigated with principal component analysis. Although stormwater pesticide composition was relatively stable across seasons and years, it varied significantly by catchment. Common pesticide associations appear to reflect 1) user application of common registered formulations containing characteristic suites of active ingredients, and 2) pesticide fate properties (e.g., environmental mobility and persistence). Importantly, catchment-specific occurrence patterns provide opportunities for focusing treatment approaches or stormwater harvesting strategies.

Screening of metal uptake by plant colonizers growing on abandoned copper mine in Kapunda, South Australia

ABSTRACT Systematic site survey for sample collection and analysis was conducted at a derelict copper (Cu) mine at Kapunda, South Australia. Cu concentrations in the soils at this former mine ranged from 65–10107 mg kg−1. The pH and EC varied widely in the 3.9–8.4 and 152–7311 µS ranges, respectively. Nine plant species growing over the copper mine site were selected to screen for metal uptake to determine their suitability for phytoremediation. The Australian native tree species Eucalyptus camaldulensis indicated enrichment factor (EF) of 2.17, 1.89, and 1.30 for Cu, Zn, and Pb, respectively, suggesting that this species of tree can accumulate these metals to some degree. The stress-resistant exotic olive, Olea europaea exhibited EF of ≤ 0.01 for Cu, Cd, and Pb, and 0.29 for Zn, which is characteristic of an excluder plant. Acacia pycnantha, the Australian pioneer legume species with EF 0.03, 0.80, 0.32, and 0.01 for Cu, Zn, Cd, and Pb, respectively, emerged as another strong metal excluder and consequently as an ideal metal stabilizer.

The role of inter-event time definition and recovery of initial/depression loss for the accuracy in quantitative simulations of highway runoff

A long-term runoff monitoring was carried out in a highway drainage system in Winterthur, Switzerland. Several runoff quantity simulations were carried out using the distributed model ‘InfoWorks-CS’. Serial rainfall monitoring data were used for investigation of water runoff behaviour from the highway. The inter-event time definition was calculated from the runoff simulation and applied for better accurate runoff volume determination. Under continuous rainfall condition, the quantity simulation showed a good agreement with the measured hydrograph. However, in some cases where rainfall was not continuous, overestimation of runoff volume and difference in peak height/timing was found after rainfall halting. It was believed that the initial/depression loss on road surface was recovered during the halting period of rainfall and caused the difference in the runoff volume and peak height/timing difference in simulation. The consideration of regenerated depression loss significantly improved runoff simulation results in the on-and-off type rainfall events. This result showed that it was essential to estimate the inter-event time definition to consider appropriateness of the initial or intermediate loss.

Occurrence of illicit drugs in water and wastewater and their removal during wastewater treatment

This review critically evaluates the types and concentrations of key illicit drugs (cocaine, amphetamines, cannabinoids, opioids and their metabolites) found in wastewater, surface water and drinking water sources worldwide and what is known on the effectiveness of wastewater treatment in removing such compounds. It is also important to amass information on the trends in specific drug use as well as the sources of such compounds that enter the environment and we review current international knowledge on this. There are regional differences in the types and quantities of illicit drug consumption and this is reflected in the quantities detected in water. Generally, the levels of illicit drugs in wastewater effluents are lower than in raw influent, indicating that the majority of compounds can be at least partially removed by conventional treatment processes such as activated sludge or trickling filters. However, the literature also indicates that it is too simplistic to assume non-detection equates to drug removal and/or mitigation of associated risks, as there is evidence that some compounds may avoid detection via inadequate sampling and/or analysis protocols, or through conversion to transformation products. Partitioning of drugs from the water to the solids fraction (sludge/biosolids) may also simply shift the potential risk burden to a different environmental compartment and the review found no information on drug stability and persistence in biosolids. Generally speaking, activated sludge-type processes appear to offer better removal efficacy across a range of substances, but the lack of detail in many studies makes it difficult to comment on the most effective process configurations and operations. There is also a paucity of information on the removal effectiveness of alternative treatment processes. Research is also required on natural removal processes in both water and sediments that may over time facilitate further removal of these compounds in receiving environments.

Urban stormwater quality monitoring: From sampling to water quality analysis

This paper presents the outcomes of urban stormwater quality monitoring and research including associated activities in South East Queensland (SEQ). The issues associated with urban stormwater quality monitoring, ranging from automated field sampling to laboratory analysis of chemical, toxicological and microbiological constituents present in stormwater are elaborated. A medium density residential stormwater supply catchment of 290 hectares in northern Brisbane is presented as a case study and discussed in detail. Preliminary results indicate that the occurrence and concentration of chemical pollutants in urban stormwater runoff and the associated baseline toxicity is relatively low. However, the microbiological quality of stormwater may not be as good as initially perceived with high numbers of faecal indicator bacteria (FIB) detected during wet weather events. In addition, the polymerase chain reaction (PCR) detection of pathogens indicated the presence of human sewage contamination during wet weather events which might be due to potential sewer overflow events. Further monitoring will be conducted to further assess the stormwater quality before undertaking a comprehensive environmental and public health risk assessment.