Barry Meehan

The acute and chronic toxicity of lanthanum to Daphnia carinata.

The rare earth elements (REEs) are increasingly being used as trace supplements in agriculture. This study measured the acute and chronic toxicity of one REE, lanthanum (La), to Daphnia carinata. The 48-h EC50 of La to Daphnia was measured in three media of differing composition and hardness. Lanthanum was most toxic to Daphnia in soft tap water (TW) with an acute 48-h EC50 of 43 microg/l compared with 1180 microg/l in ASTM hard water (ASTM). In the third daphnid growth medium (DW), based on diluted sea water, the acute 48-h EC50 was 49 microg La/l, however, there was significant precipitation of La in this media. The chronic toxicity of La to Daphnia was measured in the DW and ASTM media. Nominal exposure concentrations were 100, 200, 400, 600, 800, and 1000 microg La/l. Mortality was a more sensitive endpoint than growth or reproduction in both chronic experiments. Very little La was detected in either media after 24 h and the measured concentrations below were estimated by logarithmic mean of nominal and measured values. There was 100% mortality at concentrations > or = 80 microg La/l (400 microg/l nominal) by day six of the experiment using DW media, but no effect on survival growth or reproduction at lower concentrations. In the ASTM media, La caused significant mortality to Daphnia at concentrations > or = 39 microg/l (200 microg/l nominal), however, at least one animal survived to the end of the study at each of the tested concentrations. There was no effect of La on growth of surviving daphnids at concentrations < or = 57 microg/l (400 g/l), however, second brood clutch sizes were significantly increased at 30, 39, and 57 microg/l (100, 200, 400 g/l nominal) compared with controls. Lanthanum also caused a delayed maturation in Daphnia.

A critical review of nitrogen mineralization in biosolids-amended soil, the associated fertilizer value for crop production and potential for emissions to the environment.

International controls for biosolids application to agricultural land ensure the protection of human health and the environment, that it is performed in accordance with good agricultural practice and that nitrogen (N) inputs do not exceed crop requirements. Data from the scientific literature on the total, mineral and mineralizable N contents of biosolids applied to agricultural land under a wide range of climatic and experimental conditions were collated. The mean concentrations of total N (TN) in the dry solids (DS) of different biosolids types ranged from 1.5% (air-dried lime-treated (LT) biosolids) to 7.5% (liquid mesophilic anaerobic digestion (LMAD) biosolids). The overall mean values of mineralizable N, as a proportion of the organic N content, were 47% for aerobic digestion (AeD) biosolids, 40% for thermally dried (TD) biosolids, 34% for LT biosolids, 30% for mesophilic anaerobic digestion (MAD) biosolids, and 7% for composted (Com) biosolids. Biosolids air-dried or stored for extended periods had smaller total and mineralizable N values compared to mechanically dewatered types. For example, for biosolids treated by MAD, the mean TN (% DS) and mineralizable N (% organic N) contents of air-dried materials were 3% and 20%, respectively, compared to 5% and 30% with mechanical dewatering. Thus, mineralizable N declined with the extent of biological stabilization during sewage sludge treatment; nevertheless, overall plant available N (PAN=readily available inorganic N plus mineralizable N) was broadly consistent across several major biosolids categories within climatic regions. However, mineralizable N often varied significantly between climatic regions for similar biosolids types, influencing the overall PAN. This may be partly attributed to the increased rate, and also the greater extent of soil microbial mineralization of more stable, residual organic N fractions in biosolids applied to soil in warmer climatic zones, which also raised the overall PAN, compared to cooler temperate areas. It is also probably influenced by differences in upstream wastewater treatment processes that affect the balance of primary and secondary, biological sludges in the final combined sludge output from wastewater treatment, as well as the relative effectiveness of sludge stabilization treatments at specific sites. Better characterization of biosolids used in N release and mineralization investigations is therefore necessary to improve comparison of system conditions. Furthermore, the review suggested that some international fertilizer recommendations may underestimate mineralizable N in biosolids, and the N fertilizer value. Consequently, greater inputs of supplementary mineral fertilizer N may be supplied than are required for crop production, potentially increasing the risk of fertilizer N emissions to the environment. Thus greater economic and environmental savings in mineral N fertilizer application are potentially possible than are currently realized from biosolids recycling programmes.

Teamwork: education for entrants to the environment professions

Numerous reports over recent years emphasise the importance of teamwork training in undergraduate programs in environment education at tertiary level. This paper describes a project undertaken by a team of final year undergraduate environment students from four faculties at RMIT University in Australia working on a multi‐disciplinary environment project in Vietnam. The students clearly gained confidence in teamwork and working as professionals. Importantly, they identified some of the key issues associated with teamwork, and with professional activities. While they had not yet entered professional work, the students demonstrated that they had learnt skills that would be of direct importance to them in the professional conduct of a multi‐disciplinary project. The project also demonstrated that multi‐disciplinary teamwork fits well into environmental projects, and importantly that the experiences are recognised by students as being valuable preparation for their environmental professions.

A Project-Based Model for Professional Environmental Experience.

The projects described in this article were designed to provide a real world situation akin to the work of environmental professionals. The projects were conducted with Australian students working on environmental issues in Vietnam. The projects demonstrated that multi-disciplinary teamwork fits well into environmental projects, and importantly that the experiences are recognised by students as being valuable preparation for their environmental professions. The students demonstrated that they had learnt many skills that would be of direct importance to them in the professional conduct of a multi-disciplinary environmental project and also enhanced their cultural awareness and practice.

Micro versus macro solid phase extraction for monitoring water contaminants: a preliminary study using trihalomethanes.

Solid phase extraction is one of the most commonly used pre-concentration and cleanup steps in environmental science. However, traditional methods need electrically powered pumps, can use large volumes of solvent (if multiple samples are run), and require several hours to filter a sample. Additionally, if the cartridge is open to the air volatile compounds may be lost and sample integrity compromised. In contrast, micro cartridge based solid phase extraction can be completed in less than 2 min by hand, uses only microlitres of solvent and provides comparable concentration factors to established methods. It is also an enclosed system so volatile components are not lost. The sample can also be eluted directly into a detector (e.g. a mass spectrometer) if required. However, the technology is new and has not been much used for environmental analysis. In this study we compare traditional (macro) and the new micro solid phase extraction for the analysis of four common volatile trihalomethanes (trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane). The results demonstrate that micro solid phase extraction is faster and cheaper than traditional methods with similar recovery rates for the target compounds. This method shows potential for further development in a range of applications.

An assessment of the guidelines in Victoria, Australia, for land application of biosolids based on plant-available nitrogen

In the application of biosolids to land for agricultural purposes, the supply of plant-available nitrogen (PAN) should match the crop requirements. This ensures that the crop yield is maximised while minimising the environmental risk from over-application. In Victoria, the amount to be applied is usually calculated according to the State EPA guidelines using the nitrogen limited biosolids application rates (NLBAR). These guidelines specify the mineralisation rates to be used in the NLBAR calculation for different types of biosolids. However, these rates have not been validated for Victorian soils and agricultural production systems. To test the veracity of these rates, this study quantified the amount of PAN for two different biosolids (anaerobically digested biosolids, ANDB; and aerobically digested biosolids, ADB) added to two types of soils, a sandy loam at Lara and a clay loam at the Melton Recycled Water Plant, Surbiton Park, Melton. The PAN was calculated by determining the N fertiliser equivalence of the biosolids. To achieve this, two field calibration plots were prepared, one for the biosolids and one for urea as the N fertiliser. Biosolids were applied based on total N at six rates (0, 68, 136, 204, 340 and 510 kg N ha–1); urea was applied at six rates (0, 60, 120, 180, 240 and 280 kg N ha–1). Perennial ryegrass (Lolium perenne) was planted 1 day after the application of biosolids and harvested after 120 days. The calculated amount of mineralisable organic N in ANDB was estimated to be 41% and 39% when applied to the clay loam and sandy loam soils, respectively; for ADB, it was 12% and 9%, respectively. These values indicate that the organic N mineralisation rates provided in the EPA Victoria guidelines (15% for ANDB and 25% for ADB) might not always be applicable. Also of note is that the values obtained for the each of the biosolids appear to be independent of the soil type.

Regulated and emerging disinfection by-products in recycled waters

Disinfection is an integral component of water treatment performed daily on large volumes of water worldwide. Chemical disinfection may result in the unintended production of disinfectant by-products (DBPs) due to reactions between disinfectants and natural organic matter present in the source water. Due to their potential toxicity, levels of DBPs have been strictly regulated in drinking waters for many years. With water reuse now becoming more common around the world DBPs are increasingly becoming a concern in recycled waters, where a much larger amount and variety of compounds may be formed due to a higher abundance and diversity of organic material in the source waters. Regulation of DBPs in recycled waters is limited; generally, drinking water regulations are applied in place of specific guidelines for recycled waters. Such regulations are set for only 11, commonly observed, compounds of the 600+ that may, potentially, be found. In this review an overview of current research in this area is provided, the types of compounds that have been observed, methods for their analysis and possible regulation are also discussed. Through this review it is evident that there is a knowledge gap for the occurrence of DBPs in recycled waters, especially when comparing this information to that available for drinking waters. The concentrations of DBPs observed in recycled waters are seen to be higher than those in drinking water, though still within potable threshold limits. It is clear that there is a need for the analysis and understanding of a larger suite of compounds in recycled waters, as these will most likely be the source of future, global renewable water.

A New Method for the Fast Analysis of Trihalomethanes in Tap and Recycled Waters Using Headspace Gas Chromatography with Micro-Electron Capture Detection

Chemical disinfection of water supplies brings significant public health benefits by reducing microbial contamination. The process can however, result in the formation of toxic compounds through interactions between disinfectants and organic material in the source water. These new compounds are termed disinfection by-products (DBPs). The most common are the trihalomethanes (THMs) such as trichloromethane (chloroform), dichlorobromomethane, chlorodibromomethane and tribromomethane (bromoform); these are commonly reported as a single value for total trihalomethanes (TTHMs). Analysis of DBPs is commonly performed via time- and solvent-intensive sample preparation techniques such as liquid–liquid and solid phase extraction. In this study, a method using headspace gas chromatography with micro-electron capture detection was developed and applied for the analysis of THMs in drinking and recycled waters from across Melbourne (Victoria, Australia). The method allowed almost complete removal of the sample preparation step whilst maintaining trace level detection limits (>1 ppb). All drinking water samples had TTHM concentrations below the Australian regulatory limit of 250 µg/L but some were above the U.S. EPA limit of 60 µg/L. The highest TTHM concentration was 67.2 µg/L and lowest 22.9 µg/L. For recycled water, samples taken directly from treatment plants held significantly higher concentrations (153.2 µg/L TTHM) compared to samples from final use locations (4.9–9.3 µg/L).

Student preparation for the international environmental profession

Many universities have strategies for exposing students to international experiences, but little is reported on their implementation. One example of an implemented activity is the multidisciplinary research project for undergraduate environment students, at RMIT University, that both prepares students to work in the environment profession and exposes them to working in an international context. Feedback from project participants demonstrates that the project has played an important part in their preparation for professional employment. Responses demonstrated that the project provided a mechanism to prepare them for working in an international context regarding cultural awareness, and especially preparation for the many professional and personal challenges that may be encountered.

Disinfection By-products in Recycled Waters

Disinfection is an integral component of water treatment performed on large volumes of water worldwide. Chemical disinfection may, however, result in the unintended production of disinfectant by-products (DBPs) due to reactions between disinfectants and organic matter present in the source water. Due to their toxicity, levels of DBPs have been strictly regulated in drinking waters for many years. With water reuse becoming more common around the world, DBPs are now increasingly becoming a concern in recycled waters, where a much larger amount and variety of compounds may be formed due to higher abundance of organic material in the source water. With increasing temperatures and population growth in future, there is an increased need to make greater use of waste/recycled water to supplement supplies in countries such as Australia. This, in turn, necessitates a greater understanding of DBP formation in waste and recycled waters.