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Synthesized ferrihydrite (Fh) with the dosages of 0.3, 0.6 and 0.9 cm thickness (labeled as Fh, 2Fh and 3Fh respectively, equivalent to 248–774 g/m 2 ) were deployed to serve as the reactive capping layer covering the Ornamental Lake sediments, the Royal Botanic Garden of Melbourne. The sediments were exposed to an alternating regime of oxic/anoxic conditions using laboratory reactors for 45 days. Dynamics of dissolved oxygen (DO), pH, filterable reactive phosphorus (FRP), filterable ammonium (NH 4 + ), nitrate and nitrite (NO x ), total dissolved nitrogen (TDN) and dissolved iron (Fe) of overlying water were examined. After incubation, O 2 and H 2 S profiles across the water-sediment interface were observed with microelectrodes. The element distributions in the upper sediments were tested as well. Results showed that DO and pH kept relatively stable during oxic period, while decreased significantly during anoxic period. Fh cappings decreased both DO and pH, and inhibited the release of FRP. No significant increments of FRP in overlying waters were observedduring anoxic period. Fh cappings prompted the releases of NH 4 + and TDN, while inhibited that of NO x .NH 4 + increased while NO x decreased during anoxic period. Fe(II) and TFe increased only in 3Fh, especially during anoxic conditions. Fh cappings increased O 2 and H 2 S concentrations across the water-sediment interfaces. TP and TN in the sediments decreased after capping, while TFe increased significantly. We concluded that 0.6 cm thickness of (496 g/m 2 ) Fh capping could sequestrate P, even experiencing redox conditions. [ABSTRACT FROM AUTHOR]

Two novel, discrete lanthanide–macrocycle binary complexes for the detection of hydrogen sulfide are reported. The hydrogen sulfide sensing mechanism utilises the copper sequestration at a secondary binding site, with resulting bimetallic lanthanide(III)/copper(II) complexes (Ln = Eu3+ and Tb3+) exhibiting high selectivity, good sensitivity and excellent reversibility for aqueous hydrogen sulfide. The inclusion of the DO2A macrocycle and 4-(2-pyridyl)-1,2,3-triazole dipicolinic acid ligand, results in a complex with good solubility and stability. The europium(III) complex also displayed a low limit of detection (665 ppb) with a response time of 30 seconds with gaseous hydrogen sulfide. The improved water solubility and stability over a previous complex results in these sensors having the potential for use in environmental monitoring and biological studies for various functional settings. [ABSTRACT FROM AUTHOR]

We used δ15N-nitrate () and δ18O-to unravel the provenance and fate of in a groundwater-fed estuary. A total of 13 monthly and two time series surveys were undertaken in the Werribee River estuary near Melbourne, Australia. The different survey timescales provided a comprehensive evaluation of the hydrological effects on the biogeochemistry of, which accounted for tidal variability and episodic runoff events. The distribution of δ15N and δ18O of the estuarine along a mixing line between shallow and deep groundwater provided strong evidence for the predominance of groundwater-derived in the estuary. During dry periods when water residence time in the estuary was extended, shallow groundwater contributed 60% to 76% of the (calculated from δ15N- and δ18O-) to the estuary, and assimilation removed ~70% of this groundwater-derived . During wet periods, deep groundwater provided more (62%) than shallow groundwater, and there was no indication of consumption. Occasional sources of, which were also reflected by their δ15N- and δ18O- values, included from nitrification and sewage-derived particularly at the bay entrance to the estuary. Greater emphasis should be placed upon the role of groundwater as a substantial end member when assessing biogeochemistry using methods relying on the dual isotopic composition of. [ABSTRACT FROM AUTHOR]

The effectiveness of revegetation is usually gauged by responses in biodiversity, which may differ between isolated replanted patches. The ecological value of revegetation may be detected more effectively by monitoring ecosystem processes. In-stream metabolism has been much modified by the degradation of riparian vegetation in agricultural landscapes around the world. We sought to determine whether the spatial scale typical of most riparian replanting projects (i.e. <1 km long) influences stream metabolism., Metabolism is a functional measure that incorporates gross primary production ( GPP), ecosystem respiration ( ER) and the difference between them [net ecosystem productivity ( NEP)]. We hypothesised that replanted reaches would have lower GPP (due to greater canopy shading) and greater ER (governed by larger terrestrial energy inputs) compared with pasture reaches., We measured metabolism in paired reaches within four agricultural streams. Two streams had an untreated pasture reach contrasted with a reach replanted with native woody vegetation >17 years ago. The other two streams had similar riparian vegetation condition adjacent to both reaches, to act as reference sites., Mean daily GPP (0.27-4.9 g O2 m−2 day−1) and ER (1.1-22 g O2 m−2 day−1) were within the range of values recorded previously in agricultural streams elsewhere. Replanted reaches had rates of NEP lower than upstream untreated reaches at treatment sites, but NEP was similar between reaches at reference sites., The effects of replanting on stream ecosystem processes are detectable even when the spatial scale of restoration is relatively small in a whole-of-catchment context. Land managers can protect and restore vegetation at feasible spatial scales and benefit ecosystem processes. Ecosystem metabolism should be included in the range of responses that need to be monitored to provide a complete picture of the effectiveness of stream restoration. [ABSTRACT FROM AUTHOR]

We monitored submarine groundwater discharge (SGD) into the Werribee Estuary, Australia, using both chemical and physical methods. SGD occurred at hotspots where 222 Rn persisted through a 12 month survey period. A significant correlation between Rn222 and (r² = 0.8, p < 0.01), as well as between Rn222 and N2O (r² = 0.6, p < 0.01) at a 222Rn hotspot, and much higher and N2O concentrations in groundwater relative to surface water suggest that elevated and N2O concentrations in the estuary were derived from SGD. Two sampling campaigns over 24 h revealed that variations of 222Rn, and N²O were controlled by tide-induced hydraulic-head gradient fluctuations and, possibly to a much lesser extent, by tidal pumping and density-driven convection. A two-box 222 Rn mass-balance model was used to calculate the rate of SGD into two different layers across the pycnocline of the estuary. A higher total groundwater discharge rate of 0.12 ± 0.09 m d-1 was observed in the surface layer during ebb tide compared with 0.10 ± 0.08 m d-1 during flood tide. Fluxes of groundwater-derived and N O were higher than the riverine flux at baseflow by more than 30 fold and 20 fold, respectively. SGD derived fluxes exceeded the mean annual riverine and TN fluxes by a factor of ~ 5 and ~ 3 respectively. SGD-derived N2O fluxes were 170 µmol-2 m d-1, which are among the highest N2O fluxes observed in estuaries. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis and evaluation of two new ratiometric chemosensors for the quantification of potentially toxic free Zn2+ ions in aqueous solutions are described. Both sensors show high selectivity for Zn2+ over other cations, and are functional at environmentally relevant pH with detection limits of 0.05μM for free Zn2+. [Copyright &y& Elsevier]

Presents a cross relation in volumes of activation for electron-transfer reactions. Kinetics of reduction of Fe(H2O)63+; Kinetic ionic strength effects; Cross relations for the reduction of Fe(H2O)63+.

Examines the kinetics the self-exchange reaction of tris(1,10-phenanthroline)cobalt(III/II) in aqueous solution at variable pressure. Magnetic susceptibility of tris-phenanthroline cobalt (II) solutions; Racemization of the complex; Effects of anion on the constant of reaction for the second step of the self-exchange reaction.

• Both denitrification and DNRA decreased due to drying of sediments, but DNRA decreased more than denitrification. • Rates of both denitrification and DNRA increased with increasing temperature in slurries. • The relative increase in DNRA was more than denitrification with increasing temperature. Constructed wetlands are increasingly used within urban areas to reduce pollutant runoff, including nitrogen. These environments are exposed to frequent wetting and drying events, and also increasing temperatures due to the heat island effect and seasonal variation. In this study, we have investigated the role of drying and rewetting of sediments and temperature on the partitioning of two nitrate reduction pathways: denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) in four constructed urban stormwater wetlands in Melbourne, Australia. Our results suggest that both DNF and DNRA decreased due to drying of sediments, but DNRA decreased to a greater extent. Rates of DNRA from the drying-rewetting treatment decreased 5–90% compared to the control. Moreover, a concomitant increase in NH 4 + fluxes and a slight change in sediment oxygen demand (SOD) suggest that oxic conditions arising from sediment drying was responsible for the decreased rates of DNF and DNRA. Rates of both DNF and DNRA increased with increasing temperature in slurries. The DNF:DNRA ratio suggests that the relative increase in DNRA was more than DNF with increasing temperature. The mean activation energy of DNF ranged from 41 ± 1 to 64 ± 4 kJ mol−1 and the corresponding temperature coefficient (Q 10) values ranged from 1.3 to 2.4. In comparison, the mean activation energy of DNRA was higher and ranged from 50 ± 8 to 107 ± 14 kJ mol−1 with the corresponding Q 10 values ranging from 1.2 to 3.4. Overall, our results suggest that drying and re-wetting of sediments decreases nitrate reduction and increases nitrogen retention, whereas increased temperature enhances the recycling of bioavailable nitrogen in wet sediments in constructed urban stormwater wetlands. [ABSTRACT FROM AUTHOR]

The first discrete bimetallic europium(III)/copper(II) complex for the fast, sensitive and selective luminescent detection of both aqueous and gaseous hydrogen sulfide has been developed. The chemosensor displayed an impressive response time of 30 seconds and a low theoretical limit of detection (100 ppb) for gaseous hydrogen sulfide. [ABSTRACT FROM AUTHOR]

Abstract Denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) are two competing nitrate reduction pathways that remove or recycle nitrogen, respectively. However, factors controlling the partitioning between these two pathways are manifold and our understanding of these factors is critical for the management of N loads in constructed wetlands. An important factor that controls DNRA in an aquatic ecosystem is the electron donor, commonly organic carbon (OC) or alternatively ferrous iron and sulfide. In this study, we investigated the role of natural organic carbon (NOC) and acetate at different OC/NO 3 − ratios and ferrous iron on the partitioning between DNF and DNRA using the 15N-tracer method in slurries from four constructed stormwater urban wetlands in Melbourne, Australia. The carbon and nitrate experiments revealed that DNF dominated at all OC/NO 3 − ratios. The higher DNF and DNRA rates observed after the addition of NOC indicates that nitrate reduction was enhanced more by NOC than acetate. Moreover, addition of NOC in slurries stimulated DNRA more than DNF. Interestingly, slurries amended with Fe2+ showed that Fe2+ had significant control on the balance between DNF and DNRA. From two out of four wetlands, a significant increase in DNRA rates (p <.05) at the cost of DNF in the presence of available Fe2+ suggests DNRA is coupled to Fe2+ oxidation. Rates of DNRA increased 1.5–3.5 times in the Fe2+ treatment compared to the control. Overall, our study provides direct evidence that DNRA is linked to Fe2+ oxidation in some wetland sediments and highlights the role of Fe2+ in controlling the partitioning between removal (DNF) and recycling (DNRA) of bioavailable N in stormwater urban constructed wetlands. In our study we also measured anammox and found that it was always <0.05% of total nitrate reduction in these sediments. Graphical abstract Unlabelled Image Highlights • Natural organic carbon (NOC) and ferrous iron showed significant effect on the partitioning between DNF and DNRA. • Nitrate reduction was stimulated more by the addition of NOC than acetate. • NOC enhanced DNRA more than denitrification. • Fe2+ had a significant control on the balance between denitrification and DNRA. • There was a link between DNRA and Fe2+ oxidation in Fe2+ amended slurries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Recent advances in the field of lanthanide-based chemosensors are reviewed. • Sensors for metal cations, anions and neutral small molecules are discussed. • The design features and mechanisms by which sensors function are emphasised. • Contributions of a number of Australian-based researchers are highlighted. Abstract Recent developments (2012 and onwards) in the design and application of luminescent lanthanide-based complexes for chemical sensing are reviewed. Sensors for a variety of metal cations, anions and neutral small molecules are highlighted, including several developed by Australian researchers. Emphasis is placed on describing the general design features and range of mechanisms by which such sensors are able to elicit a luminescent response upon exposure to an analyte. [ABSTRACT FROM AUTHOR]

A simple sample preparation method based on a modified liquid‐phase extraction approach to extract selected pharmaceuticals and personal care products from freshwater organisms is described. Extracted samples were analysed using liquid chromatography with Q‐Exactive plus hybrid quadrupole Orbitrap mass spectrometry, using 2.6 μm C18 media. A 0.1% v/v acetic acid/acetonitrile mobile phase was applied over a 20 min gradient. Method detection limits in full scan mode were ca. 0.04–2.38 ng of analyte per g of sample. Linearity ranged from 0.9750 to 0.9996 over the calibration range of 0.01–100 μg/L; MS mass accuracy was <2 ppm for most analytes. This method was applied to quantify six pharmaceuticals and personal care products in seven invertebrate samples. For tandem mass spectrometry analysis, selection of precursor ions was performed for each pharmaceutical, with Mass Frontier software illustrating the fragmentation mechanism. Effects of collision energy on intensities of ions was further investigated. The tandem mass spectrometry condition resulting in the highest signal of respective selected product ion was selected to confirm each pharmaceutical, which was initially observed in the full scan mode. Results indicate that pharmaceuticals and personal care products found to be present in water‐ways, may be incorporated into organisms that live in the environment of affected water streams. [ABSTRACT FROM AUTHOR]

Abstract: Wetlands are often biogeochemical hotspots, and they can remove excess N via denitrification and assimilatory uptake. Wetlands are also susceptible to plant invasions, but the effect of invasive plants on denitrification in freshwater wetland sediments is not well‐studied. Two distinct mechanisms suggest the potential for invasive plants to alter denitrification. First, invasive plants often produce more biomass than non‐invasive species, thus potentially providing additional carbon (C) for denitrifiers. Second, some invasive wetland plants funnel more oxygen into the root zone than non‐invasive plants, potentially stimulating coupled nitrification–denitrification. Using the push–pull isotope pairing technique, we measured denitrification and coupled nitrification–denitrification in the sediments beneath monoculture plots of Phragmites australis and Typha domingensis, and beneath unvegetated sediments, in an urban wetland in Melbourne, Australia. We also measured pore water nutrient concentrations and calculated the diffusive flux of nutrients from the sediments into the overlying water column. We hypothesised that plots containing P. australis would have the highest denitrification and coupled nitrification–denitrification rates, followed by plots containing T. domingensis, with the lowest rates in the unvegetated plots, as a result of higher C and oxygen availability. Instead, we found that denitrification and coupled nitrification–denitrification rates were highly variable, with no difference among plot type. However, we did find that diffusive flux of ammonium from the sediments into the water column was lower in the vegetated plots than in the unvegetated plots, suggesting that vegetation enhances wetland N retention via plant assimilatory uptake. [ABSTRACT FROM AUTHOR]

This study developed an analytical approach for sub-ppb level detection and confirmation of 13 pharmaceuticals and personal care products (PPCPs) in water samples using ultra high pressure liquid chromatography hyphenated with a quadrupole Orbitrap mass spectrometer (UHPLC- Q-Orbitrap-MS). Sample preparation was performed by using solid phase extraction (SPE) employing hydrophilic-lipophilic balance cartridges, with elution of sorbed analytes using methanol. Acceptable automatic gain control (AGC) target and maximum injection time (IT) were 1 × 10 6 and 200 ms, respectively, resulting in a mass accuracy <2 ppm. High response signals with sufficient data points per peaks (20–30) were obtained whilst maintaining high resolution of approximately 70,000 full width at half maximum. Extracted ion chromatograms provided quantitative analysis with linearity (R 2 ) ranging from 0.9875 to 0.9993 and method detection limits ranging from 0.01–0.61 ng mL −1 . Compounds were further analysed by MS/MS analysis, with the MS operated in parallel reaction monitoring (PRM) mode under precursor ion analysis intervals and collision energies chosen for the different PPCPs. The developed method was applied to analyse water samples obtained from sources in Victoria, Australia. [ABSTRACT FROM AUTHOR]

Two new fluorescent chemosensors have been designed and synthesised through functionalisation of a common 7-aminocoumarin precursor. One sensor features a di(2-picoyl)amine metal ion-binding moiety that allows for selective detection of Zn2+ions over other common cations in aqueous solution, with the sensor exhibiting a 5.4-fold increase in fluorescence upon Zn2+binding (limit of detection = 26 nM). The second sensor incorporates an aminophenyl group designed to react with highly reactive oxygen species (hROS). This sensor reacts with ClO− in preference to other ROS, exhibiting a 27-fold increase in fluorescence upon the addition of 150 equivalents of ClO− (limit of detection = 2 μM). [ABSTRACT FROM AUTHOR]

Abstract: Herein, we report the synthesis of two lanthanide-based chemosensors, Tb-5 and Eu-6, designed to sense free zinc ions (Zn2+) in aqueous solutions. The Tb-5 complex features a bis(2-pyridinylmethyl)amine moiety as a zinc(II)-responsive lanthanide-sensitising ‘antenna’, while Eu-6 incorporates a quinoline-based moiety for this purpose. Luminescence enhancements of 210% and 340% are observed upon addition of Zn2+ ions to Tb-5 and Eu-6, respectively. Both sensors are selective for Zn2+ ions over several other cations of environmental significance. [Copyright &y& Elsevier]

Abstract: The Yarra River Estuary is a salt wedge estuary prone to hypoxia in the bottom waters during low flow periods. Rates of denitrification and dissimilatory nitrate reduction to ammonium (DNRA) were quantified using 15N in relation to oxygen, nitrate and available reductants. Denitrification was the dominant nitrate reduction pathway under all oxygen conditions, however, DNRA increased from <1% under hypoxic conditions (<50μmolL−1 O2) to ∼18% of total nitrate reduction under oxygen saturation in the water column in intact core incubations. Microprofiles of nitrate reduction pathways in intact cores using diffusive equilibrium in thin layer (DET) gels showed significant rates of DNRA only occurred under oxic conditions in the presence of Fe2+. Cores incubated anoxically, developed free sulfide within the porewater, had very low concentrations of Fe2+ and low rates of DNRA. Slurry incubations with varying concentrations of NO3 − showed that denitrifying bacteria had a higher affinity than nitrate ammonifying bacteria with K m values of 49 and 86μmolL−1 for denitrification and DNRA, respectively, however, this could not explain the change in the rates of DNRA relative to denitrification observed. Further slurry incubations to investigate the relationship between DNRA and Fe2+ oxidation were inconclusive and complicated by very high backgrounds of sorbed (HCl extractable) Fe2+. Addition of Fe2+ to the slurry did not stimulate denitrification compared to a control (no Fe2+ addition), however, there was a significant decrease in the Fe2+ concentration over the period where DNRA occurred in the Fe2+ addition treatment, and no significant decrease in the control treatment. The ratio of DNRA to Fe2+ consumption was 15±6 and 7±3 for the Fe2+ and control treatments, respectively. We suggest reduced rates of DNRA under anoxic conditions can be explained by the binding of Fe2+ with free sulfides and the formation of FeS removing available Fe2+ for DNRA. [Copyright &y& Elsevier]

Organic matter provides energy and nutrients to aquatic systems. Alterations to its sources and processing have repercussions for water quality and food-web stability and structure. Despite worldwide recognition of the impacts of urbanisation, there is limited understanding of the relative importance of catchment-scale urban stormwater drainage connection and reach-scale riparian vegetation on organic matter sources., We investigated the effects of catchment-scale urban stormwater drainage connection and reach-scale riparian vegetation cover on organic matter sources in small streams. Using stable isotopes and elemental ratios (i.e. δ13C, δ15N and C : N), we traced the origin of microbially respired carbon and standing stocks of dissolved organic carbon ( DOC), suspended particulate organic matter ( POM) and benthic coarse particulate organic matter ( CPOM)., Catchment-scale urban stormwater drainage connection significantly increased the contribution of labile organic matter to POM and DOC standing stocks. Greater POM lability was a product of increased inputs of autochthonous organic matter in more heavily urbanised streams, although the origin of labile DOC was less clear., While reach-scale riparian vegetation was the most likely source of the terrestrially dominated CPOM observed across most sites, increasing cover had no significant effect on the origin of POM or DOC standing stocks. We conclude that catchment-scale stormwater drainage impacts overwhelm the effects of reach-scale riparian vegetation on the sources and lability of POM and DOC in small streams., Our results suggest that the protection or restoration of riparian vegetation, in the absence of modifications to catchment-scale stormwater drainage connection, is insufficient to mitigate the effects of urbanisation on organic matter sources, lability and processing in these small streams. [ABSTRACT FROM AUTHOR]

Urbanization is an important ecological modifier of stream catchments and significantly alters C type and concentration and heavy metal input to aquatic systems. C and heavy metals are important determinants of microbial community structure (population dynamics) and function (physiological processes). Understanding how changes at the landscape scale affect key nutrient-transformation processes (e.g., denitrification) and C metabolism (e.g., methanogenesis) at the micro scale requires simultaneous determination of the structural and functional responses of bacterial communities. We compared total bacterial (16S ribosomal ribonucleic acid [[rRNA]] gene) and denitrifying bacterial ( gene) community structures in sediments taken from an urban and a nonurban stream before and after C and Zn additions. Microcosms containing stream sediment were supplemented with either proteinaceous or leaf-leachate C, increasing the C content by ∼36 and 130 mg/L, respectively. C was added in the presence and absence of Zn addition (200 mg/kg). Changes in community function were determined simultaneously with additions by measuring the rates of CO2, N2, and CH4 accumulation in the headspace of each mesocosm. Site had the greatest effect on total and denitrifying bacterial community structures. Added C caused a small but significant change in total bacterial community structure, but did not change denitrifying bacterial community structure. C enrichment caused a significant and rapid change in community function. Rates of methanogenesis were significantly higher at the nonurban than at the urban site and were significantly affected by C type (significant site × C interaction). Denitrification and CO2 production were unaffected by C additions but differed between sites. Zn addition changed total bacterial community structure but not denitrifying bacterial community structure. Zn affected the rate of methanogenesis, but the effect size was less than for C type. Community structures remained different between sites at the end of the study despite exposure to Zn concentrations that reflected conditions in urbanized streams and C sources that mimicked those from urban or nonurban streams. Our study supports previous observations that microbial community structure is strongly influenced by prior sediment history. The broader implication is that landscape-scale changes like urbanization alter other physical and chemical properties of the stream sediment that influence community structure more than the Zn or C concentrations in our study. [ABSTRACT FROM AUTHOR]

Abstract: Second derivative ultra-violet spectrophotometric methods are described for the measurement of nitrate and total nitrogen in freshwaters using flow analysis techniques. A simple flow system consisting of a peristaltic pump and a single-reflection flow-through cell was used for the measurement of nitrate. Quantification of total nitrogen using alkaline peroxodisulfate photo-digestion was achieved by incorporating an ultra-violet photo-reactor, a hollow-fibre filter and a debubbler into the flow system. The nitrate system featured a limit of detection of 0.04mgNL−1, 0.4%RSD (1mgNL−1 as nitrate, n =10), a coefficient of determination (R 2) of 0.9995 over the calibration range 0.0–2.0mgNL−1, and a data acquisition time of 1.5s per spectrum. The total nitrogen system featured a limit of detection of 0.05mgNL−1, 1%RSD (1mgNL−1 as ammonium chloride, n =10), a coefficient of determination of 0.9989 over the calibration range 0.0–2.0mgNL−1, and a throughput of 5sampleh−1 measured in triplicate. Digestions of five model nitrogen compounds returned recoveries of >88%. Determinations carried out using the developed systems show a high degree of agreement with data obtained using reference methods. These methods require no colorimetric reagents and eliminate the requirement for a toxic cadmium reduction column. The overlap of chloride and nitrate spectra in seawater is not eliminated entirely by the use of second derivative spectrophotometry, and consequently the methods are restricted to the analysis of freshwaters. [Copyright &y& Elsevier]

1. Urbanisation severely affects stream hydrology, biotic integrity and water quality, but relatively little is known about effects on organic matter dynamics. Coarse particulate organic matter (CPOM) is a source of energy and nutrients in aquatic systems, and its availability has implications for ecosystem productivity and aquatic communities. In undisturbed environments, allochthonous inputs from riparian zones provide critical energy subsidies, but the extent to which this occurs in urbanised streams is poorly understood. 2. We investigated CPOM inputs, standing stocks, retention rates and retention mechanisms in urban and peri-urban streams in Melbourne, Australia. Six streams were chosen along a gradient of catchment urbanisation, with the presence of reach scale riparian canopy cover as a second factor. CPOM retention was assessed at baseflow via replicate releases of marked Eucalyptus leaves where the retention distance and mechanism were recorded. CPOM and small wood (>1 cm diameter) storage were measured via cores and direct counts, respectively, while lateral and horizontal CPOM inputs were assessed using riparian litter traps. Stream discharge, velocity, depth and width were also measured. 3. CPOM inputs were not correlated with urbanisation, but were significantly higher in 'closed' canopy reaches. Urbanisation and riparian cover altered CPOM retention mechanisms, but not retention distances. Urban streams showed greater retention by rocks; while in less urban streams, retention by small wood was considerably higher. CPOM and small wood storage were significantly lower in more urban streams, but we found only a weak effect of riparian cover. 4. These findings suggest that while riparian vegetation increases CPOM inputs and has modest/weak effects on storage, catchment scale urbanisation decreases organic matter availability. Using an organic matter budget approach, it appears likely that the increased frequency and magnitude of high flows associated with catchment urbanisation exerts an overriding influence on organic matter availability. 5. We conclude that to maintain both organic matter inputs and storage, the restoration and protection of streams in urban or rapidly urbanising environments relies on the management of both riparian vegetation and catchment hydrology. [ABSTRACT FROM AUTHOR]

1. Urbanisation and landuse changes threaten the ecological integrity of rivers and streams globally. A major challenge in such impacted environments is to develop functional indicators for use by waterway managers. We first reviewed cellulose decomposition potential (CDP) as one such indicator, and here present current understanding and highlight the knowledge gaps which hinder its widespread incorporation into programmes monitoring stream health. In a field study, we also evaluated two differing cellulose materials (Shirley soil burial test material and unbleached calico) and measurement techniques. 2. We also investigated the effects of urbanisation and riparian cover on CDP as a standardised indicator of ecosystem function. Cotton fabrics were deployed in paired open and closed reaches across six stream catchments varying in degree of urbanisation (in south-eastern Australia). After 7, 14 and 21 days materials were retrieved and their decomposition assessed in conjunction with a number of physicochemical variables. 3. We observed a strong positive relationship between the decomposition of Shirley and calico materials, thus indicating unbleached calico is an effective substitute for Shirley test cloth, which is no longer available. 4. Across sites, CDP was positively correlated with ammonium concentrations and also, to a lesser extent, with filterable reactive phosphorus and sediment silt and clay content/carbon availability. Despite these relationships, cellulose decomposition was not correlated with urbanisation or riparian cover. 5. Cellulose decomposition is a simple, rapid and sensitive functional indicator of water quality and associated anthropogenic landuse changes and is thus a valuable tool for monitoring stream health. [ABSTRACT FROM AUTHOR]

Abstract: A total internal reflection (TIR) flow-through cell that is highly tolerant of schlieren effects, has limited hydrodynamic dispersion and does not trap gas bubbles, and which is suitable for sensitive photometric measurements in flow analysis, is described. Light from an optical fibre is introduced into a short length of quartz capillary through the sidewall at an incident angle of ca. 53°. Under this condition, incident light undergoes total internal reflection from the external air–quartz interface and is propagated by successive reflections from the external walls through the aqueous liquid core of the cell. Detection of the transmitted beam is enabled by intentionally introducing an optical coupling medium at a predetermined distance along the capillary wall, which allows the internally reflected light to be captured by a second optical fibre connected to a charge-couple device detector. This configuration embodies a number of the desirable features of a liquid core waveguide cell (i.e. total internal reflection), a multi-reflection (MR) flow cell (i.e. minimum susceptibility to schlieren effects, low hydrodynamic dispersion and little tendency to trap bubbles), and a conventional Z-cell (wide dynamic range). When employed with a flow injection system, a limit of detection of 2.0μgPL−1 was achieved for the determination of reactive phosphate using the TIR cell, compared with LOD values of 3.8μgPL−1 and 4.9μgPL−1 obtained using the MR and Z-cells with same manifold. The combined advantages of schlieren-tolerance and lack of bubble entrapment of the MR cell with the higher S/N ratio and wider dynamic range of a conventional Z-cell, make the TIR cell eminently useful for photometric measurements of samples with widely differing refractive indices. [Copyright &y& Elsevier]

Abstract: The development and application of a portable, hybrid reagent-injection gas-diffusion flow analysis technique is described for the underway measurement of total alkalinity in estuarine waters. Injection of pH 4.5 buffer into a continuously flowing sample stream produced gaseous CO2 that diffused across a microporous PTFE membrane into a weakly buffered acceptor stream containing bromothymol blue indicator. The resultant change in acceptor stream pH was detected photometrically using a super-bright LED with a multi-reflection flow cell and charge coupled device detector. This method gave a detection limit of 0.5mgCaCO3 L−1, with reproducibility of 1.0% R.S.D. at 160mgCaCO3 L−1, and a measurement rate of 71injectionsh−1. The portable FIA system was used for underway analysis of estuarine waters with salinities ranging from that of freshwater to seawater, and there was close agreement between the results obtained by underway analysis and from a reference titration method. [Copyright &y& Elsevier]

A reverse flow injection method (rFIA) based on the Winkler titration chemistry, is reported for the determination of dissolved oxygen (DO) in natural waters. Manganese(II) sulfate is injected into a continuously flowing stream of sample and subsequently merges with a reagent stream of sodium hydroxide and sodium iodide. Manganese(II) hydroxide that is formed reacts with DO in the sample to form an oxidized manganese hydroxyoxide floc. Addition of 10% sulfuric acid dissolves this floc, and under acidic conditions, the triiodide ion formed is detected by photometry in a flow through cell at a wavelength of 440 nm. The method is rapid (48 measurements per h), repeatable (R.S.D. ca. 3%, n=3), and has a calculated detection limit of 0.25 mg l−1 (P=0.001). No interference from nitrite or ferrous ions was observed at concentrations typically found in natural waters. The method has been successfully applied to on-line measurement of DO in sediment respiration reactors. [Copyright &y& Elsevier]

Our understanding of the effects of pharmaceuticals on key biogeochemical processes and biofilm assemblage composition in surface waters is limited despite the prevalence of ng/L to µg/L concentrations of these compounds. We examined the effects of 3 commonly-prescribed pharmaceuticals: ciprofloxacin (140 ng/L), diphenhydramine (300 ng/L), and fluoxetine (20 ng/L); both individually and as a mixture, on key ecosystem processes at environmentally-realistic concentrations. We used mesocosms to expose naturally-occurring biofilm communities and artificial benthic substrates to these pharmaceuticals and measured the effects of exposure on biofilm, seston, and sediment communities. Established biofilm functions were unaffected by pharmaceutical treatments. However, successional biofilms experienced 42 to 81% reductions in primary production and 59 to 83% reductions in community respiration. Denitrification in sediment communities was reduced by 41 to 73% in shaded conditions, but was not affected when left in ambient light. Diatom assemblage structure was unaffected by pharmaceuticals in successional biofilms, whereas the composition of established biofilm assemblages changed with exposure to treatments that contained ciprofloxacin, diphenhydramine, and all 3 pharmaceuticals. Our study adds to a growing body of evidence indicating that chronic exposure to sub-lethal concentrations of pharmaceuticals may substantially alter key ecosystem processes and communities. [ABSTRACT FROM AUTHOR]

In streams, gross primary production (GPP) and ecosystem respiration (ER) (i.e., stream metabolism) control the transport and fate of nutrients and organic carbon and vice versa. The importance of short-term and local factors in driving these processes is well known in the literature. However, little information exists regarding the extent of temporal variability of stream metabolism and how both local physicochemical and broad-scale climatic drivers affect this variability. We used 7 years of field data from an open-canopy headwater stream ecosystem in the southwestern United States to quantify the extent of seasonal and inter-annual variability in stream metabolism (GPP, ER, and net ecosystem production [NEP]) and to assess if temporal variation in these processes was related to the magnitude of snowmelt runoff. In spring, seasonal mean ER (p = 0.025, r 2 = 0.67) and NEP (p = 0.004, r 2 = 0.83) were more strongly related to discharge (Q) than GPP (p = 0.19, r 2 = 0.32), potentially because of an increased influx of nutrients and organic carbon during years with higher snowmelt runoff. There were no strong relationships between seasonal mean GPP and Q , light, temperature, turbidity, and specific conductance (p ≥ 0.27, r 2 ≤ 0.18). Our long-term data revealed unanticipated shifts from autotrophic to heterotrophic status within and across years. However, this variability was not strongly associated with environmental factors at either local (i.e., Q or photosynthetically-active radiation) or global (i.e., El Niño-Southern Oscillation) scales. Previous paradigms hold that local attributes dictated by geographic and landscape positioning (e.g., light and temperature regimes) control the trophic status of streams, but our findings suggest that complex combinations of spatiotemporally-variable factors, such as snow accumulation and melting, and their role in connecting terrestrial and aquatic ecosystems can lead to substantial within-stream variation in autotrophic or heterotrophic status. [ABSTRACT FROM AUTHOR]

Fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is frequently detected in surface waters globally, yet the effects of SSRIs on ecological processes at environmentally realistic concentrations are not currently known. We used a controlled, replicated artificial stream experiment to expose biofilm, algal and stream insect communities to two different concentrations of fluoxetine: 20 ng/L (typical concentration detected in surface waters) and 20 µg/L (concentration shown to influence insect emergence and algal productivity). We quantified a range of community and ecosystem response metrics over the course of the 21d experiment including; algal biomass (chl-a), net ecosystem production (NEP), gross primary production (GPP), ecosystem respiration (ER) and invertebrate emergence. At 20 ng/L, fluoxetine significantly suppressed algal colonization on rocks, and reduced GPP after 13 days, but by day 21 chl-a, NEP and GPP did not differ between treatments and control. Fluoxetine increased ER on leaves where invertebrates were excluded, but had no effect on leaves accessible to invertebrates. Streams receiving 20 ng/L of fluoxetine had adult insects from the order Diptera emerge sooner and at a greater rate than control streams. Our results suggest that ecosystem function, including primary production and respiration, and invertebrate population dynamics are sensitive to SSRIs and that fluoxetine may alter these key processes concentrations found in the environment. [ABSTRACT FROM AUTHOR]

Water treatment wetlands are increasingly being used to reduce pollutant loads including nitrogen (N) in urban runoff. Processes such as denitrification (DNF) and anaerobic ammonium oxidation (anammox), which remove N, and dissimilatory nitrate reduction to ammonium (DNRA), which recycles N, play an important role in controlling NOx (NO3− + NO2−) removal versus recycling in wetlands. The relative importance of DNF, anammox and DNRA was investigated in four constructed stormwater urban wetlands in Melbourne, Australia. Rates of DNF and DNRA were variable and did not differ significantly among wetlands. However, rates of DNF and DNRA were significantly different (p < 0.05) in different seasons. The relationship between NOx reduction processes and measured concentrations of water column NOx, chlorophyll a (chl-a), sediment organic carbon (OC), porewater ferrous iron (Fe2+) and sulfide (S2−) and water column temperature were examined using multiple regression analysis (MRA). Anammox was an insignificant pathway (< 0.05% of total nitrate reduction). During winter when average water column temperatures were 12 °C, DNRA was consistently higher than DNF averaging 67 ± 23% of total NOx reduction. The MRA revealed that DNF was positively associated with NOx concentration whereas DNRA was negatively associated with temperature, and porewater Fe2+, and positively associated with chl-a. The ratio between DNF and DNF:(DNF + DNRA) showed a positive correlation with both temperature and NOx concentration in the MRA. At higher temperatures and higher NOx concentrations, DNF increased over DNRA. Overall, this study suggests that at low NOx concentrations, N is recycled internally in these urban stormwater wetlands, but the portion of N removed by DNF increases as NOx concentrations increase. [ABSTRACT FROM AUTHOR]

DOI: 10.1002/elps.201800507 The cover picture shows an environment potentially impacted by pharmaceutical and personal care products (PPCP), arising from e.g. drugs, cosmetics, and household and animal care products. Receiving waters may be from sewage treatment works, or agricultural or urban run‐off. PPCP may affect the ecosystem in ways that are still not fully recognised or quantified. The extent of the problem is firstly assessed by levels in the water, then levels in various ecosystem components biota, biofilm, particulates. Invertebrates that inhabit this environment, may bio‐magnify the PPCP. Here, we report some PPCP levels in various invertebrates. [ABSTRACT FROM AUTHOR]

A bimetallic terbium(iii)/copper(ii) complex (Tb-1·Cu2+) for the time-gated luminescent detection of hydrogen sulfide in aqueous samples is reported. The probe shows excellent selectivity towards HS− over various anions and cations, including the ions common to natural waterways and waste water samples, displaying a 73-fold increase in luminescence in the presence of sulfide. The probe exhibits extremely fast reaction times and a low limit of detection (130 nM). The probe was used to quantify sulfide in an industrial “sour water” sample, with the result in excellent agreement with those from two independent assay methods (methylene blue and AzMC). [ABSTRACT FROM AUTHOR]

The regulation and management of chemical contaminants rarely use community- and ecosystem-level endpoints, partly due to a lack of suitable methods. To overcome this limitation, we propose contaminant exposure substrata ( CES), an adaptation of the widely used nutrient-diffusing substratum method, to assess responses of biofilm communities to chemical contaminants in situ., We describe methods for using CES to assess effects on biofilm biomass, community structure, process rates, biofilm-consumer interactions and biofilm chemistry. We also provide equations to calculate the flux of soluble chemicals from CES and describe an approach to compare contaminant dose in CES assays to the contaminant dose encountered by biofilms in polluted surface waters., Data from four case studies demonstrate that CES can detect impairment of biofilm structure and function., The adaptability, simplicity and cost-effectiveness of CES make them valuable tools to assess community- and ecosystem-level responses to contaminants, suggesting potential for routine use and incorporation of data generated from such assays into contaminant regulation and management. [ABSTRACT FROM AUTHOR]

The effects of pharmaceuticals on aquatic ecosystems are the subject of increasing environmental concern. Of particular interest are a suite of drugs known as selective serotonin reuptake inhibitors (SSRIs), commonly prescribed to treat depression. SSRIs are now detected in the environment worldwide, but their effects on ecosystems are not well understood. We conducted replicated experiments testing for an ecosystem effect of SSRIs in streams. We used artificial stream mesocosms to expose natural biofilms and aquatic insect communities to concentrations (20 µg/L) of fluoxetine or citalopram or a mix of both (totaling 40 µg/L). These concentrations are the lowest found to have an effect on aquatic invertebrates in other studies. Treatments suppressed gross primary production by 29% and community respiration by ≥43% on rock biofilms but did not affect algal biomass or whole-stream metabolism. A common group of dipteran midges emerged earlier in all SSRI treated streams compared with the controls. Total biomass of emerged adults at day 14 was greater in the SSRI-exposed streams, suggesting that fluoxetine and citalopram may influence developmental processes in some stream insects. Ecosystem function and invertebrate population dynamics are sensitive to pharmaceuticals. Our study demonstrates that chronic exposure to fluoxetine and citalopram has the potential to affect aquatic biota and ecosystem function. [ABSTRACT FROM AUTHOR]

Two new bifunctional macrocyclic chelate ligands that form luminescent terbium(III) complexes featuring an alkyne group for conjugation to (bio)molecules via the Cu(I)-catalyzed "click" reaction were synthesized. Upon ligation, the complexes exhibit a significant luminescent enhancement when excited at the λmax of the "clicked" products. To demonstrate the utility of the complexes for luminescent labeling, they were conjugated in vitro to E. coli aspartate/glutamate-binding protein incorporating a genetically encoded p-azido-l-phenylalanine or p-(azidomethyl)-l-phenylalanine residue. The complexes may prove useful for time-gated assay applications. [ABSTRACT FROM AUTHOR]

A new bifunctional macrocyclic chelator featuring a conjugatable alkynyl-naphthalimide fluorophore pendant group has been prepared and its Gd(III) complex coupled to a cell-penetrating lipidated azido-Tat peptide derivative using Cu(I)-catalysed "click" chemistry. The resulting fluorescent conjugate is able to enter CAL-33 tongue squamous carcinoma cells, as revealed by confocal microscopy, producing a very modest anti-proliferative effect (IC50 = 93 μM). Due to the photo-reactivity of the naphthalimide moiety, however, the conjugate's cytotoxicity is significantly enhanced (IC50 = 16 μM) upon brief low-power UV-A irradiation. [ABSTRACT FROM AUTHOR]

The storage and release of phosphorus by sediments can act as an important control on the formation of noxious blooms of cyanobacteria in lakes and estuaries. Here we studied the uptake and release of phosphorus associated with iron oxides within sediments of a lagoon system affected by recurring summer blooms of the cyanobacterium Nodularia spumigena. Using an ascorbate extraction, we observed deep pools of iron oxide associated phosphorus (P) at concentrations of ∼5 μmol g−1 dry sed to a depth of ∼20 cm. This pool rapidly decreased with the onset of water column anoxia, leading to an integrated release of ∼300 mmol of phosphorus m−2 of sediment over 3.5 months. Scaling this flux over the periodically anoxic area of the lake and over the period of an N. spumigena bloom (November-December 2011) gave a broad mass balance agreement with the increase in total phosphorus within the water column and exported from the lagoon. Over this period we estimated that P release from the sediment would have allowed ∼130-187 tonnes of nitrogen to be fixed which agrees with previous estimates of nitrogen fixation. Upon reoxygenation of the water column, a regeneration of the deep iron oxide associated phosphorus pool was observed. This deep dynamic pool of phosphorus was most likely mediated by the burrowing activity of the polychaete Capitella capitata which was observed at the study site. This study underscores the potential importance of sediments colonized by deeply irrigating fauna to become a significant source of phosphorus during water column anoxia. [ABSTRACT FROM AUTHOR]

The long-term efficacy of stormwater treatment systems requires continuous pollutant removal without substantial re-release. Hence, the division of incoming pollutants between temporary and permanent removal pathways is fundamental. This is pertinent to nitrogen, a critical water body pollutant, which on a broad level may be assimilated by plants or microbes and temporarily stored, or transformed by bacteria to gaseous forms and permanently lost via denitrification. Biofiltration systems have demonstrated effective removal of nitrogen from urban stormwater runoff, but to date studies have been limited to a ‘black-box’ approach. The lack of understanding on internal nitrogen processes constrains future design and threatens the reliability of long-term system performance. While nitrogen processes have been thoroughly studied in other environments, including wastewater treatment wetlands, biofiltration systems differ fundamentally in design and the composition and hydrology of stormwater inflows, with intermittent inundation and prolonged dry periods. Two mesocosm experiments were conducted to investigate biofilter nitrogen processes using the stable isotope tracer 15NO3− (nitrate) over the course of one inflow event. The immediate partitioning of 15NO3− between biotic assimilation and denitrification were investigated for a range of different inflow concentrations and plant species. Assimilation was the primary fate for NO3− under typical stormwater concentrations (∼1–2 mg N/L), contributing an average 89–99% of 15NO3− processing in biofilter columns containing the most effective plant species, while only 0–3% was denitrified and 0–8% remained in the pore water. Denitrification played a greater role for columns containing less effective species, processing up to 8% of 15NO3−, and increased further with nitrate loading. This study uniquely applied isotope tracing to biofiltration systems and revealed the dominance of assimilation in stormwater biofilters. The findings raise important questions about nitrogen release upon plant senescence, seasonally and in the long term, which have implications on the management and design of biofiltration systems. [ABSTRACT FROM AUTHOR]

Abstract: The development and evaluation of a portable flow analysis system for the in situ determination of total phosphorus is described. The system has been designed with rapid underway monitoring in mind. The system employs an ultra-violet photo-reactor and thermal heating for peroxodisulfate digestion of total phosphorus to orthophosphate, followed by spectrophotometric detection with a multi-reflective flow cell and low-power light emitting diode using the molybdenum blue method. Reagents are stored under gas pressure and delivered using software controlled miniature solenoid valves. The fully automated system has a throughput of 115 measurements per hour, a detection limit of 1μgPL−1, and gives a linear response over the calibration range of 0–200μgPL−1 (r 2 =0.9998), with a precision of 4.6% RSD at 100μgPL−1 (n =10). Field validation of the instrument and method was performed in Port Philip and Western Port Bays in Victoria, SE Australia, where 2499 analyses were performed over a 25h period, over a cruise path of 285km. Good agreement was observed between determinations of samples taken manually and analysed in the laboratory and those measured in situ with the flow analysis system. [ABSTRACT FROM AUTHOR]

Clustering of multivariate data is a commonly used technique in ecology, and many approaches to clustering are available. The results from a clustering algorithm are uncertain, but few clustering approaches explicitly acknowledge this uncertainty. One exception is Bayesian mixture modelling, which treats all results probabilistically, and allows comparison of multiple plausible classifications of the same data set. We used this method, implemented in the AutoClass program, to classify catchments (watersheds) in the Murray Darling Basin (MDB), Australia, based on their physiographic characteristics (e.g. slope, rainfall, lithology). The most likely classification found nine classes of catchments. Members of each class were aggregated geographically within the MDB. Rainfall and slope were the two most important variables that defined classes. The second-most likely classification was very similar to the first, but had one fewer class. Increasing the nominal uncertainty of continuous data resulted in a most likely classification with five classes, which were again aggregated geographically. Membership probabilities suggested that a small number of cases could be members of either of two classes. Such cases were located on the edges of groups of catchments that belonged to one class, with a group belonging to the second-most likely class adjacent. A comparison of the Bayesian approach to a distance-based deterministic method showed that the Bayesian mixture model produced solutions that were more spatially cohesive and intuitively appealing. The probabilistic presentation of results from the Bayesian classification allows richer interpretation, including decisions on how to treat cases that are intermediate between two or more classes, and whether to consider more than one classification. The explicit consideration and presentation of uncertainty makes this approach useful for ecological investigations, where both data and expectations are often highly uncertain. [ABSTRACT FROM AUTHOR]