Activity

Passive sampling to regularly identify the occurrence of pyrethroid insecticides in urban streams is a crucial work of risk management with respect to intrinsic toxicity of pyrethroids to aquatic organisms. Polymeric films, based on an equilibrium sampling principle, have found increasing use as passive samplers for hydrophobic contaminants. Herein, we investigated two thin-film samplers, namely silicone rubber (SR) and polyvinylchloride (PVC), compatible with a suite of 8 pyrethroids, for measuring freely dissolved concentrations (Cfree) in water. The characteristics of SR and PVC samplers were estimated in terms of equilibrium partitioning coefficients (Kf) with log units of 3.90-4.67 and sampling rates (Rs) of 0.011-0.016 L/h. The parameters were correlated positively with octanol-water partition coefficients of the compounds, whereas independent on water solubility. A strong agreement between Cfree obtained from the two samplers was observed in a range of 0.1-10 μg/L for pyrethroids under laboratory simulated conditions. Both of SR and PVC were confirmed as equilibrium samplers with faster sampling rates of pyrethroids that equilibrated on films within only one week, and higher accumulation at factors of 5.3-12.5 and 1.5-2.4 compared to a performance reference compound (PRC)-preload sampler. Additionally, the comparable results of the two passive sampling methods in multiple field applications indicated that the direct deployment of the two samplers without PRCs calibration can provide reliable assessment of trace concentrations. This study demonstrated the routine utilization of SR and PVC as promising tools for rapid and sensitive in-situ monitoring of pyrethroids, and indicators for the bioavailability against total chemical concentrations in variable aquatic environments. V.Although widely implemented, the research and understanding of the economic impacts and benefits of green infrastructure (GI) systems remain limited. Currently, few studies have investigated the economics of GI systems from a spatial perspective and typically opportunity costs related to land and property tax were ignored. This study aims at bridging these gaps by investigating both the equivalent annual costs (EAC) and cost effectiveness of seven GI systems and compare them against local wastewater treatment facilities in five different US cities. To do this, we utilized capital and maintenance cost data obtained from GI systems that are currently installed at the University of New Hampshire. The costing data were then extrapolated across five different cities considering reported local material, land, tax, and labor rates. A system dynamics model was utilized to calculate the total stormwater reduction as well as the amounts of nitrogen and phosphorous removed by each GI system over its life cycle under a certain city setting. Based upon these outcomes, the cost effectiveness (CE) in terms of stormwater reduction, nitrogen treatment, and phosphorous treatment of the GI systems was calculated. Land and tax costs were found to be a significant component of the EAC for GI systems with larger footprints in cities with higher property values, accounting for up to 78% in some cities. The rankings of the GI systems differ significantly when different types of cost effectiveness are under consideration. The tree filter performs the best when the CE is calculated based on stormwater reductions, while the subsurface gravel wetland performs the best considering nitrogen treatment, and either the subsurface gravel wetland or the sand filter performs the best considering phosphorous treatment. Our study suggests recommendations of GI systems need to be made based on local needs and issues to achieve the most cost-effective solution. It is essential to have tools that can be used to diagnose water resources. For this reason, this study sets out on the one hand to assess water quality in three reservoirs in Spain (Salas, A Baxe and Conchas) with Cyano-Habs problems through the application of water quality indexes The National Sanitation Foundation Water Quality Index (NFSWQI), the General Quality Index (GQI), the Trophic State Index (TSI), and the Trophic Contamination Index (ICOTRO). On the other hand, it seeks to learn how parameters such as nitrogen and phosphorus influence the presence of cyanotoxin, specifically Microcystis aeruginosa. To that end, samples from the three reservoirs are cultured and physical-chemical parameters and the toxicity of the water are measured. The results show that Salas reservoir has the worst water quality rating (GQI is bad and NFSWQI medium), while As Conchas and A Baxe obtain very good figures for NFSWQI. This contrasts with the data obtained via the TSI of moderately eutrophic conditions for all three reservoirs, and hypereutrophic levels for As Conchas and A Baxe downstream. Acetosyringone cost On the other hand, the toxicity analysis shows levels of 1.12 ± 0.06 μg/l microcystin-LR (MC-LR) for As Conchas, 0.64 ± 0.04 μg/l MC-LR for Salas, and 1.24 ± 0.05 μg/l MC-LR for A Baxe, of which 20% corresponds to free MC-LR. This study finds that nitrogen is the parameter that most favors the production of MC-LR. We conclude that the eutrophication indexes are more reliable when studying the presence of cyanobacteria. Furthermore, nitrogen and phosphorous are the most significant parameters in this regard. They are taken into account in the quality indices (GQI, NFSWI), but they are not sufficiently representative. It is recommended as a future line of research that water quality indices be adapted or designed to incorporate eutrophication levels and even water toxicity. Species sharing resources are predicted to compete, but co-occurring species can avoid competition through niche partitioning. Here, we investigated the inter- and intra-specific differences using stable isotope analyses in the black-bellied storm-petrel (Fregetta tropica) and the Wilson’s storm-petrel (Oceanites oceanicus), breeding sympatrically in maritime Antarctica. We analysed stable carbon, nitrogen and oxygen isotopes in samples representing different life stages; chick down (pre-laying females), chick feather (chick), and adult blood (chick-rearing adults). Pre-laying females had wider stable isotope niches than chicks or chick-rearing adults, due to pre-laying females being free roaming while chick-rearing adults were central-place-foragers. Chicks were fed at a higher trophic level than the adults (higher δ15N), likely to compensate for the high nutritional demands of the growing chicks. Wilson’s storm-petrels showed substantial overlap in stable isotope niches between all life stages, while the black-bellied storm-petrel chicks showed very little overlap.