A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis

A simple, effective mixing chamber used in conjunction with a syringe pump for flow analysis is described and evaluated. A mixing chamber was constructed using a conventional 5mL pipette tip and its performance compared with a widely used mixing coil. The results demonstrate that the mixing coil does not rapidly and completely mix solutions. Utilizing a configuration that reversed solution positions in the chamber with each mixing cycle, the proposed mixing chamber achieved complete mixing in a significantly shorter time than the mixing coil. The influence of injected sample volume on absorbance signals was evaluated by calculating an S1/2 value for the system. As tested with a minimal rinse, the system has no discernable carryover. Testing this new approach in our previously described silicate measurement system resulted in a more than twofold improvement in sensitivity

A simplified coulometric method for multi-sample measurements of total dissolved inorganic carbon concentration in marine waters

A new system requiring greatly reduced operator intervention has been developed for the determination of dissolved inorganic carbon concentration in marine waters. Based on a coulometric method, the system has an accuracy and precision comparable to more complex and expensive methods currently employed. A syringe pump equipped with a 12-port distribution valve is used to precisely dispense an acid solution and sample into a gas stripper. The system can autonomously measure eight discrete samples in duplicate or triplicate with no operator input. The best precision (%RSD) obtained was 0.022% (n = 14) or less than +/- 1.0 mu mol kg(-1). The system is calibrated against a certified reference material (CRM). Average offset from the CRM was 1.2 mu mol kg(-1). Sample throughput was 4 samples per h. Carryover effects are negligible but field sample analyses suggest that prefiltering may be necessary in highly turbid waters

An autonomous batch analyzer for the determination of trace ammonium in natural waters using fluorometric detection

An autonomous batch analyzer (ABA) is described for the measurement of ammonium in natural waters. The system combines previously described batch analysis and continuous flow analysis methods. With its simpler design, the system is robust, flexible, inexpensive, and requires minimal maintenance. The sampling frequency is ca. 8 h(-1) and the limit of detection ca. 1 nM which is comparable to the most sensitive flow through or batch analysis methods previously described. Reproducibility is 0.6% (n=10) at an ammonium level of 200 nM. There are three working ranges: 5-1000 nM, 20-4000 nM, and 0.2-25 mu M. In addition, the system produces a calibration curve by autodilution from a single stock standard solution with the same accuracy as traditional manual calibration methods. Representative field data and comparisons with standard EPA methods confirm the utility of the ABA

Capillary Scale Admittance Detection

Techniques that have been variously termed oscillometric detection or (capacitively coupled) contactless conductivity detection (C⁴D) are known actually to respond to the admittance. It is not often appreciated that the frequency range (<i>f</i>) over which such systems respond (quasi)­linearly with the cell conductance decreases acutely with increasing cell resistance. Guidance on optimum operating conditions for high cell resistance, such as for very small capillaries/channels and/or solutions of low specific conductance (σ), is scant. It is specially necessary in this case to take the capacitance of the solution into account. At high frequencies and low σ values, much of the current passes through the solution behaving as a capacitor and the capacitance is not very dependent on the exact solution specific conductance, resulting in poor, zero, or even negative response. We investigated, both theoretically and experimentally, capillaries with inner radii of 5–160 μm and σ ≈ 1–1400 μS/cm, resulting in cell resistances of 51 GΩ to 176 kΩ. A 400-element discrete model was used to simulate the behavior. As model inputs, both the wall capacitance and the stray capacitance were measured. The solution and leakage capacitances were estimated from extant models. The model output was compared to the measured response of the detection system over broad ranges of <i>f</i> and σ. Other parameters studied include capillary material and wall thickness, electrode spacing and length, Faraday shield thickness, excitation wave forms, and amplitude. The simulations show good qualitative agreement with experimental results and correctly predict the negative response behavior observed under certain conditions. We provide optimum frequencies for different operating conditions

Coral reef monitoring, reef assessment technologies, and ecosystem-based management

Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi-dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems.This paper benefited from the financial support to the authors provided by their institutions and the grants for research, monitoring and/or coordination they have secured. The development of this manuscript has been supported through ongoing work of the Global Coral Reef Monitoring Network and the Global Ocean Observing System�s Biology and Ecosystems Panel, supported by the International Coral Reef Initiative, United Nations Environment Programme, the United Nations Educational, Scientific and Cultural Organization�s Intergovernmental Oceanographic Commission, and Future Earth among others.Scopu

Coral Reef Monitoring, Reef Assessment Technologies, and Ecosystem-Based Management

Coral reefs are exceptionally biodiverse and human dependence on their ecosystem services is high. Reefs experience significant direct and indirect anthropogenic pressures, and provide a sensitive indicator of coastal ocean health, climate change, and ocean acidification, with associated implications for society. Monitoring coral reef status and trends is essential to better inform science, management and policy, but the projected collapse of reef systems within a few decades makes the provision of accurate and actionable monitoring data urgent. The Global Coral Reef Monitoring Network has been the foundation for global reporting on coral reefs for two decades, and is entering into a new phase with improved operational and data standards incorporating the Essential Ocean Variables (EOVs) (www.goosocean.org/eov) and Framework for Ocean Observing developed by the Global Ocean Observing System. Three EOVs provide a robust description of reef health: hard coral cover and composition, macro-algal canopy cover, and fish diversity and abundance. A data quality model based on comprehensive metadata has been designed to facilitate maximum global coverage of coral reef data, and tangible steps to track capacity building. Improved monitoring of events such as mass bleaching and disease outbreaks, citizen science, and socio-economic monitoring have the potential to greatly improve the relevance of monitoring to managers and stakeholders, and to address the complex and multi- dimensional interactions between reefs and people. A new generation of autonomous vehicles (underwater, surface, and aerial) and satellites are set to revolutionize and vastly expand our understanding of coral reefs. Promising approaches include Structure from Motion image processing, and acoustic techniques. Across all systems, curation of data in linked and open online databases, with an open data culture to maximize benefits from data integration, and empowering users to take action, are priorities. Action in the next decade will be essential to mitigate the impacts on coral reefs from warming temperatures, through local management and informing national and international obligations, particularly in the context of the Sustainable Development Goals, climate action, and the role of coral reefs as a global indicator. Mobilizing data to help drive the needed behavior change is a top priority for coral reef observing systems