Improving Accuracy and Precision of Marine Inorganic Carbon Measurements

提高海洋无机碳测量的准确性和精度海洋吸收了人类燃烧化石燃料和其他活动释放到大气中的二氧化碳的约三分之一。虽然海洋对二氧化碳的吸收减缓了其在大气中的增长速度，但它也给海洋和生活在那里的生物带来了代价。一旦进入海水，二氧化碳与水反应产生碳酸氢根和氢离子。氢离子的增加会降低pH值，这一过程被称为海洋酸化。并非所有海洋区域都受到同样的影响。二氧化碳在北极寒冷的沃茨中的溶解度更大，使它们更容易受到海洋酸化的影响。然而，由于北极温度低、盐度低，pH值的不确定性比其他海洋大得多。该项目评估了低温和盐度下的pH值，并提出了最佳实践建议，以提高在实验室组和研究之间比较测量结果的能力，并降低测量结果的总体不确定性。该项目为一名本科生提供培训，并通过公共宣传提高对海洋酸化的认识。高度准确和精确的测量对于监测pH值和CO2吸收随时间的变化以及对海洋生物的影响至关重要。为了改进极地沃茨的pH测量，将进行几个不同的实验。对于低盐度沃茨，pH值的温度依赖性将在30 ℃至接近冰点的范围内确定。结果将与当前的化学模型进行比较，以量化抵消和偏差。将提出用于低温和盐度海水的最佳物理化学模型的建议。此外，使用指示剂染料通过比色法测量pH。指标的编制和校准对于标准化跨空间和时间的研究并确保可比性非常重要。指标质量对于检测海洋酸化至关重要，但其稳定性目前尚不清楚。如果染料在生产后降解，则随着染料老化，可能会导致pH测量中的偏差或伪影。实验将使用从几周到10年以上的染料批次进行，以解决其降解特性。这些实验将确定一批染料在制备后保持有效的时间，而不会使测量产生偏差。这对于长期研究特别重要，例如长期研究探险和自治系统，其中一批染料可能使用一年以上。总之，通过研究低温和盐度下海水pH值化学模型的有效性，并检查pH指示剂染料的稳定性，可以减少方法的不确定性，从而更好地监测全球海洋pH值的变化。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Improving Accuracy and Precision of Marine Inorganic Carbon MeasurementsThe oceans absorb about one third of the CO2 humans release into the atmosphere from the burning of fossil fuels and other activities. While ocean uptake of CO2 slows its rate of increase in the atmosphere, it comes with costs for the oceans and the organisms that live there. Once in seawater, CO2 reacts with water to produce bicarbonate and hydrogen ions. The increase in hydrogen ions lowers the pH in a process called ocean acidification. Not all areas of the ocean are affected equally. The solubility of CO2 is greater in the cold waters of the Arctic making them more prone to ocean acidification. However, due to the low temperatures and low salinities in the Arctic, the uncertainties in pH values are much larger there than for the other oceans. This project evaluates pH at low temperatures and salinities, and develops best practice recommendations to improve the ability to compare measurements among laboratory groups and studies and reduce overall uncertainty in the measurements. The project provides training for an undergraduate student and promotes awareness of ocean acidification through public outreach. Having highly accurate and precise measurements are important for monitoring changes to pH and CO2 uptake through time and the effects on marine life. In order to improve pH measurements for polar waters, several different experiments will be conducted. The temperature dependence of pH will be determined from 30˚C to near freezing for low salinity waters. The results will be compared to current chemical models to quantify offsets and biases. Recommendations will be made for the best physical chemical model to use for low temperature and salinity seawater. Moreover, pH is measured spectrophotometrically using an indicator dye. Preparation and calibration of the indictor is important to standardize studies across space and time and ensure comparability. Indicator quality is essential for detecting ocean acidification, but its stability is currently unknown. If the dye degrades after production, biases or artifacts in pH measurements may result as the dye ages. Experiments will be undertaken using batches of dyes from weeks to over 10 years old to resolve its degradation characteristics. The experiments will establish how long a batch of dye remains valid once it is prepared without biasing the measurements. This is particularly important for long term studies such as extended research expeditions and autonomous systems where a batch of dye may be used over a year. Together, by both investigating the validity of chemical models for seawater pH at low temperature and salinity and examining the stability of the pH indicator dye, methodological uncertainties can be reduced to permit better monitoring of changes in global ocean pH.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.