Improving Accuracy and Precision of Marine Inorganic Carbon Measurements

提高海洋无机碳测量的准确性和精确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大约三分之一的二氧化碳。虽然海洋吸收二氧化碳的速度减缓了其在大气中的增长速度，但这也给海洋和生活在那里的生物带来了成本。一旦进入海水，二氧化碳就会与水反应，生成碳酸氢根和氢离子。氢离子的增加降低了被称为海洋酸化的过程中的pH值。并不是所有的海洋区域都受到同样的影响。在北极的冷水中，二氧化碳的溶解度更大，因此更容易发生海洋酸化。然而，由于北极的低温和低盐度，那里的PH值的不确定性比其他海洋大得多。该项目评估低温和盐度下的酸碱度，并制定最佳实践建议，以提高实验室小组和研究之间比较测量结果的能力，并减少测量结果的总体不确定性。该项目为本科生提供培训，并通过公众宣传提高对海洋酸化的认识。对于监测pH值和二氧化碳吸收随时间的变化及其对海洋生物的影响，拥有高度准确和精确的测量是重要的。为了改进极地水域的酸碱度测量，将进行几个不同的实验。对于低盐度水域，pH的温度依赖关系将从30℃到接近冰点确定。结果将与目前的化学模型进行比较，以量化偏移量和偏差。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，pH值是用指示染料分光光度法测量的。指标的编制和校准对于使跨空间和跨时间的研究标准化并确保可比性很重要。指示剂质量是检测海洋酸化的关键，但其稳定性目前尚不清楚。如果染料在生产后降解，随着染料的老化，可能会在pH测量中产生偏差或伪影。将使用从几周到10多年的一批染料进行实验，以解决其降解特性。这些实验将确定一批染料在不影响测量结果的情况下，在制备完成后保持有效的时间。这对于长期研究尤其重要，例如延长的研究探险和自主系统，在这些系统中，一批染料可能会在一年内使用。总而言之，通过调查低温和盐度下海水pH的化学模型的有效性和检查pH指示剂染料的稳定性，可以减少方法上的不确定性，以便更好地监测全球海洋pH的变化。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.