Groundwater sources of "new" N for benthic microalgal production in the South Atlantic Bight

用于南大西洋湾底栖微藻生产的“新”氮的地下水源

• 批准号: 1736557
• 负责人: James Pinckney
• 金额: $ 99.32万
• 依托单位: University of South Carolina at Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736557&HistoricalAwards=false
• 关键词: Groundwater; sources; new; benthic; microalgal

Continental shelves are highly productive, with both ecological and economic importance. Benthic microalgae (BMA) are key primary producers in these location. As much as 6x the water column biomass of primary producers is compressed into a layer only a few mm thick on the sediment surface. The source(s) of fixed nitrogen (N) supporting such highly concentrated BMA biomass is currently unknown. Recent studies of sub-seafloor groundwater flow at the University of South Carolina have demonstrated that upwelling saline groundwater likely supplies high concentrations of nutrients in the ridge-swale habitats in the South Atlantic Bight (SAB). The investigators suggest that groundwater input of fixed N into surficial sediments is the primary source of N supporting BMA biomass and production in the mid-shelf region of the SAB. The purpose of this project is to determine the primary source of fixed N supporting BMA biomass in the surface sediments of the shallow shelf waters (30 m), using the SAB as a field area. A secondary objective is to apply novel and innovative methods to directly quantify groundwater inputs of N into surficial sediments. Research results will fully document the spatio-temporal distributions of BMA and phytoplankton biomass and community structure in the mid-shelf region of the SAB and relate the observed patterns to groundwater inputs of fixed N sources as well as hydrographic and climatic conditions. This research will provide full support and tuition for 2 graduate students, summer support for undergraduate assistants, and involve upper level undergraduates as lab interns. The study team will also work with the Baruch Institute and other partners to develop an "Ocean Schoolyard" program to meet the needs of teachers, students, and community audiences. The project will also provide partial support for Girls Go for I.T., a coding summer camp designed to attract middle-school-aged girls to careers in I.T. and STEM fieldsThe specific objectives of the study are to (1) quantify spatial and temporal variations in N fluxes associated with hydrodynamic exchange and upward groundwater flow (2) document spatial and temporal variations in BMA biomass and (3) measure the delta15N of fixed nitrogen sources (well water, porewater and water column ammonium and nitrate; sediments), the BMA, and phytoplankton. The sampling area will be restricted to the 10 - 30 m isobath region of the SAB off the coast of Charleston, SC. Samples will be collected at both the existing groundwater well field and other regions of the shelf. At each of the groundwater wells in the well field, SCUBA divers will collect fluids from the wells to determine well water inorganic nutrient concentrations (nitrate + nitrite, ammonium, orthophosphate, silicon) and the delta 15N of well water ammonium and nitrate (when present). In nearby sediments, samples will be collected for BMA biomass and community composition, surface porewater inorganic nutrients (nitrate + nitrite, ammonium, orthophosphate, silicon), C and N of sediments, sediment grain size analysis, and delta 15N of BMA, ammonium, nitrate (when present), and sediments. Line transects, consisting of 5 sampling locations along a 50 m transect, will be conducted in each of the 4 depth strata. At 10 m intervals along each transect, divers will collect samples the same as above for the well field. Water column samples will be collected for HPLC measurements of phytoplankton biomass and community composition, inorganic nutrient concentrations (nitrate + nitrite, ammonium, orthophosphate, silicon), seston CHN, delta 15N of phytoplankton, and the delta 15N of ammonium and nitrate. The researchers will use heat as a tracer to map the depth of hydrodynamic exchange and monitor the rate of vertical groundwater flow. Results from that analysis will also allow them to then simulate transport of a conservative tracer that can be compared to observed nutrient concentrations to BMA abundance and community composition.

大陆架生产力很高，具有生态和经济重要性。底栖微藻 (BMA) 是这些地区的主要初级生产者。 初级生产者水体生物量的六倍被压缩成沉积物表面仅几毫米厚的层。支持如此高度浓缩的 BMA 生物质的固定氮 (N) 来源目前尚不清楚。 南卡罗来纳大学最近对海底地下水流的研究表明，上升的咸水地下水可能为南大西洋湾（SAB）的山脊洼地栖息地提供高浓度的营养物质。 研究人员认为，地下水输入地表沉积物中的固定氮是支持 SAB 中陆架区域 BMA 生物量和生产的主要氮源。该项目的目的是确定浅陆架水域（30 m）表层沉积物中固定氮支持 BMA 生物量的主要来源，以 SAB 作为现场区域。 第二个目标是应用新颖和创新的方法来直接量化地下水中氮输入到表层沉积物中。 研究结果将全面记录SAB中陆架区域BMA和浮游植物生物量和群落结构的时空分布，并将观察到的模式与固定氮源的地下水输入以及水文和气候条件联系起来。 这项研究将为 2 名研究生提供全额支持和学费，为本科生助理提供暑期支持，并邀请高年级本科生作为实验室实习生。 研究团队还将与巴鲁克研究所和其他合作伙伴合作开发“海洋校园”计划，以满足教师、学生和社区受众的需求。该项目还将为 Girls Go for I.T. 提供部分支持，这是一个编程夏令营，旨在吸引中学生从事 I.T 职业。该研究的具体目标是（1）量化与水动力交换和地下水向上流动相关的氮通量的空间和时间变化（2）记录BMA生物量的空间和时间变化，（3）测量固定氮源（井水、孔隙水和水柱铵和硝酸盐；沉积物）、BMA和 浮游植物。采样区域将仅限于南卡罗来纳州查尔斯顿海岸外 SAB 的 10 - 30 m 等深线区域。样品将在现有地下水井场和陆架的其他区域采集。 在井场的每个地下水井，水肺潜水员将从井中收集液体，以确定井水中无机营养物浓度（硝酸盐 + 亚硝酸盐、铵、正磷酸盐、硅）以及井水中铵和硝酸盐（如果存在）的 Delta 15N。在附近的沉积物中，将采集 BMA 生物量和群落组成、表面孔隙水无机养分（硝酸盐 + 亚硝酸盐、铵、正磷酸盐、硅）、沉积物的 C 和 N、沉积物粒度分析以及 BMA、铵、硝酸盐（如果存在）和沉积物的 Delta 15N 样本。 线样线由沿 50 m 样线的 5 个采样点组成，将在 4 个深度地层中的每一个中进行。 沿每条样线每隔 10 m，潜水员将采集与上述井场相同的样本。 将收集水柱样品，用于浮游植物生物量和群落组成、无机养分浓度（硝酸盐+亚硝酸盐、铵、正磷酸盐、硅）、seston CHN、浮游植物的 delta 15N 以及铵和硝酸盐的 delta 15N 的 HPLC 测量。研究人员将使用热量作为示踪剂来绘制水动力交换的深度并监测垂直地下水流的速率。该分析的结果还将使他们能够模拟保守示踪剂的运输，并将其与观察到的营养物浓度、BMA 丰度和群落组成进行比较。

项目成果

Nutrient breakpoints for estuarine phytoplankton communities

河口浮游植物群落的营养断点

• DOI: 10.1002/lno.11570
• 发表时间: 2020
• 期刊: Limnology and Oceanography
• 影响因子: 4.5
• 作者: Pinckney, James L.;Knotts, Eilea R.;Kibler, Krystyn J.;Smith, Erik M.
• 通讯作者: Smith, Erik M.

A Mini-Review of the Contribution of Benthic Microalgae to the Ecology of the Continental Shelf in the South Atlantic Bight

底栖微藻对南大西洋湾大陆架生态贡献的小回顾

• DOI: 10.1007/s12237-018-0401-z
• 发表时间: 2018
• 期刊: Estuaries and Coasts
• 影响因子: 2.7
• 作者: Pinckney, James L.

Predicted Episode of Submarine Groundwater Discharge Onto the South Carolina, USA, Continental Shelf and Its Effect on Dissolved Oxygen

• DOI: 10.1029/2022gl100438
• 发表时间: 2022-12
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: W. Moore;J. Vincent;James L. Pickney;Alicia M. Wilson

Seasonality of benthic microalgal community abundance in shallow shelf waters

浅陆架水域底栖微藻群落丰度的季节性

• DOI: 10.1016/j.csr.2022.104797
• 发表时间: 2022
• 期刊: Continental Shelf Research
• 影响因子: 2.3
• 作者: Pinckney, James L.;Zaunbrecher, Sarah;Lang, Susan;Wilson, Alicia;Knapp, Angela
• 通讯作者: Knapp, Angela