Mississippi River Research Articles

A numerical assessment of ocean alkalinity enhancement efficiency on a river-dominated continental shelf – a case study in the northern Gulf of Mexico

Abstract A robust high-resolution coupled hydrodynamic-biogeochemical model was applied to the northern Gulf of Mexico to assess the efficiency of river- and ocean-sourced Ocean Alkalinity Enhancement (OAE). Sensitivity tests indicate that the effectiveness of OAE-induced CO2 uptake is primarily influenced by the amount of alkalinity introduced and local wind-driven mixing, with the former determining the overall uptake and the latter affecting short-term variability. Compared to ocean-sourced OAE (direct ocean release), river-sourced OAE (elevated river alkalinity) is more effective and sustainable. River-sourced OAE has higher CO2 uptake efficiency with reduced spatial and temporal uncertainty and greater overall CO2 uptake. For river-sourced OAE, surface pH increases pronouncedly near the mouths of the Mississippi River. The ideal OAE implementation time includes spring, early summer, fall, and winter. Mid and late-summer implementation is not recommended due to weak mixing, which results in less alkalinity dispersal and greater pH variability. In addition, while the aragonite saturation state generally remains below 6 around the Mississippi River plume, it increases pronouncedly during mid to late summer, risking alkalinity loss due to CaCO3 precipitation and reduced CO2 uptake efficiency near river mouths. Scaling OAE-induced CO2 uptake to the 25 largest rivers in the world indicates that increasing riverine alkalinity concentrations by 10% could remove 23.23 megatons of CO2 annually, meeting 0.37–0.61% of the 2025–2030 CO2 removal target.

Adaptive Month Matching: A Phenological Alignment Method for Transfer Learning in Cropland Segmentation

The increasing demand for food and rapid population growth have made advanced crop monitoring essential for sustainable agriculture. Deep learning models leveraging multispectral satellite imagery, like Sentinel-2, provide valuable solutions. However, transferring these models to diverse regions is challenging due to phenological differences in crop growth stages between training and target areas. This study proposes the Adaptive Month Matching (AMM) method to align the phenological stages of crops between training and target areas for enhanced transfer learning in cropland segmentation. In the AMM method, an optimal Sentinel-2 monthly time series is identified in the training area based on deep learning model performance for major crops common to both areas. A month-matching process then selects the optimal Sentinel-2 time series for the target area by aligning the phenological stages between the training and target areas. In this study, the training area covered part of the Mississippi River Delta, while the target areas included diverse regions across the US and Canada. The evaluation focused on major crops, including corn, soybeans, rice, and double-cropped winter wheat/soybeans. The trained deep learning model was transferred to the target areas, and accuracy metrics were compared across different time series chosen by various phenological alignment methods. The AMM method consistently demonstrated strong performance, particularly in transferring to rice-growing regions, achieving an overall accuracy of 98%. It often matched or exceeded other phenological matching techniques in corn segmentation, with an average overall accuracy across all target areas exceeding 79% for cropland segmentation.

Impacts of the Bonnet Carré Spillway on common bottlenose dolphins in the Mississippi Sound from 2010 to 2021.

In the last decade, the frequency of the use of the Bonnet Carré Spillway (BCS) to divert water from the Mississippi River by the United States Army Corps of Engineers (USACE) has dramatically increased. The BCS is designed to protect the city of New Orleans, Louisiana from levee breaches and devastating floods. In 2011 and 2019, during extreme flood events, the USACE diverted 6.4 trillion gallons and 10.07 trillion gallons of Mississippi River water into Lake Borgne and Biloxi Marsh, Louisiana, and the Mississippi Sound, Mississippi. The 2011 and 2019 diversions and lower-discharge diversions in other years have coincided with high freshwater discharges of coastal Mississippi streams, the appearance of common bottlenose dolphins (Tursiops truncatus, dolphins) with skin lesions, and large numbers of stranded dolphins. To determine what might be causing dolphin skin lesions and strandings, we investigated BCS and coastal stream discharges between 2010 and 2021 as possible drivers. Generalized additive, kriging, and seasonal-trend decomposition using loess models showed that the prevalence of skin lesions in the western Mississippi Sound and Biloxi Marsh was significantly related to BCS discharge and not to stream discharge. From 2010 to 2021, the frequency of stranded dolphins across the Mississippi Sound was significantly related to BCS discharges, while coastal stream discharges had localized effects. Between 2018 and 2019, the relationship between the frequency of dolphin strandings and BCS discharge was highly significant. In this model, the relationship between dolphin strandings and stream discharge was not significant. This research provides evidence that freshwater diversions through the BCS likely increase the prevalence of skin lesions on live dolphins, strandings, and mortality in the Mississippi Sound.

Fish as Environmental Sentinels for Metal Contaminants of Human Health Concern in the Lower Mississippi River Basin

Fish as Environmental Sentinels for Metal Contaminants of Human Health Concern in the Lower Mississippi River Basin

Geographic distance to Commission on Cancer-accredited and nonaccredited hospitals in the United States.

The Commission on Cancer (CoC) establishes standards to support multidisciplinary, comprehensive cancer care. CoC-accredited cancer programs diagnose and/or treat 73% of patients in the United States. However, rural patients may experience diminished access to CoC-accredited cancer programs. Our study evaluated distance to hospitals by CoC accreditation status, rurality, and Census Division. All US hospitals were identified from public-use Homeland Infrastructure Foundation-Level Data, then merged with CoC-accreditation data. Rural-Urban Continuum Codes (RUCC) were used to categorize counties as metro (RUCC 1-3), large rural (RUCC 4-6), or small rural (RUCC 7-9). Distance from each county centroid to the nearest CoC and non-CoC hospital was calculated using the Great Circle Distance method in ArcGIS. Of 1,382 CoC-accredited hospitals, 89% were in metro counties. Small rural counties contained a total of 30 CoC and 794 non-CoC hospitals. CoC hospitals were located 4.0, 10.1, and 11.5 times farther away than non-CoC hospitals for residents of metro, large rural, and small rural counties, respectively, while the average distance to non-CoC hospitals was similar across groups (9.4-13.6 miles). Distance to CoC-accredited facilities was greatest west of the Mississippi River, in particular the Mountain Division (99.2 miles). Despite similar proximity to non-CoC hospitals across groups, CoC hospitals are located farther from large and small rural counties than metro counties, suggesting rural patients have diminished access to multidisciplinary, comprehensive cancer care afforded by CoC-accredited hospitals. Addressing distance-based access barriers to high-quality, comprehensive cancer treatment in rural US communities will require a multisectoral approach.

Bedrock Origins from Petrology and Geochemistry: Volcanic Gravel Clasts from the Rawhide Terrace in the Pleistocene Ancestral Mississippi River Pre-Loess Terrace Deposits

Situated throughout the southeastern United States within the Laurentian craton are occurrences of various aged deposits (Late Proterozoic to Early Paleogene) that contain volcanics spanning from lamprophyres to carbonatites and basalts to rhyolites. Several are intrusive, while others have been reworked detritally, deposited as river gravels out onto the Gulf Coastal Plain. The earliest occurrence of igneous gravel clasts in the coastal plain of the lower Mississippi Valley lie along the Mississippi River’s eastern valley wall in the ancestral Mississippi River’s pre-loess terrace deposits (PLTDs). The coarse clastics of the PLTDs are dominantly chert gravels derived from Paleozoic carbonate bedrock, but also include clasts of Precambrian Sioux Quartzite, glacially faceted and striated stones, and ice-rafted boulders, which indicate a direct relationship between the PLTDs and glacial outwash during the cyclic glaciation of the Pleistocene Epoch. The PLTDs also contain the oldest known examples of igneous gravels exposed at the surface in Mississippi. An understanding of their igneous bedrock provenance and the timing of their contribution to the sedimentary record of the lower Mississippi River Valley sheds a valuable light onto the geologic history and evolution of the ancestral Mississippi River during the Pleistocene Epoch. The use of fusion inductively coupled plasma mass-spectroscopy (ICP-MS) in the identification of the igneous suites of one of the pre-loess terraces, well-delineated by geologic mapping, adds important geochemical source data from the gravel constituents for the further interpretation and correlation of the individual PLTD allounits. Gravel constituent geochemistry also offers a better understanding of the evolution of the ancestral Mississippi River watershed and the contributions of bedrock sources during Pleistocene glaciation. This petrological study suggests that the igneous gravels sampled from within the Rawhide PLTD allounit originated from the St. Francois Mountains (SFMs) in southwestern Missouri, with the implications that the SFM igneous terrain was in the direct path of the Independence “Kansan” glaciation. This could indicate a glacial extent further southwest than previously documented.

Benthic communities restructure quickly under shifting salinities: a reciprocal transplant experiment

Salinity regimes in estuarine habitats will shift pending sediment diversions, which will reconnect Louisiana, USA, coastal wetlands to the Mississippi River. The river has been hydrologically disconnected from fringing estuaries for over a century, but high local rates of relative sea-level rise have contributed to land loss, and sediment diversions will be built to prevent future loss. A reciprocal transplant experiment of benthic cores was used to determine how macrofaunal communities may be altered pending salinity regime shifts. A total of 147 benthic cores (3142 cm3) were excavated and transplanted within 3 salinity regimes in Barataria Bay, LA, for 2 or 5 mo. We observed a significant effect of salinity treatment on benthic macroinfaunal community composition in every transplant, regardless of origin or date sampled. Results show that communities recolonized in as little as 2 mo, and reveal the species assemblages responsible for the restructure. Species assemblage changes included dominance of generalist species (spionid and capitellid polychaetes) and shifts between deposit feeders and suspension feeders as freshwater flow varied. Lower-salinity treatment decreased species richness, while higher-salinity treatment increased both species richness and abundance. Benthic communities will likely restructure quickly under the sediment diversion scenarios and leave few founder effects in response to changes in salinity regimes across the estuary. Pulsed diversion operations may yield different results, but only springtime operations are likely to impact benthic recruitment. Comprehensive knowledge of how benthic communities restructure post-restoration will enable both appropriate regional planning as well as future predictions in coastal estuaries undergoing hydrologic alteration.

South-central Laurentide Ice Sheet dynamics and the formation of proglacial Lake Vita during MIS 3

Abstract An understanding of the growth and demise of ice sheets over North America is essential to inform future climate models. One poorly studied subject is the glacial dynamics during interstadial Marine Isotope Stage (MIS) 3 (57–29 ka). To better constrain the southern margin of the Laurentide Ice Sheet during this time period, we re-examined a stratigraphic sequence in southeast Manitoba, Canada, and provide robust evidence for advance and retreat of ice. Around 46.6 ± 5.1 ka (1σ error), fluvial sands were deposited under similar precipitation and significantly cooler summer temperatures than present-day. Ice then advanced south over the area, before retreating once again and a return to boreal forest and grassland conditions. The area was then covered by proglacial Lake Vita, dammed by ice to the north. Geochronology constraints indicate Lake Vita existed from ca. 44.3 ± 3.6 to 30.4 ± 2.3 ka (1σ error), although gaps in the optical and finite radiocarbon ages suggest either a lack of data or plausible temporary ice-margin advances during this time period. Ice covering most of Manitoba during MIS 3 is in line with global δ18O records, and glacially influenced sediment deposition in the Mississippi River basin.

Histoplasmosis Associated with Bat Guano Exposure in Cannabis Growers: Two Cases

Abstract Histoplasma capsulatum is a pathogenic dimorphic fungus with evolving epidemiology. Initially described as endemic to the Ohio and Mississippi river valleys, the infection now regularly occurs in central and eastern United States, with cases reported across the entire country. Transmission happens via inhalation of conidia during activities that disturb fungal hyphae. Sporadic cases related to individual exposures now outnumber work-related outbreak cases in the US. We describe two fatal cases of histoplasmosis in Rochester, New York, associated with exposure to bat guano as a fertilizer for cannabis cultivation, including one case in which it was commercially obtained.

Microplastic Chemostasis and Homogeneity During a Historic Flood on the Mississippi River

Microplastic Chemostasis and Homogeneity During a Historic Flood on the Mississippi River

Coupled Impact of Climate Change and Anthropogenic Activity on the Changes of Terrestrial Organic Carbon Accumulation in the River‐Dominated Coastal Margin

AbstractRiver‐dominated marginal seas play a crucial role in the global carbon cycle. However, the centennial burial record of organic carbon (OC) remains unclear. In this study, we conducted a comprehensive analysis of bulk OC, its isotopic composition (δ13C and Δ14C), biomarkers (lignin and n‐alkanes), and sedimentological evolution based on sediment core from the Yellow River‐dominated Bohai Sea (BS). We also compiled several published OC burial records from other river‐dominated coastal margins. Our findings indicated that since the 1950s, the accumulation of terrestrial OC in central BS has shown a concurrent decline, as evidenced by a ∼50% decrease in terrigenous/aquatic ratio of n‐alkanes (TAR), which accompanied by a significant reduction in sediment load due to the watershed human activities. More intense erosion and resuspension due to stronger hydrodynamic condition under the increasing frequency of winter storms could account for the observed sediment coarsening and concomitant increase of the degraded lignin and old‐OC since the 1980s, suggesting that delta erosion‐induced sediment redistribution could influence the selective transport and accumulation of the more woody allochthonous OC components. The temporal profiles of lignin records indicated a spatial heterogeneity of recent terrestrial OC burial among the large river‐dominated coastal margins under the enhanced global delta erosion. Compared to the fluvial input‐dominated OC burial in the Yangtze River, Pearl River and Mississippi River delta margins, a more hydrodynamic forcing impact on the terrestrial OC burial was discerned in the BS due to the coupled effect of recent climate change and substantial decline in sediment load.

Patterns and Mechanisms of Wetland Change in the Breton Sound Estuary, Mississippi River Delta: A Review

Patterns and Mechanisms of Wetland Change in the Breton Sound Estuary, Mississippi River Delta: A Review

A fish community comparison upstream and downstream a high-head dam on the Upper Mississippi River

Abstract Standardized sampling is useful for detecting and monitoring variations in fish communities and the establishment and spread of invasive species. Lock and Dam 19, a high-head dam with a 10- meter hydraulic head, creates the largest impoundment on the Upper Mississippi River. Upstream, Pool 19 is characterized by static water levels and expansive macrophyte beds. Downstream, Pool 20 is characterized by lotic conditions and sparse vegetation. Lock and Dam 19 serves as barrier to upstream migration of fishes, particularly Bigheaded carp (Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molotrix). There is limited standardized fisheries data available for Pools 19 and 20, particularly in off-channel areas. In 2013 and 2014, we conducted two years of standardized electrofishing in Pools 19 and 20 to 1) detect a presence of adult or juvenile Bigheaded carp, 2) quantify differences in fish community structure (i.e., relative abundance of species) between Pools 19 and 20 and among strata (i.e., backwater, side channel, main channel, and impounded reaches), and 3) quantify hydrological differences (i.e., water quality variables) between Pools 19 and 20 and among strata. We detected two Bigheaded carp upstream Lock and Dam 19, the first to be documented using a standardized collection method. We used permutational multivariate analysis of variance using distance matrices (veganR package version 2.6-4) to determine that fish community structure differed significantly between pools (P< 0.01) and among strata (P< 0.01), except between main and side channel borders. We determined water quality variables differed significantly between the pools and among strata demonstrating strata proportional differences may drive the fish community differences between Pools 19 and 20. We have demonstrated that expanding standardized sampling efforts to Pools 19 and 20 is important to understand long-term changes in fish assemblages and the effects of Lock and Dam 19 on the ecology of the Upper Mississippi River.

Modeling the Responses of Blue Carbon Fluxes in Mississippi River Deltaic Plain Brackish Marshes to Climate Change Induced Hydrologic Conditions

Modeling the Responses of Blue Carbon Fluxes in Mississippi River Deltaic Plain Brackish Marshes to Climate Change Induced Hydrologic Conditions

Nonstationary Teleconnections Over North America Revealed in Paleoclimate Data Assimilation Reconstructions Spanning the Last Millennium

AbstractModes of climate variability, such as the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multi‐decadal Oscillation (AMO), have been shown to have large impacts on North American hydroclimate through their atmospheric teleconnections. However, short instrumental records limit our ability to examine the long‐term stability (or stationarity) of hydroclimate teleconnections. Here, we use two last millennium (LM) paleoclimate data assimilation (DA) products to assess the stationarity of hydroclimate teleconnections over two key regions: the southwestern U.S. and Lower Mississippi River basin. Moving correlations between climate indices and regional hydroclimate expose highly nonstationary regional hydroclimate teleconnections with significant periodic variations on multi‐decadal and multi‐centennial timescales. Although limitations of the DA products prohibit a robust analysis of climate mode intensity, consistent sea surface temperature (SST) patterns between DA products during strong and weak teleconnection periods suggest that changing teleconnection strength is driven by the changing relationships between climate modes over the LM. Although our results are sensitive to proxy availability, the DA techniques provide novel insight into the nonstationarity and long‐term variability of North American hydroclimate teleconnections. This work provides a baseline for teleconnection behavior from DA products, which is potentially valuable for decadal prediction.

A Hyperspectral Reflectance Database of Plastic Debris with Different Fractional Abundance in River Systems

Plastic debris pollution transported by river systems to lakes and oceans has emerged as a significant environmental concern with adverse impacts on ecosystems, food webs, and human health. Remote sensing presents a cost-effective approach to bolster interception and removal efforts. However, unlike marine environments, the optical properties of plastic debris in fresh waters remain poorly understood. This study aims to address this gap by providing an open-access hyperspectral reflectance database of floating weathered and virgin plastic debris found in river systems under controlled laboratory experiments. Utilizing natural waters from the Mississippi River, the database was assembled using a remote sensing data acquisition system deployed over a hydraulic flume operating under subcritical flow conditions and varying suspended sediment concentrations. The measurements encompass hyperspectral diffused light reflectance from ultraviolet (UV, 350 nm) to shortwave infrared (SWIR, 2500 nm) wavelengths. The database archived in Network Common Data Form (NetCDF) and Comma-separated values (CSV), offers valuable insights for better understanding key spectral signatures indicative of floating plastic debris, with different fractional abundance, in freshwater ecosystems.

Daily runoff prediction based on lightweight Mamba with partial normalization

ABSTRACT Runoff prediction serves as the cornerstone for the effective management, allocation, and utilization of water resources, playing a key role in hydrological research. This study employs a newly reported deep learning model, Mamba, to forecast river daily runoff and compared the proposed model with various benchmark methods, including statistical models, machine learning methods, recurrent neural networks, and attention-based models. Application of these models is implemented on three hydrological stations situated along the middle and lower reaches of the Mississippi River. Daily runoff from 1983 to 2023 were used to build the model for 7-day prediction. Findings demonstrate the superiority of the Mamba model over its counterparts, showcasing its potential as a backbone model. In response to the necessity for a more lightweight approach, a refined variant of the Mamba model is proposed, called LightMamba. LightMamba incorporates partial normalization and MPM (Multi-Path-Mamba) to enhance its efficacy in discerning nonlinear trends and capturing long-term dependencies within the streamflow data. Notably, LightMamba achieves commendable performance with an average NSE of 0.904, 0.907, and 0.900 on the three stations. This study introduces an innovative backbone model for time series forecasting, which offers a novel approach to hybrid modeling for future daily runoff prediction.

Plant and soil responses to sediment deposition and nutrient‐enrichment in healthy, deteriorating, and newly created coastal marshes of the Mississippi River Delta

Coastal marshes vulnerable to sea‐level rise may benefit from sediment amendments to increase elevation. However, nutrient‐loading to estuaries may counter elevation gain through reduced root production and/or increased decomposition. Here, we test if belowground plant productivity, root decomposition, and marsh accretion response to nutrient‐loading differs with sediment addition in three marsh types: a healthy intermediate salinity marsh, a deteriorating brackish marsh, and a created marsh in Barataria Basin, Louisiana, United States. In this region, wetland loss is rapid, and a major restoration project is underway to introduce Mississippi River water, sediment, and nutrients to offset marsh loss. Porewater nutrient concentrations, vegetation structure, belowground productivity and decomposition, and accretion rates were measured over 450 days. Experimental nitrate additions yielded high porewater ammonium‐N concentrations in the Deteriorating marsh but had a smaller effect in Healthy and Created marshes. Belowground productivity in the Deteriorating marsh was neutral to negatively affected by nutrient and sediment treatments, whereas positive effects occurred in Healthy and Created marshes. Despite elevation increase from sediment treatments, and substantial effects of nutrient treatments on porewater nutrient concentrations, belowground decomposition and surface accretion rates were not affected by treatments. Sediment deposition increased species richness in the Healthy marsh and added sediment and added nutrients with sediment increased plant height in the Created and Deteriorating marshes, respectively. Over the timescale measured, experimental sedimentation and pulsed nutrient input had few consistent effects on belowground ingrowth, decomposition, or surface accretion. Our findings highlight that response to nutrient pulses are complex and depend on baseline marsh conditions.

Influence of Land Use and Land Cover Changes and Precipitation Patterns on Groundwater Storage in the Mississippi River Watershed: Insights from GRACE Satellite Data

Growing human demands are placing significant pressure on groundwater resources, causing declines in many regions. Identifying areas where groundwater levels are declining due to human activities is essential for effective resource management. This study investigates the influence of land use and land cover, crop types, and precipitation patterns on groundwater level trends across the Mississippi River Watershed (MRW), USA. Groundwater storage changes from 2003 to 2015 were estimated using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. A spatiotemporal analysis was conducted at four scales: the entire MRW, groundwater regimes based on groundwater level change rates, 31 states within the MRW, and six USGS hydrologic unit code (HUC)-2 watersheds. The results indicate that the Lower Mississippi region experienced the fastest groundwater decline, with a Sen’s slope of −0.07 cm/year for the mean equivalent water thickness, which was attributed to intensive groundwater-based soybean farming. By comparing groundwater levels with changes in land use, crop types, and precipitation, trends driven by human activities were identified. This work underscores the ongoing relevance of GRACE data and the GRACE Follow-On mission, launched in 2018, which continues to provide vital data for monitoring groundwater storage. These insights are critical for managing groundwater resources and mitigating human impacts on the environment.

Rediscovery of a population of the plains spotted skunk, Spilogale interrupta, a species of conservation concern, from southern Texas, USA

Abstract The Plains Spotted Skunk (Spilogale interrupta) historically occurred across parts of the eastern and midwestern United States west of the Mississippi River. Following perceived population declines across much of its range, efforts to assess populations of this species have increased. Here, we report novel records of S. interrupta from this area of south Texas for the first time since 1961. This rediscovery demonstrates the persistence of this species in an underreported portion of its range. This information is useful for better understanding the distribution and population status of S. interrupta in Texas and broadly throughout North America and is crucial for future applied conservation policy efforts.