Sediment chemistry and toxicity in Barnegat Bay, New Jersey: Pre- and post-Hurricane Sandy, 2012-13

Use of multi-resolution, three-dimensional hydrodynamic and water-quality models to assess response to nutrient load reductions in Barnegat Bay-Little Egg Harbor estuary, New Jersey, USA

A coupled three-dimensional hydrodynamic water-quality model has been applied to Barnegat Bay-Little Egg Harbor Estuary, a shallow, back-barrier lagoon located along the central New Jersey coastline. The study aims to enhance understanding of phytoplankton dynamics and nutrient cycling and to quantify estuarine response to potential nutrient load management strategies. The model was calibrated with data from Spring and Summer of 2012 and adequately reproduced spatiotemporal water-quality variability, distribution patterns, trends, and gradients throughout the system. The calibrated model was used to run scenarios for evaluating estuarine response to various nitrogen load reduction intensities. Model results show that geographically focused, variable nitrogen reductions can mitigate the effects of eutrophication and promote improvements in water quality. This study illustrates the role of modeling in developing informed management strategies, highlights complex, nonlinear responses of estuarine environments to anthropogenic influences, and demonstrates how models can be used to develop adaptive, location-specific nutrient management practices.

Enhanced water transport when a tropical storm meets an atmospheric cold front

Weather systems that interact with one another can enhance coastal water transport, facilitating the movement of waterborne materials. In this study, we examine the influence of such weather interactions on water transport within a tidal pass along the coast of the northern Gulf of Mexico, focusing on the event when Tropical Storm Lee (2011) made landfall and merged with an atmospheric cold front, which was a leading edge of an advancing continental polar air mass. We conducted continuous surveys using an unmanned surface craft to measure water transport through a tidal pass. The transport was analyzed by calculating a regression-based time series, with additional measurements obtained from a moored side-looking horizontal acoustic Doppler current profiler (HADCP). Our findings reveal that the combination of the tropical storm and cold front substantially enhanced the total water transport, driving significant amounts of water out of the bay. The storm tide-induced water transport through the narrow 500-m pass reached ~ 13,630 m3/s, with a maximum velocity around 2.4 m/s. The cold front amplified the effect of the tropical system by reinforcing winds and vorticity from both systems. Both weather systems contributed notably to the energy density in the sub-tidal band, while also overlapping the tidal and inter-tidal frequency bands. The sub-tidal-to-tidal-energy density (power) ratio increased from an average of 21-114% during the two weather systems and 205% during the tropical storm period alone. These results highlight the significant implications of such weather interactions for coastal erosion, sediment transportation, and sediment deposition during coastal weather events.

Longitudinal patterns in sediment type and quality during daily flow regimes and following natural hazards in an urban estuary: a Hurricane Harvey retrospective

Understanding the transport of sediments in urban estuaries and their effects on water quality and microorganisms is a convergent challenge that has yet to be addressed especially as a result of natural hazards that affect the hydrodynamics of estuarine systems. This study provides a holistic view of the longitudinal nature and character of sediment in an urban estuary, the Galveston Bay Estuary System (GBES), under daily and extreme flow regimes and presents the results of water and sediment sampling after Hurricane Harvey. The sediment sampling quantified total suspended sediment (TSS) concentrations, metal concentrations, and the diversity of microbial communities. The results revealed the impact of the substantial sediment loads that were transported into the GBES in terms of sediment grain type, the spatial distribution of trace metals, and the diversity of microbial communities. A measurable shift in the percentage of silt relative to historical norms was noted in the GBES after Hurricane Harvey. Not only did sediment metal data confirms this shift and its ensuing impact on metal concentrations; microbial data provided ample evidence of the effect of leaks and spills from wastewater treatment plants, superfund sites, and industrial runoff on microbial diversity. The research demonstrates the importance of understanding longitudinal sediment transport and deposition in estuarine systems under daily flow regimes but more critically, following natural hazard events to ensure sustainability and resilience of systems such as the GBES that encounter numerous acute and chronic stresses.

The presence of Superfund sites as a determinant of life expectancy in the United States

Superfund sites could affect life expectancy (LE) via increasing the likelihood of exposure to toxic chemicals. Here, we assess to what extent such presence could alter the LE independently and in the context of sociodemographic determinants. A nationwide geocoded statistical modeling at the census tract level was undertaken to estimate the magnitude of impact. Results showed a significant difference in LE among census tracts with at least one Superfund site and their neighboring tracts with no sites. The presence of a Superfund site could cause a decrease of -0.186 ± 0.027 years in LE. This adverse effect could be as high as -1.22 years in tracts with Superfund sites and high sociodemographic disadvantage. Specific characteristics of Superfund sites such as being prone to flooding and the absence of a cleanup strategy could amplify the adverse effect. Furthermore, the presence of Superfund sites amplifies the negative influence of sociodemographic factors at lower LEs.

Typhoon Fung-wong (2008) induced heavy metals secondary pollution in Quanzhou Bay, southeast of China

The concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Al in suspended particles were measured, and temperature, salinity, flow velocity and direction during a tidal cycle were observed before and after Typhoon Fung-wong at six stations in Quanzhou Bay, respectively. The comparison results show that, after the typhoon, the salinity in Quanzhou Bay decreased, whereas the concentrations of heavy metals increased by a factor of between 2 and 10, and the high heavy metal concentration corresponded to the low value of ratio between heavy metals and Al (HMs/Al), suggesting that these increased heavy metals were mainly from natural sources. Instantaneous unit width flux calculations for heavy metals at different stations indicate that sediments are an important source of heavy metals in suspended particles under the influence of typhoon, which has significantly contribution to understanding the impact of typhoons on the heavy metal pollution in the coastal area.

Modeling water quality impacts from hurricanes and extreme weather events in urban coastal systems using Sentinel-2 spectral data

Conventional water quality measurements are nearly impossible during and immediately after extreme storms due to dangerous conditions. In this study, remotely sensed reflectance is used to develop a regression equation that quantifies total suspended solids (TSS) in near real-time after Hurricane Harvey. The application focused specifically on sediment loading and deposition and its potential impacts on the Houston Ship Channel and Galveston Bay riverine-estuarine system. The European Space Agency's Sentinel-2 satellite captured images at critical points in the storm's progression, necessitating the development of a new algorithm for this relatively new satellite mission. Several linear regressions were analyzed with the goal of developing a simple one- or two-band equation, and the final model uses the red and near infrared bands (R² = 0.74). Results show that record flows during Harvey delivered unprecedented suspended sediment loads to the Gulf of Mexico at concentrations above 125 mg/L with a mean concentration of 43 mg/L across the bay. The study findings demonstrated that it took up to 11 days after the storm for sediment transport to abate.

A geospatially resolved wetland vulnerability index: Synthesis of physical drivers

Assessing wetland vulnerability to chronic and episodic physical drivers is fundamental for establishing restoration priorities. We synthesized multiple data sets from E.B. Forsythe National Wildlife Refuge, New Jersey, to establish a wetland vulnerability metric that integrates a range of physical processes, anthropogenic impact and physical/biophysical features. The geospatial data are based on aerial imagery, remote sensing, regulatory information, and hydrodynamic modeling; and include elevation, tidal range, unvegetated to vegetated marsh ratio (UVVR), shoreline erosion, potential exposure to contaminants, residence time, marsh condition change, change in salinity, salinity exposure and sediment concentration. First, we delineated the wetland complex into individual marsh units based on surface contours, and then defined a wetland vulnerability index that combined contributions from all parameters. We applied principal component and cluster analyses to explore the interrelations between the data layers, and separate regions that exhibited common characteristics. Our analysis shows that the spatial variation of vulnerability in this domain cannot be explained satisfactorily by a smaller subset of the variables. The most influential factor on the vulnerability index was the combined effect of elevation, tide range, residence time, and UVVR. Tide range and residence time had the highest correlation, and similar bay-wide spatial variation. Some variables (e.g., shoreline erosion) had no significant correlation with the rest of the variables. The aggregated index based on the complete dataset allows us to assess the overall state of a given marsh unit and quickly locate the most vulnerable units in a larger marsh complex. The application of geospatially complete datasets and consideration of chronic and episodic physical drivers represents an advance over traditional point-based methods for wetland assessment.

Physical, Chemical, and Microbial Quality of Floodwaters in Houston Following Hurricane Harvey

Hurricane Harvey brought more than 50 in. of rainfall to some areas of the Greater Houston Metro area (GHMA) starting on August 25, 2017; the Hurricane was also associated with damage to environmental infrastructure such as wastewater facilities, superfund sites, and leaks and spills from industrial and municipal facilities. This study collected post-Harvey water quality data in multiple streams for several weeks after the Hurricane. In addition to measuring impact, the study compared the observed concentrations of several physical, chemical, and microbial constituents and water properties to their historical counterparts in an effort to understand the water quality impacts of Harvey on the natural water systems within the GHMA. Unusual water quality findings such as low pH were observed that likely had acute and chronic effects on ecosystems including the loss of oyster populations in Galveston Bay. In-stream microbial concentrations, using E. coli as the indicator, were within historical norms typically reported for the GHMA. The observed levels of measured dissolved metals post Harvey, while relatively low, when multiplied by the significant volume of water discharged from bayous to Galveston Bay, meant the delivery of a substantial load of trace metals to the estuary. Specifically, the load in the particulate phase would be expected to accumulate and gradually repartition to the dissolved phase for a long period of time. Total metal concentrations, when elevated relative to their historical counterparts, could be associated with the presence of industrial activities. Overall, anthropogenic activities including the presence of hydraulic flood control structures, local runoff from industrialized areas, and active superfund sites were recognized as key factors affecting short-term acute water quality impacts. Watersheds with very little human alterations experienced minimal water quality changes and had relatively rapid recoveries post-Harvey.

Beach-cast debris surveys on Triangle Island, British Columbia, Canada indicate the timing of arrival of 2011 Tōhoku tsunami debris in North America

We conducted beach-cast debris transect surveys on Triangle Island, British Columbia, Canada in 2012-2017 to (1) establish a baseline against which to track future changes in stranded debris on this small, uninhabited island; and (2) time the arrival in western North America of debris released by the 2011 Tōhoku tsunami. Most (90%) of the six-year total of 6784 debris items tallied was composed of Styrofoam or plastic. The number of debris items peaked in 2014 (waste Styrofoam, rope) and 2015 (waste plastic, wood), and cumulative totals for all debris types were ca. 50% higher in 2014-15 than in 2012-13 and 2016-17. The peaks in 2014-15 probably represented the arrival of the bulk of the tsunami debris, based on close correspondence with forecasting models and debris surveys elsewhere. A fuller understanding of the movement of the Tōhoku tsunami debris will require information from other beach monitoring programs.

Development of a storm surge driven water quality model to simulate spills during hurricanes

Hurricanes can cause widespread environmental pollution that has yet to be fully articulated. This study develops a predictive water quality model to forecast potential contamination resulting from buckled or ruptured storage tanks in coastal industrialized areas when subjected to storm surge. The developed EFDC-Storm Surge model (EFDC-SS) couples EPA's EFDC code with the SWAN-ADCIRC hurricane simulation model. EFDC-SS is demonstrated using the Houston Ship Channel in Texas as a testbed and hurricane Ike as a model hurricane. Conservative and decaying dye runs evaluated various hurricane scenarios, combined with spills released at different locations and release times. Results showed that tank locations with shorter distances to the main waterbody and lower ground elevations have a higher risk of inundation and rapid spill mass transport. It was also determined that hurricane strength and landfall location, the location of the spill, and the spill release time relative to peak surge were interdependent.

Distribution of hydrocarbons in seabed sediments derived from tsunami-spilled oil in Kesennuma Bay, Japan

As a result of the 2011 Great East Japan earthquake, about 11,000kL of fuel oil was spilled into Kesennuma Bay, Miyagi Prefecture. This oil either accumulated in seabed sediments or was burned in a marine fire on the sea surface. We investigated spatial and temporal variations in the concentrations of oil and hydrocarbons. The maximum concentrations of n-hexane extract (NHE), total petroleum hydrocarbon (TPH), and polycyclic aromatic hydrocarbons (PAHs) in the sediments in 2012 were 8000, 1200, and 16.2mg/kg (DW), respectively. NHE and TPH concentrations were high in the inner and west bay, and PAHs concentrations were high in the east bay. NHE and PAH concentrations didn't change; however, TPH concentrations decreased significantly with time. The total NHE in the sediment across the whole bay was estimated at 1685kL and there was still about 13% of the original amount in the sediment in December 2014.