Long-term environmental change and shifts in the aquatic plant community of Jones Creek,Thousand Islands National Park,Ontario, Canada based on plant macrofossil analysis

Plant macrofossils and pollen were analyzed from sediment cores to identify long-term changes in the aquatic plant community of Jones Creek, Thousand Islands National Park, Ontario, Canada. Six sediment cores were recovered from Jones Creek in February 2014. One complete core and five top/bottom samples were analyzed for plant macrofossil abundance and diversity. Sediment analysis and ²¹⁰Pb dating confirmed a productive wetland throughout the core, dating back beyond 1883 AD. Jones Creek is currently dominated by thick stands of cattails, particularly the hybrid white cattail (Typha x glauca Godr). The relative abundance of Typha pollen began to increase in the late nineteenth and early twentieth century, reaching a relative abundance of nearly 40% in the modern day surface sediment. Common macrofossils recovered from the sediment record included seeds of Carex, Schoenoplectus, Najas, and Eleocharis. There is evidence that community composition, as recorded by the macrofossil record, has shifted in Jones Creek in response to human activities. In particular there has been a reduction in sedge species between historical and present day conditions as the wetland shifted from a sedge dominated wet-meadow wetland to a cattail dominated system. The results of our study indicate that future restoration efforts should be directed towards reintroducing native sedge species that were present prior to major changes in land-use that occurred in the St. Lawrence region throughout the nineteenth and twentieth centuries.     

Some genetic implications of silica and aluminosilicates in peat and coal

The inorganic content of Okefenokee peat, in the absence of a significant detrital contribution, is a function of sponge spicule, phytolith, and diatom abundance in addition to the degree of organic matter decomposition and the frequency of fires. The detrital component (quartz) dominates ash composition where it is present.No clear correlation has been observed between the inorganic content of coals examined in this study and their maceral composition. Vitrinite-rich coals have a wide range of ash yield. These observations suggest that the minerals have been introduced detritally rather than accumulated as a result of peat degradation. Quartz in the coals appears to be detrital, and the presence of 2m₁ mica indicates that there is also a detrital contribution to the clay minerals present.     

Sea Level change: Environmental and socio-economic impacts

The coast was among the first of the earth’s environments to be subjected to human modification; modification that was both direct and indirect, as it is today. During the last 4.000 to 5.000 years, human impacts on the coast were at what was basically a stable sea level. Because many of the modifications were made to protect against unusual events such as typhoons and tsunami, humans developed a variety of techniques for protecting shorelines. Recent calculations that a rapid sea level rise (in response to greenhouse warming) is imminent, has prompted concerned efforts at meeting the socio-economic impacts that are likely to occur. These impacts, rather than being localized and temporary as has been true in the recent past, are likely to be universal and long-lasting. This thought, penned by Blaise Pascal, was accompanied by an artistic interpretation by Corita Kent inNewsweek, June 14,1976, p. 87.     

Sub‐Permil Interlaboratory Consistency for Solution‐Based Boron Isotope Analyses on Marine Carbonates

Boron isotopes in marine carbonates are increasingly used to reconstruct seawater pH and atmospheric pCO₂ through Earth’s history. While isotope ratio measurements from individual laboratories are often of high quality, it is important that records generated in different laboratories can equally be compared. Within this Boron Isotope Intercomparison Project (BIIP), we characterised the boron isotopic composition (commonly expressed in δ¹¹B) of two marine carbonates: Geological Survey of Japan carbonate reference materials JCp‐1 (coral Porites) and JCt‐1 (giant clam Tridacna gigas). Our study has three foci: (a) to assess the extent to which oxidative pre‐treatment, aimed at removing organic material from carbonate, can influence the resulting δ¹¹B; (b) to determine to what degree the chosen analytical approach may affect the resultant δ¹¹B; and (c) to provide well‐constrained consensus δ¹¹B values for JCp‐1 and JCt‐1. The resultant robust mean and associated robust standard deviation (s*) for un‐oxidised JCp‐1 is 24.36 ± 0.45‰ (2s*), compared with 24.25 ± 0.22‰ (2s*) for the same oxidised material. For un‐oxidised JCt‐1, respective compositions are 16.39 ± 0.60‰ (2s*; un‐oxidised) and 16.24 ± 0.38‰ (2s*; oxidised). The consistency between laboratories is generally better if carbonate powders were oxidatively cleaned prior to purification and measurement.     

Empirical observations and numerical modelling of tides,channel morphology,and vegetative effects on accretion in a restored tidal marsh

Tidal marshes form at the confluence between estuarine and marine environments where tidal movement regulates their developmental processes. Here, we investigate how the interplay between tides, channel morphology, and vegetation affect sediment dynamics in a low energy tidal marsh at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island. Poplar Island is an active restoration site where fine-grained material dredged from navigation channels in the upper Chesapeake Bay are being used to restore remote tidal marsh habitat toward the middle bay (Maryland, USA). Tidal currents were measured over multiple tidal cycles in the inlets and tidal creeks of one marsh at Poplar Island, Cell 1B, using Acoustic Doppler Current Profilers (ADCP) to estimate water fluxes throughout the marsh complex. Sediment fluxes were estimated using acoustic backscatter recorded by ADCPs and validated against total suspended solid measurements taken on site. A high-resolution geomorphic survey was conducted to capture channel cross sections and tidal marsh morphology. We integrated simple numerical models built in Delft3d with empirical observations to identify which eco-geomorphological factors influence sediment distribution in various channel configurations with differing vegetative characteristics. Channel morphology influences flood-ebb dominance in marshes, where deep, narrow channels promote high tidal velocities and incision, increasing sediment suspension and reducing resilience in marshes at Poplar Island. Our numerical models suggest that accurately modelling plant phenology is vital for estimating sediment accretion rates. In-situ observations indicate that Poplar Island marshes are experiencing erosion typical for many Chesapeake Bay islands. Peak periods of sediment suspension frequently coincide with the largest outflows of water during ebb tides resulting in large sediment deficits. Ebb dominance (net sediment export) in tidal marshes is likely amplified by sea-level rise and may lower marsh resilience. We couple field observations with numerical models to understand how tidal marsh morphodynamics contribute to marsh resilience. © 2019 John Wiley & Sons, Ltd.     

Long-Term Tsunami Data Archive Supports Tsunami Forecast, Warning, Research, and Mitigation

In response to the 2004 Indian Ocean tsunami, the United States began a careful review and strengthening of its programs aimed at reducing the consequences of tsunamis. Several reports and calls to action were drafted, including the Tsunami Warning and Education Act (Public Law 109–424) signed into law by the President in December 2006. NOAA’s National Geophysical Data Center (NGDC) and co-located World Data Center for Geophysics and Marine Geology (WDC-GMG) maintain a national and international tsunami data archive that fulfills part of the P.L. 109-424. The NGDC/WDC-GMG long-term tsunami data archive has expanded from the original global historical event databases and damage photo collection, to include tsunami deposits, coastal water-level data, DART? buoy data, and high-resolution coastal DEMs. These data are used to validate models, provide guidance to warning centers, develop tsunami hazard assessments, and educate the public about the risks from tsunamis. In this paper we discuss current steps and future actions to be taken by NGDC/WDC-GMG to support tsunami hazard mitigation research, to ultimately help save lives and improve the resiliency of coastal communities.     

Accessibility to food retailers and socio‐economic deprivation in urban New Zealand

The spatial locations of food retailers are considered to be an influential aspect of population consumption patterns. Such contextual relationships are often related to socio‐economic deprivation, with disparities in accessibility having important implications. This study used Geographic Information Systems and an Enhanced Two‐Step Floating Catchment Area model of spatial accessibility to further understand such relationships within urban areas of New Zealand. Findings, while mixed, indicate that there is generally increased accessibility to all food retailers in highly deprived areas. Understanding these socio–spatial relationships in local environments has important implications for policy initiatives, health outcomes and sustainable development.