Accuracy and precision of tidal wetland soil carbon mapping in the conterminous United States

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 8 (2018): 9478, doi:10.1038/s41598-018-26948-7.Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0 kg C m−3), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision.Synthesis efforts were funded by NASA Carbon Monitoring System (CMS; NNH14AY67I), USGS LandCarbon and the Smithsonian Institution. J.R.H. was additionally supported by the NSF-funded Coastal Carbon Research Coordination Network while completing this manuscript (DEB-1655622). J.M.S. coring efforts were funded by NSF (EAR-1204079). B.P.H. coring efforts were funded by Earth Observatory (Publication Number 197)

Routine monitoring of toxics in New Jersey fish: Fourth year (2007) of routine monitoring program Atlantic Coastal Region

Describes results of sampling program performed to assess status and trends in fish contamination

Routine monitoring of toxics in new jersey fish: Third year (2006) of routine monitoring program

Describes results of sampling program performed to assess status and trends in fish contamination

Determination of the isotopic composition of ammonium-nitrogen at the natural abundance level from estuarine waters

Abstract A method was developed to measure the stable nitrogen isotope ratio of dissolved ammonium (NH4+) at the natural abundance level from estuarine waters. This method employed rapid steam distillation with collection of ammonium on zeolite via ion-exchange. The steam distillation step had a recovery of 103±5%; subsequent exchange of the ammonium on zeolite had a yield of 96.4±1.6%. The zeolite with exchanged ammonium was converted to N2 in quartz tubes at 910°C with CuO and Cu and the isotopic composition of the gas was measured in an isotope ratio mass spectrometer. When analyzing 200 μg of N the accuracy using isotopic standards was within 4% of the true ratio, with an overall precision of ±0.5%. A benefit of this method is that samples can be distilled and preserved onboard ship, thereby minimizing storage artifacts. This method was used in a seasonal study of the isotopic composition of dissolved ammonium from the Delaware Estuary

Routine monitoring of toxics in fish-year 4 - Atlantic Coastal Inland Region: Office of Science research project summary

The Routine Monitoring for Toxics in Fish Program is a 5-year, geographically based rotating program to generate data on chemical contaminants in fish for the issuance, update and revision of fish consumption advisories. The monitoring program design is built upon fish contaminant research conducted by NJDEP since the early 1980’s. In order to investigate regional patterns in fish contamination the program includes rotating sample collections among geographic regions within the state. In addition to analyze fish contaminant temporal trends and to identify unknown hotspots, re-sampling selected waterbodies and sampling “new” (not previously sampled) locations was part of the sampling regime. This Year 4 study provides the results for the Atlantic Coastal Inland Region. The study design incorporated a variety of considerations, including sampling species that are important to recreational fishing, targeting fish species of specific trophic position that are known to bioaccumulate mercury and/or organic chemical contaminants, consider the target species body lipid content (important in organic contaminants), as well as species longevity and/or lifestyle proximity to bottom sediments. The data generated through this study are useful in developing credible consumption risk assessments, since they include the size ranges and species that are generally targeted by recreational anglers and can be used in an evaluation of contaminant trends in this region and comparable throughout the state. The results show that mercury in fish concentrations varied among species, but typically increased with fish size and are usually higher in predatory fish, such as chain pickerel and largemouth bass. Mercury levels in chain pickerel were highest in waters with pH less than 7, and for largemouth bass in lakes with pH between 5 and 6. The highest mercury concentrations were observed at drainage sites within and marginal to the Pine Barrens. As observed in this and previous studies lower pH waterbodies typically reflect conditions promoting high mercury bioavailability through methylation, and sources of mercury in the environment are both natural and anthropogenic. PCB levels in the fish sampled, however, showed a different contamination pattern with only relatively low to moderate PCB concentrations identified from these same locations. In general, PCBs and OCPs were typically higher in samples of American eel than other fish species examined. DDXs showed high variability within all sites of the study area, with some of the lowest and highest average concentrations observed when compared to previously studied regions. The variations in these xenobiotics (PCBs, OCPs, DDX) may highlight the differing contaminant sources and geo-chemistry of these contaminants, and may also reflect legacy industrial practices of production, disposal and/or use. Although these xenobiotic concentrations were variable among sites, the highest average concentrations were seen in fish from Deal Lake (PCBs and chlordanes), North Branch Metedeconk River (DDXs and chlordanes), Maurice River (PCBs), and several other smaller lakes (DDXs). Although there are large differences in contaminant concentrations in samples within regions, a comparison of fish tissue chemical data among sites from the previous studies on the Passaic and Raritan Regions, and this study show some regional contaminant differences. In general concentrations of mercury were higher in the Atlantic Coastal Region while PCBs were higher in the Raritan Region. Where comparisons between 1992 and 2007datasets for this study were possible, there was no clear trend in contaminant concentrations at previously sampled locations. When comparing these data to available health criteria, with the exception of mercury, few of the samples analyzed exceeded the USFDA action levels for advisories on commercial fish. However, the NJDEP/DHSS use USEPA supported risk-based health criteria, in establishing consumption advisories for recreationally caught fish. These criteria are typically lower than FDA thresholds for mercury, PCBs, dioxins, and OCPs. The majority of the fish samples tested in this study exceeded the various individual NJDEP/DHSS/USEPA contaminant risk-based thresholds and several samples examined exceeded thresholds for multiple contaminants. The data from this study were used by NJDEP/DHSS to develop the most recent fish consumption advisories for a variety of recreationally caught fish in New Jersey

Isotopic fractionation of ammonium and nitrate during uptake by Skeletonema costatum: Implications for δ15N dynamics under bloom conditions

Abstract: Isotopic fractionation of ammonium (NH,+ ) and nitrate (NO,-) during uptake by phytoplankton was examined in batch culture experiments with the diatom SkeZetonema costatum under nitrogen-enriched conditions (5-100 PM). The fractionation factor (E) for NOJ- uptake by Skeletonema was -9.Of0.7%0 and was concentration-independent. For NH,+, E was more variable and dependent on ambient NH,+ concentration. For NH4+ concentration ranges of 100-50, 50-20, and 20-5 PM, E was -24.6k5.5, -27.2-+ 1.6, and -7.8+3.0%. In these cultures, isotopic fractionation by phytoplankton caused variations in 615N of up to 50?& for NH4+, 1 ~%XI for NO,-, and 25% for particulate N. Similar variability in the 615N of both dissolved inorganic and particulate organic N pools should be expected during phytoplankton blooms in nature. As a result, phytoplankton-mediated isotopic variability must be considered when isotopic data are used to examine biogeochemical and physical processing of organic matter in marine ecosystems, particularly when biosynthesis and loss processes are decoupled in either space or time during bloom conditions

Polychlorinated Biphenyls in Sediment and Biota from the Delaware River Estuary

A spatially comprehensive evaluation of polychlorinated biphenyl (PCB) inventories in white perch, channel catfish, small prey fish, amphipods and sediment within four zones of the Delaware River Estuary was completed during two seasons (fall 2001 and spring 2002). Highest sediment PCB concentrations occurred adjacent to urbanized and industrialized stretches of the estuary. Whole organism MICB body burdens (on a wet weight basis) reflected the spatial distributions in sediment PCB concentrations. However, there was considerable variation in PCB concentrations among individual catfish and perch fillets within zones that were not significantly reduced by lipid normalization. This variation suggests that within a zone man), factors (e.g., dietary shifts, small-scale heterogeneity in sediment contamination, and non-equilibrium conditions in contaminant partitioning) drive PCB bioaccumulation. With increasing down-estuary distances, all biota except for perch had enhanced concentrations of more chlorinated congeners, especially nona- and deca-chlorinated biphenyls. Specific congeners such as PCB 206 and 209 may act as indicators of unique local sources of contamination within the lower portions of the Delaware River Estuary