Harmful Elements in Estuarine and Coastal Systems

Estuaries and coastal zones are dynamic transitional systems which provide many economic and ecological benefits to humans, but also are an ideal habitat for other organisms as well. These areas are becoming contaminated by various anthropogenic activities due to a quick economic growth and urbanization. This chapter explores the sources, chemical speciation, sediment accumulation and removal mechanisms of the harmful elements in estuarine and coastal seawaters. It also describes the effects of toxic elements on aquatic flora and fauna. Finally, the toxic element pollution of the Venice Lagoon, a transitional water body located in the northeastern part of Italy, is discussed as a case study, by presenting the procedures adopted to measure the extent of the pollution, the impacts on organisms and the restoration activities

Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign

Abstract: In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M ⊙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87’s spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded

Initiation of Branched Growth in Conoform Stromatolites as a Response to Microbial Community and Water Depth Changes in Lake Joyce, Antarctica

Branched, columnar stromatolites grew in perennially ice-covered Lake Joyce of the Antarctic McMurdo Dry Valleys during a period of lake level rise. These stromatolites are composed of the remains of filamentous, mat-forming cyanobacteria, sediment, and calcite. Calcite that precipitated within the stromatolites records their morphological evolution from prolate columns with inflexed apices to either branched or irregular columns. Calcite crystals also contain cylindrical molds, which have diameters similar to the trichome widths of cyanobacteria present elsewhere in Lake Joyce. These cyanobacteria have depth-dependent distributions; the shallowest mats from morphotypes, whereas deeper mats lack P. autumnale . P. autumnale-sized molds are abundant in calcite forming the oldest stromatolite layers, but are absent from younger crystals, suggesting that P. autumnale was present in the first stromatolite layers, but disappeared from the community with successive growth during lake level rise. This loss of P. autumnale-sized molds correlates with a transition from prolate columns to branched and irregular columns. Similar patterns in growth form were present in photosynthetically active mats elsewhere in Lake Joyce. Mats lacking P. autumnale commonly contained small peaks and branch-like bundles of filaments growing away from the mat surface, whereas mats that P. autumnale dominated were characterized by loss of relief with growth. Paired observations of these active mats and columnar stromatolites thus suggest that changes in microbial community composition following lake level rise initiated branched growth

Sand, Mud, and Calcite: Microbial Landscapes on Antarctic Lake Beds

Microbial mat aggradation and morphology can be strongly influenced by sedimentation and light in ice-covered lakes of the McMurdo Dry Valleys, Antarctica. In Lake Joyce, mats transitioned from prostrate with widely spaced pinnacles to having densely spaced pinnacles with complex webs and ornamentation at greater distances from inflowing melt water streams. This transition is interpreted to result from decreasing mud sedimentation, which compacted delicate microbial structures such as pinnacle tips, webs, and surface ornamentation. Mud sedimentation also changed through time at sites adjacent to inflowing streams on one of the Lake Joyce deltas; sedimentation likely increased from 1947 through 2009 as lake levels rose. Although mud sedimentation demonstrably affected mat morphology in Lake Joyce, changes in sand and mud sedimentation associated with overhanging rocks in Lake Vanda were not sufficient to dramatically change mat morphology. Instead, microbial mat pinnacles and ridges had a variety of morphological responses to their light environment. Microbial mats growing with oblique directional light both grew down from overhanging rocks with pinnacle orientation independent from the directional light and grew up from the rock-sheltered mat with pinnacles and ridges oriented relative to incident light: asymmetrical pinnacles were inclined toward and flattened perpendicular to the incident light, and ridges were oriented parallel to the incident light. Changes in mat morphology and microbial processes are also preserved in Lake Joyce stromatolites that grew over decades. Stromatolites contain ?13Ccalcite records of variable photosynthetic fractionation of local DIC under lower lake levels, followed by decades of DIC pool 13C enrichment with lower rates of photosynthesis during lake level rise. These results demonstrate that microbial responses to their environments are complex and under the right conditions can be preserved in the rock record

A Decrease to Low Carbonate Clumped Isotope Temperatures in Cryogenian Strata

Preglacial and synglacial low-latitude carbonate sediments of the Elbobreen Formation, NE Svalbard, preserve facies changes associated with low-latitude glacial advance in Cryogenian “Snowball Earth” episodes (717–635 Ma). We present the first application of carbonate clumped (Δ47) isotope thermometry on synglacial Snowball Earth carbonates and combine results with sedimentologic and petrographic observations and stable isotope (δ13C and δ18O) geochemistry to assess Neoproterozoic environmental change. We find elevated calcite Δ47 temperatures, which likely reflect solid-state reordering during burial. Dolomites, however, record lower temperatures that vary with facies and stratigraphy. Preglacial dolomite Δ47 temperatures range from 48–77°C, with a reconstructed fluid δ18OVSMOW value of +0.6‰ in the coldest sample. Glacial diamictites and dolomicrites comprise (1) reworked detrital clasts similar to preglacial strata in stable isotope composition and petrographic textures and (2) autochthonous dolomicrite with more positive δ18O values than those of preglacial dolomites or cooccurring detrital clasts. Mean glacial autochthonous dolomicrite Δ47 temperatures are 26 ± 10°C (95% CL) cooler than preglacial strata, with four samples <25°C. All dolomite Δ47 temperatures reflect diagenesis associated with lithification, yet observed stratigraphic and textural Δ47 temperature differences indicate that this occurred early and only contributes to part of the preserved temperature signal. Alteration trends within populations are consistent with low water/rock ratio diagenesis or partial solid-state reordering; either possibility supports the likelihood of preserved δ18O trends. We postulate that the preserved temperature and δ18O differences between low-latitude preglacial Tonian and synglacial Cryogenian dolomites are an imperfect reflection of primary temperature change and ice sheet expansion

Stromatolite records of environmental change in perennially ice-covered Lake Joyce, McMurdo Dry Valleys, Antarctica

Calcite-rich columnar stromatolites grew in perennially ice-covered Lake Joyce in the McMurdo Dry Valleys, Antarctica, during a period of environmental change associated with rising lake level. Stromatolite calcite contains carbon and oxygen isotope records of changes to microbial activity in response to variable light environments and water chemistry through time. The stromatolites grew synchronously with correlative calcite zones. The innermost (oldest) calcite zone has a wide range of δ13Ccalcite values consistent with variable photosynthetic effects on local DIC 13C/12C. Subsequent calcite zones preserve a progressive enrichment in δ13Ccalcite values of approximately + 2.6‰ through time, with δ[superscript 13C]calcite values becoming less variable. This enrichment likely records the removal of [superscript 12]C by photosynthesis from the DIC reservoir over decades, with photosynthetic effects decreasing as light levels became lower and more consistent through time. Mean δ[superscript 18O]calcite values of the innermost calcified zone were at least 1‰ lower than those of the other calcified zones (t test p-level < 0.001). The significant difference in δ[superscript 18O]calcite values between the innermost and other calcified zones could be a product of mixing source waters with different isotopic values associated with the initiation of lake stratification associated with rising lake level. Overall, Lake Joyce stromatolites record significant lateral variability in relative photosynthetic rate and long-lived lake water stratification with microbial modification of the DIC pool. Such processes provide criteria for interpreting microbial activity within polar paleolake deposits and may shed light on variability in lake environments associated with changing climate in the McMurdo Dry Valleys. Keywords: Antarctica; Stromatolite; Microbial mat; Carbonate; IsotopesUnited States. National Aeronautics and Space Administration (Award NNX08AO19G)United States. National Aeronautics and Space Administration (Award NNX13AI60G

CAMPAIGN CONTACT

This year’s campaign is dedicated to the memory of the 14 firefighters who lost their lives on the South Canyon fire on July 6, 1994, near Glenwood Springs, Colorado. “May we all be energized and inspired to be ever aware of the lessons learned from their sacrifice. ” (South Canyon Fire Investigation, August, 1994

Phytophthora cinnamomi and Australia’s biodiversity : impacts, predictions and progress towards control

Phytophthora cinnamomi continues to cause devastating disease in Australian native vegetation and consequently the disease is listed by the Federal Government as a process that is threatening Australia&rsquo;s biodiversity. Although several advances have been made in our understanding of how this soil-borne pathogen interacts with plants and of how we may tackle it in natural systems, our ability to control the disease is limited. The pathogen occurs widely across Australia but the severity of its impact is most evident within ecological communities of the south-west and south-east of the country. A regional impact summary for all states and territories shows the pathogen to be the cause of serious disease in numerous species, a significant number of which are rare and threatened. Many genera of endemic taxa have a high proportion of susceptible species including the iconic genera Banksia, Epacris and Xanthorrhoea. Long-term studies in Victoria have shown limited but probably unsustainable recovery of susceptible vegetation, given current management practices. Management of the disease in conservation reserves is reliant on hygiene, the use of chemicals and restriction of access, and has had only limited effectiveness and not provided complete control. The deleterious impacts of the disease on faunal habitat are reasonably well documented and demonstrate loss of individual animal species and changes in population structure and species abundance. Few plant species are known to be resistant to P. cinnamomi; however, investigations over several years have discovered the mechanisms by which some plants are able to survive infection, including the activation of defence-related genes and signalling pathways, the reinforcement of cell walls and accumulation of toxic metabolites. Manipulation of resistance and resistance-related mechanisms may provide avenues for protection against disease in otherwise susceptible species. Despite the advances made in Phytophthora research in Australia during the past 40 years, there is still much to be done to give land managers the resources to combat this disease. Recent State and Federal initiatives offer the prospect of a growing and broader awareness of the disease and its associated impacts. However, awareness must be translated into action as time is running out for the large number of susceptible, and potentially susceptible, species within vulnerable Australian ecological communities.<br /