Late Winter Biogeochemical Conditions Under Sea Ice in the Canadian High Arctic

With the Arctic summer sea-ice extent in decline, questions are arising as to how changes in sea-ice dynamics might affect biogeochemical cycling and phenomena such as carbon dioxide (CO2) uptake and ocean acidification. Recent field research in these areas has concentrated on biogeochemical and CO2 measurements during spring, summer or autumn, but there are few data for the winter or winter–spring transition, particularly in the High Arctic. Here, we present carbon and nutrient data within and under sea ice measured during the Catlin Arctic Survey, over 40 days in March and April 2010, off Ellef Ringnes Island (78° 43.11′ N, 104° 47.44′ W) in the Canadian High Arctic. Results show relatively low surface water (1–10 m) nitrate (<1.3 µM) and total inorganic carbon concentrations (mean±SD=2015±5.83 µmol kg−1), total alkalinity (mean±SD=2134±11.09 µmol kg−1) and under-ice pCO2sw (mean±SD=286±17 µatm). These surprisingly low wintertime carbon and nutrient conditions suggest that the outer Canadian Arctic Archipelago region is nitrate-limited on account of sluggish mixing among the multi-year ice regions of the High Arctic, which could temper the potential of widespread under-ice and open-water phytoplankton blooms later in the season

Tris(dimethylamido)bis(dimethylamine) titanium(IV) chlorido-bis(dimethylamine)[tris (pentafluoro-phenyl) boron-amido][tris(pentafluorophenyl)boron-nitrido]-titanate(IV) toluene solvate

The title ionic solid, [Ti(C2H6N)3(C2H7N)2][Ti(C18BF15N)(C18H2BF15N)Cl(C2H7N)2]·C7H8, (I), comprises a cation with three dimethylamide ligands in the equatorial plane and two dimethylamine ligands positioned axially in a trigonal-bipyramidal geometry about the central TiIV atom. The anion has a highly distorted octahedral structure. The two dimethylamine ligands are coordinated mutually trans. The chloride is trans to the tris(pentafluorophenyl)boron-amide, while the sixth coordination site is occupied by an ortho-F atom of the tris(pentafluorophenyl)boron-amide group in a trans disposition with respect to the tris(pentafluorophenyl)boron-nitride ligand. The most significant feature of the anion is the presence of an unprecedented terminal TiN moiety [1.665 (2) Å], stabilized by coordination to B(C6F5)3, with a TiN-B angle of 169.50 (19)°

The synthesis, structure and reactivity of B(C6F5)(3)-stabilised amide (M-NH2) complexes of the Group 4 metals

Treatment of the homoleptic titanium amides [Ti(NR2)4] (R=Me or Et) with the Brønsted acidic reagent H3NB(C6F5)3 results in the elimination of one molecule of amine and the formation of the four-coordinate amidoborate complexes [Ti(NR2)3{NH2B(C6F5)3}], the identity of which was confirmed by X-ray crystallography. The reaction with [Zr(NMe2)4] proceeds similarly but with retention of the amine ligand to give the trigonal-bipyramidal complex [Zr(NMe2)3{NH2B(C6F5)3}(NMe2H)]. Cyclopentadienyl (Cp) amidoborate complexes, [MCp(NR2)2{NH2B(C6F5)3}] (M=Ti, R=Me or Et; M=Zr, R=Me) can be prepared from [MCp(NR2)3] and H3NB(C6F5)3, and exhibit greater thermal stability than the cyclopentadienyl-free compounds. H3NB(C6F5)3 reacts with nBuLi or LiN(SiMe3)2 to give LiNH2B(C6F5)3, which complexes with strong Lewis acids to form ion pairs that contain weakly coordinating anions. The attempted synthesis of metallocene amidoborate complexes from dialkyl or diamide precursors and H3NB(C6F5)3 was unsuccessful. However, LiNH2B(C6F5)3 does react with the highly electrophilic reagents [MCp2Me(-Me)B(C6F5)3] to give [MCp2Me(-NH2)B(C6F5)3] (M=Zr or Hf). Comparison of the molecular structures of the Group 4 amidoborate complexes reveals very similar BN, TiN and ZrN bond lengths, which are consistent with a description of the bonding as a dative interaction between an {M(L)n(NH2)} fragment and the Lewis acid B(C6F5)3. Each of the structures has an intramolecular hydrogen-bonding arrangement in which one of the nitrogen-bonded hydrogen atoms participates in a bifurcated FHF interaction to ortho-F atoms

Diagnostic monitoring of a changing environment: An alternative UK perspective

Adaptive management of the marine environment requires an understanding of the complex interactions within it. Establishing levels of natural variability within and between marine ecosystems is a necessary prerequisite to this process and requires a monitoring programme which takes account of the issues of time, space and scale. In this paper, we argue that an ecosystem approach to managing the marine environment should take direct account of climate change indicators at a regional level if it is to cope with the unprecedented change expected as a result of human impacts on the earth climate system. We discuss the purpose of environmental monitoring and the importance of maintaining long-term time series. Recommendations are made on the use of these data in conjunction with modern extrapolation and integration tools (e.g. ecosystem models, remote sensing) to provide a diagnostic approach to the management of marine ecosystems, based on adaptive indicators and dynamic baselines

Gorgon CO2 Surface and Near-surface Monitoring

This report is a review of the current status of the various techniques used to monitor the near-surface environment above a GCS (geological CO2 storage) project, with specific reference to Barrow Island. The review covers a range of environments, broadly sub-divided into near-surface atmospheric, soil gas, groundwater and the near-shore and marine environment. For each environment the key parameters likely to be indicative of migrant CO2 (including CO2 directly) are considered. The techniques covered include geochemical, isotopic, geophysical, microbial, marine and near-surface atmospheric. For each technique what parameters are measured, the effectiveness of each, the stage of development, relative cost and footprint and some of the practicalities of implementing such a system on Barrow Island are described. Included in the report is a review of where these technologies are being deployed or researched at different GCS sites around the world. There are few commercial scale GCS projects, the majority are demonstration scale and the monitoring techniques being applied are as much for technology development as leakage detection. One of the major difficulties with a near-surface environmental monitoring system is the need to be able to demonstrate detectability of a small or non-existent signal within an inherently noisy system. There are potentially many ways to detect CO2 or parameters affected by its presence; however, they need to be coupled with a method to quantitatively distinguish them from the background environmental or anthropogenic variability. For each of the technologies reviewed, three common themes emerged. The first is that no single technology is likely to meet all of the monitoring objectives. The need for targeted, high intensity monitoring sites at high risk locations should be coupled with lower resolution, larger scale monitoring at low risk sites. There are technologies that are appropriate for each of these; small scale (centimetre to metres) continuous monitoring, such as soil gas or geochemistry and those more suited to periodic, regional scale characterisation and monitoring such as the airborne geophysical techniques (10's of kilometers). Some of the near-surface ambient techniques may be suitable for intermediate scale monitoring of several kilometers. The second theme is the need for modelling studies supported by field trials and data collection to quantify the effects and therefore the detectability of each parameter that may be affected by CO2. The modelling would be used to identify the areas of high risk or high uncertainty and form the foundation for building the monitoring system. The third theme is the need to collect baseline data at least one year prior to injection beginning. The collection of baseline data is fundamental to building the models and understanding the natural variation of the system, including emission sources. However, the collection of baseline data is a non-trivial exercise, particularly on Barrow Island. Each of the potentially suitable techniques would require further field based studies to determine their most effective instrument set-up and measurement resolution. Finally, the technology associated with GCS near-surface monitoring is evolving rapidly. Instrument sensitivity, data sampling rates, equipment deployability, deployment costs and processing/interpretation methods are undergoing rapid change. The monitoring system deployed on Barrow Island will need to be flexible and adaptable to account for changing conditions and technologies

Long-term oceanographic and ecological research in the western English Channel

Long-term research in the western English Channel, undertaken by the marine laboratories in Plymouth, is described and details of survey methods, sites, and time series given in this chapter. Major findings are summarized and their limitations outlined. Current research, with recent reestablishment and expansion of many sampling programmes, is presented, and possible future approaches are indicated. These unique long-term data sets provide an environmental baseline for predicting complex ecological responses to local, regional, and global environmental change. Between 1888 and the present, investigations have been carried out into the physical, chemical, and biological components (ranging from plankton and fish to benthic and intertidal assemblages) of the western English Channel ecosystem. The Marine Biological Association of the United Kingdom has performed the main body of these observations. More recent contributions come from the Continuous Plankton Recorder Survey, now the Sir Alister Hardy Foundation for Ocean Science, dating from 1957; the Institute for Marine Environmental Research, from 1974 to 1987; and the Plymouth Marine Laboratory, which was formed by amalgamation of the Institute for Marine Environmental Research and part of the Marine Biological Association, from 1988. Together, these contributions constitute a unique data series; one of the longest and most comprehensive samplings of environmental and marine biological variables in the world. Since the termination of many of these time series in 1987-1988 during a reorganisation of UK marine research, there has been a resurgence of interest in long-term environmental change. Many programmes have been restarted and expanded with support from several agencies. The observations span significant periods of warming (1921-1961; 1985-present) and cooling (1962-1980). During these periods of change, the abundance of key species underwent dramatic shifts. The first period of warming saw changes in zooplankton, pelagic fish, and larval fish, including the collapse of an important herring fishery. During later periods of change, shifts in species abundances have been reflected in other assemblages, such as the intertidal zone and the benthic fauna. Many of these changes appear to be related to climate, manifested as temperature changes, acting directly or indirectly. The hypothesis that climate is a forcing factor is widely supported today and has been reinforced by recent studies that show responses of marine organisms to climatic attributes such as the strength of the North Atlantic Oscillation. The long-term data also yield important insights into the effects of anthropogenic disturbances such as fisheries exploitation and pollution. Comparison of demersal fish hauls over time highlights fisheries effects not only on commercially important species but also on the entire demersal community. The effects of acute ("Torrey Canyon" oil spill) and chronic (tributyltin [TBT] antifoulants) pollution are clearly seen in the intertidal records. Significant advances in diverse scientific disciplines have been generated from research undertaken alongside the long-term data series