ALBERT

Description: This paper positions possibilities for human geographies of the sea. The growing volume of work under this banner has been largely qualitative in its approach, reflecting, in turn, the questions posed by oceanic scholars. These questions necessitate corresponding methods. Whilst this is not necessarily a problem, and the current corpus of work has offered many significant contributions, in making sense of the human dimensions of maritime worlds, other questions—and methods—may generate knowledge that is useful within this remit of work. This paper considers the place of quantitative approaches in posing lines of enquiry about shipping, one of the prominent areas of concern under the banner of ‘human geographies of the seas’. There is longstanding work in transport geographies concerned with shipping, logistics, freight movement and global connections, which embraces quantitative methods which could be bridged to ask fresh questions about oceanic spatial phenomena past and present. This paper reviews the state of the art of human geographies of the sea and transport geographies and navigates how the former field may be stimulated by some of the interests of the latter and a broader range of questions about society-sea-space relations. The paper focuses on Automatic Identification Systems (or AIS) as a potentially useful tool for connecting debates, and deepening spatial understandings of the seas and shipping beyond current scholarship. To advance the argument the example of shipping layups is used to illustrate or rather, position, the point.

Description: This paper positions possibilities for human geographies of the sea. The growing volume of work under this banner has been largely qualitative in its approach, reflecting, in turn, the questions posed by oceanic scholars. These questions necessitate corresponding methods. Whilst this is not necessarily a problem, and the current corpus of work has offered many significant contributions, in making sense of the human dimensions of maritime worlds, other questions—and methods—may generate knowledge that is useful within this remit of work. This paper considers the place of quantitative approaches in posing lines of enquiry about shipping, one of the prominent areas of concern under the banner of ‘human geographies of the seas’. There is longstanding work in transport geographies concerned with shipping, logistics, freight movement and global connections, which embraces quantitative methods which could be bridged to ask fresh questions about oceanic spatial phenomena past and present. This paper reviews the state of the art of human geographies of the sea and transport geographies and navigates how the former field may be stimulated by some of the interests of the latter and a broader range of questions about society-sea-space relations. The paper focuses on Automatic Identification Systems (or AIS) as a potentially useful tool for connecting debates, and deepening spatial understandings of the seas and shipping beyond current scholarship. To advance the argument the example of shipping layups is used to illustrate or rather, position, the point.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gases i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards the surface waters during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of these greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise SO283 (March 19th – May 25th, 2021) onboard the R/V SONNE from and to Emden (Germany). The main area of the sampling was the Namibian shelf between 18°S and 25°S which is suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of the concentrations of CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and trace gas was quantified in return. Dissolved CH4 and N2O were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system Dissolved Inorganic Carbon (DIC) was measured in the institute. About 5.00 ml of each fixed discrete sample was acidified by 10 % phosphoric acid, resulting in release of inorganic carbon content of the sample. An automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany) was used to quantify DIC. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gas i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards sea surface during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of the greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which are suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of dissolved CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and dissolved trace gas was quantified in return. The dissolved gases were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system, Dissolved Inorganic Carbon (DIC) was measured on board by an automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).