Herbicide contamination and the potential impact to seagrass meadows in Hervey Bay, Queensland, Australia

Low concentrations of herbicides (up to 70 ng l(-1)), chiefly diuron (up to 50 ng l(-1)) were detected in surface waters associated with inter-tidal seagrass meadows of Zostera muelleri in Hervey Bay, south-east Queensland, Australia. Diuron and atrazine (up to 1.1 ng g(-1) dry weight of sediment) were detected in the sediments of these seagrass meadows. Concentration of the herbicides diuron, simazine and atrazine increased in surface waters associated with seagrass meadows during moderate river flow events indicating herbicides were washed from the catchment to the marine environment. Maximum herbicide concentration (sum of eight herbicides) in the Mary River during a moderate river flow event was 4260 ng l(-1). No photosynthetic stress was detected in seagrass in this study during low river flow. However, with moderate river flow events, nearshore seagrasses are at risk of being exposed to concentrations of herbicides that are known to inhibit photosynthesis.     

Occurrence and seasonal variations of algal toxins in water, phytoplankton and shellfish from North Stradbroke Island, Queensland, Australia

A number of marine microalgae are known to produce toxins that can accumulate in shellfish and when eaten, lead to toxic and potentially fatal reactions in humans. This paper reports on the occurrence and seasonal variations of algal toxins in the waters, phytoplankton and shellfish of Southeast Queensland, Australia. These algal toxins include okadaic acid (OA), domoic acid (DA), gymnodimine (GD), pectenotoxin-2 (PTX-2) and pectenotoxin-2-seco acid (PTX-2-SA), which were detected in the sampled shellfish and phytoplankton, via HPLC-MS/MS. Dissolved OA, PTX-2 and GD were also detected in the samples collected from the water column. This was the first occasion that DA and GD have been reported in shellfish, phytoplankton and the water column in Queensland waters. Phytoplankton tows contained both the toxic Dinophysis and Pseudo-nitzschia algae species, and are suspected of being the most likely producers of the OA, PTX-2s and DA found in shellfish of this area. The number of cells, however, did not correlate with the amount of toxins present in either shellfish or phytoplankton. This indicates that toxin production by algae varies with time and the species present and that number of cells alone cannot be used as an indicator for the presence of toxins. The presence of OA and PTX-2s were more frequently seen in the summer, while DA and GD were detected throughout the year and without any obvious seasonal patterns.     

The implementation of reverse Kessler warm rain scheme for radar reflectivity assimilation using a nudging approach in New Zealand

Reverse Kessler warm rain processes were implemented within the Weather Research and Forecasting Model (WRF) and coupled with a Newtonian relaxation, or nudging technique designed to improve quantitative precipitation forecasting (QPF) in New Zealand by making use of observed radar reflectivity and modest computing facilities. One of the reasons for developing such a scheme, rather than using 4D-Var for example, is that radar VAR scheme in general, and 4D-Var in particular, requires computational resources beyond the capability of most university groups and indeed some national forecasting centres of small countries like New Zealand. The new scheme adjusts the model water vapor mixing ratio profiles based on observed reflectivity at each time step within an assimilation time window. The whole scheme can be divided into following steps: (i) The radar reflectivity is firstly converted to rain water, and (ii) then the rain water is used to derive cloud water content according to the reverse Kessler scheme; (iii) The cloud water content associated water vapor mixing ratio is then calculated based on the saturation adjustment processes; (iv) Finally the adjusted water vapor is nudged into the model and the model background is updated. 13 rainfall cases which occurred in the summer of 2011/2012 in New Zealand were used to evaluate the new scheme, different forecast scores were calculated and showed that the new scheme was able to improve precipitation forecasts on average up to around 7 hours ahead depending on different verification thresholds.     

Dynamics of salt marsh margins are related to their three-dimensional functional form

The three-dimensional configuration of sedimentary landforms in intertidal environments represents a major control on regional hydrodynamics. It modulates the location and magnitude of forces exerted by tidal currents and waves on the landform itself and on engineered infrastructure such as sea walls or coastal defences. Furthermore, the effect is reflexive, with the landforms representing an integrated, long-term response to the forces exerted on them. There is a strong reciprocal linkage between form and process (morphodynamics) in the coastal zone which is significantly lagged and poorly understood in the case of cohesive, vegetated sediments in the intertidal zone. A method is presented that links the geometric properties of the tidal flat–salt marsh interface to the history and potential future evolution of that interface. A novel quantitative classification scheme that is capable of separating marsh margins based on their functional form is developed and is applied to demonstrate that relationships exist between landform configuration and morphological evolution across a regional extent. This provides evidence of a spatially variable balance between self-organized and external controls on morphodynamic evolution and the first quantitative basis for a quick assessment procedure for likely future dynamism. © 2019 John Wiley & Sons, Ltd.     

Airborne Laser Sensing of Scottish Coastal Waters

An Nd:YAG-based airborne lidar system has been used to measure the optical properties of littoral waters off the northwest Scottish coast. The small-scale structure of subsurface scattering layers was also investigated. Methods of solving the Lidar Sensing Equation in the single scattering approximation are described and the values of the derived extinction indices presented. The extinction index averaged over a series of five flights to the northeast of the Gulf Stream was k = 0.224 m -1 with a standard deviation of 0.212 m -1 . Further, it was demonstrated that, in coastal waters, optical inhomogeneities with dimensions between 50 m and 200 km obey the power law Sp k ~ k -P with the parameter P close to two. In turbid or transparent areas, the water extinction index can change by several tenths of a percent with respect to the surrounding water mass. This suggests that the observed nonmonotonic behavior of the power spectra of the water extinction index fluctuations is caused by the outer scale of turbulence, in particular, by the bottom depth at the measurement site.     

Post-revanchist cities?

This intervention focuses on how national-level rhetoric aimed at impugning “others” has thrived of late, but how concomitantly 1990s-style urban revanchism has faded in cities that were once punitive crucibles against the homeless. Using Los Angeles as case study, I argue that the recent trend has been to grudgingly support the homeless, increasingly via taxpayer initiatives, leading to a potential but stymied post-revanchist city. If the spirit of revanchism remains, it is through the persistent NIMBY opposition to housing the homeless.     

Reviews

GEOMORPHOLOGY by R. J. Chorley, S. A. Schumm and D. E. Sugden.’ 19 × 25 cm, xxiii and 605 pages. Methuen: London 1984 (ISBN 0 416 32590 4) $A39.95 (cloth).

THEMES IN GEOMORPHOLOGY edited by A. F. Pitty. 13 × 21 cm, 280 pages. Croom Helm: London 1985 (ISBN 0 7099 2066 0) $A49.50 (cloth).

DESERTS AND ARID LANDS edited by F. El‐Baz. 16 × 25 cm, vi and 222 pages. Nijhoff: The Hague 1984 (ISBN 90 247 2850 9) $US46.00 (cloth).

COASTAL GEOMORPHOLOGY IN AUSTRALIA edited by B. G. Thorn. 16 × 24 cm, xv and 349 pages. Academic Press: Sydney 1984 (ISBN 0 12 687880 3) $A49.50 (cloth).

KWONGAN: Plant Life on the Sandplain edited by J. S. Pate and J. S. Beard. University of Western Australia Press: Nedlands 1984 (ISBN 0 85564 230 0) $A25.00 (limp).

THEMES IN BIOGEOGRAPHY edited by J. A. Taylor. 22 × 14 cm, xxvii and 404 pages. Croom Helm: London 1984 (ISBN 0 7099 2428 3) $A25.95 (limp).

ENVIRONMENTAL IMPACT ASSESSMENT: A Practical Guide by C. F. Porter. 22 × 15 cm, xiii and 269 pages. University of Queensland Press: St Lucia 1985 (ISBN 0 7022 1699 2) $A35.00 (cloth).

THE CLIMATIC SCENE edited by M. J. Tooley and G. M. Sheail. 16 × 24 cm, xx and 306 pages. George Allen and Unwin: London 1985 (ISBN 0 04 551089 X) $A59.95 (cloth).

VOLCANIC HAZARDS: A Sourcebook on the Effects of Eruptions by R. J. Blong. 24 × 15 cm, xvi and 424 pages. Academic Press: Sydney 1984 (ISBN 0 12 107180 4) $A68.00 (cloth).

THE ECONOMICS OF BUSHFIRES: The South Australian Experience edited by D. T. Healey, F. G. Jarrett and J. M. McKay. 22 × 15 cm, x and 152 pages. Oxford University Press: Melbourne 1985 (ISBN 0 19 554669 5) $A19.99 (cloth).