Characteristics and landcover of estuarine boundaries: implications for the delineation of the South African estuarine functional zone

This study investigated whether the current lateral boundary for estuaries in South Africa, i.e. the estuarine functional zone (EFZ), includes all estuarine habitats. The EFZ covers 173 930 ha in 304 estuaries/outlets nationally. Field surveys and analysis of available aerial images showed that 82 (12 956.70 ha) of these estuaries (26%) had estuarine habitats occurring outside of this boundary. As a result of mapping scale, the National Vegetation Map does not represent habitats that are associated with small estuaries (approximately 50% of South Africa's estuaries). For estuaries in the Western and Eastern Cape provinces, most habitats have been lost due to urban development, whereas in subtropical areas (northern Eastern Cape and KwaZulu-Natal), cultivation has removed estuarine habitat. Although delineation of boundaries can be complicated by landcover changes, the estuarine lateral boundary in Cape estuaries could be identified based on sediment characteristics (moisture content, organic content, electrical conductivity), groundwater characteristics (salinity, conductivity and depth) and plant species. The delineation of the EFZ needs to be consistent, inclusive of all estuarine physical and biological processes, and cost-effective to identify so that it can protect estuarine habitats.     

Nicholas Crisp's “Porcellien”: A petrological comparison of sherds from the Vauxhall (London; ca. 1751–1764) and Indeo Pottery (Bovey Tracey,Devonshire; ca. 1767–1774) factory sites

The character of porcelain wares made by Nicholas Crisp early and late in his career was assessed using microchemical and petrographic data for sherds excavated from the sites of the factories he operated at Vauxhall and Bovey Tracey. The results indicate that, over time, Crisp increasingly made use of diverse types of pastes as he struggled to produce a commercially viable line of porcelain. Based on the analysis of a limited number of samples, he appears to have largely restricted himself at Vauxhall to using soapstone (Mg‐rich)‐ and flint‐glass (Pb‐rich) frit‐bearing pastes that varied in the amount of calcite they contained. He also experimented with Mg+Pb‐rich pastes at Bovey Tracey, but included a novel ingredient (barite) and varied the proportion of other minor constituents (e.g., bone ash), apparently in an effort to resolve some of the firing problems that plagued him at Vauxhall. In addition, Crisp appears to have produced bone ash (phosphatic) porcelain at Bovey Tracey, and, in collaboration with William Cookworthy, the proprietor of the Plymouth factory, fired a range of true porcelain (Si+Al‐rich) pastes. Bulk compositional data indicate that Crisp's diopside‐bearing Mg+Pb‐rich wares were derived from pastes containing talc and calcite rather than dolomite. The mineralogy of these and some contemporary magnesian/plombian porcelains are interpreted using the SiO₂‐CaO‐MgO phase diagram. This diagram shows that these wares can form and preserve diopside (Ca‐Mg silicate) given suitable bulk CaO contents and kiln‐firing temperatures. Phosphatic sherds from Bovey Tracey are compositionally distinct (lower SiO₂ and higher Al₂O₃ and bone‐ash components) from a single bone‐ash sample from Vauxhall, indicating that Crisp experimented with novel bone‐ash pastes, and was not positively influenced by the Vauxhall phosphatic recipe, if indeed one existed. True porcelains from Bovey Tracey have more extreme SiO₂/Al₂O₃ ratios (= 2.0 [two sherds]; 4.5 [one sherd]) than their Plymouth/Bristol counterparts (SiO₂/Al₂O₃ = 2.3–3.0). Collectively, the analytical data underscore the experimental—and ultimately unsuccessful—character of the diverse wares produced by Nicholas Crisp. © 2000 John Wiley & Sons, Inc.     

Bayesian spatial modeling of Lavaca Bay pollutants

Locational risk of increased mercury and PAH concentrations in Lavaca Bay, Texas sediments and eastern oysters (Crassostrea virginica) harvested from Lavaca Bay, Texas were analysed. Chemical analysis results were evaluated utilizing Bayesian geo-statistical methods for comparison of the model fit of a random effects model versus a convoluted model which included both random and spatial effects. For those results fit best with the convoluted model, continuous surface maps of predicted parameter values were created. Sediment and oyster concentrations of mercury and the majority of measured PAHs were fit best with the convoluted model. The locational risks of encountering elevated concentrations of these pollutants in Lavaca Bay sediments and oysters were highest in close proximity to industrial facilities.     

Deciphering topographic signals of glaciation and rock uplift in an active orogen: a case study from the Olympic Mountains,USA

Estimating recent patterns of erosion and rock uplift within Cenozoic orogens has proven difficult as signals of these processes have been obfuscated by Plio‐Pleistocene glaciation. The topography of many mountain ranges integrates the effects of long‐lived rock uplift, Late‐Cenozoic climate variation, and post‐glacial landscape adjustment. In this study, we employ a suite of topographic analyses to study the relief of an active mountain range on a sub‐catchment scale in an effort to the separate the long‐term signal of rock uplift from perturbations due to shorter‐lived climate signals. We focus on the Olympic Mountains, USA, where patterns of exhumation and glaciation have been previously estimated; however, our methods and results are broadly applicable to other orogens. Our analysis shows that Plio‐Pleistocene alpine glaciers and the Cordilleran Ice Sheet have reduced the elevations of channel profiles and created anomalously low channel relief in the Olympic Mountains. Large low‐gradient areas formed at lower elevations where ice sheets were present and alpine glaciers widened and deepened valleys. In the more rugged core of the range, near‐threshold hillslopes along the margins of the oversteepened glacially‐carved valleys, dominate the range. This implies a strong Plio‐Pleistocene glacial climate control on the topography over the more recent evolution of the Olympic Mountains. However, the broad relief structure of the range appears to still record the regional rock uplift pattern and is suggestive of an east‐plunging antiform, consistent with folding of the subducting plate or underplating of accreted rocks. Copyright © 2017 John Wiley & Sons, Ltd.     

Overview and status of estuarine microphytobenthos ecological research in South Africa

This article presents a historical overview of estuarine microphytobenthos (MPB) research in South Africa published over the period 1950 to the present, highlighting major milestones, challenges and estuarine management problems, as well as future research needs within the South African context. The studies that were covered comprise peer-reviewed books and journal articles on relevant research conducted in any estuarine environment during the period reviewed. There was a general increase in MPB research outputs over the decades, from only two publications in the 1950s, to over 20 outputs between 2010 and the present. Whereas the MPB studies in South Africa cover a broad spectrum of themes, the research priorities in these works have changed from taxonomically biased studies to those of ecologically based research. Research in the 1950s and 1960s was exclusively taxonomic in nature, with the first ecological investigation incorporating MPB being produced in the 1970s. By the 1980s, ecological studies dominated the research outputs and this trend has persisted to the present. The 1990s and 2000s saw the rise of research into the role of fresh water as a driver of MPB dynamics, whereas the period 2010 to the present saw an increase in more diverse ecological themes, ranging from an autecological investigation to food-web studies and the assessment of multiple drivers of MPB dynamics. However, the majority of studies have focused on either diatoms or estimates of overall MPB biomass. Moreover, there is a regional underrepresentation that runs broadly along biogeographic lines, with the bulk of the work having been conducted in the warm-temperate and subtropical zones of South Africa. Challenges and future research needs for the region are outlined, as is the need to expand MPB research to include other aspects of the biology and ecology of this flora.     

用扫描电镜技术识别广州市大气颗粒物主要种类

利用扫描电镜技术对大气颗粒物的来源进行识别，采取手动分析与自动分析两种方法，得出的结果在总趋势上相互一致。手动方法和自动方法各有特点。自动分析在细颗粒，特别是含硫颗粒分析方面有优势，而手动分析在形貌观测和确定有机粗颗粒污染状况方面有独到之处。实验结果表明，大气颗粒物的来源是多样的，治理措施也应是综合性的，既要注意工业点源的污染治理和排放控制，如燃煤飞灰，钙质颗粒富铁颗粒等，也要注意面源排放，如土壤扬尘和碳质颗粒，碳质颗粒的来源复杂，可以是工业过程，燃烧过程，机动车尾气，生物质燃，树木自然排放。     

A Great Basin-wide dry episode during the first half of the Mystery Interval?

The existence of the Big Dry event from 14.9 to 13.8 ¹⁴C kyrs in the Lake Estancia New Mexico record suggests that the deglacial Mystery Interval (14.5–12.4 ¹⁴C kyrs) has two distinct hydrologic parts in the western USA. During the first, Great Basin Lake Estancia shrank in size and during the second, Great Basin Lake Lahontan reached its largest size. It is tempting to postulate that the transition between these two parts of the Mystery Interval were triggered by the IRD event recorded off Portugal at about 13.8 ¹⁴C kyrs which post dates Heinrich event #1 by about 1.5 kyrs. This twofold division is consistent with the record from Hulu Cave, China, in which the initiation of the weak monsoon event occurs in the middle of the Mystery Interval at 16.1 kyrs (i.e., about 13.8 ¹⁴C kyrs).     

The future evolution of white dwarf stars through baryon decay and time varying gravitational constant

Motivated by the possibility that the fundamental “constants” of nature could vary with time, this paper considers the long term evolution of white dwarf stars under the combined action of proton decay and variations in the gravitational constant. White dwarfs are thus used as a theoretical laboratory to study the effects of possible time variations, especially their implications for the future history of the universe. More specifically, we consider the gravitational constant G to vary according to the parametric relation G=G ₀(1+t/t _? )^?p , where the time scale t _? is the same order as the proton lifetime t _P . We then study the long term fate and evolution of white dwarf stars. This treatment begins when proton decay dominates the stellar luminosity, and ends when the star becomes optically thin to its internal radiation.     

Effects of alumina refinery wastewater and signature metal constituents at the upper thermal tolerance of: 1. The tropical diatom Nitzschia closterium

Ecotoxicological studies, using the tropical marine diatom, Nitzschia closterium (72-h growth rate), were undertaken to assess potential issues relating to the discharge from an alumina refinery in northern Australia. The studies assessed: (i) the species’ upper thermal tolerance; (ii) the effects of three signature metals, aluminium (Al), vanadium (V) and gallium (Ga) (at 32 °C); and (iii) the effects of wastewater (at 27 and 32 °C). The critical thermal maximum and median inhibition temperature for N. closterium were 32.7 °C and 33.1 °C, respectively. Single metal toxicity tests found that N. closterium was more sensitive to Al compared to Ga and V, with IC₅₀s (95% confidence limits) of 190 (140-280), 19,640 (11,600-25,200) and 42,000 (32,770-56,000) μg L⁻¹, respectively. The undiluted wastewater samples were of low toxicity to N. closterium (IC₅₀s > 100% wastewater). Environmental chemistry data suggested that the key metals and discharge are a very low risk to this species.