The National Heritage Resource Act (1999): Can legislation protect South Africa's rare geoheritage resources?

In South Africa, rare geological specimens are protected by the National Heritage Resource Act (1999). These portable geoheritage objects are neither defined nor described in this Act making their geoheritage status questionable. Thirteen categories and criteria for establishing a geological specimen's rarity status are discussed and include (1) rarity as defined by abundance per se; (2) rarity of a particular habit (external shape or form) of a mineral; (3) rare pseudomorphs; (4) rarity of a particular variety of a mineral; (5) rarity of a particular colour of a common mineral; (6) rarity defined by size; (7) rarity defined by quality; (8) a common species, but rare for a particular locality; (9) rarity of associations of minerals; (10) rarity determined by source being depleted, exhausted or mined out; (11) rare inclusions in minerals; (12) previously rare, now common specimens and (13) miscellaneous criteria that produce rare specimens. Geological specimens (resources) are complex objects when defining their rarity status and multiple rarity factors can apply to single specimens. A lack of clear criteria for defining rare geological specimens appears to place the National Heritage Resource Act (1999) in direct conflict with the more recent Mineral and Petroleum Resources Development Act (2002) which legitimizes the legal exploitation of any mineral resource.     

Spatial distribution of enhanced atrazine degradation across northeastern Colorado cropping systems

Reports of enhanced atrazine degradation and reduced residual weed control have increased in recent years, sparking interest in identifying factors contributing to enhanced atrazine degradation. The objectives of this study were to (i) assess the spatial distribution of enhanced atrazine degradation in 45 commercial farm fields in northeastern Colorado (Kit Carson, Larimer, Logan, Morgan, Phillips, and Yuma counties) where selected cultural management practices and soil bio-chemo-physical properties were quantified; (ii) utilize Classification and Regression Tree (CART) Analysis to identify cultural management practices and (or) soil bio-chemophysical attributes that are associated with enhanced atrazine degradation; and (iii) translate our CART Analysis into a model that predicts relative atrazine degradation rate (rapid, moderate, or slow) as a function of known management practices and (or) soil properties. Enhanced atrazine degradation was widespread within a 300-km radius across northeastern Colorado, with approximately 44% of the fields demonstrating rapid atrazine degradation activity (laboratory-based dissipation time halflife [DT50] < 3 d). The most rapid degradation rates occurred in fields that received the most frequent atrazine applications. Classification and Regression Tree Analysis resulted in a prediction model that correctly classified soils with rapid atrazine DT50 80% of the time and soils with slow degradation (DT50 > 8 d) 62.5% of the time. Significant factors were recent atrazine use history, soil pH, and organic matter content. The presence/absence of atzC polymerase chain reaction (PCR) product was not a significant predictor variable for atrazine DT50. In conclusion, enhanced atrazine degradation is widespread in northeastern Colorado. If producers know their atrazine use history, soil pH, and OM content, they should be able to identify fields exhibiting enhanced atrazine degradation using our CART Model.     

Enhanced desorption of fluoxetine from polyethylene terephthalate microplastics in gastric fluid and sea water

There are concerns that microplastics act as a vector of pharmaceuticals in the aquatic environment. Most studies have focussed on pharmaceutical adsorption and have not investigated desorption in the various matrices that microplastics enter. Therefore we studied the desorption of the antidepressant drug fluoxetine from polyethylene terephthalate (PET) microplastics in river water, sea water, and simulated gastric and intestinal fluids. We found that most desorption occurred rapidly, within a few hours of exposure. Fluoxetine desorption fitted well to the Freundlich isotherm with r² values ranging from 0.97 to 0.99. Desorption decreased in the following order: gastric fluid at 20 °C and 37 °C; sea water at 20 °C; intestinal fluid at 20 °C and 37 °C; then river water at 20 °C. The little difference in desorption in gastrointestinal fluids at 20 °C and 37 °C suggests a similar exposure risk to cold- and warm-blooded organisms following PET microplastic ingestion. Total desorption following sequential incubation 2 h in gastric fluid then 4 h in intestinal fluid to mimic gastrointestinal digestion was 37% at 20 °C and 41% at 37 °C. Interestingly, higher desorption of 18–23% occurred in sea water compared to river water, of 4–11%. Under a worst-case scenario, more than 44 mg kg⁻¹ body weight d⁻¹ or more than 52 mg kg⁻¹ body weight d⁻¹ of PET microplastics from river water or sea water, respectively, need to be consumed to exceed the mammalian acceptable daily intake for fluoxetine. Further studies are needed on microplastic ingestion and the bioavailability of adsorbed pharmaceuticals to a range of exposed aquatic organisms.

     

An agent-based model for simulating trading of multi-species fisheries quota

Individual transferable quotas (ITQs) are increasingly seen as a way to make fisheries more profitable and halt over-capitalisation. ITQs allocate to users of a resource a share of a total allowable catch (TAC) which they are free to use, lease, or sell. We outline an approach to modelling the effect of an ITQ system in a multi-species, multi-sector fishery and apply it to the Coral Reef Fin Fish Fishery (CRFFF) in Queensland, Australia. An ITQ model, based on the assumption that operators seek to maximize profits, simulates the use of tradeable quota units by operators in the fishery, taking account of the initial quota allocation to operators, seasonal fish prices and individual operator variable costs, their fishing efficiency and experience, and constraints on vessel movements. Rationalization of the fishery is predicted to occur under an ITQ system for the CRFFF, which will lead to reductions in effort, increases in profits, and changes over time in quota prices. The ecological consequences of transferable quota in the multi-species fishery are seen in the catch and discard levels of the less profitable species, even though a TAC was set. This had flow-on effects on biomass. For example, simulations showed that the TAC for the primary target species, coral trout, was used more fully than that for a less valuable target species, red throat emperor, and that this was achieved through increased discarding of red throat emperor. Catches of both coral trout and red throat emperor that were derived from the model were higher than those recently observed in the fishery. The effort predicted by the model, however, closely approximated the actual effort observed in the fishery following implementation of ITQ management.     

AN EVALUATION OF THE 1997 EDWARDS AQUIFER IRRIGATION SUSPENSION1

ABSTRACT: In early 1997, the Texas Edwards Aquifer Authority implemented a pilot Irrigation Suspension Program with the objectives of increasing springflow and providing relief to municipalities during drought. Irrigators were paid an average of $234 per acre to suspend water use, a price higher than regional land rental rates. Auction theory and program implementation details suggest that the program implementation partially caused inflated bids. The Irrigation Suspension Program is also compared to two alternative programs: (1) subsidizing more efficient irrigation technology and (2) buying land. The irrigation suspension is found to be more cost‐effective relative to subsidizing improved irrigation efficiency because it can be put in place only when aquifer levels are low. Land purchase is a cheaper alternative if the bid levels remain at the levels observed.     

Generation of internal waves by sheared turbulence: experiments

A series of experiments is presented that model the generation of internal gravity waves in the ocean by the forcing of turbulent eddies in the surface mixed layer.The experimental setup consists of a shallow mixed upper layer and a deep continuously stratified lower layer. A source of turbulence is dragged through the upper layer. Internal waves can freely propagate in the lower layer. The internal waves are measured using synthetic schlieren to determine the frequencies of the generated waves. Consistent with other studies, it is found that the characteristic frequencies of internal waves generated by turbulence are an approximate constant fraction of the buoyancy frequency.     

Monitoring the fate of chlorine from MSW sampling through combustion Part II: Combustion studies

Combustion measurements were carried out in a multi-kilogram capacity flow calorimeter on cellulose and cellulose/sand samples in 100% oxygen and several oxygen/nitrogen mixtures. Some measurements were made on cellulose/sand samples, which had 1 mass % of polyvinylchloride (PVC) as part of their composition, to study the conditions related to the formation/destruction of chlorinated organic compounds as combustion products. Qualitative identifications of a significant variety of chlorinated organic compounds have been made.     

The backward incidence of pollution control: A dual approach

The backward incidence of pollution control is reexamined using the techniques of duality theory. The simple geometry used establishes the results and clarifies them without the complicated mathematical manipulations required in earlier works, thereby making the material more attractive for classroom presentation.