Oxidation and fragmentation of plastics in a changing environment; from UV-radiation to biological degradation

Understanding the fate of plastics in the environment is of critical importance for the quantitative assessment of the biological impacts of plastic waste. Specially, there is a need to analyze in more detail the reputed longevity of plastics in the context of plastic degradation through oxidation and fragmentation reactions. Photo-oxidation of plastic debris by solar UV radiation (UVR) makes material prone to subsequent fragmentation. The fragments generated following oxidation and subsequent exposure to mechanical stresses include secondary micro- or nanoparticles, an emerging class of pollutants. The paper discusses the UV-driven photo-oxidation process, identifying relevant knowledge gaps and uncertainties. Serious gaps in knowledge exist concerning the wavelength sensitivity and the dose-response of the photo-fragmentation process. Given the heterogeneity of natural UV irradiance varying from no exposure in sediments to full UV exposure of floating, beach litter or air-borne plastics, it is argued that the rates of UV-driven degradation/fragmentation will also vary dramatically between different locations and environmental niches. Biological phenomena such as biofouling will further modulate the exposure of plastics to UV radiation, while potentially also contributing to degradation and/or fragmentation of plastics independent of solar UVR. Reductions in solar UVR in many regions, consequent to the implementation of the Montreal Protocol and its Amendments for protecting stratospheric ozone, will have consequences for global UV-driven plastic degradation in a heterogeneous manner across different geographic and environmental zones. The interacting effects of global warming, stratospheric ozone and UV radiation are projected to increase UV irradiance at the surface in localized areas, mainly because of decreased cloud cover. Given the complexity and uncertainty of future environmental conditions, this currently precludes reliable quantitative predictions of plastic persistence on a global scale

Guideline for the diagnosis and treatment of chronic pancreatitis

BACKGROUND: Chronic pancreatitis (CP) is defined as a continuing inflammatory disease of the pancreas characterised by irreversible morphological changes, often associated with pain and with the loss of exocrine and/or endocrine function that may be clinically relevant. Alcohol is the predominant cause of CP in the western world and is particularly prevalent in South Africa, especially in the indigent patient. CP ranks high among intractable diseases of the gastrointestinal tract. The tendency for substance abuse in the alcohol-induced group poses major psychological and socioeconomic problems. OBJECTIVE: CP is a disease with significant clinical and pathological heterogeneity. Level 1 evidence to support definitive guidelines for diagnosis, medical management and interventional therapy is lacking. Despite this paucity of robust scientific evidence, it is important to provide some assistance based on the best available evidence as to the current standard of care for CP in the South African context; this will aid all involved in the management of the disease, and includes clinicians, health care managers and funders. Scope. The guidelines were developed as recommendations addressing the diagnosis, medical management and interventions, both endoscopic and surgical, for the management of a very complex and heterogeneous disease of the pancreas. The recommendations are particularly relevant in the South African context where the predominant patho-aetiological agents are alcohol-associated with smoking. RECOMMENDATIONS: The guidelines provide clear recommendations regarding the diagnostic modalities available, both imaging (which includes MRI and endoscopic ultrasound (EUS)) and pancreatic function tests. The section on medical management makes recommendations on the use of analgesics, enzyme replacement and other therapeutic options in the non-interventional management of the majority of patients with CP. The section on interventional procedures identifies the indications and options available for the interventional management of both uncomplicated and complicated CP. The role of endoscopic and surgical modalities is defined, but it is in this context especially that the best available evidence, combined with the experience of the group, influenced the recommendations put forward. Owing to the lack of evidence and the complexity of the disease, it is recommended that, where possible, CP is managed in the context of a multidisciplinary team. Validation. The guidelines are based on best practice principles determined by the available evidence and the opinions of the group, which comprised 7 medical and surgical gastroenterologists with significant experience in dealing with patients with chronic pancreatitis in the South African context. The group convened between May 2009 and August 2010 under the auspices of the Hepato-Pancreatico-Biliary Association of South Africa (HPBASA) and the South African Gastroenterology Society (SAGES), and the guidelines are the result of broad consensus within this group. The draft was presented to other experts in this field of endeavour to ensure broader participation and consensus. Plans for guideline revision. HPBASA and SAGES will publish a revised modification of the recommendations when new levels 1 and 2 evidence data are published

Editorial: Commemorative issue in honour of Jan van der Leun, 14 June 1928–6 July 2016

No abstract availabl

Identifying knowledge levels of aquaponics adopters

Aquaponics or the integration of aquaculture and hydroponic farming, is a sustainable food production system that is currently popular more as a hobby rather than on commercial scales. Recent increase in scientific and public interest in aquaponics and its environmental benefits supports research that addresses technical, economic, and legislative barriers to wider adoption of these systems. A successful combination of hydroponics with an aquaculture system requires high levels of knowledge and skill that are not necessarily available to all aquaponic practitioners. In this short communication, we analyzed the results of a worldwide survey of commercial aquaponic growers’ statements about their own knowledge base. Most respondents (59%) had some relevant prior knowledge. Surprisingly, many respondents (41%) claimed to have insufficient knowledge of both fish and plants in their first year of operating a commercial aquaponics system. We interpret this as a rough indication that about a third of the new aquaponic businesses are started by entrepreneurs who are not farmers and have no prior training or experience in growing fish or plants. If aquaponics is to become a more widespread commercially viable enterprise and be capable of delivering its environmental benefits, its promotion must consider the importance of prior knowledge held by entrepreneurs entering aquaponics

Is aquaponics good for the environment?—evaluation of environmental impact through life cycle assessment studies on aquaponics systems

Aquaponics is often presented as a sustainable food production system that can reduce environmental costs of global food production; yet, its actual environmental effects are understudied. The aim of this research was to review the limited number of life cycle assessment studies dealing with aquaponics, and to highlight environmental cost and benefit of this practice. Our assessment highlights some of the problems, challenges, and advantages of aquaponics as a valuable food production system. We propose guidelines for future life cycle assessments of aquaponics that will facilitate policy and decision-making for farmers with respect to aquaponics

Dried mushrooms exposed to pulsed UV-Radiation generate nutritionally useful concentrations of dietary vitamin D

Background/Aims: There is a high prevalence of vitamin D deficiency in the Asia Pacific region and other parts of the world. Very few natural foods are a good source of vitamin D, with mushrooms as the only major non-animal source known to date. Upon exposure to ultraviolet (UV) radiation, mushrooms produce high levels of vitamin D, often in excess of 10 μg vitamin D/100 g fresh weight equivalent. This project assessed the efficiency of pulsed UV-radiation to generate D-vitamers in dried white button mush-rooms (Agaricus bisporus). Methods: Freshly picked mushrooms (gills enclosed) were air-dried for 22 h, then exposed to 1–4 s of pulsed UV-radiation before being freeze-dried and analyzed by liquid chromatography triple quadrupole mass spectrometer. The concentrations of vitamins D2, D3, D4, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 were measured in triplicate. Results: Vitamin D2 increased in a dose-dependent manner as UV-exposure increased (15, 26, and 32 μg/100 g for 1, 2, and 4 s respectively). A similar dose-dependent effect was seen for vitamin D4 (0.9, 1.7, and 2.6 μg/100 g for 1, 2, and 4 s respectively). Both 25-hy-droxyvitamin D2 and 25-hydroxyvitamin D3 were below the limit of detection (LoD). All D-vitamers were below the LoD in control samples (no UV-exposure). Conclusions: UV-exposed dried mushrooms could be a nutritionally useful source of vitamin D, with 100 g fresh weight (about 3–4 medium mushrooms) providing more than the typical daily requirements for vitamin D (10–20 μg/day, depending on age). Pulsed UV-radiation offers an effective method for commercial production of vitamin D-enhanced dried mushrooms

Monetizing environmental impact of integrated aquaponic farming compared to separate systems

Aquaponics is an emerging industry promoted as a sustainable agricultural practice. Economic sustainability of aquaponics is challenging, partly because some of the benefits are external to the grower, necessitating public intervention to support the industry. We used life cycle assessment to estimate the environmental impact of a proposed aquaponic system and applied a set of economic valuation methods to assess the costs of identified impact factors. We found that the system, planned to produce 60,000 ornamental fish and 108,000 lettuce heads per year would impact the environment with a cost of 10,700 EUR annually, about half the environmental cost of separate production of the same produce. Most of the external cost can be attributed to the industrial processes that prepare products used for aquaponic production. Although this method provides only a rough estimate of actual system impact, it can potentially be used to assess the cost-effectiveness of aquaponics from an environmental perspective

Consumer preferences for aquaponics: A comparative analysis of Australia and Israel

Aquaponics, the combined rearing of fish and hydroponic horticulture, has great potential for sustainable food production. Despite increasing research and investments in commercial scale systems, aquaponics is not yet a successful industry and most businesses report negative returns. Aquaponic produce is thought to contain added value to the consumer, and the environment. As most consumers are unaware of aquaponics and their benefits, little is known of its potential market. The present study addresses this gap by analysing willingness to consume aquaponic produce at different price levels in Israel and Australia. We used econometric tools to study the effects of pricing and other factors on revenues in each country. Cluster analysis was used to define groups of potential consumers. The results indicate that 17–30% of the population in both Israel and Australia would prefer to consume aquaponic produce once informed of their added value. Revenues at a given premium would be higher in Israel than in Australia, and higher for a leafy green, than for fish. Different segments of the population differed in their willingness to consume aquaponic produce, as well as in their stated motivations when purchasing food. Conclusions highlight the importance of case-specific research on consumer preferences and economic considerations preceding commercial investment in aquaponics

Spectral differences in the underwater light regime caused by sediment types in New Zealand estuaries: Implications for seagrass photosynthesis

The underwater light regime is fundamental to the ecological health of aquatic systems because it is a limiting factor for photosynthesis in marine plants such as seagrasses. Although seagrass meadows are a key component of coastal systems, their survival has been threatened by increased turbidity levels, both from resuspension of marine sediments and input of terrestrial material. The objective of this study was to investigate how marine (typically grey/white in colour) and terrestrial (typically more yellow-orange in colour with finer texture) sediments affect underwater light quality. Two experimental systems were used: (1) a large outdoor tank and (2) laboratory controlled small sampling container, using natural terrestrial and marine sediment samples (with different colours and grain sizes) from New Zealand. In the tank experiments, high concentrations of sediment reduced transmittance considerably, particularly below 450 nm. Since seagrasses absorb light optimally at wavelengths < 500 nm, as well as between 650 nm and 700 nm, the photosynthetic capacity will be less efficient with pigment absorption occurring mainly at the 650–700 nm wavebands. The difference in colour (white and grey) between marine sediments with the same grain sizes was tested in the laboratory. White sediment resulted in lower transmittance at the same concentration compared with grey sediments; concentration differences had more impact on the spectral distribution of light for white sediments. Within the ranges tested, sediment concentration contributed most to changes in overall light transmittance, with grain size being slightly less important. Sediment colour was important in changing the distribution of light, with orange and white sediments increasing attenuation of shorter wavelengths, which are most needed for seagrass photosynthesis. Our results emphasise the importance of quantifying the spectral changes to underwater light regimes in managing estuaries that are subjected to regular catchment runoff