Oxygen Consumption and Organic Matter Remineralization in Two Subtropical, Eutrophic Coastal Embayments.

There is a strong need to understand sources of organic matter in coastal lagoons because these systems often have long water residence times, are susceptible to eutrophication, and display symptoms such as low-oxygen conditions. We found that integrated dissolved oxygen (DO) consumption in the water column accounted for 67-73% of total DO consumption in two eutrophic coastal lagoons (Baffin Bay and Oso Bay) in the northwestern Gulf of Mexico. The δ13C of particulate organic carbon (δ13CPOC) showed temporal variations that corresponded with hydrological condition changes in Baffin Bay but fewer temporal changes in Oso Bay, whereas the lower δ15NPON values in Baffin Bay indicated more agricultural influence than in Oso Bay, where urban sewage influences dominated. Based on closed-system incubation experiments, water-column respiration in Baffin Bay was driven by the respiration of a combination of phytoplankton, carbon from near-shore and benthic macrophytes, and other allochthonous organic carbon sources depending on hydrological conditions. However, respiration of algal carbon dominated DO consumption in Baffin Bay sediments. In comparison, Oso Bay water-column respiration was largely attributed to the degradation of phytoplankton, the growth of which was sustained by nutrient discharge from wastewater treatment plants in the watershed. In contrast to the water column, seagrass and saltmarsh carbon appeared to be the primary organic carbon source that drove DO consumption in Oso Bay sediments. These observations highlight the complexity of organic carbon sources that contribute to DO consumption in estuaries affected by human activities, especially in systems with long water residence times that can retain both organic matter and nutrients for extended periods of time.

Water quality dynamics in an urbanizing subtropical estuary(Oso Bay, Texas).

Results are presented from a study of water quality dynamics in a shallow subtropical estuary, Oso Bay, Texas, which has a watershed that has undergone extensive urbanization in recent decades. High inorganic nutrient, dissolved organic matter and chlorophyll concentrations, as well as low pH (<8), were observed in a region of Oso Bay that receives wastewater effluent. Despite being shallow (<1 m) and subjected to strong winds on a regular basis, this region also exhibited episodic hypoxia/anoxia. The low oxygen and pH conditions are likely to impose significant stress on benthic organisms and nekton in the affected area. Signatures of eutrophied water were occasionally observed at the mouth of Oso Bay, suggesting that it may be exported to adjacent Corpus Christi Bay and contribute to seasonal hypoxia development in that system as well. These results argue for wastewater nutrient input reductions in order to alleviate the symptoms of eutrophication.

Positive outcomes of oil palm phenolics on degenerative diseases in animal models.

It is well established that plant phenolics elicit various biological activities, with positive effects on health. Palm oil production results in large volumes of aqueous by-products containing phenolics. In the present study, we describe the effects of oil palm phenolics (OPP) on several degenerative conditions using various animal models. OPP reduced blood pressure in a NO-deficient rat model, protected against ischaemia-induced cardiac arrhythmia in rats and reduced plaque formation in rabbits fed an atherogenic diet. In Nile rats, a spontaneous model of the metabolic syndrome and type 2 diabetes, OPP protected against multiple aspects of the syndrome and diabetes progression. In tumour-inoculated mice, OPP protected against cancer progression. Microarray studies on the tumours showed differential transcriptome profiles that suggest anti-tumour molecular mechanisms involved in OPP action. Thus, initial studies suggest that OPP may have potential against several chronic disease outcomes in mammals.

Oil palm vegetation liquor: a new source of phenolic bioactives.

Waste from agricultural products represents a disposal liability, which needs to be addressed. Palm oil is the most widely traded edible oil globally, and its production generates 85 million tons of aqueous by-products annually. This aqueous stream is rich in phenolic antioxidants, which were investigated for their composition and potential in vitro biological activity. We have identified three isomers of caffeoylshikimic acid as major components of oil palm phenolics (OPP). The 2,2-diphenyl-1-picrylhydrazyl assay confirmed potent free radical scavenging activity. To test for possible cardioprotective effects of OPP, we carried out in vitro LDL oxidation studies as well as ex vivo aortic ring and mesenteric vascular bed relaxation measurements. We found that OPP inhibited the Cu-mediated oxidation of human LDL. OPP also promoted vascular relaxation in both isolated aortic rings and perfused mesenteric vascular beds pre-contracted with noradrenaline. To rule out developmental toxicity, we performed teratological studies on rats up to the third generation and did not find any congenital anomalies. Thus, these initial studies suggest that OPP is safe and may have a protective role against free radical damage, LDL oxidation and its attendant negative effects, as well as vascular constriction in mitigating atherosclerosis. Oil palm vegetation liquor thus represents a new source of phenolic bioactives.

Caloric availability of polydextrose.

Polydextrose is a randomly bonded polysaccharide produced by the bulk melt polycondensation of glucose and sorbitol in vacuo. It has been used as a bulking and texturizing agent and soluble fiber ingredient in many food products worldwide for over two decades. Because of its atypical linkages between glucose moieties, polydextrose resists digestion by mammalian gastrointestinal enzymes. It is minimally absorbed in the small intestine and partially fermented in the large intestine producing volatile fatty acids, with approximately 50% of the ingested dose being excreted undigested. In this it is similar to many other poorly digested soluble fiber ingredients. Numerous energy balance and isotope-label disposition studies have been conducted in animals and man to investigate the caloric availability of polydextrose. The weight of available experimental evidence in the 14 studies described herein shows that polydextrose has a caloric value of approximately 1 kcal/g.