Optimization of dissolved oxygen levels in extender prevents development of cryocapacitation like changes, oxidative stress and augments zona binding capacity of crossbred bull spermatozoa

Following surveys recently carried out in Maputo estuary, a survey with the purpose of acquiring data required to characterize the estuary was carried out in December 1983. After reviewing the hydrology of the tributaries to the estuary, the parameters to be monitored - salinity, conductivity, temperature, and dissolved oxygen, are referred. Finally, taking also into account previous information available, an evaluation of the results, and an assessment of the estuary are done. The estuary can be classified as well mixed, since the vertical salinity gradients found are small. The Umbeluzi estuary, however, is partially mixed. Temperature decreases with the depth, and when moving downstream. Some pollution was found along the lower part of the estuary, probably due to the discharge of domestic and industrial wastewater, which brings the dissolved oxygen figures below the saturation level. As for the upper part of the estuary, the dissolved oxygen levels are not only dependent on the pollutant load, but also on the growing of algae, which by photosynthesis under daylight produce oxygen that dissolves into the water. Quite often, the dissolved oxygen figures are above the saturation level. The growth of algae could be due to the input of phosphorus and nitrogen brought in by the tributary streams. A pollutant load discharged upstream could be the reason for some pollution seen in the Umbeluzi estuary.

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A study of water quality in an urban river and potential improvement using a prototype instream aerator

Canadian Journal of Civil Engineering ◽

10.1139/l89-056 ◽

1989 ◽

Vol 16 (3) ◽

pp. 308-316 ◽

Cited By ~ 1

Author(s):

C. A. Town ◽

D. S. Mavinic ◽

B. Moore

Keyword(s):

Water Quality ◽

Dissolved Oxygen ◽

Data Base ◽

Chlorophyll A ◽

Late Summer ◽

Urban River ◽

Agricultural Activity ◽

Fish Kills ◽

Low Dissolved Oxygen ◽

Oxygen Levels

Urban encroachment and intensive agricultural activity within the Serpentine–Nicomekl watershed (near Vancouver, B.C.) have caused a series of fish (salmon) kills on the Serpentine River since 1980. Low dissolved oxygen was responsible for these kills. This field project investigated some of the dynamic chemical and biological relationships within the river, as well as the use of an instream aerator as a temporary, in situ, water quality improvement measure. Weekly sampling for a 6-month period during the latter half of 1985 established a solid data base for deriving and interpreting meaningful interrelationships. A strong correlation between chlorophyll a and dissolved oxygen levels before the algae die-off supported the hypothesis that algae blooms dying in the fall could create a serious oxygen demand. Because of these environmental conditions, the river is unable to sustain healthy dissolved oxygen levels during this period. As such, a prototype, 460 m artificial aeration line was designed, installed, and monitored to evaluate its potential for alleviating low dissolved oxygen conditions and improving overall water quality during the critical fall period.The instream aerator ran continuously for over 2 months, starting in September 1985. Despite better-than-expected weather conditions (i.e., cool, wet weather) and relatively high dissolved oxygen levels during the fall of 1985, the data base appeared to support the use of this prototype aeration unit as a means of "upgrading" a stretch of an urban river subject to periodic, low dissolved oxygen levels. As a result, a 2-year follow-up study and river monitoring was initiated. In both 1986 and 1987, late summer and early fall river conditions resulted in the potential for serious salmon kills, due to higher-than-normal river temperatures and very low dissolved oxygen. In both instances, the instream aerator prevented such fish kills in a key stretch of the river. Expansion of the system to include other critical stretches of the Serpentine and other urban river systems, near Vancouver, is being considered. Key words: algae, aerator, chlorophyll a, eutrophic, fish kills, instream aeration, river improvement, urban river.

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Critical Role of Zinc as Either an Antioxidant or a Prooxidant in Cellular Systems

Oxidative Medicine and Cellular Longevity ◽

10.1155/2018/9156285 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 48

Author(s):

Sung Ryul Lee

Keyword(s):

Oxidative Stress ◽

Zinc Deficiency ◽

Metal Binding ◽

Inflammatory Responses ◽

Binding Capacity ◽

Critical Role ◽

Cellular Systems ◽

Oxidative Stresses ◽

Dual Action

Zinc is recognized as an essential trace metal required for human health; its deficiency is strongly associated with neuronal and immune system defects. Although zinc is a redox-inert metal, it functions as an antioxidant through the catalytic action of copper/zinc-superoxide dismutase, stabilization of membrane structure, protection of the protein sulfhydryl groups, and upregulation of the expression of metallothionein, which possesses a metal-binding capacity and also exhibits antioxidant functions. In addition, zinc suppresses anti-inflammatory responses that would otherwise augment oxidative stress. The actions of zinc are not straightforward owing to its numerous roles in biological systems. It has been shown that zinc deficiency and zinc excess cause cellular oxidative stress. To gain insights into the dual action of zinc, as either an antioxidant or a prooxidant, and the conditions under which each role is performed, the oxidative stresses that occur in zinc deficiency and zinc overload in conjunction with the intracellular regulation of free zinc are summarized. Additionally, the regulatory role of zinc in mitochondrial homeostasis and its impact on oxidative stress are briefly addressed.

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