Urban-stream Waters Research Articles

Biomonitoring the effects of urban-stream waters on the health status of pale chub (Zacco platypus): A comparative analysis of biological indexes and biomarker levels

The objective of this study was to biomonitor the effects of potential environmental pollutants in urban-stream waters, on fish health. Pale chub (Zacco platypus), a dominant species in the Korea urban stream waters, was chosen and biomonitoring indicators for the different spatial characteristics were tailored in an urban watershed. Biological responses including biotic-somatic index as well as gonadal development phase and plasma steroids levels, and the biochemical responses, ethoxyresorufin-o-deethylase (EROD) and acetylcholinesterase (AChE) activities, were measured. No significant difference was observed in the length–weight relationship between the up-stream waters and the down-stream waters. However, changes in the gonad-somatic index (GSI) levels, plasma 17β-estradiol (E2) levels, and mature oocyte frequencies in the female fish collected during the spawning season were observed in the down-stream waters at each monitoring site. Moreover, intersex condition (testis-ova) in the male fish in down-stream waters was recorded, even if it was just one fish. Although no significant difference was observed in the EROD and AChE activities between the up-stream waters and the down-stream waters, changes in the reproductive biomarker levels, including the GSI levels, plasma E2 levels, and gonadal maturation, lead to variable biomonitoring endpoints between the spatial different sites. These results imply that exposure to the down-stream waters can cause reproductive impairment in wild Z. platypus, individual variability in the biological responses further indicate the reproductive health was affected more by the down-stream waters than the up-stream waters. The finding from this study can provide the biomonitoring endpoint on the wild fish health in urban watershed that is crucial to the early risk assessment of its biological impacts. More multi-biomarkers studies reflecting the variation in the biological organization of wild fish and, therefore, the effects of urban-stream waters in the fish health are warranted.

Cameroonian Urban Floodwater Retaliations on Human Activity and Infrastructural Developments in Channel Flood Ways of Kumba

In Cameroonian cities, floods from solid pollutant barriers constitute environmental hazards of new distinct dimension, nature and characteristics. This study examines geographical settings provoking floods in cities and the way it affects the population. It suggests appropriate policy mitigation options. Primary and secondary data collected through fieldwork and documentary sources were treated. Findings show that national and local rules and legislation are weakly applied exposing urban natural floodway to varied forms of human colonisation activities. These urban stream flood ways that ought to be downstream water evacuation role players reversed into inhabited neighbourhoods of diverted water. Human activities and infrastructural urban inputs that unconsciously imposed directional dictates unto urban stream flow have become self-made victims of wicked egocentrism over urban stream channels. As nature is permanently in a state of dynamic re-equilibration the urban stream waters have in retaliation taught its trouble givers a disproportionately unequal negative response in enormous fatalities for the humans who dare to resist its floods and abandonment for those who have been repeatedly humbled by its floods. The response from this no man’s land of aborted human conquest requires comprehensive and multidimensional environmental management in stream-bordered urban built.

Tracing anthropogenic DIC in urban streams based on isotopic and geochemical tracers

To elucidate the type and extent of anthropogenic DIC (dissolved inorganic carbon), carbon isotopic composition of DIC and dissolved ion concentration were determined in three streams (Gap, Yudeung and Daejeon) draining populated Daejeon metropolitan area, South Korea. Seasonal variations in water chemistry and carbon isotopic composition of DIC (δ13CDIC) reflected changing contribution from two main DIC sources, i.e., soil weathering and sewages. DIC input from the soil weathering was characterized by δ13CDIC values ranging from −16.7 to −16.0 ‰ and higher during Jun–Nov. The sewage-derived DIC became dominant during Dec–May with δ13CDIC values ranging from −11.4 to −7.4 ‰. Si and Cl served as indicators of DIC inputs from soil weathering and sewages, respectively. The higher δ13CDIC values of sewages in the study area indicated that detergents (δ13CDIC of −12.0 to −6.5 ‰) carried by the urban sewages were the main anthropogenic DIC component. The extent of anthropogenic DIC relative to soil-derived DIC in stream waters increased when the precipitation was low and discharge decreased. The results of this study provide a method to quantify anthropogenic DIC, which can help manage water quality in urban stream waters.