Urban Rivers as Pollutant Sinks and Sources: a Public Health Concern for Recreational River Users?

Abstract

Although the area of urban river sediment quality has received increasing attention over the last 10 years, the presence of contaminated sediments in urban rivers and the potential risk to public health it poses has yet to be rigorously addressed within the urban river restoration context. This is an issue of particular concern at the current time, as the openingup of urban rivers is being strongly promoted by many legislative and non-legislative bodies as a multibenefit approach to tackling a range of urban challenges; from decreasing the risk of flooding to increasing the quality-of-life in urbanised areas. This paper brings together these two contrasting concepts; urban rivers as pollutant sinks and sources (presentation of data on urban river sediment quality) and urban rivers as sites of flood alleviation, amenity, recreation and wildlife value (review of the drivers and initiatives behind the increasing implementation of urban river rehabilitation schemes). In light of this combined assessment, the urgent need for a risk assessment of restored urban river sites to establish whether the presence of contaminated sediments poses a risk to public health is strongly recommended. Should such a risk be demonstrated, a tiered approach to supporting the identification and pro-active management of these risks is proposed as a way to inform and enable, rather than to prevent, the safe and appropriate use of the increasing number of urban river restoration schemes being implemented.

The role of vegetation in the retention of fine sediment and associated metal contaminants in London's rivers

“…It is therefore important that in the design of urban river restoration schemes, the potential effects of the scheme upon sediment availability and channel hydraulics is understood in terms of managing the impact upon sediment related contaminant storage. A very useful framework for minimizing the risk from contaminated sediments in the restoration of urban rivers was presented in Scholes et al (2008). This involves: undertaking sediment sampling to understand the contaminant risks; assessing if contaminant sources can be controlled; modelling the hydraulics and sediment dynamics at the site; designing the scheme based on knowledge from the modelling feeding in to an understanding of how increases in sediment availability and changes in hydraulics will affect finer sediment; and, finally, if necessary incorporating minimum exposure to the public by fencing off areas.…”

“…As a result of the polluted nature of many urban sediment sources (Scholes et al, 2008;Taylor and Owens, 2009;Poleto et al, 2010), sediments accumulating within urban rivers often display elevated concentrations of metals as well as other contaminants including nutrients, coliforms and organic compounds (hydrocarbons, PCBs and PAHs). Additionally, metals and other contaminants in the dissolved phase can bind with substrates and accumulate in the particulate form, adding to the sediment associated contaminant load (Luoma and Rainbow, 2008).…”

An overview of non‐native species invasions in urban river corridors

“…Although there has been substantial research into urban rivers as sinks for pollutants (Scholes, Faulkner, Tapsell, & Downward, ) and more recently plastics (Nel, Dalu, & Wasserman, ), more work is needed on patterns and processes of non‐native species accumulation, and river and riparian seed banks in particular.…”

A combined application of different engineering and biological techniques to remediate a heavily polluted river

“…Rapid industrialization, urbanization, and population growth has led to the pollution of rivers and degradation of ecosystems, especially in municipal rivers in developing countries (Scholes et al, 2008;Longe and Omole, 2008). River water is easily polluted by domestic wastewater effluent, rainwater, agricultural run-off, and industrial wastewater, which result in severe degradation of water quality, the water becoming black and odorous, and loss of fish (Scholes et al, 2008;Palmer, 2009;Caraballo et al, 2011).…”

“…River water is easily polluted by domestic wastewater effluent, rainwater, agricultural run-off, and industrial wastewater, which result in severe degradation of water quality, the water becoming black and odorous, and loss of fish (Scholes et al, 2008;Palmer, 2009;Caraballo et al, 2011). In northern China, the majority of rivers have been used for agricultural irrigation due to the shortage of water, especially in arid seasons.…”