Effects of full-scale beach renovation on fecal indicator levels in shoreline sand and water

WATER RESEARCH

卷:48

Article

Hernandez, Rafael J.^1,2  Hernandez, Yasiel^1,2  Jimenez, Nasly H.¹  Piggot, Alan M.^1,3  Klaus, James S.^1,3,4  Feng, Zhixuan^1,5  Reniers, Ad^1,5  Solo-Gabriele, Helena M.^1,6 

[1] Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Ctr Oceans & Human Hlth, Miami, FL 33149 USA

[2] Univ Miami, Dept Biol, Coral Gables, FL 33124 USA

[3] Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Div Marine Geol & Geophys, Miami, FL 33149 USA

[4] Univ Miami, Dept Geol Sci, Coral Gables, FL 33124 USA

[5] Univ Miami, Rosenstiel Sch Marine & Atmospher Sci, Div Appl Marine Phys, Miami, FL 33149 USA

[6] Univ Miami, Dept Civil Architectural & Environm Engn, Coral Gables, FL 33124 USA

关键词: Beach sand;    Fecal indicator bacteria;    Enterococci;    Fecal coliform;    Recreational water quality;    Beach renovation;   

DOI  :  10.1016/j.watres.2013.10.020

来源: Elsevier

【 摘 要 】

Recolonization of enterococci, at a non-point source beach known to contain high background levels of bacteria, was studied after a full-scale beach renovation project. The renovation involved importation of new exogenous sand, in addition to infrastructure improvements. The study's objectives were to document changes in sand and water quality and to evaluate the relative contribution of different renovation activities towards these changes. These objectives were addressed: by measuring enterococci levels in the sand and fecal indicator bacteria levels (enterococci and fecal coliform) in the water, by documenting sediment characteristics (mineralogy and biofilm levels), and by estimating changes in observable enterococci loads. Analysis of enterococci levels on surface sand and within sediment depth cores were significantly higher prior to beach renovation (6.3-72 CFU/g for each sampling day) when compared to levels during and after beach renovation (0.8-12 CFU/g) (P < 0.01). During the renovation process, sand enterococci levels were frequently below detection limits (<0.1 CFU/g). For water, exceedances in the regulatory thresholds that would trigger a beach advisory decreased by 40% for enterococci and by 90% for fecal coliform. Factors that did not change significantly between pre- and post-renovation included the enterococci loads from animals (approx. 3 x 10(11) CFU per month). Factors that were observed to change between pre- and post- renovation activities included: the composition of the beach sand (64% versus 98% quartz, and a significant decrease in biofilm levels) and loads from direct stormwater inputs (reduction of 3 x 10(11) CFU per month). Overall, this study supports that beach renovation activities contributed to improved sand and water quality resulting in a 50% decrease of observable enterococci loads due to upgrades to the stormwater infrastructure. Of interest was that the change in the sand mineralogy also coincided with changes in biofilm levels. More work is needed to evaluate the relationships between beach sand mineralogy, biofilm characteristics, and the retention of fecal indicator bacteria in sand. (C) 2013 Elsevier Ltd. All rights reserved.

【 授权许可】

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