scholarly journals Investigation of the relationship between wave action and the transport of bacteria in freshwater : implications for the management of aquatic and human health risk

2021 ◽  
Author(s):  
Andrew Sousa
Keyword(s):  
Wave Energy ◽  
Human Health Risk ◽  
Microbiological Quality ◽  
S Wave ◽  
Associated Bacteria ◽  
Wave Flume ◽  
Quality Of Water ◽  
Environmental Test ◽  
Beach Water Quality ◽  
Transport Of Bacteria

The sampling regime used to monitor the microbiological quality of water typically involves the collection of whole water samples, where bacteria are assumed to be planktonic. This practice ignores sedimentary pathogen sources and highlights the lack of understanding regarding the effect of shear stress on the erosion of bacteria from sediment particles. This study utilized a wave flume and an environmental test bacterial strain to examine the effect of increasing wave energy on bacterial loading and the partitioning of free-floating and floc-associated bacteria in water. A positive correlation was found between wave energy, total suspended solids, and bacterial loading in water. Experiments examining free-floating and floc-associated bacteria under low (0.60 N/s) and high (5.35 N/s) wave energy demonstrated the importance of floc as a vector for the transport of bacteria. These results imply that current beach sampling and analysis methods may not reflect overall beach water quality.

scholarly journals Investigation of the relationship between wave action and the transport of bacteria in freshwater : implications for the management of aquatic and human health risk

2021 ◽  
Author(s):  
Andrew Sousa
Keyword(s):  
Wave Energy ◽  
Human Health Risk ◽  
Microbiological Quality ◽  
S Wave ◽  
Associated Bacteria ◽  
Wave Flume ◽  
Quality Of Water ◽  
Environmental Test ◽  
Beach Water Quality ◽  
Transport Of Bacteria

The sampling regime used to monitor the microbiological quality of water typically involves the collection of whole water samples, where bacteria are assumed to be planktonic. This practice ignores sedimentary pathogen sources and highlights the lack of understanding regarding the effect of shear stress on the erosion of bacteria from sediment particles. This study utilized a wave flume and an environmental test bacterial strain to examine the effect of increasing wave energy on bacterial loading and the partitioning of free-floating and floc-associated bacteria in water. A positive correlation was found between wave energy, total suspended solids, and bacterial loading in water. Experiments examining free-floating and floc-associated bacteria under low (0.60 N/s) and high (5.35 N/s) wave energy demonstrated the importance of floc as a vector for the transport of bacteria. These results imply that current beach sampling and analysis methods may not reflect overall beach water quality.

scholarly journals Influence of wave action on the partitioning and transport of unattached and floc-associated bacteria in fresh water

2015 ◽  
Vol 61 (8) ◽  
pp. 584-596 ◽  
Author(s):  
Andrew J. Sousa ◽  
Ian G. Droppo ◽  
Steven N. Liss ◽  
Lesley Warren ◽  
Gideon Wolfaardt
Keyword(s):  
Shear Stress ◽  
Water Column ◽  
Wave Energy ◽  
Microbiological Quality ◽  
Wave Action ◽  
Bed Sediment ◽  
Associated Bacteria ◽  
Wave Flume ◽  
Quality Of Water ◽  
Bacterial Concentrations

The dynamic interaction of bacteria within bed sediment and suspended sediment (i.e., floc) in a wave-dominated beach environment was assessed using a laboratory wave flume. The influence of shear stress (wave energy) on bacterial concentrations and on the partitioning and transport of unattached and floc-associated bacteria was investigated. The study showed that increasing wave energy (0.60 and 5.35 N/s) resulted in a 0.5 to 1.5 log increase in unattached cells of the test bacterium Pseudomonas sp. strain CTO7::gfp-2 in the water column. There was a positive correlation between the bacterial concentrations in water and the total suspended solids, with the latter increasing from values of near 0 to up to 200 mg/L over the same wave energy increase. The median equivalent spherical diameter of flocs in suspension also increased by an order of magnitude in all experimental trials. Under both low (0.60 N/s) and high (5.35 N/s) energy regime, bacteria were shown to preferentially associate with flocs upon cessation of wave activity. The results suggest that collecting water samples during periods of low wave action for the purpose of monitoring the microbiological quality of water may underestimate bacterial concentrations partly because of an inability to account for the effect of shear stress on the erosion and mobilization of bacteria from bed sediment to the water column. This highlights the need to develop a more comprehensive beach analysis strategy that not only addresses presently uncharacterized shores and sediments but also recognizes the importance of eroded flocs as a vector for the transport of bacteria in aquatic environments.

scholarly journals Are the defined substrate-based methods adequate to determine the microbiological quality of natural recreational waters?

2009 ◽  
Vol 8 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Marta Sofia Valente ◽  
Paulo Pedro ◽  
M. Carmen Alonso ◽  
Juan J. Borrego ◽  
Lídia Dionísio
Keyword(s):  
Standard Method ◽  
Membrane Filtration ◽  
Microbiological Quality ◽  
Recreational Waters ◽  
Total Coliforms ◽  
E Coli ◽  
Quality Of Water ◽  
Routine Monitoring ◽  
Rapid Tests

Monitoring the microbiological quality of water used for recreational activities is very important to human public health. Although the sanitary quality of recreational marine waters could be evaluated by standard methods, they are time-consuming and need confirmation. For these reasons, faster and more sensitive methods, such as the defined substrate-based technology, have been developed. In the present work, we have compared the standard method of membrane filtration using Tergitol-TTC agar for total coliforms and Escherichia coli, and Slanetz and Bartley agar for enterococci, and the IDEXX defined substrate technology for these faecal pollution indicators to determine the microbiological quality of natural recreational waters. ISO 17994:2004 standard was used to compare these methods. The IDEXX for total coliforms and E. coli, Colilert®, showed higher values than those obtained by the standard method. Enterolert® test, for the enumeration of enterococci, showed lower values when compared with the standard method. It may be concluded that more studies to evaluate the precision and accuracy of the rapid tests are required in order to apply them for routine monitoring of marine and freshwater recreational bathing areas. The main advantages of these methods are that they are more specific, feasible and simpler than the standard methodology.

Spatial distribution of high-frequency energy radiation on the fault of the 1995 Hyogo-Ken Nanbu, Japan, earthquake (MW 6.9) on the basis of the seismogram envelope inversion

1999 ◽  
Vol 89 (1) ◽  
pp. 22-35 ◽  
Author(s):  
Hisashi Nakahara ◽  
Haruo Sato ◽  
Masakazu Ohtake ◽  
Takeshi Nishimura
Keyword(s):  
Spatial Distribution ◽  
Wave Energy ◽  
High Frequency ◽  
Fault Plane ◽  
Time Window ◽  
Source Region ◽  
Inversion Method ◽  
S Wave ◽  
Energy Radiation ◽  
Initial Rupture

Abstract We studied the generation and propagation of high-frequency (above 1 Hz) S-wave energy from the 1995 Hyogo-Ken Nanbu (Kobe), Japan, earthquake (MW 6.9) by analyzing seismogram envelopes of the mainshock and aftershocks. We first investigated the propagation characteristics of high-frequency S-wave energy in the heterogeneous lithosphere around the source region. By applying the multiple lapse time window analysis method to aftershock records, we estimated two parameters that quantitatively characterize the heterogeneity of the medium: the total scattering coefficient and the intrinsic absorption of the medium for S waves. Observed envelopes of aftershocks were well reproduced by the envelope Green functions synthesized based on the radiative transfer theory with the obtained parameters. Next, we applied the envelope inversion method to 13 strong-motion records of the mainshock. We divided the mainshock fault plane of 49 × 21 km into 21 subfaults of 7 × 7 km square and estimated the spatial distribution of the high-frequency energy radiation on that plane. The average constant rupture velocity and the duration of energy radiation for each subfault were determined by grid searching to be 3.0 km/sec and 5.0 sec, respectively. Energy radiated from the whole fault plane was estimated as 4.9 × 1014 J for 1 to 2 Hz, 3.3 × 1014 J for 2 to 4 Hz, 1.5 × 1014 J for 4 to 8 Hz, 8.9 × 1012 J for 8 to 16 Hz, and 9.8 × 1014 J in all four frequency bands. We found that strong energy was mainly radiated from three regions on the mainshock fault plane: around the initial rupture point, near the surface at Awaji Island, and a shallow portion beneath Kobe. We interpret that energetic portions were associated with rupture acceleration, a fault surface break, and rupture termination, respectively.

scholarly journals The pursuit of good microbiological conditions in domestic softeners: a new improvement

2020 ◽  
Vol 18 (2) ◽  
pp. 200-206
Author(s):  
L. Bolelli ◽  
Elida Nora Ferri ◽  
Stefano Sangiorgi ◽  
Giuseppe Novelli ◽  
Stefano Girotti
Keyword(s):  
Pathogenic Bacteria ◽  
Microbiological Quality ◽  
Global Network ◽  
Plate Count ◽  
Bacteria Growth ◽  
Warm Environment ◽  
Quality Of Water ◽  
Softened Water ◽  
Generous Support

Abstract Effective resin disinfection is mandatory to ensure the microbiological quality of water treated by domestic softeners. The wet and sometimes warm environment inside the softener is ideal for bacteria growth. Our research was focused on the evaluation of the microbial quality of water from softeners sanitized by chlorine solutions or by electrolytic systems. We employed the heterotrophic plate count and specific tests to monitor the presence of opportunistic and pathogenic bacteria (Pseudomonas aeruginosa, Escherichia coli, enterococci, and coliforms). Completely new devices were equipped with a commercially available electrolytic system or with a newly patented one or sanitized by automatic or manual addition of chlorine solutions. In all cases, the contamination was reduced, not completely avoided. In particular, the patented electrolytic system significantly reduced bacterial proliferation in strongly contaminated devices. Our data confirm the difficulties encountered to solve the problem of microbiological quality of softened water and offer encouraging information on new possible solutions. This article has been made Open Access thanks to the generous support of a global network of libraries as part of the Knowledge Unlatched Select initiative.

Sign in / Sign up

Export Citation Format

Share Document