We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March – May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2–5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI – 6.66–14.06) and antibiotic resistance indices (ARI – 0.29–0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.

To determine if local onsite treatment systems affect nearshore water quality, seasonal and rain event monitoring of bacteria and nitrogen was conducted on the Gulf and estuary sides of Captiva Island. Monitoring wells were used to examine the relationship between surface water and groundwater quality. Nitrates were found to be significantly greater in ground water samples from the areas of Captiva using onsite treatment compared to areas with sewer. However, groundwater enterococci were no greater in areas with onsite treatment. Surface water nitrogen was significantly greater near onsite systems than areas with sewer, linking groundwater and surface water quality. Surface water enterococci increased significantly after rain events. Study results indicated stormwater runoff disperses indicator bacteria from diffuse terrestrial sources into nearshore waters, elevating the concentrations. This study reveals local onsite treatment systems produce elevated surface water nitrogen levels but do not contribute to elevated indicator bacteria concentrations in this system.

Three microorganisms were assayed to evaluate the microbiological quality in the seawater at a resort on the Mexican Pacific coast, and to test for possible associations among the titers of the various bacteria, their possible correlations with environmental conditions, and with the location of potential wastewater outflows. Significant microorganism levels were found (at Caletilla beach, Hornos beach, and Papagayo beach, respectively: for Enterococcus 157, 153, and 149, for C. perfringens 35, 89, and 56, for S. aureus 244,137, and 279CFU/100ml), often in excess of the presently set guideline values. In general, bacterial titers were higher during rainy season than in dry season. For S. aureus, in both seasons, highest concentrations were found at 3pm, the time of highest tourist presence at the beaches. Our results argue for the use of these three microorganisms as part of a set of indicators in the routine microbiological evaluation of Mexican beachwaters.

Southern California is an increasingly urbanized hotspot for surfing, thus it is of great interest to assess the human illness risks associated with this popular ocean recreational water sport from exposure to fecal bacteria contaminated coastal waters. Quantitative microbial risk assessments were applied to eight popular Southern California beaches using readily available enterococcus and fecal coliform data and dose-response models to compare health risks associated with surfing during dry weather and storm conditions. The results showed that the level of gastrointestinal illness risks from surfing post-storm events was elevated, with the probability of exceeding the US EPA health risk guideline up to 28% of the time. The surfing risk was also elevated in comparison with swimming at the same beach due to ingestion of greater volume of water. The study suggests that refinement of dose-response model, improving monitoring practice and better surfer behavior surveillance will improve the risk estimation.

In Stone Town, Zanzibar, sewage treatment is minimal, with a biological oxygen demand reduction to 60% and no removal of bacteria or nutrients. Here, Stone Town’s sewage pollution was studied by measuring Enterococci and NH₄ ⁺ concentrations in seawater and δ¹⁵N of benthic organisms; samples were collected along the Stone Town shoreline and from offshore coral reefs. Public perceptions of sewage pollution were investigated via interviews. Enterococci from the Stone Town shoreline exceeded USEPA guidelines for recreational use. Benthic organisms from two of the four reefs were relatively enriched (δ¹⁵N>10‰), indicative of sewage derived N. δ¹⁵N values of organisms from Stone Town exceeded 16‰. A strong correlation was found between Enterococci and δ¹⁵N across sites, while step-wise regression indicated rainfall and tidal stage as important predictors for bacterial concentrations. These data provide an important impact assessment from which the efficacy of future policy and management change can be assessed.

Faecal contamination of drinking water extracted from alluvial aquifers can lead to severe problems. River water infiltration can be a hazard for extraction wells located nearby, especially during high discharge events. The high dimensionality of river–groundwater interaction and the many factors affecting bacterial survival and transport in groundwater make a simple assessment of actual water quality difficult. The identification of proxy indicators for river water infiltration and bacterial contamination is an important step in managing groundwater resources and hazard assessment. The time resolution of microbial monitoring studies is often too low to establish this relationship. A proxy-based approach in such highly dynamic systems requires in-depth knowledge of the relationship between the variable of interest, e.g. river water infiltration, and its proxy indicator. In this study, continuously recorded physico-chemical parameters (temperature, electrical conductivity, turbidity, spectral absorption coefficient, particle density) were compared to the counts for faecal indicator bacteria, Escherichia coli and Enterococcus sp. obtained from intermittent sampling. Sampling for faecal indicator bacteria was conducted on two temporal scales: (a) routine bi-weekly monitoring over a month and (b) intense (bi-hourly) event-based sampling over 3 days triggered by a high discharge event. Both sampling set-ups showed that the highest bacterial concentrations occurred in the river. E. coli and Enterococcus sp. concentrations decreased with time and length of flow path in the aquifer. The event-based sampling was able to demonstrate differences in bacterial removal between clusters of observation wells linked to aquifer composition. Although no individual proxy indicator for bacterial contamination could be established, it was shown that a combined approach based on time-series of physico-chemical parameters could be used to assess river water infiltration as a hazard for drinking water quality management.

While interest in and adoption of graywater reuse for irrigation has rapidly grown in recent years, little is known about the long-term effects of graywater irrigation. Concerns exist in relation to the presence of pathogenic organisms, fate of personal care products, and accumulation of salts. The purpose of this research was to evaluate the long-term effects of graywater irrigation to soil quality under real conditions where homeowners may not always apply graywater in a highly controlled manner. Four households from different climatic and geological conditions were selected for sampling (AZ, CA, CO, and TX) where graywater was applied for irrigation for a minimum of 5 years. Soil samples were collected in areas irrigated with graywater and areas irrigated with freshwater within the same yard. Soil cores were taken at depths of 0–15, 15–30, and 30–100 cm and analyzed separately for surfactants, antimicrobials, sodium adsorption ratio (SAR), electrical conductivity (EC), extractable boron, fecal indicator organisms (E. coli, enterococci, and Clostridium perfringens), and soil dehydrogenase activity. In surface soil samples (0–15 cm), the average total surfactant concentration (over all sites) was higher in graywater-irrigated soil (0.078 ± 0.033) compared to freshwater-irrigated soil (0.030 ± 0.025 mg kg⁻¹). This difference was not found to be significant (P > 0.05). Triclosan and triclocarban were detected in surface soil samples at some locations (3.8–6.3 and 3.5–9.1 μg kg⁻¹, respectively), but not in samples deeper than 15 cm. Among the sampling locations, the TX household appeared to be most impacted by graywater, as evidenced by elevated SAR, potentially toxic levels of B, and relatively high numbers of E. coli and enterococci due to 30 years of graywater application for irrigation.

PURPOSE: The aim of this paper was to develop a new recreational water quality index (RWQI) as a tool to ensure the health of swimmers and to take practical decisions. METHODS: RWQI was elaborated with epidemiological data, and we carried out an exhaustive study of the different guidelines for recreational waters proposed by different organisations around the world. Different parameters were chosen, considering, as a priority, the swimmer’s contact and the possibility of ingestion of water during the recreational activity. Furthermore, rating curves were established for pH, chemical oxygen demand, nitrate, phosphate, detergents, enterococci, total coliforms, faecal coliforms and Escherichia coli. RESULTS AND CONCLUSIONS: The index was applied to the data set on water quality of the Potrero de los Funes River (San Luis, Argentina), generated during 2 years (2009–2010). Following the RWQI values classification, most of the Potrero de los Funes water samples fell in the good quality range during the study period.