• 22 genera of cyanobacteria were found, 3 were reported as toxic genera (Anabaena spp., Microcystis spp. and planktothrix spp.).

Results and Discussions

• Very high concentration of phosphorus and nitrogen in twenty water samples indicates a hypertrophic condition.

• Cyanobacterial biovolume higher than recommended threshold of alert level 1 for drinking waters (fig. 2).

• Increased levels of pH are more favourable for cyanobacterial growth (fig.3).

• Sampled at 18 lakes and ponds in Hanoi, Vietnam (Fig. 1).• Phytoplankton and zooplankton were collected to know water quality degradation and counted with inverted microscopy.

• Nutrient analysis were performed with phenate, colorimetric, ultraviolet spectrophotometric and ascorbic acid method.• Biovolume was used as a proxy for phytoplankton biomass.• Multivariate statistical analyses were used to explore the phytoplankton and zooplankton data as well as their relation to the environment.

Methodology

Conclusions

WATER QUALITY DEGRADATION AND CYANOBACTERIALBLOOMS OF LAKES AND PONDS IN HANOI, VIETNAM: an overview of current state and potential health risk

(based on thesis of Hien Nguyen Tranh, 2009)

Fig 1. Map of Hanoi indicating the geographical positions of the lakes and ponds.

Recommendations

• Alarming degradation of water quality due to extreme hypereutrophication in combination with tropical climate condition. This has led to massive phytoplankton growth in all water bodies of the city.• All the lakes and ponds ranged from moderate probability of adverse health effects to high probability of adverse health effects.

• Conduct comprehensive monitoring to build up a best practice for restoration and to provide information on environmental hazard.• Implement a pilot study based on acquired information to improve water quality and halter cyanobacterial blooms.

Fig 2. Cyanobacteria biovolume in relation to the vigilance and

allert level for drinking water supplies.

Fig 3. CCA triplots (sites, species and environmental variables.)

Introduction Objectives

• Cyanobacterial blooms are an increasing concern throughout the world. Once they occur they contribute aesthetic problems, impair recreational use and even effect the taste of treated drinking water. • In Hanoi, Vietnam, lakes and ponds are highly polluted which results to harmful cyanobacterial blooms. These have led to an alarming underestimate of the risk of such environmental hazards. Therefore, to minimize the adverse impacts of harmful blooms, this study is important to understand the dynamic of cyanobacteria and their interactions with the environment.

• To assess the human risk and to estimate the dynamic of cyanobacteria in relation to different environmental conditions in lakes and ponds in Hanoi, Vietnam. • To determine the composition of phytoplankton, zooplankton and their biomass in relqtion to physico-chemical parameters.• To assess the state of cyanobacteria with respect to human health risk. and to investigate the relationship between cyanobacteria proliferation with environmental variables.

Poster by: Aryshandy, C., Cotillas, C., Prasetiya, F. and Vaes, T.

Vrije Universiteit Brussel – Universiteit Antwerp BELGIUM

Fig 3. CCA triplots (sites, species and environmental variables.)

Fig 3. CCA triplots (sites, species and environmental variables.)

• Lakes with higher cyanobacteria biomass showed higher values of pH, DO and temperature. The correlation between pH and cyanobacteria biovolume (CBV) (r = 0.48).