The occurrence frequency, intensity, and scale of eutrophication are increasing globally, causing multiple deleterious impacts on ecosystems and human health, and negatively influencing sustainable development. Given their location, urban lakes are particularly impacted by this phenomenon. This article presents the results of an investigation into the trophic status of 13 lakes in inner Hanoi city between 2021 and 2023. The Trophic Status Index (TSI) of the lakes averaged 61.3. Twelve lakes are classed as eutrophic (TSI: 55.1-66.6) and one as hypertrophic (TSI: 70.9). The individual TSI values of different water quality variables revealed that neither N nor P, but light is a limiting factor to algae growth in all lakes studied. Eight lakes presented silica to nitrogen (Si/N) or Si/P ratios that are considered conducive to non-siliceous algae instead of diatom growth. Mitigation measures that combine decreased untreated wastewater inputs with internal nutrient reduction strategies are proposed in order to reduce eutrophication and improve urban lake quality in Hanoi city.
The distribution and ecological risks of 11 phenolic compounds and 16 PAHs were studied in the bottom sediments of Abu Qir Bay in the Mediterranean of Egypt. The total concentration of 11 phenolic compounds (& sum;PC11) in sediment ranged from 540.48 to 11986.44 ng/g with an average of 6469.46 n/g. For individual phenolic compound, the mean concentration of 2,4-Dichlorophenol was the highest in sediment (7883.83 n/g). The total concentration of 5 chlorophenols (& sum;CP5) was significantly higher than that of 4 nitrophenols (& sum;NP4) in all sites. This study had the greatest average concentration of PAHs, LMW ranged between 27.5 and 54.1 % with an average of 43.8% of the Sigma PAHs concentration. High molecular weight (HMW) compounds made up the bulk of PAHs in the study area. The LMW/HMW ratio ranged between 0.39 and 1.18, indicating both pyrolytic and petrogenic sources. The aggregate amount of possibly carcinogenic PAHs (& sum;PAH7) ranged between 296.85 to 481.30 ng/g suggests that these sediments have a negative impact on human health. Controlling wastewater discharge into the Bay is therefore essential to lowering the possible hazards that phenols in the sediments of Abu Qir Bay pose to the marine environment and, in turn, to humans.
