Temporal and spatial characteristics of flocculated suspended solids in a deep reservoir: an in situ observation in the Biliuhe Reservoir

The amount of total suspended solids (TSS) is the most visible indicator for evaluating water quality in reservoirs. Previous investigations paid more attention to TSS of the surface layer in reservoirs, while suspended particles are prone to settle, resuspend, and aggregate at the bottom of reservoir. There may be different patterns of the TSS in different depths. This study is to assess the TSS concentration by weight analysis, find the evidence of the existence of flocculated suspended particles by in situ underwater imaging analysis, and discuss the impact of the flocculation process of suspended solids on water quality in deep reservoirs. Although the TSS concentration is lower than other reservoirs with the same trophic level, many flocs were found at the bottom of the deep-water area (> 15 m) in the Biliuhe Reservoir according to the recordings of the in situ underwater camera. The further comprehensive analysis demonstrates that the fine particle in flood season and resuspension is the main source of suspended flocs at the bottom of the reservoir. While the slow settling velocity results in the flocculation of fine suspended particles and long-term residence in the bottom layer of the reservoir. TSS has a significant correlation with iron and total phosphorus. Resuspension, flocculation, and settling impact on the transport of suspended sediment and associated contaminants. The evidence from this study suggests that the impact of flocs on water quality should be further discussed to ensure water supply safety.

A new-type HOCl-activatable fluorescent probe and its applications in water environment and biosystems

The outbreak and spread of Corona Virus Disease 2019 (COVID-19) has led to a significant increase in the consumption of sodium hypochlorite (NaOCl) disinfectants. NaOCl hydrolyzes to produce hypochlorous acid (HOCl) to kill viruses, which is a relatively efficient chlorine-based disinfectant commonly used in public disinfection. While people enjoy the convenience of NaOCl disinfection, excessive and indiscriminate use of it will affect the water environment and threaten human health. Importantly, HOCl is an indispensable reactive oxygen species (ROS) in human body. Whether its concentration is normal or not is closely related to human health. Excessive production of HOCl in the body contributes to some inflammatory diseases and even cancer. Also, we noticed that the concentration of ROS in cancer cells is about 10 times higher than that in normal cells. Herein, we developed a HOCl-activatable biotinylated dual-function fluorescent probe BTH. For this probe, we introduced biotin on the naphthalimide fluorophore, which increased the water solubility and enabled the probe to aggregate in cancer cells by targeting specific receptor overexpressed on the surface of cancer cell membrane. After reacting to HOCl, the p-aminophenylether moiety of this probe was oxidatively removed and the fluorescence of the probe was recovered. As expected, in the PBS solution with pH of 7.4, BTH could give full play to the performance of detecting HOCl, and it has made achievements in detecting the concentration of HOCl in actual water samples. Besides that, BTH had effectively distinguished between cancer cells and normal cells through a dual-function discrimination strategy, which used biotin to enrich the probe in cancer cells and reacted with overexpressed HOCl in cancer cells. Importantly, this dual-function discrimination strategy could obtain the precision detection of cancer cells, thereby offering assistance for improving the accuracy of early cancer diagnosis.

The effects of turbulence on phytoplankton and implications for energy transfer with an integrated water quality-ecosystem model in a shallow lake

Turbulence has significant influences on the growth rate and community structure of phytoplankton in large shallow lakes. Phytoplankton in moving water may be influenced by turbulence and nutrient concentration gradients on a short time scale. To assess this issue, our research used an ensemble water quality and ecological model by internally coupling the three-dimensional hydrodynamic model, the Environmental Fluid Dynamics Code (EFDC), and the one-dimensional ecosystem model, PCLake. The results showed that turbulence dramatically inhibited phytoplankton growth, while nutrients had the opposite effect. In addition, turbulence was the key factor contributing to phytoplankton growth. However, the effects of turbulence on phytoplankton correlated with nutrient concentrations. For lower nutrient concentrations, phytoplankton growth was controlled by nutrients. Logistic regression models were established with the modeled chlorophyll a, total nitrogen (TN), total phosphorus (TP) and turbulent kinetic energy (K_e). The results also showed that turbulence could improve nutrient uptake by phytoplankton, especially at low nutrient levels. The effects of turbulence on phytoplankton may imply that energy transfer occurs between water turbulence and phytoplankton. Our study will provide insight into management and remediation strategies of ecosystems based on energy processes in the future.

A comparison study of in-situ coagulation and magnetic ion exchange (MIEX) as pre-treatments for ultrafiltration: Evaluating effectiveness of organic matters removals and fouling mitigation

This work was designed to compare the effectiveness of in-situ coagulation and MIEX as pre-treatments prior to ultrafiltration (UF) to improve organic matter (OM) removal and mitigate membrane fouling. Three kinds of OMs, i.e. salicylic acid (SA), humic acid (HA) and bovine serum albumin (BSA) were employed. The experimental results show that coagulation-UF led to most effective removal of HA (almost 90%), while the SA was uncoagulated and least removable, with the rejection rate of about 55%. Conversely, MIEX present superior ability for removing SA, contributing to additional efficiency of 71.95-77.21% than UF alone. Proper dosage of Al-based coagulants could alleviate flux loss, especially in the cases of HA and BSA. Increasing coagulant dose resulted in continuous decrement of irreversible resistance (R_ir), which dominated the membrane fouling development by the SA water. For HA and BSA waters, alternatively, variations of R_r determined the flux declines. Floc compact degree was the decisive factor for R_r for coagulated SA; while for HA and BSA, R_r was most related to the floc size and foulant-foulant interaction. MIEX was most effective for alleviating flux loss when treating the hydrophilic SA with small molecules and for all the cases, MIEX exerted little influence on the R_r values.

A Method for the Highly Selective, Colorimetric and Ratiometric Detection of Hg(2+) in a 100% Aqueous Solution

Mercury (Hg) and its derivatives pose a serious threat to the environment and human health. Thus, the development of methods for the selective and sensitive determination of Hg(2+) is very important to understand its distribution, and to implement more detailed toxicological studies. Herein, we developed a new method for the detection of Hg(2+) based on the tricyanoethylene derivative and mercaptoethanol. This method could selectively detect Hg(2+) in a 100% aqueous solution by the naked-eye within the range of 1 - 60 μM. Importantly, this method also could detect Hg(2+) quantitatively by ratiometic absorption spectroscopy in the range of 0.1 - 6 μM with a detection limit of 55 nM. We anticipate that this proposed method will be used widely to monitor Hg(2+) in the environment.

[A randomized multicentre clinical trial on different doses of mifepristone alone and in combination with anordrin as emergency contraception]

OBJECTIVES

To investigate the effectiveness and side-effects of different doses of mifepristone alone or in combination with anordrin given orally within 96 hours after unprotected intercourse as an emergency contraceptive.

METHODS

2,400 cases of healthy women were recruited and allocated randomly in 4 groups: single dose of 25 mg mifepristone, 25 mg mifepristone plus 7.5 mg anordrin, 10 mg mifepristone plus 5 mg anordrin and 10 mg mifepristone alone. The efficacy rates of contraception were estimated according to Dixon method.

RESULTS

The total expected number of pregnancy was 171.9 for 2,387 subjects enrolled in the study. The number of observed pregnancies related to method failure was 32 cases. The contraceptive effectiveness rates for the above 4 groups were 80.9%, 85.3%, 90.6% and 67.3%, respectively. For the group received 10 mg mifepristone plus 5 mg anordrin, pregnancy rate was 0.7% which was significantly lower than that in 10 mg mifepristone alone group (2.2%, P < 0.05). The incidences of withdrawal bleeding were 9.2%, 4.9%, 3.4% and 6.7% for the 4 group respectively. Two groups received mifepristone in combination with anordrin showed significant lower incidence of withdrawal bleeding than those in mifepristone alone groups.

CONCLUSION

Single oral administration of 25 mg mifepristone alone, and the combination of 10 mg mifepristone plus 5 mg anordrin were safe and effective treatment regimen for emergency contraception with no serious adverse reaction and disturbance on menstrual pattern.

[A phase III multicentre study on medical termination of early pregnancy with two regimens of mifepristone followed by PG05]

OBJECTIVE

To compare use-effectiveness and side-effects of medical termination of early pregnancy by oral administration of separated doses of mifepristone 150 mg or single dose of mifepristone 200 mg followed by PG05 1 mg vaginally in 4500 healthy pregnant women with amenorrhea < or = 49 days in a phase I multicentre study.

METHODS

All subjects were recruited in 30 clinics after obtaining informed consents.

RESULTS

The complete, incomplete abortion and continuous pregnancy rates were 88.6%, 8.1%, 1.7% and 92.0%, 5.8%, 0.8% in single dose and separated doses groups, respectively. The efficacy of termination of early pregnancy by mifepristone 150 mg in separated doses was higher than that in single dose of mifepristone 200 mg when both in combination with PG05 1 mg (P < 0.01). One case of allergic rash was noted after administration of mifepristone. No severe side-effects were observed except bleeding problems. 65 cases received emergency vacuum aspiration and 7 of them received blood transfusion due to heavy bleeding. In addition, 2 cases of ectopic pregnancies required blood transfusion as heavy bleeding caused by exfetation disruption. There was no significant difference in to the time to start bleeding and the days of bleeding lasted between two treatment groups. However, there was a significant positive correlation (P < 0.001) between diameters of SAC and the days of bleeding lasted.

CONCLUSIONS

Logistic regression analysis suggested that subject's age, gravidity and days of amenorrhea have significant effects on abortion efficacy. 75.2% of subjects are satisfactory in self-assessment of the treatment, and 81.8% of subjects will choose medical abortion method in case they need to terminate undesired early pregnancy in the future.