The residues of pharmaceuticals in surface waters of megacities and ecotoxicological implications are of particular concern. In this study, we combined field investigations and model simulations to explore the contamination of cardiovascular and lipid-lowering drugs, one group of the most prescribed medications globally, in surface waters of a typical megacity, Shanghai, with a high wastewater treatment ratio (≈96%). Among 26 target substances, 19 drugs were detected with aqueous concentrations ranging from 0.2 (ketanserin) to 715 ng/L (telmisartan). Of them, angiotensin II receptor antagonists, telmisartan and irbesartan, were dominant besides β-blockers. Spatial distribution analysis demonstrated their much higher levels in tributaries compared to the mainstream. The results of model simulations and field investigation revealed relatively low concentrations of cardiovascular and lipidlowering drugs in surface waters of Shanghai compared to other cities in highly developed countries, which is associated with low per capita usage in China. Ecotoxicological studies in zebrafish embryos further revealed developmental effects, including altered hatching success and heart rate, by irbesartan, telmisartan, lidocaine, and their mixtures at ng/L concentrations, which are typical levels in surface waters. Overall, the present results suggest that the high wastewater treatment ratio was not sufficient to protect fish species in the aquatic ecosystem of Shanghai. Exposure to cardiovascular and lipid-lowering drugs and associated risks will further increase in the future due to healthcare improvements and population aging.
It has been verified that the discharge pulse generated by the pantograph-catenary system has the biggest impact on the high-speed EMU as the electromagnetic interference source. But the spectrum obtained from the existing pantograph discharge model does not contain high frequencies and is far from the measurement results. In this paper, a novel scheme based on Newton’s method and finite difference time domain (FDTD) algorithm was presented to solve this problem. Firstly, Newton’s method was utilized to solve the Habedank model, and the dynamic conductance of the arc was obtained. Then, the equivalent distributed parameter circuit model of the traction power supply system was established, which was solved by the FDTD and state variable method to obtain the time-domain waveform of the arc voltage. The significant features of this scheme are that it can realize the synchronous calculations of the arc dynamic conductance and the voltage responses along the catenary. Through this scheme, a stable arc voltage time domain waveform can be obtained, and the arc voltage spectrum is highly consistent with the test results.
As a widely used plasticizer and fire retardant, tri-o-cresyl phosphate has been commonly found in global water sources, sediments and biota. However, its potential toxicity to aquatic organisms is not fully understood. Here, we assessed its developmental effects by use of a zebrafish (Danio rerio) model at tri-o-cresyl phosphate concentrations between 0.15 and 88.5 μg/L. Diverse impairments of zebrafish embryos, such as altered morphological and physical characteristics and locomotor behaviors, were observed at different tri-o-cresyl phosphate concentrations. Furthermore, swimming behaviors were significantly inhibited at tri-o-cresyl phosphate concentrations ranging from 3.0 μg/L to 88.5 μg/L. The swimming activity during light-to-dark transition significantly increased at tri-o-cresyl phosphate concentrations of 14.5 μg/L to 88.5 μg/L. Taken together, our present data help to clarify the potential developmental toxicity of tri-o-cresyl phosphate that was not yet fully recognized, and thus contribute to its environmental risk assessment.
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