Comprehensive risk assessment of algae and shellfish in the middle route of South-to-North Water Diversion Project.

Since the main canal of the middle route of South-to-North Water Diversion Project was put into operation, the species, quantity, and biomass of algae and shellfish have responded quickly to the environment, and a single dominant species has appeared in the community, demonstrating the remarkably abnormal proliferation property of algae and shellfish. In order to evaluate the safety risk of abnormal proliferation of algae and shellfish in the middle route and realize dynamic analysis of all kinds of influencing factors, a comprehensive risk evaluation system of algae and shellfish in the middle route of South-to-North Water Diversion Project based on comprehensive weighting and four-element connection number was constructed by integrating the analytic hierarchy process (AHP) and the weight assignment theory of criteria importance through intercriteria (CRITIC). The system consists of 21 evaluation indexes selected from risk factors and carriers. Taking Henan section in the middle route as an example, comprehensive risk evaluation system of algae and shellfish in the middle route of South-to-North Water Diversion Project was applied to calculate the partial connection number of each order and obtain the risk development trend of each indicator. The results showed that algae and shellfish in the middle route were in a very safe state at the safety risk level of level I. Finally, reasonable measures to reduce the risks facing algae and shellfish in the middle route of South-to-North Water Diversion Project are given, which effectively make up the deficiency of existing evaluation methods.

Occurrence of antibiotics and antibiotic resistance genes and their correlations in river-type drinking water source, China.

The occurrence and distribution of antibiotics and antibiotic resistance genes (ARGs) in natural water has attracted worldwide attention. Antibiotic and ARG pollution in the surface water of drinking water sources might directly/indirectly affect human health. In this study, the distribution of 38 antibiotics, 10 ARGs, 2 integrons, and 16S r DNA in river-type water sources in a large city of China were monitored in winter, which was a period with high level of antibiotic pollution. The results showed that 20 antibiotics were detected with different detection frequencies. The antibiotic pollution in December 2019 was relatively high, with the total concentrations of antibiotics ranging from 281.95 to 472.42 ng/L, followed by that in January 2020 (191.70-337.29 ng/L) and November 2019 (161.25-309.72 ng/L). Sulfacetamide was dominant in November 2019 (23.52-219.00 ng/L) and in January 2020 (113.18-209 ng/L), while norfloxacin in December 2019 (146.72-290.20 ng/L). All the target antibiotics posed low or medium risk for aquatic organisms, and posed low health risk for mankind. Sul1 and erm36 were the predominant ARGs, and intI1 was the predominant integron in drinking water sources. Only tetA showed positive correlations with its corresponding antibiotic (tetracycline). The rest of ARGs showed no correlations with antibiotics or positive / negative correlations with their non-corresponding antibiotics. Overall, the antibiotics and ARG pollution in these water sources was relatively low. These findings provided some reference data for the distribution of antibiotics and ARGs in river-type drinking water sources of large cities in China.

Distribution and potential risk assessment of antibiotic pollution in the main drinking water sources of Nanjing, China.

The distribution character of 41 antibiotics belonging to 6 groups, sulfonamides (SAs), quinolones (QUs), tetracyclines (TCs), macrolides (MLs), penicillins (PLs), and chloramphenicol (CHL), was investigated in drinking water sources of Nanjing during 2017-2019. MLs (42.98%) were the most abundant category, followed by SAs (25.94%) and QUs (22.52%). The dominant antibiotic was ofloxacin (OFX) in Dec. 2017 (average concentration, 3.14 ng/L; range, ND-35.20 ng/L) and Nov. 2018 (2.16 ng/L, ND-12.26 ng/L), and sulfadiazine (SDZ) in Mar. 2019 (16.37 ng/L, ND-25.90 ng/L). For Dec. 2017, the total concentrations in Zhongshan Waterworks (S15) and Jinniushan Reservoir (S16) were significantly higher than the other sampling sites, which may be attributed to point source pollution. The ecological and human risk of the main antibiotics was assessed by risk quotients (RQs) and target hazard quotient (THQ), respectively. Most of the RQ values were below 0.1, except enrofloxacin (ERX, 0.11) and enoxacin (ENX, 0.62) in Dec. 2017, lomefloxacin (LOM, 0.14) in Nov. 2018, and LOM (0.28) and ERX (0.10) in Mar. 2019. This indicated that the risk of the target antibiotics to aquatic organisms in the 3 years was moderate or low level. Meanwhile, results of the THQ values showed that antibiotic exposure caused no risk to human health. This research provides scientific information for antibiotic pollution control and enriches environmental monitoring data in the drinking water sources.

[Occurrence Characteristics and Risk Assessment of Antibiotics in Source Water of the Nanjing Reach of the Yangtze River].

Occurrence characteristics of antibiotics in the source water of the Nanjing section of the Yangtze River were analyzed preliminarily by solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The results showed that the cumulative concentration of 16 sampling points ranged from 13.37 ng·L-1 to 780.5 ng·L-1, with an average concentration of 92.95 ng·L-1. Four sulfonamides, three fluoroquinolones, one tetracycline, five macrolides, and one chloramphenicol antibiotic were detected with average concentration ranging from 0.14 ng·L-1 to 49.91 ng·L-1,including enrofloxacin (ERX) and clarithromycin (CLR) with the highest detection rate of 100%, and clindamycin (CLI) with the highest concentration of 739.44 ng·L-1. Overall, the concentration levels of antibiotics in the Nanjing section of the Yangtze River were low compared with other rivers and lakes in China. The risk assessment results showed that the largest cumulative risk of S2 was 0.31, and the environmental risk of sulfamethoxazole (SMX), doxycycline (DOX), and roxithromycin (ROX) had lower risk levels;the health risk indexes of nine antibiotics for different age groups were between 2.22×10-6and 4.86×10-3, while CLI and DOX are the main potential health risk factors for humans.

[Simultaneous determination of five types of 40 antibiotics in surface water using high performance liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of five categories of 40 antibiotics in surface water by using solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The water samples were enriched and cleaned-up by filtration and with SPE cartridges. All antibiotics were separated by gradient elution with the mobile phase of 0.2% (v/v) formic acid aqueous solution and acetonitrile, and then analyzed with an electrospray ionization source in the positive ion and multiple reaction monitoring (MRM) modes. The results showed that the 40 antibiotics achieved great linearity in the range of 1-200 µg/L, and the average recoveries ranged from 41.3% to 112.6%. Using the developed method, thirteen antibiotics were identified in surface water from Nanjing section of the Yangtze River. The total antibiotic contents in the real samples ranged from 13.4 ng/L to 780.5 ng/L. The established method is efficient, sensitive and reliable, and is suitable for the determination of different antibiotics in real water samples.

Occurrence and partitioning behavior of organophosphate esters in surface water and sediment of a shallow Chinese freshwater lake (Taihu Lake): Implication for eco-toxicity risk.

Organophosphate esters (OPEs) are ubiquitous in the aquatic environment, which have been considered or suspected as carcinogens and neurotoxicants. In this study, the occurrence, spatial distribution, potential sources, partitioning character and potential risks of OPEs in the surface water and sediment collected from Taihu Lake were investigated. The concentrations of ∑12 OPEs varied from 1.0 × 102 to 1.7 × 103 ng/L for the surface water and from 8.1 to 4.2 × 102 ng/g dw for the sediment. Trimethyl phosphate (TEP) was the predominant congener in the surface water, while Tris(2-ethylhexyl) phosphate (TEHP) in the sediment. Positive correlations between OPEs indicated that they may have the same sources and/or similar environmental behavior. The pseudo-partitioning values of OPEs ranged from 0.59 to 6.5 × 104 L/kg. TEHP has the highest pseudo-partitioning coefficient, which indicated that TEHP inclined to be enriched in the sediment in Taihu Lake. Risk assessment (RQ) showed that individual OPEs in the surface water and sediment posed no/low risk to aquatic organisms, except 2-Ethylhexyl diphenyl phosphate (EHDPP) (moderate risk) in water.