High Ecological Risk Research Articles

Riverine antibiotic occurrence and potential ecological risks in a low-urbanized and rural basin of the middle Yangtze River: Socioeconomic, land use, and seasonal effects

This study firstly investigated the effects of season, land use, and socioeconomic on the spatiotemporal changes of riverine antibiotic concentrations in a low urbanized and rural watershed. In the dry and wet seasons, water samples were collected and analyzed for 15 antibiotics. The results indicated that 14 antibiotics, excluding leucomycin, were detected. Monsoon led to significantly lower total antibiotic concentrations in the wet season (22.0ngL−1) than in the dry season (51.2ngL−1). Total antibiotic concentrations were dominated by amoxicillin (below limit of detection (<LOD)-34.7ngL−1)), erythromycin-H2O (<LOD-14.7ngL−1), roxithromycin (<LOD-27.9ngL−1), and trimethoprim (<LOD-6.34ngL−1). The total antibiotic concentrations were usually higher in the downstream areas of urban land than in the river reaches of forest land and agricultural land. At county or city scales, total antibiotic concentrations in the dry season were significantly correlated with the rural population, public budget, husbandry product and output, effluent volume, fishery product and output, and hospital number, which generally depend on land use in the basin. Amoxicillin poses a high ecological risk to aquatic algae, whereas erythromycin-H2O, ofloxacin, and norfloxacin pose medium ecological risks. However, trimethoprim poses a medium ecological risk to mollusks. These results provide improved insights into the characteristics of antibiotic occurrence and ecological risks in the waters of low-urbanized and rural areas in China and can be extrapolated worldwide.

Potential Ecological Risk Assessment of Critical Raw Materials: Gallium, Gadolinium, and Germanium.

In recent years, the demand for critical raw materials such as gallium, gadolinium and germanium (G(s)) has steadily increased in various industries. However, treatment or recycling rates of these elements are extremely low, which can lead to environmental pollution. An assessment of the ecological risks was also not possible until now, as there were no calculated toxicity coefficients for G(s). In this study, a well-known method, the so-called potential ecological risk index (PERI), was used for the first time to calculate the toxicity coefficients of these elements using data from recent literature studies on G(s) elements. The toxicity coefficient of each of the three elements was determined as five (5). The results show that G(s) have the same toxicity coefficient as Cu and Pb and are higher than that of Cr. The ecological risk index results varied from 4 to 414, 0.98 to 25.98 and 2.50 to 284.64 for Ga, Gd and Ge, respectively. The results show that Ga and Ge pose high ecological risk while the Eri of Gd is low. The toxicity coefficients of these elements have been calculated for the first time in the literature and provide a practical use for calculating the potential ecological risk index.

Heavy metal(loid)s contamination in water and sediments in a mining area in Ecuador: a comprehensive assessment for drinking water quality and human health risk.

Elevated heavy metal(loid)s concentrations in water lower its quality posing a threat to consumers. This study aims to assess the human health risk caused by heavy metal(loid)s in tap water in Santa Rosa city, Ecuador, and the ecological risk of stream water and sediments in the Santa Rosa River. Concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn were evaluated in tap waters, stream waters, and sediment samples during the rainy and dry seasons. The Metal Index (MI), Geo-accumulation Index (Igeo), Potential Ecological Risk Index (PERI), and the levels of carcinogenic (CR) and non-carcinogenic risk (HQ) were determined. The results revealed severe pollution levels, mainly in Los Gringos and El Panteon streams, both tributaries of the Santa Rosa River, the primary water source for Santa Rosa inhabitants. More than 20% of the surface water samples showed severe contamination (MI > 6), and 90% of the tap water samples presented a MI value between 1 and 4, which indicates slight to moderate pollution. Drinking water displayed high levels of As, with 83% of the tap water samples collected from households in the dry season above the recommended concentration set by the World Health Organization and Ecuadorian legislation. The Igeo-Cd in the sediment samples was significantly high (Igeo > 3), and the PERI showed very high ecological risk (PERI > 600), with Cd as the main pollutant. HQ and CR were above the safe exposure threshold, suggesting that residents are at risk from tap water consumption, with As being the primary concern.

Organophosphate flame retardants and plastics in soil from an abandoned e-waste recycling site: significant ecological risks derived from plastic debris

The distribution of 9 organophosphate flame retardants (OPFRs) was determined in plastic debris and soil samples separated from twenty soil samples collected from an abandoned e-waste recycling area. Tris-(chloroisopropyl) phosphate (TCPP) and triphenyl phosphate (TPhP) were the main chemicals, with median concentrations of 124-1930ng/g and 143-1170ng/g in soil, and 712-803ng/g and 600-953ng/g in plastics, respectively. Plastics contributed less than 10% of the total OPFR mass in bulk soil samples. No apparent OPFR distribution trend was observed in different sizes of plastics and soil. The ecological risks of plastics and OPFRs were estimated by the species sensitivity distributions (SSDs) method, which resulted in lower predicted no-effect concentrations (PNECs) of TPhP and decabromodiphenyl ether 209 (BDE 209) than the standard values derived from limited toxicity tests. In addition, the PNEC of polyethene (PE) was lower than the plastic concentration in the soil of a previous study. TPhP and BDE 209 had high ecological risks with risk quotients (RQs) > 0.1, and RQ of TPhP was among the highest values in literature.

Occurrence, distribution, and risk assessment of quinolone antibiotics in municipal sewage sludges throughout China

A nationwide study of the occurrence, distribution, potential drivers, and ecological risks of 24 quinolone antibiotics (QNs) in 74 Chinese sludge samples from 48 wastewater treatment plants (WWTPs) was conducted. In domestic sludge, the ∑QNs concentrations were <LOD to 21,925.10 ug/kg (mean: 4808.67 ug/kg), and ofloxacin had the highest concentration (<LOD-11,138.52 ug/kg), and detection frequency (98.48%). Of four generations QNs, the levels showed the following order: 2nd-generation QNs > 3rd-generation QNs > 4th-generation QNs > 1st-generation QNs. Meanwhile, abundant veterinary and human/veterinary quinolones (<LOD-2606.96 and <LOD-12,643.47 ug/kg, respectively) were detected in municipal sludge. Interestingly, the relatively low levels of veterinary quinolones (<LOD-299.21 ug/kg) were also found in industrial sludge (the relevant WWTPs receiving ≤ 10% domestic wastewater, without other direct entry of antibiotics). The correlation analysis demonstrated QNs contamination was negatively influenced by the air temperature of sampling days. The positive correlation between moxifloxacin contents and regional economy possibly suggested local regions with relatively high economic levels face a more difficult situation of QNs antibacterial activity. Environmental risk assessment indicated ofloxacin, ciprofloxacin, and moxifloxacin posed high ecological risks to the domestic sludge. This work delineates a valuable nationwide QNs contamination profile to support their safe use and control in China.

Regional planning for ecological protection of rivers in highly urbanized areas

The ecological risks associated with rapid urbanization have seriously undermined the river’s ecological security. Especially for developing countries, the weak ecological foundation and enormous population pressure have increased the difficulty of river ecological protection. It is urgent to propose a bottom-line planning and management approach for river ecological protection in highly urbanized areas of developing countries. We quantified the minimum cumulative resistance of the river protection and construction land expansion processes. Then, based on the difference between these two minimum cumulative resistances, we assessed the river ecological risk in the Beijing plain area and presented a complete method to regional-level planning and management for river ecological protection. The results show that: 1) The spatial distribution of river ecological risks follows a three-tier ring structure, decreasing from the city center to the suburbs and then to the outer suburbs. The number of river segments with ecological risk levels 1, 2, and 3 are 44, 42, and 23, respectively, accounting for 39.2% of the total length of all river sections, which indicates that a larger number of rivers are facing high ecological risk. 2) The study area was divided into three zones according to the suitability of river ecological protection, with 2476.89, 765.51, and 3832.09 km2, respectively. Zone I and Zone II can be developed as protection nodes and riparian protection zones to develop the river ecological network in the central city. 3) We extracted 133 large ecological patches and 219 potential ecological corridors, which should be connected with the river network to enhance the connectivity of the local ecological landscape. The complete method proposed in this study is more focused and implementable to assist administrators in protecting and restoring the ecological security of urban rivers.

Toxic metals and the risks of sludge from the treatment of wastewater from beryllium smelting

The release of highly toxic beryllium in sludge (BCS) produced by physico-chemical treatment of beryllium-containing wastewater from Be smelting production has become a growing concern with the widespread use of Be in the defense industry. This work investigated the potential mobility of Be in BCS. The toxicity characteristic leaching procedure (TCLP) of BCS showed that the amount of leached Be was up to 202 mg L−1, which exceeded the regulated limit by nearly 10,000 times. The chemical fractionation analysis further revealed that the excessive amount of Be leached from BCS was contributed to the high content of acid-soluble fraction and reducible fraction of Be, which accounted for over 70% of the Be content. The results obtained from mineralogical automatic analyzer (MLA) showed that gypsum (23.23%) and epidote (19.55%) were the two major mineralogical phases of BCS. Both were small and loosely structured agglomerated particles with a D50 of 6.61 μm and 3.31 μm. ToF-SIMS results revealed that the Be distribution on the surface of BCS particles was relatively dispersed, with no aggregation or encapsulation. Be co-precipitated with gypsum and chlorite in the form of unstable Be(OH)2, which attached to the surface of these small particles. The unstable state of Be and the small size, loose structure and high liberation of the host material phases are the main reasons for the high leaching mobility of Be. The results of the risk assessment indicated that BCS posed an extremely high potential ecological risk, with Be being the most significant contributor.

Geochemical fractionation, bioavailability, ecological and human health risk assessment of metals in topsoils of an emerging industrial cluster near New Delhi.

Urban spaces have become sink for metal-rich waste, particularly in unorganized industrial clusters and metro-cities. Geochemical distribution of metals in different forms and their mobility and bioavailability in topsoils of Bhiwadi Industrial Cluster (BIC) near New Delhi are studies following m-BCR-SEP. Contamination factor (Cf), risk assessment code (RAC), ecological risk assessment (Er), and carcinogenic and non-carcinogenic health risk (HRA) were calculated to assess health and environmental risks. Residual fraction (F4) contained considerable amounts of Cd (57.2%), Cr (81.5%), Fe (86.1%), Mn (62.5%), Ni (58.3%), and V (71.4%). Pb was present in reducible fraction (F2; 52.8%), whereas Cu was distributed in F2 (33.3%) and F4 (31.6%). Zn showed equal distribution in acid exchangeable (F1; 33.9%) and oxidizable fraction (F3; 32.5%). High Cf was observed for Zn (0.9-20.9), Cu (0.46-17) and Pb (0.2-9.9). RAC indicated high risk of Cd, Cu, Mn, Ni, and Zn due to their high mobility and toxicity. High potential bioavailability of Cu, Pb, and Zn (> 65%) was found in samples collected near to metal casting, electroplating, and automobile part manufacturing industries. Considerable to extremely high ecological risk was observed for Cd, low to high risk for Cu, low risk to moderate risk for Cr, Mn, Ni, Zn, and Pb. All topsoil samples were in low to very high-risk range for metals. Ingestion was major pathway of metals followed by dermal and inhalation. Children were more prone to non-carcinogenic risks (hazardous index: 3.6). Topsoils had high carcinogenic risk to exposed population for Cd, Cr, Ni, and Pb.

Abundance, characteristics, and ecological risks of microplastics in the riverbed sediments around Dhaka city

Microplastic (MP) pollution has become an escalating problem in Bangladesh due to its rapid urbanization, economic growth, and excessive use of plastics; however, data on MP pollution from fresh water resources in this country are limited. This study investigated microplastics pollution in riverbed sediments in the peripheral rivers of Dhaka, the capital of Bangladesh. Twenty-eight sediment samples were collected from the selected stations of the Buriganga, Turag, and Balu Rivers. Density separation and wet-peroxidation methods were employed to extract MP particles. Attenuated total reflectance-Fourier transform infrared spectroscopy was used to identify the polymers. The results indicated a medium-level abundance of MPs in riverbed sediment in comparison with the findings of other studies in freshwater sediments worldwide. Film shape, white and transparent color, and large-size (1–5 mm) MPs were dominant in the riverbed sediment. The most abundant polymers were polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Pollution load index (PLI) values greater than 1 were observed, indicating that all sampling sites were polluted with MPs. An assessment of ecological risks, using the abundance, polymer types, and toxicity of MPs in the sediment samples, suggested a medium to very high ecological risk of MP pollution of the rivers. The increased abundance of MPs and the presence of highly hazardous polymers, namely; polyurethane, acrylonitrile butadiene styrene, polyvinyl chloride, epoxy resin, and polyphenylene sulfide, were associated with higher ecological risks. Scanning electron microscopy (SEM) analysis indicated that the MPs were subjected to weathering actions, reducing the size of MPs, which caused additional potential ecological hazards in these river ecosystems. This investigation provides baseline information on MP pollution in riverine freshwater ecosystems for further in-depth studies of risk assessment and developing strategies for controlling MP pollution in Bangladesh.

Comprehensive distribution characteristics and risks of heavy metals in typical intertidal zones and their relationship with urban economic indicators

Human activities have increased heavy metal pollution in intertidal environments. However, the comprehensive ecological risks of heavy metals in the active zones and their relationship with urban economic indicators are still poorly understood. This study investigated the multiphase distribution characteristics of heavy metals (Cr, Ni, Cu, Zn, Pb, and Cd) in 14 typical intertidal zones in the Guangdong–HongKong–Macao Greater Bay Area. The results showed that the concentrations of heavy metals varied greatly among different cities, and the highest average concentrations in Dongguan city were 695.27, 243.79, 1482.36, 980.24, 66.36 and 4.95 mg.kg−1, respectively. The proportion of bioavailable state Cd was the highest as 54.20%, followed by Zn > Cu > Pb > Ni > Cr. The comprehensive ecological risks (RCER) of the two intertidal zones in Dongguan were 1.45 ∼ 7.70 times higher than those of other sampling areas, indicating a very high ecological risk. Correlation analysis showed that total organic carbon in surface water, ammonia nitrogen in pore water, and solid organic carbon and the proportion of clay in sediments were significantly correlated with RCER values, and the linear regression coefficients were 0.784, 0.919, 0.962 and 0.914, respectively. The modified environmental Kuznets curve (EKC) model was used to describe the relationship between RCER values and urban economic indicators, and an inverted U shaped curve relationship was found, indicating that regional heavy metal pollution seemed to have reached a peak and entered a period of emission reduction. Nevertheless, given the increasing proximity of the intertidal zone to human daily life, long-term follow-up assessments are recommended.

Ecological Compensation in Zhijiang City Based on Ecosystem Service Value and Ecological Risk

Using Zhijiang City, Hubei Province as an example, this study constructed an ecological risk assessment model based on land use data from the three phases of 2000, 2010, and 2020. We then determined the ecological compensation priority sequence based on the ecosystem services value (ESV) and the economic status of the research area. The findings revealed that there was a significant spatial differentiation in ESV during the study period, with the ESV being higher south of the Yangtze River than north. Overall, in Zhijiang City, the ESV generally decreased over the course of the study period, with a decrease of CNY 812 million in 20 years. The loss of wetland and grassland was the greatest, and was most obvious between 2010 and 2020, whereas the loss of construction land was the lowest among the different types of landscapes. The ecological risk index of Zhijiang City showed a declining trend between 2000 and 2020. The extent of high-ecological risk areas shrank by 55.83 km2, and their predominant landscape types were grassland and forest land. The low-ecological risk area expanded by 340.50 km2 and was primarily distributed in construction land along the Yangtze River Basin. The ecological compensation priority sequence was divided into five levels in each town in Zhijiang City, with Gujiadian Town and Baiyang Town receiving the highest grades and being designated as priority compensation areas. The study intends to serve as a model for the construction of ecological cities, ecological environmental protection, and sustainable development in the Yangtze River Basin.

Meta-analysis reveals cyanotoxins risk across African inland waters

Global eutrophication and climate warming exacerbate production of cyanotoxins such as microcystins (MCs), presenting risks to human and animal health. Africa is a continent suffering from severe environmental crises, including MC intoxication, but with very limited understanding of the occurrence and extent of MCs. By analysing 90 publications from 1989 to 2019, we found that in various water bodies where MCs have been detected so far, the concentrations were 1.4–2803 times higher than the WHO provisional guideline for human lifetime exposure via drinking water (1 µg/L) in 12 of 15 African countries where data were available. MCs were relatively high in the Republic of South Africa (averaged 2803 μg/L) and Southern Africa as a whole (702 μg/L) when compared to other regions. Values were higher in reservoirs (958 μg/L) and lakes (159 μg/L) than in other water types, and much higher in temperate (1381 μg/L) than in arid (161 μg/L) and tropical (4 μg/L) zones. Highly significant positive relationships were found between MCs and planktonic chlorophyll a. Further assessment revealed high ecological risk for 14 of the 56 water bodies, with half used as human drinking water sources. Recognizing the extremely high MCs and exposure risk in Africa, we recommend routine monitoring and risk assessment of MCs be prioritized to ensure safe water use and sustainability in this region.

Assessment of Groundwater and Surface Soil using Multivariate Statistical Techniques and Contamination Indices: A Case Study of Gurugram Millennium City, Haryana, India

Abstract Pollution of various environmental components, such as air, water, and soil, is caused by industrialization and urbanization in urban agglomerates. This study provides information about groundwater quality and the levels of heavy metals in the surface soils of Gurugram city. The groundwater and soil samples were analyzed for various chemical parameters. Heavy metals in groundwater and soil were measured using atomic absorption spectrophotometer (AAS). Groundwater samples show higher electrical conductivity (EC), bicarbonates (HCO3-), and chlorides (Cl-). Water quality index (WQI) indicates that groundwater is not suitable for drinking purposes. Most of the groundwater samples surpassed the prescribed limits for heavy metals. While in the case of soil, Cd, Ni and Cr were found above the average background value for soils. Contamination factors (CF) and Pollution load index (PLI) for various heavy metals in soil were found to vary from 0.006 to 20.9 and 0.64 to 1.93, respectively. The 70% of samples found with PLI &amp;gt;1, indicate deterioration of soil quality. Three soil samples have a high ecological risk index (ERI) with values of more than 600. Average value of geo-accumulation index (Igeo) varies in the order Cd&amp;gt;Pb&amp;gt;Cu&amp;gt;Zn&amp;gt;Ni&amp;gt; Cr&amp;gt;Fe with average value 3.43, 1.73, 0.86, 0.029, -.23, -1.2 and - 7.14, respectively. Principal component analysis (PCA), a multivariate statistical technique, shows that the first three principal components (PC) account for 84.99% of the variance in groundwater samples. In soil samples, the first two PCs account for 76.97% of the variance. Hierarchical cluster analysis (HCA) shows three clusters for groundwater samples and two clusters for soil samples. The study area shows higher pollution levels and needs an improved environmental management plan.

Ecological Risk Assessment of Geological Disasters Based on Probability-Loss Framework: A Case Study of Fujian, China.

Geological disaster could pose a great threat to human development and ecosystem health. An ecological risk assessment of geological disasters is critical for ecosystem management and prevention of risks. Herein, based on the "probability-loss" theory, a framework integrating the hazard, vulnerability, and potential damage for assessing the ecological risk of geological disasters was proposed and applied to Fujian Province. In the process, a random forest (RF) model was implemented for hazard assessment by integrating multiple factors, and landscape indices were adopted to analyze vulnerability. Meanwhile, ecosystem services and spatial population data were used to characterize the potential damage. Furthermore, the factors and mechanisms that impact the hazard and influence risk were analyzed. The results demonstrate that (1) the regions exhibiting high and very high levels of geological hazard cover an area of 10.72% and 4.59%, respectively, and are predominantly concentrated in the northeast and inland regions, often distributed along river valleys. Normalized difference vegetation index (NDVI), precipitation, elevation, and slope are the most important factors for the hazard. (2) The high ecological risk of the study area shows local clustering and global dispersion. Additionally, human activities have a significant influence on ecological risk. (3) The assessment results based on the RF model have high reliability with a better performance compared with the information quantity model, especially when identifying high-level hazard areas. Our study will improve research on the ecological risk posed by geological disasters and provide effective information for ecological planning and disaster mitigation.

Levels and ecological risk of pharmaceuticals in River Sosiani, Kenya.

The continued frequent detection of pharmaceuticals in the environment is of major concern due to potential human and ecological risks. This study evaluated 30 antibiotics from 8 classes: sulphonamides (SAs), penicillins (PNs), fluoroquinolones (FQs), macrolides (MLs), lincosamides (LINs), nitroimidazoles (NIs), diaminopyrimidines (DAPs), salfones and 4 anthelmintics benzimidazoles (BZs) in surface water and sediments from River Sosiani in Eldoret, Kenya. Samples were collected during the wet and dry seasons and subjected to solid phase extraction using HLB cartridges. A liquid chromatography tandem mass spectrometry (LC-MS/MS) method was used for the simultaneous quantification of the compounds. Chromatographic separation was on a reversed-phase Zorkax Eclipse Plus C18 column eluted in a gradient program and compounds detected by mass spectrometer operated in a positive electrospray ionization (+ ESI) mode. Twenty-eight antibiotics were detected in water where 22 had a 100% detection frequency and the remaining 4 showed detection frequencies ranging from 5 to 47%. Three BZs had a 100% detection frequency. Detectable concentrations of the pharmaceuticals in water ranged between 0.1 and 247ngL-1 and 0.01 and 974µgkg-1 in the sediments. The sulfonamide, sulfamethoxazole, had the highest concentration in water (247ngL-1), whereas penicillin G showed the highest concentrations in sediments (414-974µgkg-1). Quantified pharmaceuticals decreased in the order SAs > DAPs > FQs > ATs > PNs≈MCs≈LNs > NIs in water, and followed the order PNs > BZs > FQs > MLs > DAPs ≈ LNs > NIs > SAs in sediments. Risk quotients (RQw) showed that sulfamethoxazole and ciprofloxacin were of high ecological risk in the surface water (RQw values of 1.11 and 3.24, respectively), whereas penicillin V, ampicillin, penicillin G, norfloxacin, enrofloxacin, erythromycin, tylosin, and lincomycin were of medium ecological risk in the aquatic system. The findings show high prevalence of pharmaceuticals in surface water and sediments and are therefore potential ecological hazards. Such information is vital when devising mitigation strategies.

Ecological Risk Assessment and Prediction Based on Scale Optimization—A Case Study of Nanning, a Landscape Garden City in China

Analysis and prediction of urban ecological risk are crucial means for resolving the dichotomy between ecological preservation and economic development, thereby enhancing regional ecological security and fostering sustainable development. This study uses Nanning, a Chinese landscape garden city, as an example. Based on spatial granularity and extent perspectives, using 30 m land use data, the optimal scale for an ecological risk assessment (ERA) and prediction is confirmed. This study also explores the patterns of spatial and temporal changes in ecological risk in Nanning on the optimal scale. At the same time, the Patch-generating Land Use Simulation model is used to predict Nanning’s ecological risk in 2036 under two scenarios and to propose ecological conservation recommendations in light of the study results. The study results show that: a spatial granularity of 120 m and a spatial extent of 7 km are the best scales for ERA and prediction in Nanning. Although the spatial distribution of ecological risk levels is obviously different, the overall ecological risk is relatively low, and under the scenario of ecological protection in 2036, the area of high ecological risk in Nanning is small. The results can provide theoretical support for ERA and the prediction of landscape cities and ecological civilization construction.

A holistic approach to the eco-geochemical risk assessment of trace elements in the estuarine sediments of the Southeastern Black Sea

The estuarine sediments were sampled seasonally along the southeast coast of the Black Sea, to assess the concentrations, sources, distributions, and possible ecological risks of trace elements (TEs). The mean concentrations of TEs (mg/kg) were ranked as Fe (56,659.83) > Al (39,758.00) > Mn (1168.53) > Zn (155.03) > Cr (120.75) > Pb (93.71) > Cu (82.66) > Ni (44.93) > Co (17.98) > As (13.66) > Cd (0.99) > Hg (0.18), respectively. The stations S4 and S6 showed “very high contamination” for Pb, “significantly enrichment” for Pb and Cd, “high ecological risk” for Cd, and “heavily polluted” for Pb and Cd according to the results of CF, EF, Eri, Igeo, respectively. The rest of the stations were in the low or moderate contamination through the all seasons as assessed by different eco-geochemical risk assessment indices. The integrated risk evaluation indices indicated no contamination in stations S3 and S5.

Pharmaceutical active compounds in a heavily industrialized and urbanized bay, Eastern China.

Bays are transition zones connecting freshwater ecosystems and marine ecosystems, and they are strongly influenced by intensive human activities. Pharmaceuticals are of concern in bay aquatic environments because of their potential threat to marine food web. We studied the occurrence, spatial distribution, and ecological risks of 34 pharmaceutical active compounds (PhACs) in Xiangshan Bay, a heavily industrialized and urbanized area in Zhejiang Province, Eastern China. PhACs were ubiquitously detected in the coastal waters of the study area. A total of twenty-nine compounds were detected in at least one sample. Carbamazepine, lincomycin, diltiazem, propranolol, venlafaxine, anhydro erythromycin, and ofloxacin had the highest detection rate (≥ 93%). These compounds were detected with maximum concentrations of 31, 127, 0.52, 1.96, 2.98, 75, and 98ng/L, respectively. Human pollution activities included marine aquacultural discharge and effluents from the local sewage treatment plants. These activities were the most influential sources in this study area based on principal component analysis. Lincomycin was an indicator of veterinary pollution of coastal aquatic environment, and the concentrations of lincomycin were positively related to the total phosphorus in this area (r = 0.28, p < 0.05). Typical PhACs such as venlafaxine, ofloxacin, norfloxacin, roxithromycin, and clarithromycin were significantly and positively correlated with nitrate and total nitrogen (r > 0.26, p < 0.05) based on Pearson's correlation analysis. Carbamazepine was negatively correlated with salinity (r < - 0.30, p < 0.01). Land use pattern was also correlated with the occurrence and distribution of PhACs in the Xiangshan Bay. Some PhACs, i.e., ofloxacin, ciprofloxacin, carbamazepine, and amitriptyline posed medium to highecological risks to this coastal environment. The results of this study could be helpful to understand the levels of pharmaceuticals, potential sources, and ecological risks in marine aquacultural environment.

Improving the efficiency of machine learning in simulating sedimentary heavy metal contamination by coupling preposing feature selection methods

Sediment cores were collected from Taihu Lake in China. The chronology was determined by radionuclide. Heavy metals and magnetic properties of each core slice were assessed, respectively. The concentrations of most heavy metals in sediments surged at 20 cm from the surface, accompanying the increase in the concentrations of single-domain magnetic particles. This may be resulted from the influence of anthropic activities on the lake's environment after the 1970s. Two feature selection methods, random forest (RF) and maximal information coefficient (MIC), were combined with support vector machine (SVM) model to simulate heavy metals, with the inclusion of selected magnetic and physicochemical parameters. Compared with the modeling results obtained with the full set of parameters, a reasonable simulation performance was obtained with RF and MIC. RF performed better than MIC by increasing the R2 of simulation models for Cd, Cr, Cu, Pb, and Sb. For heavy metals with high ecological risks (As, Cd, Cr, Hg, Pb, Sb), the correlation coefficients for observed and predicted data ranged from 0.73 to 0.97 with only 14–27% of the parameters selected by RF as input variables. The RF-RBF-SVM enabled heavy metal predictions based on the magnetic properties of the lake sediments.

In situ investigation of N deposit effects on polycyclic aromatic hydrocarbons (PAHs) photolysis in snow

As snow is an ideal scavenger of polycyclic aromatic hydrocarbons (PAHs) for both particulate- and gas-phase PAHs, a large amount of PAHs are accumulated in snowpacks. These PAHs could be released from seasonal snowpacks into environment over a short time during the snow melting period, causing a flush of contaminants. Understanding the fate of PAHs in snow therefore is important to evaluate the contaminant flush during snow melting. However, as an important natural process, PAH photolysis in snow is still unclear, especially in the context of global climate change. Therefore, photolysis of the 16 PAHs, which are listed as priority controlled pollutants by United States Environmental Protection Agency (US EPA), was investigated with N deposit in field in snow in this study. A mixture of the 16 US EPA priority PAHs and nitrate/ammonia were spiked into sealed quartzose bottles containing snow samples in field. The bottles were then exposed to solar radiation in field for 6 h. Experimental results showed that >50% of PAHs were lost during 6 h photolysis, mostly occurred in the first hour. Generally, HMW PAHs were photolyzed faster than LMW PAHs, though the photolysis rate did not strictly increase with molecular weight. Low concentrations of nitrate can enhance photolysis of Ant and Pyr, while photolysis of investigated PAHs was inhibited with nitrate concentration increasing. In contrast, both low and high concentration of ammonium can inhibit PAH photolysis. The inhibiting effect of both nitrate and ammonia on photolysis of HMW PAH is stronger than that of LMW PAHs, indicating direct photolysis of PAHs is the main pathway of PAH degradation in snow in situ. This study firstly showed the effect of N deposition on PAH photolysis in snow. Under current increasing N deposition in northeast China, this study implied that more PAHs in snow could be preserved during winter and released shortly during snowmelt, resulting in high ecological risk in spring.