Associations of urinary volatile organic compounds with cardiovascular disease among the general adult population.

This study was to estimate the associations of volatile organic compounds (VOCs) exposure with the prevalence of total and specific cardiovascular disease (CVD) among the general adult population. This cross-sectional study analyzed 15 urinary VOC metabolites in the general population using the 2011-2016 National Health and Nutrition Examination Survey (n = 5,213). The weighted study population with 47.0 years median age, was primarily female (51.2%). The prevalence of total CVD in the overall population was 7.9%. The single-exposure analyzes of AAMA, ATCA, CEMA, CYMA, DHBMA, 3HPMA, and 3MHA +4MHA were significantly associated with increased prevalence of total CVD. Qgcomp regression consistently showed that urinary VOCs-mixed exposure was positively correlated with the prevalence of total and specific CVDs (chronic heart failure, angina, and stroke), and highlighted each VOCs metabolite weights and direction. The similar results were observed for the WQS regression using mixed analysis methods. In conclusion, exposure to VOCs increases CVD prevalence and advances the identification of risk factors for CVD for environmental study.

Nontarget screening analysis of organic compounds in river sediments: a case study in the Taipu River of the Yangtze River Delta Region in China.

Sediments are the vital fate of organic compounds, and the recognition of organic compounds in sediments is constructive in providing comprehensive and long-term information. In this study, a three-step nontarget screening (NTS) analysis workflow using comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) revealed the extensive existence of organic compounds in the Taipu River sediment. Organic compounds (705) were detected and divided into four structure-related groups or eight use-related classes. In the Taipu River's mainstream, a significant difference was found in the composition profiles of the identified organic compounds among various sites, demonstrating the organic compounds were more abundant in the midstream and downstream than in the upstream. Meanwhile, the hydrodynamic force was recognized as a potential factor influencing organic compounds' occurrence. Based on multiple statistical analyses, the shipping and textile printing industries were considered the significant contributors to the identified organic compounds. Considering the principles of the priority substances and the current status of the substances, two traditional pollutants and ten emerging organic compounds were recognized as the priority organic compounds for the Taipu River. Conclusively, this study established a workflow for NTS analysis of sediment samples and demonstrated the necessity of NTS analysis to evaluate the impact of terrestrial emissions of organic compounds on the aquatic environment.

Improved Method of Background Value Determination for Sb and Cd in Freshwater Sediment-Insights from Controlling Factors on Spatial Variability.

Variability in the distribution of natural total Sb and Cd in freshwater sediments leads to difficulties in background value (BV) determination. This study aimed to establish a method to determine BV more accurately by investigating the vertical distribution of Sb and Cd in sediment cores collected from a typical river in alluvial plain in China and revealed the factors that control the variation of Sb and Cd BV, which has not been studied in alluvial freshwater sediment. The results suggested that uncontaminated samples for BV calculation should be determined by statistical analysis as human and natural disturbance led to high variation in contamination depth, from <5 cm to >55 cm. The sequential chemical extraction method showed a considerable amount of non-residual fractions of Sb and Cd, which accounted for 48% and 43% of the total, respectively. Acid extractable Cd (16%) was associated to the limestone geology in the area. Fine particles which governed by sedimentary environment contained more natural Sb and Cd, as strong positive correlation was found between clay content and Sb concentration (r = 0.89, p < 0.01), as well as Cd concentration (r = 0.54, p < 0.01). Based on these findings, a method combined with standard deviation and geochemical method was established to calculate the BV of Sb and Cd, and counter maps were made to cover the variation of BV in the Taipu river sediment. The pollution level has been evaluated by the geoaccumulation index more accurately.

Impact of Textile Industries on Surface Water Contamination by Sb and Other Potential Toxic Elements: A Case Study in Taihu Lake Basin, China.

Contamination of industry-derived antimony (Sb) is currently of great concern. This study was conducted to identify the source of Sb together with other potential toxic elements (PTEs) in a typical industrial area in China and emphasize the contribution of Sb to ecological risk in the local aquatic environment. By investigating the distribution of nine PTEs in surface water in Wujiang County in dry and wet seasons, this study revealed that textile wastewater was the main source of Sb. The distribution of Sb (0.48~21.4 µg/L) showed the least seasonal variation among the nine elements. Factor analysis revealed that the factor that controlled Sb distribution is unique. In general, Sb was more concentrated in the southeastern part of the study area where there was a large number of textile industries, and was affected by the specific conductivity and total dissolved solids in water (p < 0.01). Sb concentration in 35.71% of samples collected from the drainage outlet exceeded the standard limit of 10 µg/L. Results from three pollution assessment methods suggested that >5% of the sampling sites were slightly too heavily polluted and Sb contributed the most. Therefore, it is necessary to strengthen the administrative supervision of local textile enterprises and elevate the local standard of textile wastewater emission.

Co-Effects of Hydrological Conditions and Industrial Activities on the Distribution of Heavy Metal Pollution in Taipu River, China.

In Taipu River, after being transformed from a drainage channel to a drinking water supply river in 1995, heavy metals that have accumulated in sediments have become an environmental issue. Herein, we collected sediments of Taipu River in 2018, 2020, and 2021 and analyzed the distribution of Sb, As, Cd, Cu, Pb, Cr, and Zn to identify their sources. The results revealed that the mean concentrations of heavy metals were above the background values, except for Cr and As. During the non-flood season, the midstream of Taipu River becomes a heavy metal hotspot, with their concentrations 2-5 times higher than those in upstream sediment. There were significant correlations (r = 0.79-0.99) among drainage, precipitation and flow rate, which indicated that drainage caused by both the opening of Taipu Gate and precipitation control the flow rate and, then, possibly influenced the distribution of heavy metals. Moreover, three sources (industrial sources, particle deposition sources, and natural sources) were characterized as the determinants for the accumulation of heavy metal by the Positive Matrix Factorization model, with the contribution rates of 41.7%, 32.9%, and 25.4%, respectively. It is recommended that the influence of hydrological conditions and industrial activities should be a key consideration when developing regulations for the management of heavy metals in rivers.

Monte Carlo study of TG-43 dosimetry parameters of GammaMed Plus high dose rate 192 Ir brachytherapy source using TOPAS.

PURPOSE: To develop a simulation model for GammaMed Plus high dose rate 192 Ir brachytherapy source in TOPAS Monte Carlo software and validate it by calculating the TG-43 dosimetry parameters and comparing them with published data. METHODS: We built a model for GammaMed Plus high dose rate brachytherapy source in TOPAS. The TG-43 dosimetry parameters including air-kerma strength SK , dose-rate constant Λ, radial dose function gL (r), and 2D anisotropy function F(r,θ) were calculated using Monte Carlo simulation with Geant4 physics models and NNDC 192 Ir spectrum. Calculations using an old 192 Ir spectrum were also carried out to evaluate the impact of incident spectrum and cross sections. The results were compared with published data. RESULTS: For calculations using the NNDC spectrum, the air-kerma strength per unit source activity SK /A and Λ were 1.0139 × 10-7 U/Bq and 1.1101 cGy.h-1 .U-1 , which were 3.56% higher and 0.62% lower than the reference values, respectively. The gL (r) agreed with reference values within 1% for radial distances from 2 mm to 20 cm. For radial distances of 1, 3, 5, and 10 cm, the agreements between F(r,θ) from this work and the reference data were within 1.5% for 15° < Î¸ < 165°, and within 4% for all θ values. The discrepancies were attributed to the updated source spectrum and cross sections. They caused deviations of the SK /A of 2.90% and 0.64%, respectively. As for gL (r), they caused average deviations of -0.22% and 0.48%, respectively. Their impact on F(r,θ) was not quantified for the relatively high statistical uncertainties, but basically they did not result in significant discrepancies. CONCLUSION: A model for GammaMed Plus high dose rate 192 Ir brachytherapy source was developed in TOPAS and validated following TG-43 protocols, which can be used for future studies. The impact of updated incident spectrum and cross sections on the dosimetry parameters was quantified.

ETS Proto-Oncogene 1 Suppresses MicroRNA-128 Transcription to Promote Osteogenic Differentiation Through the HOXA13/ß-Catenin Axis.

ETS proto-oncogene 1 (ETS1) has been implicated in osteoporosis (OP), but the exact molecular mechanisms are complex. This work focuses on the impact of ETS1 on the osteogenic differentiation and the molecules involved. A mouse pre-osteoblast cell line MC3T3-E1 was used for in vitro experiments. ETS1 was upregulated during the process of osteogenic differentiation of MC3T3-E1 cells. Overexpression of ETS1 promoted expression of osteogenic markers, alkaline phosphate concentration, and calcareous accumulation in cells. ETS1 was found to specifically bind to miR-128 promoter to suppress its transcription, while miR-128 could target homeobox A13 (HOXA13). Therefore, ETS1 suppressed miR-128 transcription to upregulate HOXA13 expression. Overexpression of HOXA13 promoted the osteogenic differentiation ability of cells and increased the protein level of ß-catenin. Either overexpression of miR-128 or downregulation of ß-catenin by CWP232228, a ß-catenin-specific antagonist, blocked the promoting roles of ETS1 in cells. To conclude, this study provided evidence that ETS1 suppresses miR-128 transcription to activate the following HOXA13/ß-catenin axis, therefore promoting osteogenic differentiation ability of MC3T3-E1 cells. This finding may offer novel ideas for OP treatment.

Ecological risk assessment of trace metals in sediments under reducing conditions based on isotopically exchangeable pool.

Determination of potential mobility of toxic trace metals in sediments under changing redox condition is important in ecological risk assessment. Current methods are limited in risk prediction in such dynamic environment. In this study, we have discussed the general disagreement from widely used methods (sediment quality guideline (SQGs), potential ecological risk index (PERI), risk assessment code (RAC) using BCR fraction information). In addition, the stable isotopic dilution method (IDM) was also modified to quantify metal lability in a microcosm experiment mimicking river bank sediment turning into anaerobic. The isotopically exchangeable Cd, Cu, Pb, and Zn quantified by IDM (%E incub) was used in the RAC to reveal the trend of risk during this process. Strong risks from Cd are suggested by the PERI and RAC as a result of high toxicity and mobility of the element, while SQGs suggests medium risk for Cu, Pb, and Zn in certain samples. The disagreement between the results of RAC assessed by metal lability (%E dry) and by BCR metal fractionation reflects the effect of sediment properties and source of metal contamination. The RAC based on the non-residual fractions is likely to overestimate the potential risk for most metals even there is a significant change in sediment Eh. The RAC assessed by %E incub reveals that the variability in risk in response to the reducing Eh is not consistent. Large fluctuation in %E incub for Cd (28.5%, 49.5%), Pb (27.6%, 18.2%), and Cu (14.4%, 24.7%) can shift the risks to a higher level in certain range of Eh in two sediments. In sediment with lower contents of metal binding phases (e.g. mineral oxides, organic matters), the release of metals can be more significant, thus higher ecological risk in changing redox condition.

The rainfall effect onto solidification and stabilization of heavy metal-polluted sediments.

Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient (De ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient (De ) for Cu was 1.28 × 101 cm2 s-1, indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients (Di ) for Cd, Cu and Pb were 7.44 × 10-11, 8.18 × 10-12 and 7.85 × 10-12 cm2 s-1, respectively, indicating their relatively low mobility of heavy metal in S/S sediments.

A multi-criteria evaluation system for arable land resource assessment.

This study proposed a multi-criteria evaluation system for arable land resources by combining the soil integrated fertility index (IFI) with a soil cleanliness index (based on heavy metals and metalloid content). A total of 16 typical arable land units in Chongming District, China, were evaluated using the proposed evaluation system based on 104 collected soil samples in 16 towns. The comprehensive soil evaluation scores of arable lands in 16 towns were in the range of 90.7 to 99.2 with a mean of 96.2, indicating that the arable land in all 16 towns was at the level of excellent (≥ 90.0). Lower cleanliness indices had a significant impact on the final evaluation score. In comparison with single-index evaluation systems (i.e., the IFI or soil cleanliness index), the proposed multi-criteria system better reflects the quality of the soil. In the practice of arable land requisition and subsidy policy, the proposed multi-criteria evaluation system not only encourages farmers to preserve arable lands during farming but also helps agricultural authorities make effective and reliable management decisions.

The source apportionment, pollution characteristic and mobility of Sb in roadside soils affected by traffic and industrial activities.

Antimony (Sb), as an emerging pollutant, has aroused people's concerns for its wide usage in industrial production. In this study, we identify and quantify the traffic-derived Sb and investigate its mobility in roadside soils affected by traffic and industrial activities. 73 surface roadside soils and 5 transects in three areas nearby different industries (smelting, power and refining, and waste incineration) were collected and analyzed. Results showed that the Sb concentration ranged between 0.54 and 9.32 mg/kg, and the mean EFs value was 4.63, which indicated moderate to significant Sb enrichment. Significantly high concentrations of Sb occurred at locations with heavy traffic and frequent braking process, with an average concentration of 4.13 mg/kg, compared to the control sites (2.01 mg/kg). Moreover, Sb diffused exponentially with increasing distance from road edges. These results suggested that traffic activities were the main source of Sb in roadside soils. According to the quantitative calculation, the average contributions from traffic, industrial activities and soil parent material to Sb accumulation in roadside soils were 50.73%, 21.38% and 27.88%, respectively. Even though Sb was slightly mobile, roadside soils was a persistent source of potentially mobile Sb which may release into water and cause long-term environmental risk.

Factors controlling the accumulation and ecological risk of trace metal(loid)s in river sediments in agricultural field.

There is an increasing concern of ecological risk from toxic trace metals in sediments to aquatic environment in agricultural field. However, the knowledge of factors that control the accumulation and risk of trace metals in such environment is limited. In this study, we conducted source apportionment of 9 trace metal(loid)s in river sediments on Chongming Islands, China, where there had been >120 years of agricultural practice. The influence from sediment properties on metal accumulation and mobility were also discussed. The results indicate that anthropogenic metal input generally elevated Cd, Sb, Pb and Zn concentrations as their average values were 3.3, 2.6, 1.6 and 1.6 times of the background respectively. Significantly high As (max = 28.2 mg/kg) and Cu (max = 145.6 mg/kg) were also found in some individual sites. Positive matrix factorization analysis suggests that atmospheric deposition contributed 53.5% and 54.7% of the total Sb and Pb respectively, while most anthropogenic Cd, Cu, As and Zn was agriculture-derived. Amorphous Fe, Mn and Al oxides and organic matter were the most important binding phases which favour trace metal accumulation. Fractionation information from BCR sequential extraction suggests high potential mobility of Cd (>37% in acid extractable fraction). Fe/Mn oxides bound As, Cd, Cu, Pb and Zn (reducible fraction), which comprised 15-26% of the total, increased the ecological risk in anoxic sediments. The potential ecological risk index and risk assessment code identified more than 74% of the sampling sites as high to extremely high ecological risk because of the high toxicity and mobility of Cd.

Urgent caution to trace organometal pollution: Occurrence, distribution and sources of methyltins, butyltins and phenyltins in sediments from South Hangzhou Bay, China.

The concentrations of seven organotin compounds (OTCs) were determined seasonally in 22 sediment samples (brackish, freshwater and shrimp pond sediments) in South Hangzhou Bay, China. For the brackish and freshwater sediments, methyltins of up to 43.0 ng Sn g-1 dw showed no significant variation with seasons or locations (p > 0.05). However, butyltin levels in summer (44.0 ±â€¯30.2 ng Sn g-1 dw) were about two folds higher than those in spring (20.4 ±â€¯18.7 ng Sn g-1 dw) and four folds higher than in autumn or winter (both≈10 ng Sn g-1 dw), which is mainly attributed to the heavy contamination near the shipyard, mariculture and textile plants in summer. Phenyltins in spring reached the peak level of 28.4 ng Sn g-1 dw, about three times of other seasons. Meanwhile, there was a significant variation of phenyltins in summer with high-value sites also in the vicinity of mariculture. Thus, excepting the contribution of agricultural activities to phenyltins, mariculture is likely to be a potential source of butyltins and phenyltins into the marine environment (particularly in summer). This hypothesis has been partly validated by determining adjacent shrimp pond sediments, which showed ubiquitous contamination of butyltins and phenyltins in summer and spring (14.2-44.2 ng Sn g-1 dw and 2.2-16.9 ng Sn g-1 dw), but only one sample had the detectable methyltin levels with 8.8 ng Sn g-1 dw of momomethyl-tin. On the other hand, seven OTCs showed a stronger affinity to brackish sediments than the adjacent freshwater sediments, probably owing to the differences of physicochemical parameters and microbial activities in sediments. Overall, OTC contaminants have become more diversified and complicated in coastal zones, suggesting that future studies should pay attention to other OTC species like phenyltins and methyltins, not only the butyltins.

Enrichment assessment of Sb and trace metals in sediments with significant variability of background concentration in detailed scale.

Variability of background concentration of toxic trace metal(loid)s in sediments can often lead to under/over-report of contamination level, even in detailed scale. In this study, both surface (5-10 cm) and subsurface (> 10 cm) sediments were collected at many sites in a small lake (0.528 km2) with multi-function (irrigation, aquaculture, and watercourse) in an industrial area. Total concentration of trace metal(loid)s (Cd, Cr, Co, Cu, Ni, Sb, Pb, and Zn) and potential reference elements (Ti, Zr, Rb, and Li) were analyzed. The results showed that although the trace metal(loid)s were mainly lithogenic in subsurface sediments, the variability of baseline concentration was significant. For Sb, this variability was a result of alteration in hydrological parameters as well as sediment properties including Fe/Mn oxide contents, particle size distribution, and organic matter contents. Comparison of the normalized Sb concentration in samples from two sediment cores indicated that Ti is the best reference element for normalizing Sb to reduce the impact from particle size and natural source. Enrichment assessment using modified EFs (Ti as reference element) and Igeo index (measured baseline concentration) suggested that about 70% of the surface sediments were at least moderately polluted by Sb in the lake, as a result of recent anthropogenic input, mainly from nearby industries, e.g., concrete factory and textile factory. Modified EFs should be used, instead of Igeo index, when Sb enrichment was relatively low in sediment. The anomalies of Sb background concentration may need regulator attention when assessing the level of sediment contamination.

Enrichment and sources of trace metals in roadside soils in Shanghai, China: A case study of two urban/rural roads.

The road traffic has become one of the main sources of urban pollution and could directly affect roadside soils. To understand the level of contamination and potential sources of trace metals in roadside soils of Shanghai, 10 trace metals (Sb, Cr, Co, Ni, Cu, Cd, Pb, Hg, Mn and Zn) from two urban/rural roads (Hutai Road and Wunign-Caoan Road) were analyzed in this study. Antimony, Ni, Cu, Cd, Pb, Hg and Zn concentrations were higher than that of soil background values of Shanghai, whereas accumulation of Cr, Co and Mn were minimal. Significantly higher Sb, Cd, Pb contents were found in samples from urban areas than those from suburban area, suggesting the impact from urbanization. The concentrations of Sb and Cd in older road (Hutai) were higher than that in younger road (Wunign-Caoan). Multivariate statistical analysis revealed that Sb, Cu, Cd, Pb and Zn were mainly controlled by traffic activities (e.g. brake wear, tire wear, automobile exhaust) with high contamination levels found near traffic-intensive areas; Cr, Co, Ni and Mn derived primarily from soil parent materials; Hg was related to industrial activities. Besides, the enrichment of Sb, Cd, Cu, Pb and Zn showed a decreasing trend with distance to the road edges. According to the enrichment factors (EFs), 78.5% of Sb, Cu, Cd, Pb and Zn were in moderate or significant pollution, indicating considerable traffic contribution. In particular, recently introduced in automotive technology, accumulation of Sb has been recognized in 42.9% samples of both roads. The accumulation of these traffic-derived metals causes potential negative impact to human health and ecological environment and should be concerned, especially the emerging trace elements like Sb.

Distribution and risk assessment of trace metals in sediments from Yangtze River estuary and Hangzhou Bay, China.

The Yangtze River estuary (YRE) and Hangzhou Bay (HZB) is of environmental significance because of the negative impact from industrial activities and rapid development of aquaculture on the south bank of HZB (SHZB) in recent years. This study investigated the distribution and risk assessments of trace metals (Cr, Cu, Zn, Hg, Pb, and Cd) accumulated in surface sediments by sampling in YRE, outer and south HZB. Copper and Zn concentration (avg. 35.4 and 98.7 mg kg-1, respectively) in surface sediments were generally higher than the background suggesting a widespread of Cu and Zn in the coastal area of Yangtze River Delta. High concentrations of Cu (~ 42 mg kg-1), Zn (~ 111 mg kg-1), Cd (~ 0.27 mg kg-1), and Hg (~ 0.047 mg kg-1) were found in inner estuary of YRE and decreased offshore as a result of terrestrial input and dilution effect of total metal contents by "cleaner" sediments from the adjacent sea. In outer HZB, accumulation of terrestrial derived metal has taken place near the Zhoushan Islands. Increase in sediment metal concentration from the west (inner) to the east (outer) of SHZB gave rise to the input of fine-grained sediments contaminated with metals from outer bay. According the results from geoaccumulation index, nearly 75% of samples from YRE were moderately polluted (1.0 < I geo < 2.0) by Cd. Cadmium and Hg contributed for 80~90% to the potential ecological risk index in the YRE and HZB, with ~ 72% sites in HZB under moderate risk (150 ≤ RI < 300) especially near Zhoushan Islands.

Source-oriented variation in trace metal distribution and fractionation in sediments from developing aquaculture area-A case study in south Hangzhou bay, China.

Elevation in toxic trace metal concentration found in coastal sediments in recent years (2013-2016) increased the risk to the aquaculture industry in south Hangzhou bay. This study assessed the main factors controlling the metal distribution and mobility in sediments by sampling from 20 sites along the bank. Spatial distribution and cluster analysis indicated that Cd, As, Hg and Sb attributed to anthropogenic terrestrial sources; while Cr, Co, Cu, Ni, Zn, and Pb, carried by fine-grained sediments and accumulated on tidal flat, were inputted from marine sources. High mobility of Cd was expected because of its considerable proportion (~50%) associated with the acid extractable fraction. Pb, Cu and Co in redox sensitive fraction should also be taken into concern in management of reclaimed area affected by tide. Risk assessments by potential ecological risk index (PERI) emphasised the importance of further monitor and proper treatment of 4 terrestrial generated metals in sediments.

Comparative analysis of water quality and toxicity assessment methods for urban highway runoff.

In this study, comparative analyses of highway runoff samples obtained from seventeen storm events have been conducted between the traditional water quality assessment method and biotoxicity tests, using zebrafish (Danio rerio) embryos and luminous bacteria (Vibrio qinghaiensis. Q67) to provide useful information for ecotoxicity assessment of urban highway runoff. The study results showed that the Nemerow pollution index based on US EPA recommended Criteria Maximum Concentrations (CMC) (as traditional water quality assessment method) had no significant correlation with luminous bacteria acute toxicity test results, while significant correlation has been observed with two indicators of 72 hpf (hours post fertilization) hour hatching rate and 96 hpf abnormality rate from the toxicity test with zebrafish embryos. It is therefore concluded that the level of mixture toxicity of highway runoff could not be adequately measured by the Nemerow assessment method. Moreover, the key pollutants identified from the water quality assessment and from the biotoxicity evaluation were not consistent. For biotoxic effect evaluation of highway runoff, three indexes were found to be sensitive, i.e. 24 hpf lethality and 96 hpf abnormality of zebrafish embryos, as well as the inhibition rate for luminous bacteria Q67. It is therefore recommended that these indexes could be incorporated into the traditional Nemerow method to provide a more reasonable evaluation of the highway runoff quality and ecotoxicity.

Effects of dissolved organic matter from a eutrophic lake on the freely dissolved concentrations of emerging organic contaminants.

The authors studied the effects of dissolved organic matter (DOM) on the bioavailability of bisphenol A (BPA) and chloramphenicol by measuring the freely dissolved concentrations of the contaminants in solutions containing DOM that had been isolated from a mesocosm in a eutrophic lake. The abundance and aromaticity of the chromophoric DOM increased over the 25-d mesocosm experiment. The BPA freely dissolved concentration was 72.3% lower and the chloramphenicol freely dissolved concentration was 56.2% lower using DOM collected on day 25 than using DOM collected on day 1 of the mesocosm experiment. The freely dissolved concentrations negatively correlated with the ultraviolent absorption coefficient at 254 nm and positively correlated with the spectral slope of chromophoric DOM, suggesting that the bioavailability of these emerging organic contaminants depends on the characteristics of the DOM present. The DOM-water partition coefficients (log KOC ) for the emerging organic contaminants positively correlated with the aromaticity of the DOM, measured as humic acid-like fluorescent components C1 (excitation/emission=250[313]/412 nm) and C2 (excitation/emission=268[379]/456 nm). The authors conclude that the bioavailability of emerging organic contaminants in eutrophic lakes can be affected by changes in the DOM.

[Temporal and spatial distribution of environmental factors and chlorophyll-a and their correlation analysis in a small enclosed lake].

About four year's field observation was conducted from July 2007 to September 2011, in a small enclosed eutrophic lake located in Qianwei Village, Chongming Island. The temporal and spatial distribution of environmental factors (including physical-chemical factors and hydrodynamic condition) and chlorophyll-a (Chl-a) were studied and their correlation was analyzed. Results indicated that there were significant differences in the spatial and temporal distribution of Chl-a in the lake. Significantly positive correlation was found between Chl-a and water temperature, turbidity, TN and TP. Water temperature and nutrients were the main limited factors of seasonal changes of phytoplankton. It could be the result of phytoplankton growth that caused the seasonal change of turbidity. It was found that hydrological changes were the primary factor affecting the spatial difference of Chl-a concentration. Lower average Chl-a concentration (35. 30 microg.L-1) was recorded in the north watercourse, in condition with higher wind driven flow velocity ranging from 0. 08 m.s- 1 to 0. 22 m.s -1. A strong negative correlation was found between Chl-a concentration and flow velocity. Higher average Chl-a concentration (53. 11 microg.L-1) was frequently found under flow conditions ranged from 0 m.s-1 to 0. 10 m.s-1. These findings indicated that increasing hydrodynamic condition would significantly inhibit the growth of phytoplankton and reduce the risk of algae blooming in summer in these eutrophic water bodies.