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Effects of root exudates on the activation and remediation of cadmium ion in contaminated soils Full text
2020
Chen, Cheng | Li, Zhongbao | Li, Shengjin | Deng, Nanxin | Mei, Ping
To screen out plants with hyperaccumulation of heavy metals and explore the effects of root exudates on the phytoremediation in contaminated soils. The germination rates of five plants including Lolium perenne L. (L. perenne), Sorghum sudanense (Piper) Stapf. (S. sudanense), Pennisetum alopecuroides (L.) Spreng. (P. alopecuroides), Medicago sativa L. (M. sativa), and Trifolium repens L. (T. repens) in different concentrations of cadmium ion solution (0–100 mg/kg) were determined. The growth adaptability of these five plants under conditions of contaminated soils with the above cadmium ion concentrations was also evaluated. S. sudanense and P. alopecuroides had higher germination rates and better growth than the three other plants and were selected as the latter experimental varieties. The activation amounts of cadmium ion in soils were measured using AAS in the presence of three types of root secretions (citric acid, glycine, and maltose) with different concentrations (10–500 mmol/L). The activation amounts decrease in the following order: citric acid > glycine > maltose. The effect of these three root exudates on the removal of cadmium-contaminated soils in combination with S. sudanense and P. alopecuroides was also tested. For S. sudanense and P. alopecuroides, the maximum biomass and removal rate reaches the maximum at 100 mmol/L of citric acid. Conversely, low concentrations (approximately 10–50 mmol/L) of glycine and maltose are more effective for plant growth and phytoremediation. The addition of citric acid at 100 mmol/L and approximately 10–50 mmol/L of glycine and maltose can effectively promote the transfer of cadmium ion from roots to leaves and the accumulation of cadmium ion in leaves.
Show more [+] Less [-]The effects of climate change and groundwater exploitation on the spatial and temporal variations of heavy metal content in maize in the Luan River catchment of China Full text
2020
Ma, Rong | Zhang, Bin | Zhou, Xiaoni
The effects of climate change and anthropogenic activities on the concentration of heavy metal in maize were quantitatively characterized in this study to help us better understand the complex interactions among the groundwater, vadose, plant, and atmosphere layers in the critical zone. We hypothesized that climate change and groundwater resource exploitation firstly affected the shallow groundwater level, and then the groundwater table fluctuation (GTF) impacted the concentration of heavy metal in maize through the critical zone (CZ) structure and parameters. To test our hypothesis, we collected 960 soil and 288 maize samples from the Luan River catchment in the North China Plain. The Groundwater Modeling System software was used to describe the effects of precipitation and groundwater resource exploitation on the groundwater table, and then, the structural equation method was employed to characterize the quantitative effects of GTF, precipitation, and air temperature on the concentration of heavy metal in maize. The results indicate that the influence coefficients of the effects of climate change and anthropogenic activities on the concentrations of Fe, Mn, Cr As, Pb, and Sr were 0.1595, 0.088, 0.0042, − 0.0092, 0.2219, and 0.0493 in the north plain, respectively, and 0.0256, 0.0151, 0.0816, − 0.2264, 0.1125, and − 0.0106 in the south plain of the study region, respectively. Since the human health risks of metals were mainly attributed to Fe, Mn, and Cr in the Luan River catchment, increasing the groundwater resource exploitation volume is an effective way to decrease the Fe, Mn, and Cr contents in maize by decreasing the shallow groundwater table.
Show more [+] Less [-]Association between ambient temperature and daily emergency hospitalizations for acute coronary syndrome in Yancheng, China Full text
2020
Guo, Shumei | Niu, Yue | Cheng, Yuexin | Chen, Renjie | Kan, Julia | Kan, Haidong | Li, Xu | Li, Jiading | Cao, Jingyan
Acute coronary syndrome (ACS) is a major public health concern worldwide. Few studies have directly evaluated the associations between ambient temperature and ACS incidence. To explore the association between ambient temperature and ACS emergency hospitalizations in the area of subtropical monsoon climate, data on ACS emergency hospitalizations were collected from two highest-ranking hospitals in the central urban area of Yancheng, China, from January 1, 2013, to December 31, 2018. We applied the time-series method to investigate the potentially lagged and non-linear effects of ambient temperature on ACS using the generalized linear model combined with the distributed lag non-linear model after adjusting for time trend, day of the week, holiday, and relative humidity. We identified a total of 5303 cases of ACS emergency hospitalizations during the study period. The exposure-response curves between ambient temperature and ACS hospitalizations were inverse “J-shaped.” The effects of extreme low temperature on ACS hospitalizations occurred on the present day and lasted for 3 days, followed by the harvesting effect. The effects of extreme high temperature occurred on the present day and lasted for 5 days. The cumulative relative risks of ACS were 2.14 [95% confident interval (CI): 1.32 to 3.47] for extremely low temperature and 1.66 (95% CI: 1.33 to 2.06) for extremely high temperature over the lag of 0–5 days, compared with the reference temperature (25.0 °C). Both low and high temperatures were significantly associated with higher risks of emergency hospital admissions for ACS in Yancheng, China.
Show more [+] Less [-]The use of rice and coffee husks for biosorption of U (total), 241Am, and 137Cs in radioactive liquid organic waste Full text
2020
Ferreira, Rafael Vicente de Pádua | de Araujo, Leandro Goulart | Canevesi, Rafael Luan Sehn | da Silva, Edson Antonio | Ferreira, Eduardo Gurzoni Alvares | Palmieri, Maurício Cesar | Marumo, Júlio Takehiro
Rice and coffee husks (raw and chemically activated) are examined as potential biosorption materials regarding their capacity to remove U (total), ²⁴¹Am, and ¹³⁷Cs. The physical parameters evaluated were the morphological characteristics of the biomass, real and apparent density, and surface area. Contact times for the batch experiments were 0.5, 1, 2, and 4 h, and the concentrations tested ranged between 10% of the total concentration and the radioactive waste itself without any dilution. The results were evaluated by experimental sorption capacity, ternary isotherm, and kinetics models. The kinetics results showed that equilibrium was reached after 2 h for all biomass. Raw coffee husk showed the best adsorption results in terms of maximum capacity (qₘₐₓ) for all three radionuclides, which were 1.96, 39.4 × 10⁻⁶, and 46.6 × 10⁻⁹ mg g⁻¹ for U, Am, and Cs, respectively. The biosorption process for the raw and activated rice husks was best represented by the Langmuir ternary isotherm model with two sites. For the coffee husk, in the raw and activated states, the biosorption process was best described by the modified Jain and Snoeyink ternary model. These results suggest that biosorption with these biomaterials can be applied in the treatment of liquid organic radioactive waste containing mainly uranium and americium.
Show more [+] Less [-]Heavy metals and persistent organic pollutants contamination in river, estuary, and marine sediments from Atlantic Coast of Democratic Republic of the Congo Full text
2020
Suami, Robert Bueya | Sivalingam, Periyasamy | Al Salah, Dhafer Mohammed | Grandjean, Dominique | Mulaji, Crispin Kyela | Mpiana, Pius Tshimankinda | Breider, Florian | Otamonga, Jean-Paul | Poté, John
The pollution assessment and the evaluation of potential risks in the Atlantic Coastal Region of the Democratic Republic of the Congo are still very limited. Consequently, the present study investigates for the first time the concentrations of heavy metals and persistent organic pollutants (organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs)) in river, estuary, and marine sediments from this area. The results highlighted high concentrations of Cr, Zn, As, and Pb exceeding the probable effect level (PEL) on aquatic life. Zn was the most dominant element detected at a range of 180–480 mg kg⁻¹ in marine sediment, 132–382 mg kg⁻¹ in estuary sediment, and 121–687 mg kg⁻¹ in river sediment. Total PCBs (∑7 × 4.3) ranged from 1995 to 20,156 μg kg⁻¹, 2013–12,058 μg kg⁻¹, and 1861–36,417 μg kg⁻¹ in marine, estuary, and river sediments, respectively. Total PCBs (∑7 × 4.3) were above PEL for all sediments, suggesting potential adverse effects on benthic organisms. The OCP, PBDE, and PAH levels were low to moderate for all sediments. Taking into consideration, the concentrations of Zn, Pb, PCBs, and DDTs, probable environmental risks, are present.
Show more [+] Less [-]Economic losses and willingness to pay for haze: the data analysis based on 1123 residential families in Jiangsu province, China Full text
2020
Wu, Xianhua | Guo, Ji | Wei, Guo | Zou, Yi
Haze pollution is a key obstacle for environmental management faced by China and many other developing countries. The survey on residential families’ economic losses and willingness to pay (WTP) are regarded as an essential reference for the implementation of environmental policies for haze treatment. For Jiangsu province of China, the authors of this paper first conducted three qualitative interviews with respectively meteorologists, meteorological administrators, and residents, a questionnaire was then elaborately designed, and subsequent surveys of 1123 families were administered in Jiangsu province. Further, the authors investigated measurements of direct economic losses by using the contingent valuation method (CVM) and explored influential factors of WTP by utilizing the binary logistic regression. From this survey, the estimated total economic loss incurred by haze disasters and total treatment cost for haze-related diseases were respectively 22.38 billion (in RMB) and 8.4 billion for Jiangsu province. 55.9% of residential families were willing to pay 11.6 billion RMB annually (51.97% of total loss) for haze treatment, leaving a shortage of 11.05 billion RMB, which the government is responsible to pay. These findings provide empirical information reflecting the opinions of communities and residential families, useful for the governments and industrial sectors to design environmental policies to meet the requirements of the public and control environmental pollution in an effective way to achieve sustainable development.
Show more [+] Less [-]Efficient photoreduction of Cr(VI) on TiO2/functionalized activated carbon (TiO2/AC-AEMP): improved adsorption of Cr(VI) and induced transfer of electrons Full text
2020
Gao, Zhao | Yang, Hanpei | Fu, Xiaofei | Jin, Qiu | Wu, Qiangshun | Kang, Li | Wu, Junming
Slow and random transfer of pollutants and photo-induced carriers on photocatalysts causes loss of efficiency in photodegradation of contaminants. Enhancing and directing mass transfer of them are considered as two major methods for improving the photodegradation of pollutants over photocatalysts. Here in this work, we focused on the design of a novel photocatalyst which not only accelerated the transfer rate of Cr(VI) and electrons but also provided specific transfer routes for them. By careful characterizations, it is indicated that 2-((2-(2-aminoethylamino)ethylimino)methyl)phenol (AEMP) was covalently attached onto activated carbon (AC), which enhanced Cr(VI) transfer from bulk solution to AC through electrostatic or coordinative interactions. The external mass transfer coefficient (Kf) of Cr(VI) over TiO₂/AC-AEMP was estimated as 1.75 × 10⁻⁶ m s⁻¹, which was ~ 12.79 and ~ 5.96 times that of TiO₂ and TiO₂/AC, respectively. Dense and homogeneous heterojunctions between AC and TiO₂ were acquired synchronically by forming Ti–O–C linkages, which increased traveling of electrons from TiO₂ to AC. Accordingly, Cr(VI) can capture photo-induced electrons on the surface of AC via concrete routes and then be reduced efficiently. The results showed that the photoreduction rate of Cr(VI) on TiO₂/AC-AEMP reached to ~ 92.7%, and the overall photocatalytic activity of this well-designed TiO₂/AC-AEMP has been enhanced significantly by 5.5 times compared to TiO₂/AC. The enhanced photocatalytic activity of TiO₂/AC-AEMP was mainly attributed to an improved synergetic process of mass transfer–induced adsorption–photoreduction by forming specific transfer routes for accelerative motion of Cr(VI) and electrons. This work provides a feasible strategy to improve the photoactivity of photocatalysts for the degradation of pollutants by effective mass transfer. Graphical abstract
Show more [+] Less [-]DNA repair and metabolic gene polymorphisms affect genetic damage due to diesel engine exhaust exposure Full text
2020
León-Mejía, Grethel | Quintana-Sosa, Milton | de Moya Hernandez, Yurina | Rodríguez, Ibeth Luna | Trindade, Cristiano | Romero, Marco Anaya | Luna-Carrascal, Jaime | Ortíz, Ludis Oliveros | Acosta-Hoyos, Antonio | Ruiz-Benitez, Martha | Valencia, Karen Franco | Rohr, Paula | da Silva, Juliana | Henriques, João Antônio Pêgas
Diesel engine exhaust (DEE) is a complex mixture of toxic gases, halogenated aromatic hydrocarbons, alkyl polycyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, benzene derivatives, metals and diesel exhaust particles (DEPs) generated from the incomplete combustion of diesel fuel. Many of the compounds in this mixture can cause oxidative damage to DNA and are considered carcinogenic for humans. Further, chronic DEE exposure increases risks of cardiovascular and pulmonary diseases. Despite these pervasive health risks, there is limited and inconsistent information regarding genetic factors conferring susceptibility or resistance to DEE genotoxicity. The present study evaluated the effects of polymorphisms in two base excision repair (BER) genes (OGG1 Ser326Cys and XRCC1 Arg280His), one homologous recombination (HRR) gene (XRCC3 Thr241Met) and two xenobiotic metabolism genes (GSTM1 and GSTT1) on the genotoxicity profiles among 123 mechanics exposed to workplace DEE. Polymorphisms were determined by PCR-RFLP. In comet assay, individuals with the GSTT1 null genotype demonstrated significantly greater % tail DNA in lymphocytes than those with non-null genotype. In contrast, these null individuals exhibited significantly lower frequencies of binucleated (BN) cells and nuclear buds (NBUDs) in buccal cells than non-null individuals. Heterozygous hOGG1 326 individuals (hOGG1 326 Ser/Cys) exhibited higher buccal cell NBUD frequency than hOGG1 326 Ser/Ser individuals. Individuals carrying the XRCC3 241 Met/Met polymorphism also showed significantly higher buccal cell NBUD frequencies than those carrying the XRCC3 241 Thr/Thr polymorphism. We found a high flow of particulate matter with a diameter of < 2.5 μm (PM₂.₅) in the workplace. The most abundant metals in DEPs were iron, copper, silicon and manganese as detected by transmission electron microscopy–energy-dispersive X-ray spectroscopy (TEM-EDX). Scanning electron microscopy (SEM-EDS) revealed particles with diameters smaller than PM₂.₅, including nanoparticles forming aggregates and agglomerates. Our results demonstrate the genotoxic effects of DEE and the critical influence of genetic susceptibility conferred by DNA repair and metabolic gene polymorphisms that shed light into the understanding of underlying mechanisms.
Show more [+] Less [-]Levels and distribution of polychlorinated biphenyls in two edible fish species from Izmir Bay (eastern Aegean): a health risk assessment Full text
2020
Yurdakul, Onur | Kucuksezgin, Filiz
The concentrations of polychlorinated biphenyl (PCB) congeners were examined in two fish species from the Izmir Bay. A total of 624 individuals of different fish samples were sampled by trawling from three regions in Izmir Bay between 2010 and 2013. The total levels of indicator PCBs in all samples varied LOD (limit of detection) to 34.3 ng g⁻¹ (dry weight) in the study area. The highest concentrations of PCBs were found in Gulbahce for Mullus barbatus and Diplodus annularis in 2011 and 2010, respectively. PCB153 was the major contributed congener in both fish species during sampling periods. Principal component analysis (PCA) was performed to evaluate the correlation of the determined variables in fish species. According to PCA, the PCBs are not related with fish length. One-way ANOVA test indicated that significant temporal variations were generally detected for PCBs, while non-significant spatial variations were examined between sampling sites. Six PCB congeners were found as 0.59–6.64 ng g⁻¹ (wet weight, wwt) and compared with iPCB6 limits of 75 ng g⁻¹ (wwt) revealed by the Environmental Food Safety Authority. Accordingly, all fish species analyzed did not surpass the safe limits of iPCB6 suggested by EU. The estimated daily intake of 6 PCB congeners by the people were less than the tolerable daily intake (TDI, 10-ng kg⁻¹ body weight day⁻¹) recommended by WHO (2003), suggesting that this intake would not cause adverse effects to residents of Izmir.
Show more [+] Less [-]Adaptation towards climate change impacts among highland farmers in Malaysia Full text
2020
Hayrol Azril Mohamed Shaffril, | Idris, Khairuddin | Sahharon, Hamizah | Asnarulkhadi Abu Samah, | Bahaman Abu Samah,
This study aims to gain more understanding on highland farmers’ adaptation towards the impacts of climate change in Malaysia. Via a multi-stage cluster sampling, this quantitative study has surveyed a total of 400 highland farmers as respondents. The results indicated that the highest climate change-resilient farmers were from Kundasang, specifically among the females, Dusun ethnic group, and those who work side jobs to cover household expenses. Furthermore, recorded factors such as age and years of experience yielded significant negative relationship with adaptation whereas income yielded significant positive relationship with adaptation. The paper concludes with recommendations related to occupational diversification, consistent information disseminations, access to financial assistance, and the need to empower extension officers and local leaders in the hope that a comprehensive approach can help implement any community climate change-adaptation plan.
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