Causes of low mercury levels in fish from the Three Gorges Reservoir, China

Previous studies have suggested that growth dilution may be an important factor contributing to the low fish Hg levels in China. To evaluate the impact of growth rate to MeHg bioaccumulation in fish in the Three Gorges Reservoir (TGR), this study used two fish species, Aristichthys nobilis (A. nobilis) and Coilia nasus (C. nasus), which differ significantly in their growth rates. A combined bioenergetic-toxicokinetic model was used to simulate methylmercury (MeHg) concentrations in these two species. The model simulations were compared with the field data and showed good fits. It explained 44.0% and 46.5% of the variation in MeHg concentrations in A. nobilis and C. nasus, respectively. Sensitivity analysis revealed that growth rate accounted for 50.9% and 16.0% of MeHg concentrations in A. nobilis and C. nasus, respectively. This indicated that growth rate was the most critical factor affecting MeHg concentrations in fast-growing fish, such as A. nobilis. However, in species with low growth rate, such as C. nasus, the effect of growth rate was not as prominent as that in fast-growing fish. As a result, MeHg elimination rates and diet MeHg levels could offset the effect of growth, and become the decisive factors for MeHg concentrations in slow-growing fish.

Multifactor effects on the N2O emissions and yield of potato fields based on the DNDC model

Maintaining or increasing grain yields while also reducing the emissions of field agricultural greenhouse gases is an important objective. To explore the multifactor effects of nitrogen fertilizer on nitrous oxide (N₂O) emissions and the yield of potato fields and to verify the applicability of the denitrification-decomposition (DNDC) model when used to project the N₂O emission load and yield, this research chooses a potato field in Shenyang northeast China from 2017 to 2019 as the experiment site. The experiment includes four nitrogen levels observing the emission of N₂O by static chamber/gas chromatograph techniques. The results of this study are as follows: (1) DNDC has a good performance regarding the projection of N₂O emissions and yields. The model efficiency index EFs were 0.45 ~ 0.88 for N₂O emissions and 0.91, 0.85, and 0.85 for yields from 2017 to 2019. (2) The annual precipitation, soil organic carbon, and soil bulk density had the most significant influence on the accumulated N₂O emissions during the growth period of potatoes. The annual precipitation, annual average temperature, and CO₂ mass concentration had the most significant influences on yield. (3) Under the premise of a normal water supply, sowing potatoes within 5 days after the 5-day sliding average temperature in this area exceeds 10℃ can ensure the temperature required for the normal growth of potatoes and achieve the purpose of maintaining and increasing yield. (4) The application of 94.5 kg·hm^-2 nitrogen and 15 mm irrigation represented the best results for reducing N₂O emissions while also maintaining the yield in potato fields.

Year-round observation of atmospheric inorganic aerosols in urban Beijing: Size distribution, source analysis, and reduction mechanism

To investigate particle characteristics and find an effective measure to control severe particle pollution, year-round observation of size-segregated inorganic aerosols was conducted in Beijing from January to December, 2016. The sampled atmospheric particles all presented bimodal size distribution at four pollution levels (clear, slight pollution, moderate pollution and severe pollution), and peak values appeared at the size range of 0.7-2.1 μm and >9.0 μm, respectively. As dominant particle compositions, NO₃^-, SO₄^2-, and NH₄⁺ in four pollution levels all showed significant peaks in fine mode, especially at the size range of 1.1-2.1 μm. Secondary inorganic aerosols accounted for about 67.6% (36.3% (secondary sulfates) + 31.3% (secondary nitrates)) of the total sources of fine particles in urban Beijing. Severe pollution of fine particles was mainly caused by the air masses transported from nearby western and southern areas, which are industrial and densely populated region, respectively. Sensitivity tests further revealed that the control measures focusing on ammonium emission reduction was the most effective for particle pollution mitigation, and fine particles all showed nonlinear responses after reducing ammonium, nitrate, and sulfate concentrations, with the fitting curves of y = -120.8x - 306.1x² + 290.2x³, y = -43.5x - 67.8x², and y = -25.8x - 110.4x² + 7.6x³, respectively (y and x present fine particle mass variation (μg/m³) and concentration reduction ratio (CRR)/100 (dimensionless)). Overall, our study presents useful information for understanding the characteristics of atmospheric inorganic aerosols in urban Beijing, as well as offers policy makers with effective measure for mitigating particle pollution.

Study of climatology parameters on COVID-19 outbreak in Jordan

To control the spread of COVID-19 disease and reduce its mortality, an early and precise diagnose of this disease is of significant importance. Emerging research data show that the current COVID-19 pandemic may be affected by environmental conditions. Therefore, the impact of weather parameters on COVID-19 distribution should be explored to predict its development in the next few months. This research aims to study the association between the daily confirmed COVID-19 cases in the three major cities of Jordan; Amman, Zarqa, and Irbid and climate indicators to include the average daily temperature (°C), wind speed (m/s), relative humidity (%), pressure (kPa), and the concentration of four pollutants (CO, NO₂, PM_10, and SO₂). The data were obtained from the World Air Quality Project website and the Jordanian Ministry of Environment. A total of 305 samples for each city was used to conduct the data analysis using multiple linear regression and a feedforward artificial neural network. It was concluded that the multiple linear regression and feedforward artificial neural network could forecast the COVID-19 confirmed cases in the case studies; Amman, Irbid, and Zarqa. Finally, global sensitivity analysis using Sobol analysis indicated that pressure in Amman and Zarqa and the concentration of NO₂ in Irbid has a high rate of positive cases that supports the virus's spread.

Are routine microbiological samplings in acute dental infections justified? Our 10-year real-life experience

PURPOSE

Most patients with severe odontogenic infections are successfully treated with large spectrum probabilistic antibioc therapy, drainage of the collections and tooth treatment or extraction and are discharged home before antibiotic sensitivity results were available. The investigators hypothesized whether bacteriological sampling should be systematically performed in the management of patients with severe odontogenic infections.

METHODS

The investigators implemented a prospective observational study. The sample was composed of patients managed between January 2004 and December 2014 for severe odontogenic infection based on three criteria: hospital admission, intravenous antibiotic therapy, tooth extraction and collections drainage under general anesthesia. The predictor variable was the results of bacteriological sampling, culture and sensitivity. The outcome variable was antibiotic therapy adaptation according to antibiotic sensitivity results.

RESULTS

The sample was composed of 653 patients; 386 (59%) were male and 267 (41%) female, with a mean age of 37 years (range 18-88); 378 (58%) patients had been receiving oral antibiotics before admission to hospital, for a mean duration of 4.1 days (range 1 - 30). About 535 (81.9%) patients had swabs taken during surgery. Microorganisms were observed in 477 (89.1%) patients but in 377 (70.5%) they were polymorphic oropharyngeal flora. After culture, at least one antibiogram was obtained for 91 (17%) patients and the results led to antibiotic therapy being adapted in 23 (4.3%) patients.

CONCLUSION

The results suggest that bacteriological analysis had an impact on evolution in less than 5% of patients. Future studies will focus on the patients for whom the bacteriological analysis is essential.

Evaluating subchronic toxicity of fluoxastrobin using earthworms (Eisenia fetida)

Potential toxicity to soil organisms by fluoxastrobin, a new strobilurin-type fungicide has drawn increasing attention. Thus, the present study investigated the subchronic toxicity induced by exposure to several concentrations (0, 0.1, 1.0, and 2.5 mg kg^-1) of fluoxastrobin to earthworms on days 7, 14, 21, and 28. Biochemical indicators (e.g., reactive oxygen species (ROS) content, activities of antioxidase and detoxifying enzymes (superoxide dismutase, catalase, and glutathione S-transferase), lipid peroxidation (malonaldehyde) and degree of DNA damage) were measured. No earthworm deaths were observed during the entire experimental period. For ROS and malonaldehyde, the bioassay values of the three doses reached a maximum on day 21 and then decreased. For superoxide dismutase and glutathione S-transferase, the values increased with the exposure doses of 0.1 and 1.0 mg kg^-1 and then decreased. In contrast, the values for catalase were lower on days 7, 14, and 28 and greater on day 21 compared to those of the controls. In addition, the comet assay was more sensitive than other biomarkers, and the degree of DNA damage was dose and time -dependent.

Risk factors associated with E. coli causing neonatal calf diarrhea

Calf diarrhea is one of the major health challenges in cattle herds. The bacteriological examination of fecal samples collected from apparently healthy and diarrheic calves' revealed isolation of 26 E. coli isolates out of 56 calves with an incidence of 46.4%. Serogroups O1, O26, O44, O55, O115, O119, O125, O146, and O151 were identified from the collected fecal samples. Using PCR all isolates was positive for ompA gene species specific for E. coli. While stx1 and eaeA genes detected with incidence of 3.8 and 19.2% respectively from the isolates. The presence of stx2 gene was negative in the fecal isolates. Among colostrum samples 4 E. coli isolates were detected and serogrouped to O26, O55 and O119. They were negative for eaeA, stx1 and stx2 except strain number 4 (O55) was positive for stx1. E. coli strains were sensitive to norfloxacin (80.7%) and resistant to ampicillin and cefotaxime (100% each). Based on our findings, there was no association between occurrence of E. coli and age of calf (2–14 days), while bottle feeding calf colostrum may be a source of E. coli contamination.

Exposed zebrafish (Danio rerio) to imidazolium-based ionic liquids with different anions and alkyl-chain lengths

Ionic liquids (ILs) were considered new "green solvents" in consideration of the low volatility. Since their inception, ionic liquids (ILs) have attracted widespread attention. However, ILs were not safe enough as what we thought. The toxicity of 1-ethyl-3-methylimidazolium ILs ([C₂mim]R, R = Cl^-, Br^-, BF₄^-) and 1-alkyl-3-methylimidazolium bromine ([C_nmim]Br, n = 2, 4, 8, 10, 12) using 50% lethal concentration (LC₅₀) were studied in the present study to enrich the toxicological information. Besides the LC₅₀ values, the sensitivity test using potassium dichromate (K₂Cr₂O₇) and residue determinations of the tested ILs were also performed. The sensitivity and dynamic changes of IL doses both catered for the stipulation that declared the accuracy of the toxicological test results, which illustrated that the alkyl-chain lengths contributed more than anions to the toxicity of the ILs described above to zebrafish. Additionally, the present study also enriched the toxicological information on imidazolium-based ILs to aquatic systems.

The acute toxic effects of imidazolium-based ionic liquids with different alkyl-chain lengths and anions on zebrafish (Danio rerio)

With the increasing applications of ionic liquids (ILs), the toxicity of ILs has drawn increasing attention in recent years, especially the influences of different anions and alkyl-chain lengths on the acute toxicity to aquatic organisms. We performed a study on the acute toxicity of 1-alkyl-3-methylimidazolium nitrate ([C_nmim]NO₃ (n=2, 4, 6, 8, 10, 12)), 1-hexyl-3-methylimidazolium ILs ([C₆mim]R (R=Cl^-, Br^-, BF₄^-, PF₆^-)) to zebrafish (Danio rerio). We also evaluated the sensibility of the investigated animals and the stability of ILs in water via high performance liquid chromatography (HPLC, Agilent 1260, Agilent Technologies Inc., USA) to prove the reliability of the present study. The results illustrated that the test zebrafish (Danio rerio) were sensitive to the reference toxicant and that the investigated ILs in water were stable. The 50% lethal concentration (LC₅₀) was used to represent the acute toxicity to zebrafish (Danio rerio). The present study showed that the highest toxic IL is [C₁₂mim]NO₃ and the lowest toxic IL is [C₂mim]NO₃ on Danio rerio. The LC₅₀s for ILs with different anions had similar values. Accordingly, we believe that ILs with different alkyl-chain lengths cause greater effects than other anions on acute toxicity to aquatic organisms. Furthermore, the present study can also provide scientific methods for future studies to select and assess ILs.

Vulnerability and impact assessment of extreme climatic event: A case study of southern Punjab, Pakistan

Understanding of frequency, severity, damages and adaptation costs of climate extremes is crucial to manage their aftermath. Evaluation of PRECIS RCM modelled data under IPCC scenarios in Southern Punjab reveals that monthly mean temperature is 30°C under A2 scenario, 2.4°C higher than A1B which is 27.6°C in defined time lapses. Monthly mean precipitation under A2 scenario ranges from 12 to 15mm and for A1B scenario it ranges from 15 to 19mm. Frequency modelling of floods and droughts via poisson distribution shows increasing trend in upcoming decades posing serious impacts on agriculture and livestock, food security, water resources, public health and economic status. Cumulative loss projected for frequent floods without adaptation will be in the range of USD 66.8-79.3 billion in time lapse of 40years from 2010 base case. Drought damage function @ 18% for A2 scenario and @ 13.5% for A1B scenario was calculated; drought losses on agriculture and livestock sectors were modelled. Cumulative loss projected for frequent droughts without adaptation under A2 scenario will be in the range of USD 7.5-8.5 billion while under A1B scenario it will be in the range of USD 3.5-4.2 billion for time lapse of 60years from base case 1998-2002. Severity analysis of extreme events shows that situation get worse if adaptations are not only included in the policy but also in the integrated development framework with required allocation of funds. This evaluation also highlights the result of cost benefit analysis, benefits of the adaptation options (mean & worst case) for floods and droughts in Southern Punjab. Additionally the research highlights the role of integrated extreme events impact assessment methodology in performing the vulnerability assessments and to support the adaptation decisions. This paper is an effort to highlight importance of bottom up approaches to deal with climate change.

Two-Point Discrimination Test in the Treatment of Right-handed Females with Lumbosacral Radiculopathy

Non-somatic causes of pain may aggravate painful complaints and complicate the conservative management of diseases such as lumbo-sacral disk root disease. The two-point discrimination test has been used for assessment of diseases, which change patients' skin sensation. This study aims to find out how applicable is two-point discrimination test in the conservative treatment of lumbo-sacral disk diseases. Twenty right-handed females suffering from unilateral lumbo-sacral disk disease were admitted for a conservative treatment from 2006 to 2009. The treatment consisted of a week bed rest, physiotherapy, and medication. They were subjected to straight leg raising tests, and their pains were evaluated using visual analog scale. The values of two-point discrimination test were obtained bilaterally for L(4), L(5) and S(1 )dermatomes. Changes between the involved and intact lower limbs as well as values of two-point discrimination test before and after the treatment were also compared. In addition, the correlation between the outcome of two-point discrimination, straight leg raising tests, or pain scores were evaluated. There was a significant (P<0.001) difference between the changes in the values of two-point discrimination test, pain scales, or straight leg raising tests in the involved and intact limbs before and after the treatment. However, correlation among variables did not reach statistical significance (P<0.94, r=0.017). The results indicated that although two-point discrimination test is a feasible and objective tool to evaluate patients' improvements during the conservative management of lumbo-sacral disk diseases, there were no strong correlations between two-point discrimination test and straight leg raising tests, or pain scale.