Agricultural non-point sources and their effects on chlorophyll-a in a eutrophic lake over three decades (1985–2020)

Environmental Science and Pollution Research - Erhai Lake is the second largest freshwater lake in Yunnan Province but suffers from the deterioration of water quality and agricultural non-point...     

Conditional effect of governance quality on the finance-environment nexus in a multivariate EKC framework: evidence from the method of moments-quantile regression with fixed-effects models

This paper investigates the mitigating effect of governance quality on the finance-environment nexus in a multivariate EKC framework in 123 selected countries during the 1990–2017 period. We mainly employ the method of moments-quantile regression (MM-QR) with the fixed-effects model, among others. First, the MM-QR estimator reveals that financial development reduces environmental quality more significantly in countries with initially higher levels (the 75^th and 90^th quantiles) of CO₂ emissions than in other countries (the 25^th and 10^th quantiles). Second, the attenuating effect of governance quality on the finance-environment nexus is more remarkable in nations with low initial levels (the 25^th and 10^th quantiles) of CO₂ emissions. Third, we find that the marginal positive effect of financial development on CO₂ emissions is smaller under a good regulatory framework than under corruption control and the rule of law, especially in the top emitters (the 75^th and 90^th quantiles). Fourth, unlike oil, which has a considerable negative impact on the environmental quality of the major emitters, renewable energy usage reduces CO₂ emissions in countries in all quantiles, primarily in the lowest quantiles. Fifth, the findings also show that urbanization dramatically worsens environmental quality in all economies, particularly those in the lowest quantiles. Finally, we confirm that the EKC hypothesis holds in all countries across different quantiles. The study’s final section discusses policy implications for sustainable development in all countries.

     

SDG-oriented multi-scenario sustainable land-use simulation under the background of urban expansion

Environmental Science and Pollution Research - With the continuous improvement of urbanization level and the continuous expansion of city scale, there are some unreasonable land development and...     

A model for evaluation of the phytoavailability of trace elements to vegetables under the field conditions

Currently, several single extraction methods are used for the evaluation of the phytoavailability of metals using pot experiments. A systematic comparison, however, is lacking. It is especially true for the field studies. This study was to investigate the phytoavailability of trace elements to vegetables grown on metal-contaminated soils under the field conditions. All soils collected were typical calcareous soils in northern China. Four frequently used methods using CaCl2, diethylenetriaminepentaacetic acid (DTPA), CH3COOH, and water as extractants were compared for phyto-availability. The concentrations of metals extracted by these four extraction methods ranged from 3.42 to 815, 1.51- 6965, 0.732-24473, 0.688-7863, 0.246-685, 1.99-5337 0.203-4649 ng/g for Cr, Ni, Zn, Cu, Cd, Pb and REEs, respectively. Simple correlation analysis indicated that a significant correlation (Cr: r = 0.5411**; Zn: r = 0.6352**; Cd: r = 0.6979**; Pb: r = 0.5537** and REEs: r = 0.5185** -0.6684**) was observed between the CaCl2-extractable metals in soil solution and that in Chinese cabbage. In addition, soil pH, organic matter (OM), and cation exchange capacity (CEC) also affect the phytoavailability. An empirical model was developed to express the combined effect of soil properties on the phytoavailability. The stepwise multiple regression analysis demonstrated that the phytoavailability of trace elements strongly correlated with the extractable fraction by CaCl2, total metal concentration in soils, and soil pH, OM, CEC. This model can describe approximately 75-95% of the variability of metal uptake and the r2 values ranged from 0.741** to 0.954**, which were much better than the single correlation analysis. For celery and cole, a strong correlation was obtained for Cr, Ni, Zn, Cu, Cd, La, Ce, Pr and Nd. For spinach and Chinese cabbage, however, a positive correlation was only observed for 1 and 3 metals, respectively. Generally, the developed empirical model can integrate the combined effects of soil properties, extractable metal fractions in soil solutions and plant species on the phytoavailability of metals to vegetables in the field conditions.     

Acute toxicity and genotoxicity of two novel pesticides on amphibian, Rana N. Hallowell

Imidacloprid [1-(6-chloro-3-pyridylmethyl)-N-nitro-imidazolidin-2-ylideneamine] and RH-5849 [2'-benzoyl-l'-tert-butylbenzoylhydrazinel] are two pesticides used in China since 1992. In the present study we conducted acute toxicity test, micronucleus (MN) test and comet assay of the two pesticides on amphibian, Rana N. Hallowell, a sensitive organism suitable for acting as the bio-indicator of aquatic and agricultural ecosystems. The values of LC50-48 h of imidacloprid were found to be 165 mg l(-1) for tadpoles of Rana limnocharis and 219 mg l(-1) for tadpoles of Rana N. Hallowell. On the other hand, RH-5849 showed no acute toxicity to tadpoles during the 96 h exposure even it was saturated in the test solutions. There were significant differences in the MN frequencies between the negative controls and the treated groups at the dose of 8 mg l(-1) for imidacloprid (p < 0.05) and 40 mg l(-1) for RH-5849 (p < 0.01). Comet assay found significant differences (p < 0.01) in the distributions of DNA damage grades between the negative controls and groups treated in vitro with 0.05, 0.1, 0.2 and 0.5 mg l(-1) of imidacloprid and 5, 25, 50 and 100 mg l(-1) of RH-5849, respectively. DNA damage scores increased with the exposure levels of the two pesticides and dose-effect relationships were observed for both imidacloprid (r2 = 0.92) and RH-5849 (r2 = 0.98). The MN test and comet assay revealed potential adverse effects of the two pesticides on DNA in the erythrocytes of amphibians in aquatic and agricultural ecosystems.     

Effects of four chlorobenzenes on serum sex steroids and hepatic microsome enzyme activities in crucian carp, Carassius auratus

Four chlorobenzenes (chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, p-chloro-methylbenzene) were administrated to the crucian carps (Carassius auratus) by peritoneal injections in the laboratory for 30 days. Serum testosterone and 17 beta-estradiol concentrations were detected using radioimmunology assay (RIA), and the activities of two hepatic microsome enzymes, glutathione s-transferase (GST) and UDP-glucuronosyltransferase (UDPGT), were measured using the modified methods as described by Habig and Owens. Results showed that the four chlorobenzenes caused significant increases in serum testosterone concentration in the crucian carps (P < 0.05) compared to the controls, but they caused no significant effect on 17 beta-estradiol level. All test chemicals caused a change in hepatic GST activity in crucian carps, with significant increases in enzyme activity (P < 0.05). Chlorobenzene, 1,3-dichlorobenzene and p-chloro-methylbenzene resulted in a marked inhibition to UDPGT activity in crucian carp (P < 0.05) except 1,4-dichlorobenzene. The changes in hepatic microsome enzyme activities may have resulted in the alterations of serum sex steroids levels in the crucian carps. The results indicated that these four chlorobenzenes may result in the changes of endocrine functions and may affect the reproductive success of this and other species.     

人工神经网络和专家系统在污水生物处理系统中的应用

对近年来国内外污水生物处理系统中人工神经网络和专家系统的应用进行了简要的回顾。分析了废水生物处理工艺难于控制的原因及人工神经网络和专家系统的结构和特点。结果表明．国外智能控制发展迅速,并且应用领域遍及污水生物处理的各个方面,国内尚处于起步阶段。简要探讨了废水生物处理智能控制今后应深入研究的问题及方向。     

低浓度Pb2+、Cd2+对鲫鱼肝脏组织中 HSP70诱导的影响

以鲫鱼(Carassius auratus)作为实验对象,经过40 d Pb2+、Cd2+不同浓度的暴露后,运用SDS-PAGE和Western Blotting方法检测鱼肝脏组织内应激蛋白HSP70的诱导表达情况.结果表明,在实验浓度下,与对照组相比,Pb2+、Cd2+对鱼肝脏内HSP70有显著的诱导(P＜0.05),但在Cd2+浓度为0.2 mg/L有停止表达HSP70的现象,可能是由于浓度过高造成了组织病理损伤而破坏了诱导表达机制.实验还发现,在实验浓度低于国家渔业用水标准时,HSP70仍然表现为明显诱导(P＜0.05),充分说明运用分子生物学指标要比传统的环境检测指标敏感,具有对污染物早期预警的作用.     

污染底泥及其间隙水分层特性的模拟实验研究

底泥冲刷沉降、再悬浮是作用于水环境内源污染的主要因素,而底泥间隙水的污染释放则是主要途径。通过底泥培养实验,研究了污染底泥及其间隙水的分层特性。结果表明,底泥及其污染物具有显著的分层特性。底泥间隙水中CODMn随深度的增加略有下降的趋势;底泥湿容重和干容重呈增大的趋势;含水率随底泥深度的增加而减小。底泥深度对底泥泥沙颗粒的级配有很大影响,在表层以细颗粒为主,随着深度的增加．底泥粒径增加,但趋势衰减较快。这对底泥冲刷作用下的再悬浮有很大影响。     

氯化汞对小鼠睾丸生殖细胞的DNA损伤作用

探索氯化汞对雄性小鼠生殖细胞毒性的分子遗传机制。分别以 0 .0 1、0 .10、1.0 0 mmol/L的氯化汞体外处理小鼠睾丸细胞和以 0 .5、1.0、5 .0 μmol/kg的氯化汞体内暴露小鼠 ,应用单细胞凝胶电泳技术检测生殖细胞 DNA的损伤。体外处理 3种剂量组小鼠睾丸生殖细胞 DNA损伤率显著高于阴性对照组 ( 0 mmol/L组 ,P<0 .0 0 1) ;0 .1、1.0 mmol/L剂量组慧星细胞迁移率显著高于阴性对照组 ( P<0 .0 0 1,P<0 .0 5 )。体内暴露 3种浓度氯化汞组小鼠睾丸生殖细胞 DNA损伤率显著高于阴性对照组 ( 0μmol/kg,P<0 .0 0 1) ,5 .0 μmol/kg组慧星迁移率显著高于阴性对照组 ( P<0 .0 5 )。一定剂量的氯化汞处理引起生殖细胞 DNA损伤作用可能是氯化汞细胞毒性的机制之一。