氟离子慢性暴露对中国林蛙蝌蚪生长发育的毒性效应研究

氟元素以不同的结合形式广泛存在于自然界中,适量氟的摄取有益于龋齿预防和骨骼发育,然而过量氟的摄取会对动物及人体健康造成危害。近年来,大量的人类活动导致水环境中氟含量持续升高。为探究水域氟污染对中国林蛙的毒性影响,本研究以中国林蛙(Rana chensinensis)胚胎为试验材料,对卵黄栓期(G12期)胚胎进行了0、0.7、4.2、19.4、42.8 mg·L~(-1)F-慢性水体暴露直至胚胎发育到变态高峰期(G42期)的研究。分别于暴露25 d和40 d后取样测定了蝌蚪全长、体长、体重和发育分期;此外,分析了F-慢性暴露对变态率、G42期蝌蚪的全长、体长、体重和后肢长以及G42期蝌蚪骨骼发育的影响。结果表明:暴露25 d时,4.2 mg·L~(-1)F-处理组促进了林蛙蝌蚪的生长发育,而42.8 mg·L~(-1)F-处理组显著抑制了蝌蚪的生长发育;暴露40 d时,19.4 mg·L~(-1)F-和42.8 mg·L~(-1)F-处理组蝌蚪的生长发育均受到显著抑制。持续进行慢性暴露78 d后,4.2 mg·L~(-1)F-处理组蝌蚪的变态率显著升高,而42.8 mg·L~(-1)F-处理组蝌蚪的变态率受到了显著抑制。此外,42.8 mg·L~(-1)F-处理组G42期蝌蚪形态指标(全长、体长和后肢长)以及骨骼发育均受到抑制。依据G42期中国林蛙蝌蚪的生长发育指标和变态率为观察指标,氟离子慢性暴露对中国林蛙蝌蚪的最低可观察效应浓度(LOEC)为0.7 mg·L~(-1)。研究表明,水环境中高浓度的氟污染会对中国林蛙蝌蚪的生长发育、变态和骨骼发育等造成潜在的不利影响,水体氟污染的生态毒性效应理应引起高度重视。     

重金属汞对海洋底栖动物毛蚶和紫贻贝毒性效应研究

本文基于我国近海典型底栖双壳类生物毛蚶、紫贻贝急性和慢性毒性效应实验数据,分析了重金属汞对受试生物体质量、体长及消化腺超氧化物歧化酶(superoxide dismutase, SOD)酶活力的影响,获取了无观察效应浓度(No Observed Effect Concentration, NOEC),并以生存率为反应终点分析计算了重金属汞的非检测毒性效应浓度及半致死浓度。结果表明,各实验组SOD酶活力的组内方差与组间方差的差异整体上并不显著(P > 0.05),实验周期内仅在个别时间处理组间存在显著性差异(P < 0.05);实验周期内毛蚶和紫贻贝体质量、体长的组内方差与组间方差并没有显著性差异(P > 0.1),体长及体质量不适合作为毒性效应的评价终点。重金属汞对毛蚶、紫贻贝的非检测毒性效应浓度分别为23.7 μg·L-1、87.8 μg·L-1,半致死浓度分别为683.4 μg·L-1、773.2 μg·L-1。     

Arbuscular mycorrhiza confers lead tolerance and uptake in Miscanthus sacchariflorus

The effects of an arbuscular mycorrhizal fungi (AMF) association on the growth, survival capabilities, nutrients and lead (Pb) uptake of Miscanthus sacchariflorus under different Pb concentrations were studied in the form of pot cultures. The treatments comprised inoculation or non-inoculation of the AMF, Gigaspora margarita, and the addition of three Pb concentrations to the soil (0, 100 and 1000?mg?kg^?1). The addition of Pb significantly decreased mycorrhizal colonisation. The inoculation of AMF with Pb increased chlorophyll content, Fv/Fm, total dry mass, indole-3-acetic acid (IAA), total nitrogen, and total phosphorus, whereas H₂O₂ level, indole-3-acetic acid oxidase (IAAO) activity, and peroxidase (POD) activity were low compared to those in the non-inoculated treatments. Moreover, the application of AMF together with Pb doses induces concentrations of Pb in the plant, where the higher dose of Pb (1000?mg?kg^?1) induces a lower content of Pb in the aerial part of the plant but a higher content in the root. G. margarita enhanced the tolerance of M. sacchariflorus against Pb toxicity, and facilitated the accumulation of Pb in the plant roots, whereas translocation to the shoots was inhibited at the highest dose Pb (1000?mg?kg^?1). However, in contaminated soil, the Pb removal capability of M. sacchariflorus with AMF was remarkable.     

Detecting the effects of coal mining,acid rain,and natural gas extraction in Appalachian basin streams in Pennsylvania (USA) through analysis of barium and sulfate concentrations

To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO₄], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO₄] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO₄] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO₄] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO₄] are related to releases from coal mining or burning rather than oil and gas development.

     

Metals and metalloids in PM10 in Nandan County,Guangxi, China,and the health risks posed

Intense mining, smelting, and tailing activities of polymetallic ore deposits have affected the environment in Nandan County, Guangxi, China. Samples of particulates with aerodynamic diameters low or equal 10 μm (PM₁₀) were collected in Nandan County to investigate the concentrations of and health risks posed by 17 metals and metalloids in the PM₁₀. The metal and metalloid concentrations were lower than those found in other industrial cities. The mean Cr concentration was 7.48 ng/m³. Significant higher metal and metalloid concentrations were found in PM₁₀ from mining areas (Dachang and Chehe) than from the control area (Liuzhai) (p < 0.05). Principal component analysis indicated that the main sources of Ba, Co, Cr, Fe, K, Mg, Mo, Na, and Sr were resuspension of the soil produced through mineral erosion, the main sources of As, Cd, Cu, Pb, Sb, and Zn were smelting and mining activities, and the main source of Ni was fossil fuel combustion. Higher non-carcinogenic and carcinogenic risks were posed in Dachang and Chehe than in Liuzhai. The non-carcinogenic risks posed to adults and children by individual metals and metalloids in PM₁₀ at all the sites were low, but the non-carcinogenic risks posed to children by all the metals and metalloids together exceeded the safe level (i.e., risk value > 1). The carcinogenic risks posed by Cd, Ni, and Pb were negligible at all sites, while As, Co, and Cr posed potential carcinogenic risks to the residents.

     

Stabilization of Cd-, Pb-, Cu- and Zn-contaminated calcareous agricultural soil using red mud: a field experiment

Red mud (RM) was used to remediate heavy metal-contaminated soils. Experiments with two different dosages of RM added to soils were carried out in this study. It was found that soil pH increased 0.3 and 0.5 unit with the dosage of 3 and 5% (wt%), respectively. At the dosage of 5%, the highest stabilization efficiencies for Cd, Pb, Cu and Zn reached 67.95, 64.21, 43.73 and 63.73%, respectively. The addition of RM obviously transferred Cd from the exchangeable fraction to the residual fraction. Meanwhile, in comparison with the control (no RM added), it reduced 24.38, 49.20, 19.42 and 8.89% of Cd, Pb, Cu and Zn in wheat grains at the RM addition dosage of 5%, respectively. At the same time, the yield of wheat grains increased 17.81 and 24.66% at the RM addition dosage of 3 and 5%, respectively. Finally, the addition of RM did not change the soil bacterial community. These results indicate that RM has a great potential in stabilizing heavy metals in calcareous agricultural soils.

     

Species diversity variation of Cupressus funebris secondary forest in landslide site after 5.12 Wenchuan Earthquake北大核心CSCD

The characteristics of species diversity in Cupressus funebris secondary forest under the effect of geological hazard were explored by selecting the typical landslide surface of Fenghuang Mountain, Leigu Town, Beichuan County, which was derived from the 5.12 Wenchuan earthquake. The results showed that 93 species belonged to 42 families, and 78 genera were found in the landslide area, where the main families were Compositae, Leguminosae, and Gramineae-based. Further, 97 species in the transition area belonged to 39 families and 80 genera, and the main families were Compositae, Gramineae, and Rosaceae-based. In all, 108 species were recorded in the non-landslide area, which belonged to 59 families and 92 genera, the main families of which were Compositae, Rosaceae, and Gramineae-based. Compositae and Gramineae played important roles in the landslide recovery process after earthquake. The Pielou index (JSW) was the highest in the non-landslide area of the herb layer, whereas the richness index (D) was the lowest; the Shannon-Wiener index (H) and Simpson index (H') showed medium values. In the non-landslide area, the D, H, and H' were the highest in the shrub layer, whereas the JSW was the lowest. Further, the species diversity index of the transitional area was higher than that of the landslide area. In the tree layer, the D and H were both the highest and lowest in the landslide area and transition area, respectively. In contrast, the H' and JSW were the highest in the transition area and the lowest in the non-landslide area. The distribution of vegetation was generally consistent with the distribution of soil nutrients in the spatial distribution of surface soil nutrients. The succession of trees in the landslide area was relatively slow and at the initial stage, and the pioneer species were Coriaria nepalensis, Leptopus chinensis, and Arthraxon lanceolatus in this area. Taken together, the findings suggested that the stability of a plant community can be increased by improving the soil and stabilizing the slope. © 2018 Science Press. All rights reserved.     

Recent advances in three typical configurations and applications of bioelectrochemical systems北大核心CSCD

As the world's freshwater resources and available energy are alarmingly decreasing, the bioelectrochemical system (BES) is a cutting-edge technology for the resolution of the resource and energy issue. Researchers have paid much attention to t he application of t he BES configuration. Based on t he brief i ntroduction of m icrobial f uel cell a nd m icrobial electrolytic cell structure, principles, and domestic and foreign research, the BES and its influencing factors are introduced, specifically including: microbial activity, electrode materials, and configuration. Three important aspects (i.e., the electrode chamber, the reaction chamber, and micro-sensor) are summarized, and the advantages and disadvantages of single-electrode and multi-electrode chambers are compared, based on the microbial desalination cell. Microbial electrolysis desalination cell: Microbial electrolysis desalination and chemical-production cell have been discussed to introduce increasing reaction chamber configuration; this review focuses on the research of BES monitoring with regards to biochemical oxygen demand. The potential applications of the research progress are explored. The results show that the configuration of multi-chamber microbial fuel cell is complex and its efficiency is low, while the single chamber configuration is advantageous. The reaction chamber added is mainly aimed at desalination, and the study of the desalination pool still needs to be focused on optimizing the cation exchange membrane to maintain the anode pH balance and reduce the air cathode dissolved oxygen. Microbial electrode sensor can be applied in more areas, and its sensitivity and long-term stability need to be further improved. However, there is relatively less research on the abundance and activity of electricigen communities; the configurations and scopes of application of BES are still the research priority. © 2018 Science Press. All rights reserved.     

Changes in CO2 flux for different recovery processes of desertification in the alpine meadows of Northwest Sichuan北大核心CSCD

Desertification has emerged as a serious threat to the alpine meadows of Northwest Sichuan in recent decades. Artificial vegetation had certain effects on desertification recovery, while how the CO2 flux changed and its reasons are still unclear. During the growing season in 2016 (i.e., from July to September), we selected the desertified alpine meadows with different recovery degrees, including the early stage of restoration, the middle stage of restoration, the late stage of restoration, and control (the unrecovered desertification meadow) as four transects. CO2 flux was measured by the instrument LI-8100, and the microenvironment factors that affected CO2 flux changes were analyzed. The results showed that the carbon sequestration function of desertified alpine meadows gradually increased with the degree of recovery. Net ecosystem exchange (NEE) were -1.61, -3.55, and -4.38 μmol m-2 s-1 in the early, mid-term, and late transects, respectively, and the most dramatic changes occurred from the early stage to mid-term stage, increasing by 120.50%. Both ecosystem respiration (ER) and soil respiration (SR) were enhanced significantly with restoration (P < 0.05). In mid or late July, NEE, ER, and SR reached their maximum values, and thereafter, the indicators varied to near zero (P < 0.05). During the whole growing season, the daily dynamic in CO2 flux for the control alpine meadow was mild and retained the trend of continuous release all day, but that in the desertified alpine meadow was a single peak pattern. Moreover, with restoration process, the peak of CO2 flux increased and reached a peak in the late stage of the recovery process. The regression analysis showed that there was a significant positive correlation between CO2 flux and vegetation coverage, aboveground biomass, and soil moisture (0-5 cm) (P < 0.01), and a weak correlation with 0-5-cm soil temperature (P < 0.01). This indicates that topsoil moisture (5 cm) is a more significant factor for CO2 flux than topsoil temperature during the growing season in the restoration of desertified alpine meadows in Northwest Sichuan. In general, the vegetation recovery significantly improved the carbon-sequestration ability of the desertified alpine meadows during the growing season in Northwest Sichuan, and at the middle stage of restoration, the carbon-sequestration ability improved significantly due to vegetation restoration and increase in topsoil (0-5 cm) moisture. © 2018 Science Press. All rights reserved.     

Effects of different endogenous fungi on the mass loss and nutrient content of leaf litter of Cunninghamia lanceolata北大核心CSCD

To explore the role of endophytic fungi in the decomposition of litter, the endophytic fungi Penicillium sp. strain CG2 (A), Fusarium flavum strain AY13 (B), and Talaromyces strain AJ14 (C) of Cunninghamia lanceolata were added to experimental pots in different forms (mycelium, sterilized fermentation broth, single fungus, and mixed fungi), and a control treatment (CK) was set up (no fungi added). At 10, 30, 60, 90, and 120 days after litter decomposition, a study on the decomposition dynamics of C. lanceolata litter under different treatments was performed. The results showed that the rate of leaf mass loss was the highest in the sterilized fermentation broth treatment A after 120 days, and that there was a significant difference (P < 0.05) between the mycelium treatment AC and the control treatment after 60 days (23.97% higher than the control group). On day 60, the litter carbon content from the mycelium treatment A was significantly different from that of the control (P < 0.05), showing a 16.74% lower value, whereas the litter carbon content of the mycelium treatment B was 21.13% lower than that of the control after 90 days. The nitrogen content of the litters of most mycelium and sterilized fermentation broth treatments was increased compared to that of the control group; there was significant difference (P < 0.05) between the sterilized fermentation broth treatment A and the control (P < 0.05), with a 17.05% higher value than that of the control. Similar to nitrogen, the litter phosphorus content also increased; there was a statistically significant difference between the mycelium treatment A and the control group, with treatment A showing a 46.67% higher value than the control group. The potassium content was 28% lower than that of the control group under the sterilized fermentation broth treatment C, a result that was significantly different from that of the control group (P < 0.05). After treatment for 90 days, the ratio of carbon to nitrogen was the lowest under the treatments with the mycelium A and the mycelium B, with values 25.54% and 25.11% lower than that of the control group, respectively, and a statistically significant difference from that of the control group (P < 0.05). The ratio of carbon to phosphorus was the lowest under the treatment with mycelium A after 60 days, and the result was significantly different from that of the control (P < 0.05), with a 43.05% lower value than the control. Thus, the three endophytic fungi had different effects on the mass loss rate and nutrient content of the litter. The Penicillium sp. strain CG2 (A) had statistically significant effects on the mass loss and nutrient content of leaf litter, which was within the range of fungi fertilizer reference values for the breeding of C. lanceolata. © 2018 Science Press. All rights reserved.