Socioeconomic evaluation of the impact of natural resource stressors on human-use services in the Great Lakes environment: A Lake Michigan case study

The Great Lakes watershed is home to over 40 million people (Canadian and U.S.) who depend on a healthy Great Lakes ecosystem for economic, societal, and personal vitality. The challenge to policymakers and the public is to balance economic benefits with the need to conserve and replenish regional natural resources in a manner that ensures long term prosperity. Nine critical broad-spectrum stressors of ecological services are identified, which include pollution and contamination, agricultural erosion, non-native species, degraded recreational resources, loss of wetlands habitat, climate change, risk of clean water shortage, vanishing sand dunes, and population overcrowding. Many of these stressors overlap. For example, mining activities alone can create stress in at least five of these categories. The focus groups were conducted to examine the public’s awareness of, concern with, and willingness to expend resources on these stressors. This helped generate a grouping of stressors that the public is especially concerned about, those they care little about, and everything else in between. Stressors that the respondents have direct contact with tend to be the most important to them. This approach of using focus groups is a critical first step in helping natural resource managers such as Trustees and NGOs understand what subsequent steps to take and develop policy measures that are of most interest and value to the public. Skipping or glossing over this key first task could lead to difficulties with respect to survey design and model development in a non-market valuation study. The focus group results show that concern related to pollution and contamination is much higher than for any of the others. It is thus clear that outreach programs may be necessary to educate the public about the severity of some low-ranked stressors including climate change.     

Mercury and selenium in blue shark (Prionace glauca, L. 1758) and swordfish (Xiphias gladius, L. 1758) from two areas of the Atlantic Ocean

Muscle, liver and stomach contents of 64 blue sharks and 52 swordfishes, caught between September 2004 and February 2005 near the Azores (area A) and the Equator (area E), were analysed for mercury and selenium. Levels of mercury were relatively high (blue shark: 0.032-2.5microgg(-1); swordfish: 0.031-9.8microgg(-1)) and comparable to values reported in the literature. However, mercury and organic mercury concentrations in muscle and liver of specimens from E were significantly higher than those from A. A similar trend was registered in stomach contents, suggesting higher uptake of Hg in specimens from E. This difference was also observed in the relationship between concentration in muscle and size, indicating a higher accumulation rate in specimens from E. The accumulation of Se in the liver of both species showed a positive correlation with inorganic mercury concentrations, pointing to a detoxifying mechanism of organic mercury in these species through Se-Hg liasons.     

Enhanced adsorption of Methylene Blue from aqueous solution by chitosan-g-poly （acrylic acid）/vermiculite hydrogel composites

A series of chitosan-g-poly (acrylic acid)/vermiculite hydrogel composites were synthesized and used as adsorbents for the investigation of the e ect of process parameters such as vermiculite content, pH of dye solution, contact time, initial concentration of dye solution, temperature, ionic strength and concentration of surfactant sodium dodecyl sulfate on the removal of Methylene Blue (MB) from aqueous solution. The results showed that the adsorption capacity for dye increased with increasing pH, contact time and initial dye concentration, but decreased with increasing temperature, ionic strength and sodium dodecyl sulfate concentration in the present of the surfactant. The adsorption kinetics of MB onto the hydrogel composite followed pseudo second-order kinetics and the adsorption equilibrium data obeyed Langmuir isotherm. By introducing 10 wt.% vermiculite into chitosan-g-poly (acrylic acid) polymeric network, the obtaining hydrogel composite showed the highest adsorption capacity for MB, and then could be regarded as a potential adsorbent for cationic dye removal in a wastewater treatment process.     

Adsorption of Disperse Blue SBL dye by synthesized poorly crystalline hydroxyapatite

The present study has been undertaken to evaluate the adsorption in batch mode of a disperse dye (Disperse Blue SBL) by poorly crystalline hydroxyapatite synthesized by coprecipitation between Ca(NO_3)_2 and (NH_4)_2HPO4 reagents in aqueous solution at room temperature. The adsorption experiments were carried out to investigate the factors that influence the dye uptake by the adsorbent, such as the contact time under agitation, adsorbent dosage, initial dye concentration, solution temperature, and pH. The e...     

化学发光法检测空气中NO_2研究

以0.2%的三乙醇胺水溶液作为二氧化氮吸收液,将空气中二氧化氮转化为亚硝酸盐,进而测出空气中二氧化氮的浓度。通过实验发现,进样方式、载流速度、硫酸浓度、溴酸钾浓度和酸性铬蓝K的浓度对该体系的发光强度都有影响,确定了体系的最优条件,建立了标准曲线,亚硝酸根的浓度在6.0×10-9～1.0×10-5mol/L范围内分段有很好的线性关系,检出限为8.5×10-11mol/L。对1.0×10-8mol/L和1.0×10-6mol/L的亚硝酸根进行11次平行测定,相对标准偏差分别为1.8%和2.2%。用该方法对氧化剂实验室空气中的二氧化氮含量进行了检测并进行标准加入和回收实验,回收率在95%～104%之间,该法可用于大气环境中的NO2测定。     

重庆市“蓝天行动”的历史回顾与新一轮实施发展

通过对2005年以来重庆市“蓝天行动”实施的历史回顾,梳理和总结出重庆市环境空气污染治理监管的成果和经验,并提出了新一轮“蓝天行动”(2018—2022年)以控制细颗粒物PM_2.5污染和减少臭氧污染为重点,以降低氮氧化物浓度为突破点,坚持全民共治、源头防治为目标,制定了“四控两增”针对性的防治工程措施。截止2020年,重庆市优良天数达到333天,PM_2.5年均浓度达到33μg/m³,空气质量评价六项指标首次实现有监测记录以来全部达标,为历史最好水平。     

Cladistic biogeographic analysis suggests an early Caribbean diversification in Mexico

The Great American Biotic Interchange has been the predominant paradigm for explaining biotic diversification in the Nearctic/Neotropical overlap or Mexican Transition Zone, which is commonly explained by the collision of the North and South American continental plates, which began in the Oligocene and fused both landmasses. In the most far-reaching cladistic biogeographical analysis of the area to date, evidence has been found supporting the existence of a remnant Caribbean region extending from eastern Mexico to southeastern USA, a hypothesis that challenges current views of the Great American Biotic Interchange and the Mexican Transition Zone. We show herein that an older terrane, which has drifted to the present day positions of Yucatan and Cuba, may be biogeographically linked to an early ‘Gondwanan’ biota of the Paleocene (ca. 60 Ma). The evidence indicates an east–west biotic divide in Mexico, existing before the collision and formation of Central America. The south–north division of the country, previously recognized by several authors as associated with the Great American Biotic Interchange and the Mexican Transition Zone, is of a younger age. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Enhanced photocatalytic activity of TiO2 by surface fluorination in degradation of organic cationic compound

Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.     

Electropolymerized poly（Toluidine Blue）-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0). Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs. Ag/AgCl. The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH. The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca. 30 samples/hr) at 4.1 mL/min. The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 mol/L (sensitivity: 0.318 A/( mol/L); correlation coefficient: 0.997). The lower detection limit was found to be 0.3 mol/L (S/N = 3).