改性聚乙烯醇吸附镍离子的动力学与热力学研究

研究了自制改性聚乙烯醇对Ni~(2+)的吸附行为,在不同的吸附条件下,探讨相关因素的影响,并对实验数据进行动力学与热力学的拟合。结果表明,室温下,在溶液p H=6.0,NaNO_3的浓度为0.1 mol/L,吸附时间为60 min,液固比为250 m L/g,改性聚乙烯醇对浓度为0.1 mol/L Ni2+的吸附效果好,去除率达到98.05%;当干扰因子设定为0.1 mol/L的Ca(NO_3)_2,对Ni2+的去除率降到59.29%。改性聚乙烯醇对Ni2+的吸附动力学符合准二级动力学方程;Langmuir等温模型的拟合度较高,推测改性聚乙烯醇表面是均一的等质体,计算的最大吸附量为1.35 mmol/g,与实验结果一致;D-R等温模型的拟合度次之,在各温度下,E16 k J/mol,说明改性聚乙烯醇对Ni2+的吸附是以化学吸附为主。通过Van’t Hoff方程的拟合,计算得到的吉布斯自由能以及熵变和焓变表明该吸附过程为吸热化学反应。     

Removal of nutrients and veterinary antibiotics from swine wastewater by a constructed macrophyte floating bed system

The potential of three varieties of Italian ryegrass (Lolium multiflorum Lam.), Dryan, Tachimasari and Waseyutaka, to improve the water quality of swine wastewater was evaluated using a constructed macrophyte floating bed system. With respect to reductions in levels of nutrients, chemical oxygen demand (COD), and sulfonamide antimicrobials (SAs, including sulfadiazine, sulfamethazine, and sulfamethoxazole), Dryan performed better than Tachimasari and Waseyutaka. For Dryan, total N was reduced by 84.0%, total P by 90.4%, COD by 83.4% and sulfonamide antimicrobials by 91.8–99.5%. Similar results were observed for Tachimasari and Waseyutaka. The results indicated that the treatment of swine wastewater using the constructed macrophyte floating bed system was effective in the removal of nutrients and veterinary antibiotics.     

生态旅游环境容量研究进展

生态旅游环境容量是在生态旅游研究成熟后的另一个热点,通过对国内外相关文献梳理后发现,国外对生态旅游环境容量的研究起步较早、成果颇丰、用途广泛且研究体系自成一脉,国内对生态旅游环境研究取得成绩的同时还有很多不足,特别是现有的测量方法已落后于生态旅游的发展,今后需系统梳理生态旅游容量的理论,并在理论指导下提出适合自身的动态测量模式,进一步向旅游环境容量综合管理转变。     

Population genetics of Crassostrea ariakensis in Asia inferred from microsatellite markers

Crassostrea ariakensis is an important aquacultured oyster species in Asia, its native region. During the past decade, consideration was given to introducing C. ariakensis into Chesapeake Bay, in the United States, to help revive the declining native oyster industry and bolster the local ecosystem. Little is known about the ecology and biology of this species in Asia due to confusion with nomenclature and difficulty in accurately identifying the species of wild populations in their natural environment. Even less research has been done on the population genetics of native populations of C. ariakensis in Asia. We examined the magnitude and pattern of genetic differentiation among 10 wild populations of C. ariakensis from its confirmed distribution range using eight polymorphic microsatellite markers. Results showed a small but significant global θ _ST (0.018), indicating genetic heterogeneity among populations. Eight genetically distinct populations were further distinguished based on population pairwise θ _ST comparisons, including one in Japan, four in China, and three populations along the coast of South Korea. A significant positive association was detected between genetic and geographic distances among populations, suggesting a genetic pattern of isolation by distance. This research represents a novel observation on wild genetic population structuring in a coastal bivalve species along the coast of the northwest Pacific.     

Effectiveness of protected areas for vertebrates based on taxonomic and phylogenetic diversity

Establishing protected areas is the primary goal and tool for preventing irreversible biodiversity loss. However, the effectiveness of protected areas that target specific species has been questioned for some time because targeting key species for conservation may impair the integral regional pool of species diversity and phylogenetic and functional diversity are seldom considered. We assessed the efficacy of protected areas in China for the conservation of phylogenetic diversity based on the ranges and phylogenies of 2279 terrestrial vertebrates. Phylogenetic and taxonomic diversity were strongly and positively correlated, and only 12.1–43.8% of priority conservation areas are currently protected. However, the patterns and coverage of phylogenetic diversity were affected when weighted by species richness. These results indicated that in China, protected areas targeting high species richness protected phylogenetic diversity well overall but failed to do so in some regions with more unique or threatened communities (e.g., coastal areas of eastern China, where severely threatened avian communities were less protected). Our results suggest that the current distribution of protected areas could be improved, although most protected areas protect both taxonomic and phylogenetic diversity.     

Nitrous oxide generation in denitrifying phosphorus removal process: main causes and control measures

Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N₂O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N₂O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N₂O generation, based on which the control measures were subsequently proposed. The results showed that N₂O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N₂O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N₂O reductase for electrons and the high nitrite accumulation were the two main causes for N₂O generation, evidenced by N₂O production and reduction rates under different conditions. Accordingly, the reduction of N₂O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N₂O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N₂O generation by around 69.8 %.     

Impacts of Dung Combustion on the Carbon Cycle of Alpine Grassland of the North Tibetan Plateau

Alpine grassland of Tibet is a frangible ecosystem in terms of carbon (C) emission. Yak dung is an important resident energy with about 80 % of yak dung combusted for energy in the north Tibetan plateau. This paper investigated the impact of dung combustion on the C cycle of the alpine grassland ecosystem in north Tibet, China. During the growing season of 2011, from a field survey and household questionnaires, the main impacts of dung collection for fuel on the C cycle of the ecosystem were identified. (1) The C sequestration and storage capacity, including the dung-derived C stored in soil and C captured by vegetation, decreased. The net primary production decreased remarkably because of the reduction of dung returned to soil. (2) In a given period, more C was emitted to the atmosphere in the dung combustion situation than that in the dung returned to soil situation. (3) The energy grazing alpine meadow ecosystem changed into a net C source, and the net biome production of the ecosystem dropped to ?15.18 g C/m² year in the dung combustion situation, 42.95 g C/m² year less than that in the dung returned situation. To reduce the CO₂ emission derived from dung use, the proportion of dung combustion should be reduced and alternative renewable energy such as solar, wind, or hydro energy should be advocated, which is suitable for, and accessible to, the north Tibetan plateau.     

Reviewing the strategies for climate change and sustainability after the US defiance of the Paris Agreement: an AHP–GMCR-based conflict resolution approach

Environment, Development and Sustainability - In the landmark Paris Agreement, the global economies agreed to put forward their best efforts in mitigation and adaptation of climate change. The...     

Nutrient removal from biogas slurry and biogas upgrading by microalgae-fungi-bacteria co-cultivation under different carbon nanotubes concentration

In this study, Chlorella vulgaris, Ganoderma lucidum, and endophytic bacteria were co-cultivated with the stimulation of strigolactone analogs GR24 to prepare pellets. During the purification of biogas slurry and biogas, multi-walled carbon nanotubes (MWCNTs) were introduced to enhance the removal efficiencies of nutrients and CO₂. The results showed that both GR24 and MWCNTs affected the purification of biogas slurry and biogas. The maximum chemical oxygen demand, total nitrogen, total phosphorus, and CO₂ removal efficiencies of the Chlorella vulgaris-Ganoderma lucidum-endophytic bacterial symbionts were 82.57 ± 7.96% (P < 0.05), 82.14 ± 7.87% (P < 0.05), 84.27 ± 7.96% (P < 0.05), and 63.93 ± 6.22% (P < 0.05), respectively, with the induction of 10⁻⁹ M GR24 and 1 mg L⁻¹ MWCNTs. Moreover, the growth and photosynthetic performance of the symbionts were consistent with the removal effects. The Chlorella vulgaris-Ganoderma lucidum-endophytic bacterial symbionts obtained high growth rates and enzyme activity with the maximum growth rate of 0.365 ± 0.03 d⁻¹, mean daily productivity of 0.182 ± 0.016 g L⁻¹ d⁻¹, and carbonic anhydrase activity of 31.07 ± 2.75 units, respectively. These results indicated that an appropriate concentration of GR24 and MWCNTs could promote the growth of symbionts, reinforce the purification effects of biogas slurry and biogas, and provide a new idea for the simultaneous purification of wastewater and biogas.

     

东江流域水环境中颗粒态和胶体态金属元素的分布和来源

运用连续流离心机和切面流超滤分离技术,从东江流域的水库、河流、河口3种水体中分离了大量的悬浮颗粒物(0.45μm)和胶体(1 nm~0.45μm),并用元素分析仪和电感耦合等离子体/质谱(ICP-MS)对有机碳和金属进行了表征.通过对比3种水体中颗粒态金属的含量(μg·g-1)和浓度(ng·L-1)发现,水库颗粒物有更高的重金属含量,与其在有机碳上的富集有关;河流颗粒物有更高的金属浓度,与地表径流和人为排放有关.另外,随着有机质含量的增加,湖泊水体中多种重金属的含量呈现先增加后降低的关系,显示了生物富集和生物稀释的双重作用.从东江中游到河口样品,Mg、Ti、Co、Ni等元素在颗粒物中的含量依次升高,Cu、As、Cd、Sn、Sb等元素则依次降低,这与海水的稀释作用以及与盐度变化引起的絮凝沉降有关.河流中胶体态金属的含量与浓度均大于水库,显示了河流受到更多的人类活动影响.虽然重金属主要分布在颗粒物中,但对比各种重金属的含量在颗粒态和胶体态中的顺序变化,发现地表径流带来的地壳元素倾向于分布在颗粒态中,而人为排放来源的金属倾向于分布在胶体态中.