A novel integrated step-feed biofilm process for the treatment of decentralized domestic wastewater in rural areas of China

For wastewater treatment in rural areas, a novel three-stage step-feed wastewater treatment system, combined with a drop-aeration biofilm process, was tested in the laboratory to investigate its performance in removing suspended solids (SS), chemical oxygen demand (COD), NH4+-N, total nitrogen (TN), and total phosphorus (TP). The removal rates of SS, COD and NH4+-N were 90%, 80%, and 90% in efluent concentrations less than 10 mg/L, 50 mg/L and 8 mg/L, respectively. The TP removal rate was less satisfactory....     

煤吸附硫化氢混合气体的试验研究*

为研究煤层硫化氢（H2S）吸附特性,厘清煤层H2S赋存规律及改善H2S防治效果,采用分压测试法研究煤对H2S的吸附规律。以山西保利铁新煤业有限公司9#煤为研究对象,分别使用N2,He/H2S,N2/H2S为吸附介质开展等温吸附试验,分析煤对H2S及含H2S混合气体的吸附特性及影响因素。结果表明:煤对H2S的吸附量随压力升高而增加,随温度升高而降低,且温度对煤吸附H2S吸附量影响较大;H2S及N2/H2S混合气体的吸附曲线均符合Langmuir吸附模型,煤吸附N2/H2S混合气体时,H2S和N2存在竞争吸附,且N2吸附能力优于H2S;等温条件下,N2竞争吸附量随吸附压力的增加而增大,等压条件下,N2的竞争吸附量受温度影响较小。     

New molecular method to detect denitrifying anaerobic methane oxidation bacteria from different environmental niches

The denitrifying anaerobic methane oxidation is an ecologically important process for reducing the potential methane emission into the atmosphere. The responsible bacterium for this process was Candidatus Methylomirabilis oxyfera belonging to the bacterial phylum of NC10. In this study, a new pair of primers targeting all the five groups of NC10 bacteria was designed to amplify NC10 bacteria from different environmental niches. The results showed that the group A was the dominant NC10 phylum bacteria from the sludges and food waste digestate while in paddy soil samples, group A and group B had nearly the same proportion. Our results also indicated that NC10 bacteria could exist in a high pH environment (pH 9.24) from the food waste treatment facility. The Pearson relationship analysis showed that the pH had a significant positive relationship with the NC10 bacterial diversity (p < 0.05). The redundancy analysis further revealed that the pH, volatile solid and nitrite nitrogen were the most important factors in shaping the NC10 bacterial structure (p = 0.01) based on the variation inflation factors selection and Monte Carlo test (999 times). Results of this study extended the existing molecular tools for studying the NC10 bacterial community structures and provided new information on the ecological distributions of NC10 bacteria.     

Plants with phytotoxic potential: Wollemi pine (Wollemia nobilis)

Herbicide resistance in annual ryegrass (ARG, Lolium rigidum) threatens the quality and yield of winter wheat crops in Australia, prompting research to discover novel natural plant compounds with herbicidal properties. Due to its novel nature and potentially interesting chemistry, the Australian native, Wollemi pine (Wollemia nobilis), was tested for its ability to suppress ARG growth and its feasibility for use in weed control strategies. The leaf extract of Wollemi pine significantly inhibited the growth of ARG and wild radish (Raphanus raphanistrum) in laboratory bioassays at concentrations above 1% extract. In soil trials, the 100% extract (100 g dried plant material/L) inhibited the dry weight of ARG by 25%. The addition of a wetting agent to the extract increased the suppression of ARG to 80% which was as phytotoxic as a 4-fold increase in the extract concentration (“400%” extract). Using bioassay-guided fractionation, the most phytotoxic fraction was identified and further analysed via GC/MS. Several compounds not previously identified in Wollemi pine leaf extracts have been identified, namely, 2-propylphenol, 3,4-dimethoxyphenol, 2-methoxybenzoic acid, vanillyl alcohol and isovanillic acid. These results suggest that Wollemi pine is an important potential source of compounds for the control of ARG and wild radish in winter crops.     

近50 a甘肃省气象干旱时空变化分析

气象干旱是影响人类社会最严重的气象灾害之一,且对中纬度干旱半干旱地区的危害更为显著。为探究气候变化背景下我国甘肃地区干旱事件的时空分布,首先根据甘肃1969—2018年月值气象资料计算标准化降水蒸散指数（SPEI）,通过游程理论提取干旱事件。随后采用REOF旋转正交分解将研究区划分成5个气候子区,并以每个子区为单位,基于B-G分割算法细致对比各子区不同时间尺度干旱事件的变化特征和演变趋势。最后,采用相关性分析探究各子区干旱事件的驱动因素。主要结论有：（1）研究区干旱累积历时呈微弱增加趋势（0.475 d·(10a)⁻¹）并存在19 a的主周期,干旱强度呈先缓和再加剧趋势,尤其是2000年后干旱加剧显著,并呈现出西北部干旱减轻、东南部干旱加剧的空间变化趋势。（2）REOF分解的前五个模态累积贡献率为53.06%,主要的空间分布模态为：全区一致型模态和南北反向分异模态。将研究区分为5个干旱子区：河西地区、河东中部地区、河东东部地区、乌鞘岭地区和河东西部地区。（3）河西地区自1988年以来气象干旱显著缓和（P＜0.01）;河东东、中、西部地区存在不同程度的干旱加剧趋势（0.120·(10a)⁻¹、0.129·(10a)⁻¹、0.072·(10a)⁻¹,P＞0.05）;乌鞘岭地区在1975年以后气象干旱显著缓和（P＜0.01）,形成了干旱缓和与加剧变化的分水岭区域。（4）季节上,河西地区仅夏季呈缓和趋势;河东东部地区春季呈显著干旱化趋势,而秋季相反;河东西部地区春夏两季气候干旱化趋势明显而秋冬两季相反;河东中部地区和乌鞘岭地区季节变化呈明显一致性,前者四季均呈干旱化趋势,且春季干旱化最剧烈,后者四季均呈缓和趋势,且冬季最明显。（5）研究区气象干旱受当地气候因子和环流因子因素的共同影响,河西地区和河东西部地区对气温的响应明显而河东中、东部地区则对降水量的响应明显;乌鞘岭地区对日照时数的响应明显;NAO指数对研究区夏季气象干旱存在重要影响而ENSO事件（厄尔尼诺-南方涛动）对研究区春秋两季（尤其是春季）气象干旱存在重要影响。     

全过程管理视角的上海市垃圾分类回顾与展望

为掌握分类投放全面推广对城市生活垃圾全过程管理的影响,系统回顾了上海生活垃圾分类的推行历程,从生命周期角度预测了不同分类水平下上海生活垃圾处理与处置的环境效应。上海垃圾分类经历了试点、推广、调整、强制推广4个阶段,指导思路从资源化主导转变为"减量化、资源化、无害化"并行,减量效果从调整阶段开始逐渐显现,其他垃圾热值提高。在模拟的8种场景中,当湿垃圾、可回收物、其他垃圾混合投放并处置时,总环境影响潜值最高,达到1.22×10-13 PET₂₀₀₀/t;湿垃圾、可回收物、其他垃圾分出量占比分别为30%、20%和50%时(上海市生活垃圾厌氧消化、焚烧和回收的最大处理能力分别占总处理能力的25%、60%和15%),可实现原生垃圾零填埋,并获得最佳环境效益,环境影响潜值降为8.13×10-14 PET₂₀₀₀/t。从生活垃圾全过程管理角度看,分类投放是前提条件,配套适当的处理处置设施才能更好地显现环境效益优势。     

我国36个重点城市饮用水中多环芳烃健康风险评价

分别用2种基于不确定性的风险评价方法(蒙特卡洛法和三角模糊数法)和1种基于确定性的风险评价方法(美国EPA终身致癌风险)对我国36个重点城市饮用水中多环芳烃的终生致癌风险进行评价。所研究的98个水厂出水中多环芳烃浓度范围为17.5~408.3 ng·L-1,致癌性多环芳烃(苯并[a]蒽,屈,苯并[b]荧蒽,苯并[k]荧蒽,苯并[a]芘,茚并[1,2,3-cd]芘)的总量浓度为nd~94.7 ng·L-1。所有水厂出水中苯并[a]芘浓度均小于10 ng·L-1。假设出厂水即为最终饮用水,对16种PAHs浓度用毒性当量因子法转化为相对于苯并[a]芘等效浓度(TEQ BaP)。使用概率风险评价方法计算,结果显示在95%的概率区间我国居民通过饮水途径暴露多环芳烃的终生致癌风险小于5.45×10-6(蒙特卡洛法)和7.56×10-6(三角模糊数法)。而采用确定性风险评价方法,计算得到的最大风险为7.12×10-6。两种计算方法得到的我国饮用水中多环芳烃的终生致癌风险都处于可接受水平。比较不同的评价方法后发现,不同方法获得的信息并不完全重合,相对于通常的基于确定性的非概率健康风险评价方法,基于不确定性的概率风险评价方法获得的结果更为保守。     

喀斯特高镉地质背景区水稻镉的富集、转运特征与机理

西南喀斯特地区土壤镉(Cd)具有"高地质背景、低污染风险"特征,但超过《土壤环境质量农用地土壤污染风险管控标准》风险管制值的区域是否仍具有低风险性,是迫切需要回答的问题.本文在罗甸县喀斯特峰丛谷地选择一个高Cd 土壤水稻种植区,开展土壤-水稻系统Cd含量特征和土壤Cd赋存形态等方面的研究,评价水稻各部位Cd的富集、转运...     

Modelling tritrophic interactions mediated by induced defence volatiles

Many plant species defend themselves against herbivorous insects indirectly by producing and releasing induced volatiles to attract natural enemies of the herbivores. In this paper, we consider the recruitment of natural enemies attracted by plant-induced volatiles and introduce the An–Liu–Johnson–Lovett model into the Lotka–Volterra model in an attempt to add this missing vital link in tritrophic interaction. Increase in attraction strength of plant-induced volatiles to the natural enemy leads to high fluctuation amplitude of plant biomass and herbivore population. When the attack strength of natural enemies reaches a certain level, fluctuation amplitude of plant biomass and herbivore population will decrease and plant biomass will approach to its environmental carrying capacity. The simulation demonstrates that plant volatile compounds induced by insects have led to the introduction of a third tritrophic level, e.g., natural enemies, into the plant–herbivore system, resulting in the coexistence of plants, insects, and natural enemies during the evolution process.