Estimating non-native plant richness with a species-accumulation model along roads

Monitoring non-native plant richness is important for biodiversity conservation and scientific research. The species-area model (SA model) has been used frequently to estimate the total species richness within a region. However, the conventional SA model may not provide robust estimations of non-native plant richness because the ecological processes associated with the accumulation of exotic and native plants may differ. Because roads strongly dictate the distributions of exotic plants, we propose a species-accumulation model along roads (SR model), rather than an SA model, to estimate the non-native plant richness within a region. Using 270 simulated data sets, we compared the differences in performance between the SR and SA models. A decision tree based on prediction accuracy was created to guide model application, which was validated using field data from 3 national nature reserves in 3 different provinces in China. The SR model significantly outperformed the SA model when non-native species were restricted to the roadsides and the proportion of uncommon exotic species was small. More importantly, the SR model accurately estimated the non-native plant richness in all field sites with an error of <1 species per site. We believe our new model meets the practical need to efficiently and robustly estimate non-native plant richness, which may facilitate effective biodiversity conservations and promote research on non-native plant invasion and vegetation dynamics.     

Effects of biochar addition on the anaerobic digestion of carbohydrate-rich,protein-rich,and lipid-rich substrates

ABSTRACT

Although biochar addition into the anaerobic digestion of food waste (FW) is an efficient means to enhance methane production, the effects of biochar on various FW components remain unclear. Laboratory batch experiments were conducted to investigate the impact of sewage sludge-derived biochar (SSB) supplementation on the anaerobic digestion (AD) of major FW components, including carbohydrate-rich, protein-rich, and lipid-rich substrates. The lag phase of AD with the carbohydrate-rich substrate was 48.6% shorter when SSB was added, and the cumulative methane yield was 4.74 times higher compared to AD without biochar. SSB supplementation also increased the rate of methane production from the lipid-rich substrate. However, the effect of SSB addition on AD of the protein-rich substrate was minor. Analysis of the microbial communities revealed that methanogen growth was enhanced during AD of the carbohydrate-rich and lipid-rich substrates, but not the protein-rich substrate, following SSB supplementation. Also, the most dominant methanogenic genus varied with the substrates. SSB addition promoted the growth of hydrolytic and fermentative bacteria, particularly phylum Bacteroidetes.

Implications: Biochar supplementation has been studied to overcome the shortcomings of anaerobic digestion (AD). However, the effects of biochar on different substrates remain unclear. This study compared carbohydrate-rich, protein-rich, and lipid-rich substrates in anaerobic digestion with sewage sludge-derived biochar (SSB). SSB supplementation improved methane generation from all but the protein-rich substrate. The study results imply that the effect of SSB addition on AD varied with the substrate due to the substrates underwent different degradation processes with different microbial communities.     

Cut-off net acid generation pH in predicting acid-forming potential in mine spoils

Acidification of mine wastes can lead to a series of environmental problems, such as acid drainage, heavy metal mobilization, and ecosystem degradation. Prediction of acid-forming potential is one of the key steps in management of sulfide-bearing mine wastes. In this paper, the acid-forming potential of 180 mine waste samples collected from 17 mine sites in China were studied using a net acid generation (NAG) method. The samples contained different contents of total sulfur (ranging from 0.6 to 200 g kg(-1)), pyritic sulfur (ranging from 0 to 100 g kg(-1)), and acid neutralization capacity (ANC, ranging from -41 to 274 kg H2SO4 t(-1)). Samples with high acid-forming potential are generally due to their high sulfur content or low acid neutralization capacity. After the samples were oxidized by H2O2, the amounts of acid generation and the final NAG pH were measured. Results indicated that the final NAG pH gave a well-defined demarcation between acid-forming and non-acid-forming materials. Samples with final NAG pH >or= 5 could be classified as non-acid-forming materials, while those with NAG pH 2.5, but < 5, had low risk of being acid-forming. The confirmation of cut-off NAG pH will be used as a rapid and cost-effective operational monitoring tool for the in-pit prediction of acid-forming potential of mine wastes and classification of waste types.     

Anaerobic co-digestion of food waste and landfill leachate in single-phase batch reactors

In order to investigate the effect of raw leachate on anaerobic digestion of food waste, co-digestions of food waste with raw leachate were carried out. A series of single-phase batch mesophilic (35 ± 1 °C) anaerobic digestions were performed at a food waste concentration of 41.8 g VS/L. The results showed that inhibition of biogas production by volatile fatty acids (VFA) occurred without raw leachate addition. A certain amount of raw leachate in the reactors effectively relieved acidic inhibition caused by VFA accumulation, and the system maintained stable with methane yield of 369–466 mL/g VS. Total ammonia nitrogen introduced into the digestion systems with initial 2000–3000 mgNH₄–N/L not only replenished nitrogen for bacterial growth, but also formed a buffer system with VFA to maintain a delicate biochemical balance between the acidogenic and methanogenic microorganisms. UV spectroscopy and fluorescence excitation–emission matrix spectroscopy data showed that food waste was completely degraded.We concluded that using raw leachate for supplement water addition and pH modifier on anaerobic digestion of food waste was effective. An appropriate fraction of leachate could stimulate methanogenic activity and enhance biogas production.     

污泥脱水絮凝剂消耗的控制措施

污泥脱水是污水处理中的一个重要环节,影响脱泥用药(絮凝剂)的因素很多.水厂结合实验分析,发现污泥脱水中不同参数对耗药率影响较大.因此,采取了相应的工艺控制方法,在保障运行效率的基础上,有效降低污泥脱水运行成本.     

浅谈石化企业员工心理健康管理模式的建立

分析了国内外企业员工心理健康管理实施现状,阐述了石化企业引入员工心理健康管理模式的重要性和必要性,提出加强心理健康管理模式建设的建议.     

氧化亚铁硫杆菌脱除不同煤种硫分实验研究

利用氧化亚铁硫杆菌对煤中硫分的脱除作用,探讨了其对3种不同地域且不同矿物含量煤的脱硫作用。进行了未酸化与酸化处理煤样脱硫试验、温度影响试验、初始pH值影响试验。结果表明：未预处理条件下煤样I、n、Ⅲ的脱硫率分别为29．3％、3．9％、3．5％,酸处理后迭到39．8％、40．7％、4．2％。煤样Ⅰ、Ⅱ的最佳脱硫温度分别为35℃、30℃;温度30℃,初始pH为2．3时,煤样Ⅰ、Л的脱硫效果最好,分别为54％、67％;温度和pH的变化对煤样山的影响不大。30℃,初始pH为2．3时煤样Ⅰ、Ⅱ、Ⅲ的黄铁矿硫去除率分别为77％、83％、67％。     

炼厂罐区排气减排及集中收集设计

在对储罐排气达标治理时,首先需要采用源头减排措施,减少储罐排气量。在此基础上,核算储罐排气量、吸气量及安全承压等,设计合理的储罐氮气保护系统、储罐排气集中收集系统、罐区排气压力控制系统,实现储罐排气密闭收集和罐区安全稳定运行。某炼油厂储运部21台储罐在正常工况时其大呼吸和小呼吸最大吸气量为876m3/h;但当遇暴雨时,罐区瞬时最大吸气量为2760m3/h,以0.6MPa氮气为补氮源,补氮总管管径需设计为DN100;该罐区最大排气量876m3/h,为了满足储罐排气安全输送,排气收集总管管径需设计为DN200。以混合二甲苯储罐为例,核算了储罐的承压压力、呼吸阀工作压力等,设置储罐排气操作压力范围为600~1200Pa、补氮操作压力范围为200~500Pa。     

Urban air quality, meteorology and traffic linkages: Evidence from a sixteen-day particulate matter pollution event in December 2015, Beijing

A heavy 16-day pollution episode occurred in Beijing from December 19, 2015 to January 3,2016. The mean daily AQI and PM_(2.5) were 240.44 and 203.6 μg/m~3. We analyzed the spatiotemporal characteristics of air pollutants, meteorology and road space speed during this period, then extended to reveal the combined effects of traffic restrictions and meteorology on urban air quality with observational data and a multivariate mutual information model. Results of spatiotemporal analysis showed that five pollution stages were identified with remarkable variation patterns based on evolution of PM_(2.5) concentration and weather conditions. Southern sites(DX, YDM and DS) experienced heavier pollution than northern ones(DL, CP and WL). Stage P2 exhibited combined functions of meteorology and traffic restrictions which were delayed peak-clipping effects on PM_(2.5).Mutual information values of Air quality–Traffic–Meteorology(ATM–MI) revealed that additive functions of traffic restrictions, suitable relative humidity and temperature were more effective on the removal of fine particles and CO than NO_2.