北部湾南流江流域土地覆盖及生物多样性模拟

以北部湾独流入海河流南流江流域为研究对象,基于研究区2000年和2015年遥感数据解译的土地利用数据以及社会经济等数据,采用CLUE-S模型对未来2030年生态保护情景、自然增长情景以及粮食安全情景的土地利用格局进行了模拟预测,在此基础上采用InVEST模型对流域过去和未来不同情景的生物多样性进行了评估,探讨了流域生物多样性的生境质量和生境退化程度.结果表明：2000~2015年南流江流域建设用地、园地、水域和未利用地呈现出增加趋势,其中建设用地的增幅最大,而耕地和林地减幅最大.流域土地系统中共存在着34种土地网络转移流关系,上游存在24种,中游20种,下游28种,耕地与建设用地、耕地与林地以及林地与园地之间的转换占到流域总土地利用变化的70.74%.CLUE-S模型模拟未来土地利用的Kappa系数达到0.86,表明模型模拟未来情景的土地利用精度满足要求.2000年、2015年、2030年生态保护情景、2030年自然增长情景以及2030年粮食安全情景流域生境质量总得分和平均得分分别为866630,900357,921055,876231,865370和0.7457,0.7747,0.7925,0.7539,0.7466.2030年3种情景的中上游和下游地区生物多样性都呈现出不同程度的改善趋势,而中游地区则表现出退化趋势.     

Performance of different macrophytes in the decontamination of and electricity generation from swine wastewater via an integrated constructed wetland-microbial fuel cell process

Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH_4~+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH_4~+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m~3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.     

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli: Effects of Fe3+, ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials, and thus, the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag⁺ ratios. Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays, and shifts to both Ag particles and released Ag⁺ in 48 hr bioassays. Herein, as a continued study, the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically. The cytotoxicity and mechanisms of nano-Ag colloids are dynamic throughout exposure and are derived from both Ag ions and particles. Ag accumulation by E. coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure, and thereafter mainly from intracellular Ag ions. Fe³⁺ accelerates the oxidative dissolution of nano-Ag colloids, which results in decreasing amounts of Ag particles and particle-related toxicity. Na⁺ stabilizes nano-Ag colloids, thereby decreasing the bioavailability of Ag particles and particle-related toxicity. Humic acid (HA) binds Ag⁺ to form Ag⁺-HA, decreasing ion-related toxicity and binding to the E. coli surface, decreasing particle-related toxicity. HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na⁺ or Fe³⁺. The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors, and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.     

Development of a static test apparatus for evaluating the performance of three PM2.5 separators commonly used in China

PM_(2.5) separator directly affects the accuracy of PM_(2.5) sampling.The specification testing and evaluation for PM_(2.5) separator is particularly important,especially under China's wide variation of terrain and climate.In this study,first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM_(2.5) separators.A uniform mixing chamber was developed to make particles mix completely.The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%,and the particle size distribution obeyed logarithmic normal distribution with an R~2 of 0.996.The flow rate deviation between the measurement and the set point flow rate agreed to within ± 1.0% in the range of -40 to 50℃.Secondly,the separation,flow and loading characteristics of three cyclone separators(VSCC-A,SCC-A and SCC112) were evaluated using this system.The results showed that the 50% cutoff sizes(D_(50)) of the three cyclones were 2.48,2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates,respectively.The geometric standard deviation(GSD) of the capture efficiency of VSCCA was 1.23,showed a slightly sharper than SCC-A(GSD = 1.27),while the SCC112 did not meet the relevant indicator(GSD = 1.2 ± 0.1) with a GSD = 1.44.The flow rate and loading test had a great effect on D_(50),while the GSD remained almost the same as before.In addition,the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.     

Synergistic effects of Cu species and acidity of Cu-ZSM-5 on catalytic performance for selective catalytic oxidation of n-butylamine

In this work, a series of Cu-ZSM-5 catalysts with different SiO₂/Al₂O₃ ratios (25, 50, 100 and 200) were synthesized and investigated in n-butylamine catalytic degradation. The n-butylamine can be completely catalytic degradation at 350°C over all Cu-ZSM-5 catalysts. Moreover, Cu-ZSM-5 (25) exhibited the highest selectivity to N₂, exceeding 90% at 350°C. These samples were investigated in detail by several characterizations to illuminate the dependence of the catalytic performance on redox properties, Cu species, and acidity. The characterization results proved that the redox properties and chemisorption oxygen primarily affect n-butylamine conversion. N₂ selectivity was impacted by the Brønsted acidity and the isolated Cu²⁺ species. Meanwhile, the surface acid sites over Cu-ZSM-5 catalysts could influence the formation of Cu species. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra was adopted to explore the reaction mechanism. The Cu-ZSM-5 catalysts are the most prospective catalysts for nitrogen-containing volatile organic compounds removal, and the results in this study could provide new insights into catalysts design for VOC catalytic oxidation.     

UV/H2O2 oxidation of tri(2-chloroethyl) phosphate: Intermediate products, degradation pathway and toxicity evaluation

Tri(2-chloroethyl) phosphate (TCEP) with the initial concentration of 5 mg/L was degraded by UV/H₂O₂ oxidation process. The removal rate of TCEP in the UV/H₂O₂ system was 89.1% with the production of Cl^? and PO₄^3? of 0.23 and 0.64 mg/L. The removal rate of total organic carbon of the reaction was 48.8% and the pH reached 3.3 after the reaction. The oxidative degradation process of TCEP in the UV/H₂O₂ system obeyed the first order kinetic reaction with the apparent rate constant of 0.0025 min^?1 (R²=0.9788). The intermediate products were isolated and identified by gas chromatography-mass spectrometer. The addition reaction of HO? and H₂O and the oxidation reaction with H₂O₂ were found during the degradation pathway of 5 mg/L TCEP in the UV/H₂O₂ system. For the first time, environment risk was estimated via the “ecological structure activity relationships” program and acute and chronic toxicity changes of intermediate products were pointed out. The luminescence inhibition rate of photobacterium was used to evaluate the acute toxicity of intermediate products. The results showed that the toxicity of the intermediate products increased with the increase of reaction time, which may be due to the production of chlorine compounds. Some measures should be introduced to the UV/H₂O₂ system to remove the highly toxic Cl-containing compounds, such as a nanofiltration or reverse osmosis unit.     

Polycyclic aromatic hydrocarbons in benthos of the northern Bering Sea Shelf and Chukchi Sea Shelf

Eighteen polycyclic aromatic hydrocarbons (PAHs) were detected in benthos collected onboard the ‘Snow Dragon’ in the Northern Bering Sea Shelf and Chukchi Sea Shelf during the 6^th Chinese National Arctic Research Expedition (CHINARE 2014). Σ₁₈PAHs for all biota samples ranged from 34.2 to 128.1 ng/g dry weight (dw), with the highest concentration observed in fish muscle (Boreogadus saida) samples close to St. Lawrence Island. The PAH composition pattern was dominated by the presence of lighter 3 ring (57%) and 2 ring (28%) PAHs, indicating oil-related or petrogenic sources as important origins of PAH contamination. Concentrations of alkyl-PAHs (1-methylnaphthalene and 2-methylnaphthalene) were lower than their parent PAH (naphthalene) in all biological tissue, and their percentage also decreased significantly (p<0.05) compared with those in the corresponding sediment. There were no significant relationships between PAH concentrations and trophic levels, which is possibly due to the combined results of the complex benthic foodweb in the subarctic/Arctic shelf region, as well as a low assimilation/effective metabolism for PAHs. According to toxic potency evaluation results from TCDD toxic equivalents (TEQs) and BaP-equivalent (BaPE) values, whelk (Neptunea heros) and starfish (Ctenodiscus crispatus) are two macroinvertebrate species showing relatively higher dioxin-like toxicity and carcinogenic risk.     

固体样品六价铬的检测比对和验证

采用碱溶液提取/火焰原子吸收法(HJ 687—2014《固体废物六价铬的测定 碱消解/火焰原子吸收分光光度法》和HJ 1082—2019《土壤和沉积物 六价铬的测定 碱溶液提取-火焰原子吸收分光光度法》)测定了固体废物和土壤样品中六价铬含量,比对和验证了2种方法实验流程、分析方法性能及不确定度评定结果。结果表明:HJ 687—2014的方法检出限相对较高,不适合测定浓度较低的土壤;HJ 1082—2019要求按照试样制备的步骤配置工作曲线,考虑了基体干扰的影响。HJ 687—2014的检出限为0.28 mg/kg,相对标准偏差为0.69%~0.93%,样品加标回收率为95.7%~97.2%;HJ 1082—2019的检出限为0.17 mg/kg,相对标准偏差为0.6%~3.0%,样品加标回收率为76.0%~83.1%。对于同一实际样品,2种方法的测定结果相近,HJ 687—2014和HJ 1082—2019的测定结果分别为(48.1±4.2),(46.6±5.4) mg/kg。比对发现,影响HJ 687—2014和HJ 1082—2019不确定度的最主要环节分别为曲线拟合和样品消解。     

白洋淀流域地表水化学特征及控制因素

为探究半干旱区地表水化学特征及物质来源,以白洋淀流域为研究对象,利用Piper三线图和Gibbs水岩模型,对地表水的主要离子组成特征及其来源进行分析。结果表明:白洋淀流域地表水pH为7.56~8.23时,呈弱碱性,且溶解性总固体（TDS,100~650 mg/L）在流域的不同空间区域表现为淀区 > 下游 > 上游。白洋淀流域地表水阳离子以Na+和Ca2+为主,离子总量占比76.60%;阴离子以HCO₃-为主,约占阴离子总量61.52%。地表水的水化学类型为HCO₃-Ca型（上游水体）和HCO₃·SO₄·Cl-Na·Ca型（下游河流和淀区）。白洋淀水文地球化学过程受到人类活动和自然作用的双重控制;自然作用下,白洋淀流域地表水中的离子来源于岩石风化（碳酸盐岩及硅酸盐岩的风化溶解）,同时受到蒸发-结晶作用影响。     

全球海洋初级生产力与海洋环境要素时空关联模式挖掘分析

全球海洋初级生产力在海洋环境要素的驱动下呈现不同的时空分布特征,但在不同的海域两者之间的关联模式并不清晰。本文从地理时空规则挖掘的角度,利用1998年1月—2016年12月之间的序列多源遥感产品数据,探讨了全球海洋初级生产力和海洋表面温度、海面高度异常、海面降雨、混合层深度和ENSO（El Ni?o-Southern Oscillation）事件的时空关联模式。研究结果表明:1）在西赤道太平洋,海面高度异常降低、海面降雨异常降低和混合层深度异常升高会提升真光层营养盐供应,致使海洋初级生产力的异常升高。2）在中赤道太平洋,海面高度异常升高、海面降雨异常升高和混合层深度异常降低会抑制真光层营养盐供应,致使海洋初级生产力的异常降低。3）在东赤道太平洋,海面高度异常升高和海面降雨异常升高会抑制真光层营养盐供应、混合层深度异常升高降低了铁元素含量,从而导致海洋初级生产力的异常降低。4）在南太平洋,浮游植物丰度与营养盐呈负相关,海洋表面温度异常升高/异常降低会提升/抑制微生物光合作用效率、海面高度的异常升高/异常降低会抑制/提升真光层营养盐供应,致使海洋初级生产力的异常升高/异常降低。5）厄尔尼诺事件相较于拉尼娜事件更容易引起海洋初级生产力的异常变化。