不同混合方案对气溶胶辐射特性的影响

利用体积权重平均,Maxwell-Garnett和Bruggeman理论,分别处理半径为0.5 μm 75%H₂SO₄气溶胶和黑碳气溶胶(BC),以及硫酸盐气溶胶与黑碳气溶胶内混合的情况,求出其复折射指数.利用Mie理论计算内混合单个气溶胶粒子在0.55 μm波长处的辐射特性参量,其目的在于比较分析3种不同混合方案处理的同一混合情况下内混合单个气溶胶粒子辐射特性的差别. 结果表明:辐射特性的总体变化趋势大致相同,但采用不同的混合方案处理相同的内混合情况时,其结果在黑碳混合比为10%～30%时差异较大.      

京津冀与长三角地区氢氯氟碳化物本底特征

基于北京上甸子与浙江临安区域大气本底站2011—2019年氢氯氟碳化物(HCFCs)采样观测数据,开展了京津冀与长三角地区6种HCFCs(HCFC-22、HCFC-141b、HCFC-142b、HCFC-124、HCFC-132b和HCFC-133a)本底特征研究。研究结果表明:临安站HCFCs浓度水平和浓度变率比上甸子站明显更高,尤其是HCFC-133a,其浓度及浓度变率均比上甸子站高1个量级,表明长三角地区HCFCs排放量可能较京津冀地区更大。2个站点HCFCs本底浓度基本一致,差异范围为-6.1%~7.1%。上甸子站本底数据占比为26.4%~69.0%,而临安站本底数据占比不足23%。在《关于消耗臭氧层物质的蒙特利尔议定书》的约束下,2个站点多数HCFCs年均浓度呈下降趋势或变化较小。2个站点HCFC-132b浓度相对较低,但2019年相比2018年有明显升高。结合风向进行分析,发现上甸子站HCFC-22、HCFC-141b、HCFC-142b和HCFC-132b高浓度水平主要由西南扇区(北京城区方向)的WSW、SSW及SW方向贡献,而HCFC-124和HCFC-133a在各风向上的浓度和载荷差异较小。临安站HCFC-124高浓度水平主要由SSE和NNE方向贡献,分别对应金华和湖州方向;其他5种HCFCs的高浓度水平主要由东北扇区的ENE方向贡献,对应杭州城区方向。     

Urinary dialkyl phosphate levels before and after first season chlorpyrifos spraying amongst farm workers in the Western Cape,South Africa

The study investigated urinary levels of dialkyl phosphates resulting from pesticide exposure amongst 40 farm workers. Workers were tested (urinary dialkyl phosphate levels, anthropometry, short exposure questionnaire) before and after the first day of seasonal chlorpyrifos spraying. Median baseline urinary dialkyl phosphates was high amongst both non-applicators (1587.5 μg/g creatinine, n = 8) and applicators (365.6 μg/g creatinine, n = 9). There was not much evidence of an increase in post-spray dialkyl phosphates levels from pre-spray levels amongst both applicators and non-applicators. Hours mixing, spraying, driving a tractor and hours worked by non-applicators were not significantly associated with an increase in post-spray dialkyl phosphate levels, adjusting for age, height, weight, gender, use of empty pesticide containers and self-reported kidney problems. Past applicator status was weakly positively associated with pre-spray dialkyl phosphate levels adjusting for age, height, weight, and gender, self-reported kidney problems, smoking and alcohol (β= 1019.5, p = 0.307, R²= 0.28). The high dialkyl phosphate levels call for an epidemiological investigation into the health effects of organophosphorous pesticides.     

Development of a nonlocal convective mixing scheme with varying upward mixing rates for use in air quality and chemical transport models

BACKGROUND, AIM, AND SCOPE: Asymmetrical convective non-local scheme (CON) with varying upward mixing rates is developed for simulation of vertical turbulent mixing in the convective boundary layer in air quality and chemical transport models. MATERIALS AND METHODS: The upward mixing rate form the surface layer is parameterized using the sensible heat flux and the friction and convective velocities. Upward mixing rates varying with height are scaled with an amount of turbulent kinetic energy in layer, while the downward mixing rates are derived from mass conservation. RESULTS: This scheme provides a less rapid mass transport out of surface layer into other layers than other asymmetrical convective mixing schemes. DISCUSSION: In this paper, we studied the performance of a nonlocal convective mixing scheme with varying upward mixing in the atmospheric boundary layer and its impact on the concentration of pollutants calculated with chemical and air-quality models. This scheme was additionally compared versus a local eddy-diffusivity scheme (KSC). Simulated concentrations of NO(2) and the nitrate wet deposition by the CON scheme are closer to the observations when compared to those obtained from using the KSC scheme. CONCLUSIONS: Concentrations calculated with the CON scheme are in general higher and closer to the observations than those obtained by the KSC scheme (of the order of 15-20%). Nitrate wet deposition calculated with the CON scheme are in general higher and closer to the observations than those obtained by the KSC scheme. RECOMMENDATIONS AND PERSPECTIVES: To examine the performance of the scheme, simulated and measured concentrations of a pollutant (NO(2)) and nitrate wet deposition was compared for the year 2002. The comparison was made for the whole domain used in simulations performed by the chemical European Monitoring and Evaluation Programme Unified model (version UNI-ACID, rv2.0) where schemes were incorporated.     

深水湖泊水质模型研究及其在抚仙湖中的应用

本文在深水湖泊的水质模型研究中成功地引入等效混合体积的概念，从而推导，建立一全新、实用的深水湖泊水质模型Ｃｓ＝Ｍｉｎ－ＭｏｕｔＫＶｎｙ＋Ｋ·△Ｑ＋Ｑｏｕｔｆ，并将之应用于抚仙湖。一方面证实了模型的合理性、适应性，另一方面揭示了抚仙湖水质变化的主要特征。     

西秦岭温泉岩浆混合花岗岩的地球化学特征

西秦岭温泉岩体是壳、幔岩浆混合的产物。寄主岩石(酸性端元)属铝过饱和钙碱性系列,贫CaO富FeOtotal,ANKC值大于1 1,NK/A均小于0 9,富Mo、Sn、Bi、W等高温热液成矿元素及Co、Ni、Cr等亲铁元素,LREE/HREE为10～15。基性端元暗色微细粒镁铁质包体及基性岩墙,富Na2O、K2O,而贫FeOtotal,异常富集轻稀土和Ba、Rb、Sr、Zr、Th、Hf、Nb等大离子亲石元素,而贫Co、Ni、Cr等亲铁元素,LREE/HREE为9 98～13 5,异常富轻稀土。由2端元岩浆混合形成的岩浆混合花岗岩,地球化学特征介于2端元间,并有显著的过渡特征和依从关系,反映了重要的岩浆混合信息。     

人工强制混合充氧对分层型水库细菌群落演替的影响

为深度解析人工强制混合充氧过程中细菌群落的演替，以西安金盆水库为研究对象，对2018年8月~2019年4月水库主库区垂向细菌种群结构进行连续监测.结果表明，受人工强制混合充氧作用影响，水库水体中的优势菌群蓝细菌门（Cyanobacteria）的丰度由11.7%~19.2%降至6.3%~8.9%.其中，表层、中层和底层水体蓝细菌的丰度分别由18.3%、11.7%、19.2%降至8.9%、6.3%、7.9%.人工强制混合作用使垂向水体细菌的种群结构差异降低，样本之间的离散度逐渐减小，其中优势菌群放线菌门（Actinobacteria）和变形菌门（Proteobacteria）在水体垂向的丰度分别由"中 > 底 > 表"和"表 > 底 > 中"，逐渐变为表、中、底层趋于均一.人工强制充氧作用使底部水体溶解氧（DO）含量逐渐升高，好氧型细菌的丰度得到明显的增加，其中Polynucleobacter的丰度从0.06%增加到1.06%，甲基孢囊菌属（Methylocystis）的丰度由0.18%增至2.20%，甲基杆菌属（Methylobacter）的丰度由0.02%增加到1.96%.通过冗余分析可知，影响细菌群落组成的主要因素为水体热分层稳定性、水温、DO、总磷（TP）和总氮（TN）.     

铁炭微电池电解填充流化床反应器水力学行为研究

本文提出了一种新型的铁炭微电池电解反应器———填充流化床反应器 ,并对该反应器的水力学行为进行了研究。通过床层压降法测定临界流化气速 ,建立了关于临界流化气速Uc 的经验关联式 :Uc=0 .0 15 6C0 .2 7Vt0 .14 H0 .31。通过脉冲示踪物信号法测得停留时间分布密度函数E(t) ,结果表明该反应器水力混合特性接近于完全混合反应器     

Spatiotemporal variations of nitrate sources and dynamics in a typical agricultural riverine system under monsoon climate

Nitrogen pollution is a serious environmental issue in the Danjiangkou Reservoir region (DRR), the water source of the South-to-North Water Diversion Project of China. In this research, seasonal surveys and a bi-weekly time series survey were conducted in the Qihe River Basin, one of the most densely populated agricultural basins in the DRR. Hydrochemical compositions (NO₃^? and Cl^?), dual isotopes (δD-H₂O, δ¹⁸O-H₂O, δ¹⁵N-NO₃^?, and δ¹⁸O-NO₃^?), and a Markov Chain Monte Carlo isotope mixing model were jointly applied to unravel the sources, migrations, and transformations of the nitrate (NO₃^?) in the basin. It was revealed that the mixing between different sources was the main process controlling the isotopic compositions of the riverine NO₃^? in the upper-middle reaches. In contrast, denitrification occurred in the lower reaches. For the first time, the sources of NO₃^? were quantified at a basin scale in the DRR. Overall, the river transported 484.2 tons/year of NO₃-N to the reservoir, of which 32.6%, 36.4%, 28.0%, and 3.0% was from soil organic nitrogen, chemical fertilizer, residential sewage and atmospheric precipitation, respectively. The NO₃-N fluxes of the different sources were regulated by the monsoon climate and anthropogenic activities. For example, high precipitation and intense fertilization resulted in severe nonpoint source pollution. Denitrification thrived in soils and reservoirs in wet seasons. Temperature could regulate the migration, nitrification and denitrification processes. Based on the results, we suggest that the management strategies dealing with nitrogen pollution issue in the DRR should follow the specific spatiotemporal characteristics of NO₃^? sources, migration and transformation mechanisms.     

扰动强度对太湖水华微囊藻群体生长和叶绿素荧光的影响

风浪扰动在湖泊和水库中频繁发生,是影响湖泊生态系统的重要因素之一.为了解太湖风浪扰动对水华微囊藻群体生长的影响,并探究其影响机理,利用室内摇床试验,设置不同的扰动强度（0、50、100、200、400 r/min）来模拟太湖风浪扰动,扰动时间为24 h,并测定不同扰动强度下水华微囊藻群体生长和叶绿素荧光参数.结果表明,所有试验组中,100 r/min组的ρ（Chla）、微囊藻数量、F_v/F_m（潜在最大光合效率）、ETR_max（潜在最大光合速率）、I_k（半饱和光强）和α（光能利用效率）增加最快,试验结束时分别为扰动前的3.29、10.75、1.20、2.30、2.21和1.21倍;并且扰动结束后,100 r/min组中3~10细胞群体细胞数量占比由25.80%降至20.70%,显著低于对照组（P < 0.05）,而>10细胞群体细胞数量占比由0增至25.55%,显著高于对照组（P < 0.05）.方差分析表明,试验第7~11天,100 r/min组的ρ（Chla）、水华微囊藻数量、F_v/F_m、ETR_max和α显著高于对照组（P < 0.05）;第1~5天,400 r/min组的ρ（Chla）、ETR_max和I_k显著低于对照组（P < 0.05）.研究显示,适宜的扰动强度（100 r/min）促进水华微囊藻群体生长和光合活性,过高的扰动强度（400 r/min）则抑制水华微囊藻群体生长和光合活性.