昆明市分流制排水区域污水厂进水水质特征的统计学分析

应用多元统计方法系统分析了昆明市某分流制排水区域污水处理厂进水水质特征.结果表明,95％保证率时,该污水处理厂进水BOD5、COD、SS、TN、NH3-N和TP质量负荷分别为11 100、30 000、39 400、2 000、1 600和390 kg/d.进水水质指标中除了SS和NH3-N之间无相关性外,其余各指标间显著相关(α＜0.01).进水SS分别与BOD5、TP、COD有较强的相关性,其Pearson相关系数分别为0.845、0.786和0.915,进水BOD5分别与TP、COD亦有较强的相关性,其Pearson相关系数分别为0.808和0.918.进水BOD5/TN值＞4和BOD5/TP值＞20的累积概率分别为35％和94％,表明该污水处理厂进水有机物浓度不能满足微生物反硝化的需求,但可满足生物除磷对有机物和磷的理论需求量.     

某污水厂A~2O和倒置A~2O工艺脱氮除磷性能分析

针对昆明市某污水处理厂A2O和倒置A2O工艺二级出水NO3-N和TP较高的问题,利用沿程分析和批式实验相结合的方法,对2套工艺进出水水量水质和沿程污染物转化进行分析,探究2套系统出水NO3-N和TP较高的原因。结果表明,污水厂进水水量变化不大进水污染物波动较大;A2O和倒置A2O工艺对有机物和NH3-N的去除效果较好,对有机物去除率分别达到90%和89.4%,对NH3-N的去除率分别为99.3%和98.6%。A2O缺氧池内碳源不足导致反硝化反应受到限制,倒置A2O优先利用进水中的碳源反硝化效果高于A2O,但其受到回流溶解氧(DO)的影响较大。2套系统平均污泥龄(SRT)长达27.6 d,不利于驯化聚磷菌,因而在系统中几乎没有强化生物除磷。通过实际运行分析,SRT小于17 d时出水氮磷相对较好。     

Exchange-rate economics for the resources sector

The paper provides an account of aspects of exchange-rate economics that are of particular relevance to the resources sector. The issues discussed include exchange-rate volatility and the risk management practices used to deal with it, the role of productivity differences across countries, and the impact of a booming resources sector on the country's exchange rate. The discussion is organized around a simple stylized model that emphasizes the quantity theory of money and purchasing power parity as a long-run link between prices and exchange rates.     

环境规制对碳排放的门槛效应及其区域差异

为了深入探究我国环境规制的政策效应及其区域差异,采用我国30个省区2004—2014年的面板数据（不含港澳台及西藏自治区数据,下同）,分别以能源强度、产业结构和FDI（外商直接投资）作为门槛变量,以环境规制为核心解释变量,利用面板门槛模型分析我国环境规制对碳排放的门槛效应及其在东部、中部和西部存在的区域差异.结果表明:由于能源强度、产业结构、FDI这3个门槛变量的作用,环境规制对碳排放的影响体现出非线性特征,且环境规制的政策效应在东部、中部和西部3个区域内存在较为明显的差异.东部地区的环境规制在3个门槛变量的中低门槛区间均不能促进碳减排,处于高门槛区间时,能源强度会促进碳排放,而产业结构和FDI这两个门槛变量则对碳排放有抑制作用,其中能源强度跨过第2个门槛值（1.111 8）后仍表现出对碳排放的促进作用,产业结构（0.566 1）和FDI（1 159.40×108元）分别跨过第2个门槛值后,对碳排放表现出抑制作用;中部地区在能源强度的影响下,环境规制对碳排放一直为抑制作用,在产业结构和FDI的影响下则一直是促进作用;西部地区的能源强度与碳排放呈倒“U”型关系,两个门槛值分别为1.200 8与2.153 3,以产业结构和FDI为门槛变量时,环境规制均未能发挥碳减排作用,一直体现为促进作用.因此,政府在实施环境规制政策时不能采取一刀切的措施,要根据东部、中部和西部的不同情况针对性地实施相应的环境规制政策.      

基于GIS和RUSLE模型的水土保持功能重要性评价——以深圳市为例

以广东省深圳市为研究区域,运用GIS和RUSLE模型,结合全市的土壤数据集、气象数据集和高程数据集,以水土保持量作为生态系统水土保持功能的评价指标,通过对深圳市水土保持功能重要性的评价,为生态功能重要性评估的等级划分提供参考,进而为深圳市生态保护红线的划定提供依据。结果显示:全市水土保持功能的重要性可分为4级,即极重要、高度重要、重要和一般重要,受地形及人类活动等因素的影响,空间上呈现出由西北部逐渐向东南部增强的分布趋势;由于城市开发建设活动较少,森林资源丰富,地形地貌变化较大,丘陵山体较多,东南部的水土保持能力相对较强;水土保持功能极重要区域面积为61.90km2,高度重要区面积为161.93km2,二者总面积为223.82km2,占全市国土面积的11.21%,主要以连片斑块集中分布在深圳市东南部。     

西安市O3时空分布及影响因子研究

通过对西安市空气自动站监测数据和相关气象要素进行分析,得出西安市O_3污染特点如下,西安市典型O_3污染期集中在4至9月份,每日的14时至17时达到峰值,且空间分布呈现出郊外高于城区的特点。O_3最大值出现时段与NO_2、CO最低值出现时段吻合。     

Comparisons in subcellular and biochemical behaviors of cadmium between Iow-Cd and high-Cd accumulation cultivars of pakchoi （Brassica chinensis L.）

Subcellular distributions and chemical forms of cadmium （Cd） in the leaves, stems and roots were investigated in low-Cd accumulation cultivars and high-Cd accumulation cultivars ofpakchoi （Brassica chinensis L.）. Root cell wall played a key role in limiting soil Cd from entering the protoplast, especially in the low-Cd cultivars. The high-Cd cultivars had significantly higher leaf and stem Cd concentrations than the low-Cd cultivars in cell wall fraction, chloroplast/trophoplast fraction, organelle fraction and soluble fraction. In low-Cd cultivars, which were more sensitive and thus had greater physiological needs of Cd detoxification than high-Cd cultivars, leaf vacuole sequestrated higher proportions of Cd. Cd in the form of pectate/protein complexes （extracted by 1 tool. L~ NaC1） played a decisive role in Cd translocation from root to shoot, which might be one of the mechanisms that led to the differences in shoot Cd accumulation between the two types of cultivars. Furthermore, the formation of Cd- phosphate complexes （extracted by 2% HAc） was also involved in Cd detoxification within the roots of pakchoi under high Cd stress, suggesting that the mechanisms of Cd detoxification might be different between low- and high-Cd cultivars.     

High cadmium pollution risk on vegetable amaranth and a selection for pollution-safe cultivars to lower the risk

A pot experiment was carried out by growing 29 different genotypes (Amaranthus spp.) of vegetable amaranth under low- (0.12 mg·kg^-1) and middle- (0.40 mg·kg^-1) cadmium (Cd) exposure. The result showed that amaranth was vulnerable to cadmium (Cd) contamination in soil. Variations of Cd concentrations in both roots and edible parts among genotypes were significant (P<0.001) in both treatments. Cd concentrations in edible parts of the tested genotypes grown under low- and middle-Cd levels were significantly correlated (p<0.01), implying that Cd-accumulating property of amaranth is genotype-dependent. Differences in Cd chemical forms between cv. Nanxingdayemashixian (cv. Nan), a selected typical pollution-safe cultivar (Cd-PSC), and cv. Pennongjianyexian (cv. Pen), a selected typical non-Cd-PSC, under different Cd exposure conditions were compared. It was found that the alternation of Cd in F_NaCl (Cd form extracted by 1 mol·L^-1 NaCl) may be a key factor in regulating Cd accumulation of different amaranth genotypes and that the protein-binding Cd is considered to be associated with Cd translocation. The results indicated that amaranth is capable of enduring high level of Cd pollution when grown as vegetable crop, and accordingly, consuming vegetable amaranth would bring high health risk. Therefore, adopting Cd-PSC strategy would help reducing the risk of Cd pollution in amaranth. In this study, cv. Nan was identified as a Cd-PSC and recommended to be applied production practice.     

Distribution of bacterial communities across plateau freshwater lake and upslope soils

Microorganisms are involved in a variety of biogeochemical processes in natural environments. The differences between bacterial communities in freshwaters and upslope soils remain unclear. The present study investigated the bacterial distribution in a plateau freshwater lake, Erhai Lake (southwestern China), and its upslope soils. Illumina MiSeq sequencing illustrated high bacterial diversity in lake sediments and soils. Sediment and soil bacterial communities were mainly composed of Proteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi and Planctomycetes. However, a distinctive difference in bacterial community structure was found between soil and sediment ecosystems. Water content, nitrogen and pH affected the distribution of the bacterial community across Erhai Lake and its upslope soils. Moreover, the soil bacterial community might also be shaped by plant types. This work could provide some new insights into plateau aquatic and terrestrial microbial ecology.     

新冠疫情管控期间西安细颗粒物中碳组分浓度变化特征

于2019年1月27日—3月18日及2020年1月27日—3月18日对西安市细颗粒物(PM_2.5)的碳组分浓度进行了在线观测,对比分析了非疫情与疫情期间各常规污染因子、气象要素、PM_2.5中有机碳(OC)和元素碳(EC)的污染特征。结果表明：非疫情与疫情期间西安市的气象条件总体水平较为相近。疫情期间的二氧化硫(SO₂)、臭氧(O₃)浓度相对升高。重污染天气下,除PM_2.5外,其他污染物浓度均降低,说明疫情管制对重污染天气污染物浓度的削弱作用明显。疫情期间,PM_2.5中的OC组分浓度及占比有显著升高,与疫情期间的各类交通管制导致的机动车尾气排放量显著降低有关。另外,OC与EC的相关性较强,说明污染来源与人类日常生活有关。疫情期间西安市颗粒物中碳组分主要来自各类生物质燃烧,并且存在SOC污染,SOC在OC中的占比达到37.8%。疫情期间重污染天气下,SOC在OC中的占比达到87.5%,说明SOC对重污染天气OC的贡献较大。