Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem

Elevated CO₂ can stimulate wetland carbon (C) and nitrogen (N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO₂ enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant-water-soil system. The results showed: (1) elevated CO₂ stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively. (2) Elevated CO₂ significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0-15 cm layer, and 22.7% and 26.0% in the 15-30 cm soil layer. (3) Averaged across the rice growing period, elevated CO₂ greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%, respectively. (4) The TOC/TN ratio and natural δ¹⁵N value in the surface soil showed a decreasing trend under elevated CO₂. The above results indicate that elevated CO₂ can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns.     

CEM-UF组合膜-硝化/反硝化系统处理低C/N废水及种群结构分析

本研究采用具有氨氮富集分离特性的阳离子交换膜-超滤(CEM-UF)组合膜与硝化/反硝化结合处理低C/N废水,考察该系统不同流量比下低C/N废水的硝化、反硝化脱氮特性,并通过对硝化、反硝化活性污泥进行16Sr DNA高通量测序,分析功能微生物群落结构特征.结果表明,系统进水TN为60 mg·L-1,COD/TN为2.65下,各流量比下硝化均有较好效果,平均氨氮去除率为98.7%,流量比值由1∶2上升到1∶6过程中,反硝化m(COD)/m(NO-3-N)随之升高,1∶6时平均硝氮去除率达到最高,为86.28%,系统总氮去除率由22.56%上升到46.8%.Illumina高通量测序结果表明,硝化污泥中可以固氮的Proteobacteria菌门占30.9%,重要的亚硝酸盐氧化菌Nitrospirae菌门占3.06%,属水平上检测到氨氧化菌(AOB)Nitrosomonas和Nitrosospira,亚硝酸盐氧化菌(NOB)Nitrospira和Nitrobacter,AOB与NOB菌比例较高,与硝化反应器中较好的硝化效果相一致.反硝化污泥中Proteobacteria菌门占主导地位(53.13%),其次是Bacteroidetes菌门(10.93%),在属的水平上检测到Dechloromonas、Thauera、Castellaniella、Alicycliphilus、Azospira、Comamonas、Caldilinea和Saccharibacteria多种具有反硝化脱氮作用的相关菌属,反硝化菌所占比例为25.91%,反硝化污泥中具有反硝化功能的微生物丰富,反硝化效果良好.     

保定地区PM2.5中重金属元素的污染特征及健康风险评价

为了解保定市大气环境中PM_2.5中重金属的污染特征及其健康风险,在保定市设立观测站点,利用中流量颗粒物采样器对保定市大气PM_2.5进行了连续昼夜采集,并使用微波消解-电感耦合等离子质谱法分析了样品中的V、Cr、Mn、Co、Ni、Cu、Zn、As、Cd和Pb等10种重金属元素的质量浓度.结果表明,保定市大气PM_2.5浓度范围为16.84~476.19 μg·m^-3,采样期间有65d高于我国《环境空气质量标准》（GB 3095-2012）中的二级标准,超标率为54.2%.保定市PM_2.5中重金属元素的浓度变化趋势为：除Ni、Mn和Co外,夜间浓度略大于日间;大部分重金属元素秋冬季浓度大于春夏季.富集因子分析可知,保定市Cu、Zn、Pb、Cd主要来自于人为源,特别是受到交通源的影响较大.健康风险评估结果表明,保定市大气PM_2.5中的重金属污染的非致癌风险较小,致癌风险主要是As、Cr、Cd和Co,且成年人的致癌风险大于儿童.     

部分植物富集镉能力探讨

综述了农作物、油料作物、蔬菜、水果、杂草和树木等植物富集镉的不同情况,指出了现在研究植物富集镉能力的弊端,提出寻找自然生长在镉污染区生物量大的耐镉植物是植物修复镉污染土壤的一条重要途径。     

好氧段碳源浓度对同步去除和富集磷酸盐生物膜的影响

利用聚磷菌以循环交替O/A模式运行,对生活污水处理厂的主流工艺中实现磷酸盐的同步去除和富集,探究了好氧段碳源浓度对聚磷生物膜去除和富集磷酸盐性能以及生物膜中微生物种群结构的影响.结果表明,好氧COD质量浓度从200 mg·L~(-1)降低到0 mg·L~(-1),吸磷速率提升1. 29倍,出水磷质量浓度稳定在0. 5 mg·L~(-1)以下;释磷速率提升3. 56倍,富集液磷酸盐质量浓度从27. 125 mg·L~(-1)升高到55. 91 mg·L~(-1).微生物群落变化中,鉴定为聚磷菌的变形菌门(Proteobacteria)的含量增加约2倍,红环菌科(Rhodocyclaceae)和厌氧绳菌科(Anaerolineaceae)的富集效果分别提高了2. 28和5倍.降低好氧段碳源浓度,有利于聚磷菌的筛选和富集,强化了好氧段磷酸盐的去除以及厌氧段磷酸盐的释放,获得了更高的磷酸盐富集液,并且为以资源回收为目的的未来城市污水处理厂提供降低好氧段碳源需求的理论基础.     

Metaprotella Sandalensis (Crustacea: Amphipoda: Caprellidae): A Bioindicator of Nutrient Enrichment on Coral Reefs?

The population of the caprellid Metaprotella sandalensis Mayer (Crustacea: Amphipoda) associated with the seaweed Turbinaria ornata (Turner) J. Agardh was studied on a spatial scale in relation to the influence of physico-chemical factors on the coral reef system at Mauritius Island. Some areas of the coast of Mauritius are currently subject to disturbance due to industrialisation and rapidly growing tourist development programmes, meanwhile other sites of the island are still unaltered. T. ornata was sampled at 12 stations, distributed around the whole island to represent the heterogeneous conditions. The density of Metaprotella sandalensis living on T. ornata was measured. The linear regression and the multivariate analysis showed a strong correlation between the densities of the caprellid and the physico-chemical parameters. The highest densities of M. sandalensis were found in the most stressed sites characterised by the highest values of nitrate, phosphate, chemical oxygen demand and silting. According to these results and taking into account that M. sandalensis and T. ornata are widely distributed in most of the tropical ecosystems, we preliminarily propose usage of the density of this caprellid as a new monitoring tool on coral reefs or, at least, as a first diagnosis for the detection of nutrient enrichment on these ecosystems.     

Characteristics of metal enrichment in Deep Bay, Hong Kong

Abstract: Sediment cores, suspended particles and overlying water were collected in Deep Bay, Hong Kong. Enrichment of Zn in surface sediments in the landward direction and the decreasing of exchangeable Cd, Ni and Zn in sediment from the inner bay to the outer bay indicated the influence of anthropogenic pollutants discharged from the riparian runoffs.     

沥青烟中苯并（a）芘的等速采样与监测

新的大气污染综合排放标准对沥青及碳素制品生产和加工制定了标准，然而空气和废气监测分析，方法没有给出沥青烟气中苯并（ａ）芘的分析方法，该文用气相色固定谱固定液滤筒等速采样，进行沥青烟苯并（ａ）芘的分析，及其设计的气态衍生物富集器，为执行新的大气污染物综合排放标准提供了可行的技术保证。