Temporal variability of atmospheric particulate matter and chemical composition during a growing season at an agricultural site in northeastern China

This study presents the observations of PM_(10) and PM_(2.5) concentrations at an agricultural site from April to October 2012 in Dehui city,China.Ambient air was sampled by filter-based samplers and online PM monitors.The filter samples were analyzed to determine the abundance of ionic/inorganic elements,organic carbon(OC) and elemental carbon(EC).The daily PM_(10) concentrations varied significantly over the monitoring period,with an average of168 ± 63(in the range of 52-277) μg/m~3 during the land preparation/planting period(26 April-15 June),85 ± 65(36-228) μg/m~3 during the growing season(16 June-25 September),and 207 ±88(103-310) μg/m~3 during the harvest period(26 September-31 October).PM_(2.5) accounted for44%,56%and 66%of atmospheric PM_(10) during these periods,respectively.The PM_(10) diurnal variation showed a distinct peak from 16:00 to 21:00(LST) during the growing and harvesting seasons,while a gradual increase throughout the daytime until 17:00 was observed during tilling season.Mineral dust elements(Al,Ca,Fe,and Mg) dominated the PM_(10) chemical composition during the tilling season;OC,NO_3~-,SO_4~(2-) and NH_4~+ during the growing season;and carbonaceous species(i.e.,OC and EC) during the harvesting season.Our results indicate that the soil particles emitted by farm tillage and organic matter released from straw burning are the two most significant sources of PM_(10) emissions contributing to the recurring high pollution events in this region.Therefore,development of agricultural PM inventories from soil tillage and straw burning is prioritized to support air quality modeling.     

Nitrogen to phosphorus ratios of two understory plant species in response to nitrogen and phosphorus addition in tropical forest of southern China北大核心CSCD

The secondary tropical forests in southern China have suffered from frequent human disturbance and increasing high N deposition. In order to explore the nutrient limitation status in secondary tropical forests of South China, this 3-year field experiment of nitrogen (+N) and phosphorus (+P) addition investigated nitrogen (N) and phosphorus (P) concentrations of the aboveground tissue (leaf and branch) of two widely distributed understory native species Clerodendrum cyrtophyllum and Uvaria microcarpa in a secondary tropical forest of South China. The results showed that: 1) the N and P concentrations of the two species were significantly different (P < 0.001); N and P concentrations of different tissues in the same species were different; N&P addition greatly affected N and P concentrations in branch rather than new leaf and older leaf. 2) +N treatment had no significant effect on N or P concentrations of either species, but significantly decreased N:P ratios (P = 0.001), at the level of 9% for C. cyrtophyllum and 50% for U. microcarpa, respectively. 3) +P treatment had no significant effect on tissue N concentrations, but significantly increased plant P concentrations (P < 0.001), at 54% for C. cyrtophyllum and 88% for U. microcarpa, respectively; +P treatment significantly decreased plant N:P ratios (P < 0.001), at 28% and 60%, respectively. 4) The alterations of P concentrations of two species had significantly negative correlations with N:P alterations under +N/+P treatment (P < 0.001), suggesting that the alteration of P concentrations in plant tissue was the major driver for N:P alteration. Our results show that N and P addition would affect tissue N and P concentrations of the two species, with +P treatment having relatively greater effect on nutrient concentrations than +N treatment; the branch is more sensitive than new or older leaf in response to nutrient addition. Therefore, P availability may be the limiting factor for plant growth in the tropical forests.     

三维电极法对印染废水脱色的实验研究

对三维电极方法处理模拟印染废水的脱色进行了实验研究,初步探讨了三维电极处理印染废水的机理,对影响处理效果的各种因素,如曝气、填充物质种类、活性炭与铁屑重量比、槽电压、电极间距、初始废水pH值等进行了条件实验。实验结果表明：不曝气的脱色效果比曝气的脱色效果好;填充物为混合物活性炭与铁屑比活性炭、无填充物的脱色效果好;混合物活性炭和铁屑重量比为2：1时的脱色效果最佳;槽电压越高,脱色效果越好,但当大于某个值16v时,处理效果反而会下降;电极间距越小,脱色效果越好,但间距小于1．5cm时易短路而影响脱色效果;中性条件下的脱色率要优于酸性和碱性条件下的;综合考虑,在不曝气,活性炭和铁屑重量比为2：1,槽电压为16v,电极间距为6cm,溶液浓度为200mg／L,pH=6的条件下,降解时间为90win,脱色率可达98．7％。     

南通龙王桥河沉积物中酸挥发性硫化物的研究

本研究对南通通甲河支流龙王桥河的表层沉积物中酸挥发性硫化物(AVS)随时间的变化情况,AVS与同步浸提重金属(SEM)的关系,以及AVS与有机质(OM)的关系进行了一个月的监测。结果表明:①龙王桥河表层沉积物中AVS的平均含量为1700mg/kg,远高于其他河段,上覆水中AVS的含量达到1.0mg/L,污染严重;②归一法算得SEM/AVS1,沉积物中重金属主要以硫化物形式存在;③沉积物中OM含量与AVS有相关性,OM较高时AVS的含量也较高。     

江苏近岸海域富营养化特征研究

近年来,江苏近岸海域水质不佳,赤潮、绿潮等生态灾害屡屡发生,富营养化是其潜在原因之一。本文对该海域2019年和2020年春、夏、秋季航次监测的无机氮（DIN）、活性磷酸盐（SRP）、叶绿素a（Chl a）等水质参数进行了空间分析,采用指数评价法量化了该海域的富营养化程度,并基于统计分析研究了该海域的富营养化特征。结果表...     

CNTs-CeO_2/H_2O_2复合光催化氧化体系降解水中酸性橙Ⅱ

运用"化学沉淀法",将Ce O2负载到碳纳米管(CNTs)上制备复合光催化剂,采用"单因素实验法"优化了制备条件。运用透射电镜和X射线衍射仪对复合光催化剂进行了表征。结果表明,负载到CNTs上的Ce O2为多晶面心立方结构,尺寸大小在6~10 nm之间,其在CNTs上分散效果好,负载均匀且负载率高。在溶液p H为5,CNTs-Ce O2用量为0.50g/L并光照2 h后,酸性橙Ⅱ的光脱色率和TOC去除率分别达到64.71%和44.25%;加入0.02 mmol/L H2O2后,CNTsCe O2/H2O2复合体系对酸性橙Ⅱ的光脱色率和TOC去除率分别提高至91.35%和82.40%。这预示着CNTs-Ce O2/H2O2复合光催化氧化体系在对水中偶氮染料的光催化处理方面具有潜在的应用价值。     

基于GIS的广西农业暴雨洪涝灾害风险评估

以自然灾害风险评估理论和方法为指导,遥感本底数据、气象数据、基础地理信息数据、社会经济数据为基础数据,构建广西农业暴雨洪涝灾害风险评估指标体系,采用层次分析及加权综合法建立农业暴雨洪涝灾害风险评估模型;借助GIS技术,计算广西农业暴雨洪涝灾害致灾因子危险性、孕灾环境敏感性、承灾体易损性、防灾减灾能力及综合风险指数,并对广西农业暴雨洪涝灾害进行风险区划,采用相关分析法将广西农业暴雨洪涝灾害风险结果与广西历史暴雨洪涝灾情数据进行对比验证,研究结果表明,农业暴雨洪涝风险分布结果与洪涝灾情损失的空间分布基本吻合,南部沿海的风险性最强,西部风险性最小。     

环境监理在龙岗气田的实践与探索

文章简要介绍了龙岗气田试采工程特点、环境保护要求及过程管理的难度,以及开展环境监理工作的必要性和重要性。重点总结了龙岗气田工程环境监理工作开展过程中,在前期准备、人员组织、资源配置、目标实现、现场实施、成果体现等方面所做的探索与实践,对今后大型油气地面工程建设开展环境监理工作具有一定的借鉴意义和参考作用。     

The use of food waste-based diets and Napier grass to culture grass carp: growth performance and contaminants contained in cultured fish

The present study used commercial feeds, food waste feeds, Napier grass, and mixed feeds (food waste feed to Napier grass ratio, 1:10) to feed grass carp (Ctenopharyngodon idellus). The results indicated that grass carp fed with food waste feeds and mix feeds achieved growth performance (based on specific growth rate and feed conversion ratio) that was similar to commercial feeds (p?>?0.05). Concentrations of metalloid/metals in food waste feeds and polycyclic aromatic hydrocarbons (PAHs) in Napier grass were relatively higher than other types of fish feeds (p?<?0.05). However, most of the metalloid/metals and PAH levels in fish fed with four types of fish feeds were not significantly different (p?>?0.05). These findings show that food waste feeds are suitable for using in the production of fish feed and Napier grass can be served as supplemental feeds for grass carp, and hence reducing the production cost.