Relationship between carbon dioxide/methane emissions and the water quality/sediment characteristics of Taiwan's main rivers

River and sediment have unique carbon dynamics and are important sources of the dominant greenhouse gases (GHG), carbon dioxide (CO2) and methane (CH4). To understand the relationship between CO2/CH4 emissions and water quality/sediment characteristics, we have investigated critical parameters in the river water. Eight parameters of water quality (dissolved oxygen, oxidation-reduction potential [ORP], chemical oxygen demand, biochemical oxygen demand [BOD5], suspended solid, nitrate [NO3-], NH4+, and bacteria) and four sediment characteristics (total organic carbon [TOC], total nitrogen [T-N], NO3-, and ammonium [NH4+]) were measured in two of the larger rivers in Taiwan, and relevant environmental conditions were recorded. The experimental results indicated that CO2 emissions from the river were mainly affected by BOD5 concentrations and the levels of bacteria. CH4 emissions, on the other hand, were greatly affected by the ORP in the river. The correlation between CO2 emissions and sediment characteristics was insignificant (R2 < 0.3). However, TOC and T-N in the sediment may lead to increases in CH4 emissions into the atmosphere. A deeper analysis of the relationship between the different parameters and GHG emissions by ANOVA and the multiple regression method revealed that CO2 emission (y) was significantly related to bacteria number (x1) and BOD concentration (X2). The regression equation takes the form y = 0.00032x1 + 3.18089x2 + 25.37304. Also, the regression relationship between CH4 emission (y) and ORP (x) in the river can be described as y = -0.825216x + 169.02257. The relationship between CH4 emission and sediment characteristics may be described as y = 5.073962x1(TOC) + 2.871245x2(T-N) - 12.3262. Extra sampling data were collected to examine the feasibility of the developed multiple regression equations. The experimental results suggest that the emissions of such GHGs as CO2 and CH4 from rivers can be predicted using the regression equations developed here. Moreover, the emissions may be reduced by manipulating the proper factors.     

中蒙边境典型草原可燃物热解动力学研究

以中蒙边境(包括东乌旗、 二连浩特市、 新巴尔虎右旗)的草原可燃物为研究对象,利用STA 6000热重分析仪,采用热重分析法以5 ml/min,10 ml/min,20 ml/min,30 ml/min的氧气为载气,在空气气氛下,升温速率分别为40℃/min,60℃/min,80℃/min时对三个地区草原可燃物的热失重...     

科技英语文摘的文体与表达

科技论文的文摘是关系到论文能否被录用、发表及检索的重要因素。文章从文体的角度论述科技文摘的写作与翻译方法及注意问题,指出科技论文摘要应与国际惯例接轨,注意文体的严谨、准确、明了和科学性等问题;并为科技论文文摘撰写提供了重要依据。     

真空紫外光降解五氯酚钠以及过硫酸盐对反应的促进作用

研究了真空紫外光(VUV,185 am)对于水溶液中五氯酚钠的降解,反应2 h后,初始浓度为10 mg/L的五氯酚钠的去除率达到99%以上,有机氯的脱除率达到70%以上,有效地实现了五氯酚钠的脱毒.溶液初始pH值对五氯酚钠的真空紫外光解有很大影响,pH=10.9时的降解速率常数是pH=3.1时的3倍.表观一级反应速率常数随初始浓度的增加而线性下降.在反应溶液中加入过硫酸盐,可有效提高五氯酚钠的真空紫外光降解速率和矿化速率,过硫酸盐和五氯酚钠摩尔比为24时,降解速率提高3倍,反应4 h后TOC去除率达到95%.     

静电放电电磁辐射模式的建立与仿真

介绍了静电放电电磁辐射场的理论模型;针对长导体模型分析了其数学模型的建立方法;讨论了长导体模型实验仿真方法与结果.     

城乡养狗隐患多

近几年来,对于城乡居民来说,养狗已是生活中的一部分。然而狗养多了,隐患也会出现。一是盲目养狗、只养少管。尤其是农村,很多家庭养狗,少则一只,多则二三只,以散养为主。这些狗到处乱窜,咬人伤人,防不胜防。二是养狗户防疫知识欠缺,养狗者为狗打     

Prenatal sonographic appearance of Beare-Stevenson cutis gyrata syndrome: two- and three-dimensional ultrasonographic findings

Beare-Stevenson cutis gyrata syndrome is characterized by craniofacial anomalies, particularly craniosynostosis, ear defects, cutis gyrata, acanthosis nigricans, anogenit anomalies, skin tags, and prominent umbilical stump. The prenatal two- and three-dimensional ultrasonographic findings of this rare condition is reported. The detection was made at 32 weeks of gestation in a woman with polyhydramnios and fetal head anomaly. The ultrasound appearance and postnatal follow‒up are presented. Copyright © 2001 John Wiley & Sons, Ltd.     

Photodegradation of the endocrine-disrupting chemical 4-nonylphenol in biosolids applied to soil

There is increasing concern about the environmental fate and impact of biosolids-associated anthropogenic organic chemicals, among which 4-nonylphenol (4-NP) is one of the most studied chemicals. This is primarily because 4-NP is an endocrine disruptor and has been frequently detected in environmental samples. Due to its high hydrophobicity, 4-NP has high affinity for biosolids. Land application of 4-NP-containing biosolids could potentially introduce large quantities of this chemical into the environment. A laboratory experiment was conducted to investigate the effect of artificial sunlight on 4-NP degradation in biosolids applied to soil. When exposed to artificial sunlight for 30 d, the top-5-mm layer of biosolids showed a 55% reduction of 4-NP, while less than 15% of the 4-NP was degraded when the biosolids were kept in the dark. Our results indicate that sensitized photolysis reaction plays an important role in reducing the levels of 4-NP in land-applied biosolids. Surface application rather than soil incorporation of biosolids could be effective in reducing biosolids-associated organic chemicals that can be degraded through photolysis reactions. However, the risks of animal ingestion, foliar deposition, and runoff should also be evaluated when biosolids are applied on the soil surface.