A model on the carbon cycling in Lake Taihu, China

A model of the carbon cycling in Lake Taihu was developed based on the previous developed model EcoTaihu Model, which couples the hydrology, the nutrient cycling and a number of biological processes. The carbon cycling model (abbreviated CCM) has in addition to the states variables of the EcoTaihu Model, the carbon in phytoplankton, zooplankton, fish, macroplant, hydrogen carbonate carbon, carbonate carbon, dissolved carbon, abiotic organic carbon in water, organic carbon in sediment, soluble organic carbon in pore water, inorganic carbon in sediments, soluble inorganic carbon in pore water and pH. The calibration and validation of the CCM showed that the model results are in good accordance with the observations (from the period February17 to December. 5, 2003). It implies that the model can be used to assess the variation of the carbon dioxide flux at the water-air interface, and to find the pH value of the lake water as function of time. According to the model, the carbon dioxide flux at the water-air interface has clear, diurnal variations. Eutrophied water is a sink for the atmospheric carbon dioxide due to the phytosynthesis during the summer. Due to the terrestrial input of carbon to the lake, Lake Taihu is, however, a source of atmospheric carbon dioxide. The total annual flux is almost equal to the terrestrial input of carbon to the lake.     

A review on sustainable reuse applications of Fenton sludge during wastewater treatment

• The sustainable approaches related to Fenton sludge reuse systems are summarized. • Degradation mechanism of Fenton sludge heterogeneous catalyst is deeply discussed. • The efficient utilization directions of Fenton sludge are proposed. The classical Fenton oxidation process (CFOP) is a versatile and effective application that is generally applied for recalcitrant pollutant removal. However, excess iron sludge production largely restricts its widespread application. Fenton sludge is a hazardous solid waste, which is a complex heterogeneous mixture with Fe(OH)₃, organic matter, heavy metals, microorganisms, sediment impurities, and moisture. Although studies have aimed to utilize specific Fenton sludge resources based on their iron-rich characteristics, few reports have fully reviewed the utilization of Fenton sludge. As such, this review details current sustainable Fenton sludge reuse systems that are applied during wastewater treatment. Specifically, coagulant preparation, the reuse of Fenton sludge as an iron source in the Fenton process and as a synthetic heterogeneous catalyst/adsorbent, as well as the application of the Fenton sludge reuse system as a heterogeneous catalyst for resource utilization. This is the first review article to comprehensively summarize the utilization of Fenton sludge. In addition, this review suggests future research ideas to enhance the cost-effectiveness, environmental sustainability, and large-scale feasibility of Fenton sludge applications.     

农桐间作的养分循环

对农桐间作（以桐为主间作型）的养分循环规律进行了研究。结果表明，泡桐各器官营养元素的含量随季节而变化。对营养元素的年吸收量为４７１．９５９５ｋｇ／ｈｍ￣２，其中氮１５５．１４２９ｋｇ／ｈｍ￣２，磷８０．０８２１ｋｇ／ｈｍ￣２，钾８７．０３９４ｋｇ／ｈｍ￣２，钙１１９．４６０３ｋｇ／ｈｍ￣２，镁３０．２３４８ｋｇ／ｈｍ￣２。营养元素的年归还量为３３１．６１５５ｋｇ／ｈｍ￣２，其中氮１０２．５７２１ｋｇ／ｈｍ￣２，磷４３．２９２２ｋｇ／ｈｍ￣２．钾６３．６４９７ｋｇ／ｈｍ￣２，钙９７．３５８６ｋｇ／ｈｍ￣２，镁２４．７４２９ｋｇ／ｈｍ￣２。营养元素的循环率为７０、２６％，其中氮６６．１１％，磷５４．０６％，钾７３．１３％，钙８１．５０％，镁８１．８４％。     

中国钢铁工业职业卫生40年回顾和今后展望

通过对中国钢铁工业职业卫生四十年的回顾,笔者认为:钢铁工业卫生管理体制已基本形成,但管理水平急需提高;主要的传统职业危害有所抑制,而今后任务仍十分艰巨;随着钢铁工业生产技术的发展广大职工又面临新的职业危害的挑战。本文最后对90年代钢铁工业职业卫生的形势进行了展望,提出了新的对策。在执行「八五」职业卫生规划的基础上,还需加强职业互生服务机构,扩大服务覆盖面,提高专业素质、开展普及教育、加强专业队伍的自身建设,这些任务是实现十年战略目标的重要保证。     

Social environment versus cycling competency predicting risk-taking in 11- to 13-year-old cyclists in The Netherlands

Abstract

Objectives: From age 12 onwards, cycling injuries begin rising in The Netherlands. A known contributing factor is younger children’s underdeveloped competency to deal with complex and hazardous traffic situations, and their exposure to such situations strongly increases after transitioning to secondary school. Little is known about intentional risk-taking as a contributing factor. In this developmental stage, children become increasingly vulnerable because of intentional risk-taking, affecting their safety and health. The incidence, predictors in the child’s social environment, and trends of such risks are systematically monitored; for instance, for alcohol use, smoking, and cyber bullying. Such monitors do not include risky road behavior. This exploratory field study examined the frequency of intentional risky cycling, its relationship with the perceived social environment, and relative to cycling competency measured as the ability to detect emerging hazards quickly.

Methods: Three hundred thirty-five students between 11 and 13 years of age (51% male) completed computerized tests of hazard perception skill and surveys on crashes, risk-taking, peer pressure, perceived risk-taking by parents or friends, and exposure to risky driving as passenger.

Results: Frequent risk-taking was associated with higher crash frequency. Stepwise regression confirmed that children who more often took risks on the road were also more sensitive to peer pressure, had more often been passengers of risky drivers, had parents and friends who exhibited risky behaviors in traffic more often, and perceived hazards as less dangerous but, in contrast to expectations, did not do worse on the detection of hazards. The predictors explained 28% of the variance in total risk-taking but varied from 6 to 20% depending on the specific risk-taking behavior concerned.

Conclusions: At least 20% of children sometimes or more often take risks in traffic. Children who feel peer pressure to behave in a risky manner, observe parents and friends behaving in a risky manner in traffic, and have been exposed as passengers to risky driving more often take risks in traffic themselves. These results provide support for including items on risky road behavior in health monitors and to design interventions that address the risk factors in the child’s perceived social environment.     

Ozone-enhanced catalytic oxidation of monochlorobenzene over iron oxide catalysts

In this study, we examined the experimental catalytic oxidation of gaseous monochlorobenzene (MCBz) with O₃ over Fe₂O₃ in a packed bed reactor to investigate the feasibility of economical low temperature decomposition at a high space velocity (SV). We investigated the effects of several reaction parameters (temperature, O₃ concentration, and SV) on the MCBz oxidation. At 150 °C, the conversion of MCBz over Fe₂O₃ in the absence of O₃ was only 3%; it increased to 91% over Fe₂O₃ in the presence of 1200 ppm of O₃ at a high SV of 83 s⁻¹. A long-term operation study revealed that the conversion of MCBz was stable for more than 96 h. In the steady state, the carbon and chlorine balances were 88% and 86%, respectively. Applying a Langmuir-Hinshelwood kinetic model, we estimated an activation energy of 16.7 kJ mol⁻¹ for MCBz oxidation over Fe₂O₃ in the presence of O₃.     

The littoral zone of lake okeechobee as a source of phosphorus after drawdown

Following a period of prolonged drought or intentional lake level drawdown, large littoral areas that once contained submersed aquatic vegetation (SAV) are reinundated when lake levels rise. A complete assessment of the contribution made by decomposing SAV to the in-lake phosphorus (P) concentration is important in both the management of Lake Okeechobee and understanding basic P processes. The P contribution to the open waters of Lake Okeechobee from a rapid inundation of exposed SAV was calculated by four methods: cores of field-desiccated SAV, cores of lab-desiccated SAV in the presence and absence of sediments, in situ decomposition, and sequential macrophyte harvesting. P releases, given such an episodic event, were similar among the four methods, ranging from 116±48 to 384±528 mg/m² in the absence of sediment. When SAV is in contact with sediment, which is the realistic field situation, the amount of P released was four times less (30±14 mg/m²) than in the absence of sediment. The calculated P releases would result in total P concentration increases in the lake from 2 to 15 μg/liter (upper 95% CI=2–25 μg/liter) in the absence of sediment; only 1 μg/liter increase was predicted when SAV released P in contact with sediment. Thus it is unlikely that a significant rise in total P concentrations in the limnetic zone of the lake would occur from the export of P released during the desiccation of SAV in the littoral-marsh zone during a drawdown.     

武钢循环冷却水钢管腐蚀的原因及其对策

针对武钢循环冷却水系统部分钢管腐蚀,造成管管漏水,严重影响正常生产的问题.探讨了钢管产生腐蚀的原因及其对策.近2年,通过实施减缓循环冷却水钢管腐蚀的对策,取得了明显的效果.     

常温下铁的硫化产物自燃性

含硫油品储运过程中H2S腐蚀产物是常温下硫铁化合物的主要来源,以H2S与铁粉反应制备的硫铁化合物来模拟设备内H2S的腐蚀产物,利用自然氧化的方法测定了硫化反应产物的一次氧化升温和二次氧化升温,考察了铁粉含水量对硫化反应及硫化反应产物自燃性的影响,采用XRD和SEM手段对硫化反应产物进行了表征。结果表明:H2S与铁粉的硫化反应产物为FeS,呈微小颗粒状,覆盖在铁粉表面;硫化反应产物具有自燃性,一次氧化升温最高达到87℃;未被完全氧化的硫化反应产物密封放置一段时间后自燃性明显增加,其二次氧化升温速率最高超过39℃/min;铁粉中含有适量的水可以增加硫化反应速率,提高硫化反应产物的自燃性。