关中地区PM2.5时空演化及人口暴露风险

近年来以细颗粒物PM_2.5为代表的大气污染已给人体健康带来严重风险.基于PM_2.5遥感反演数据和人口格网分布数据,测度关中地区人口暴露于PM_2.5的风险程度,并采用Theil-Sen Median趋势分析、Mann-Kendall检验和空间自相关分析等方法,探索2000～2016年关中地区PM_2.5及人口暴露风险的时空演化过程.结果表明:①2006、2007和2013年关中地区污染重且范围广,这3 a在40%以上区域PM_2.5年均质量浓度超过了35μg·m^-3的限值,2000～2016年关中地区PM_2.5空间分布范围不断扩大,形成了自中部向东北部的连续带状集中分布区;②2000～2016年,关中地区几乎每年都有超过60%的人口暴露在PM_2.5年均35μg·m^-3质量浓度限值以上,且人口暴露风险不断加剧,尤其是2011年后,人口暴露的高风险区范围持续增加;③2000～2016年关中地区PM     

Ergonomics improvements of the visual inspection process in a printed circuit assembly factory.

An ergonomics improvement study was conducted on the visual inspection process of a printed circuit assembly (PCA) factory. The process was studied through subjective assessment and direct observation. Three problems were identified: operators' eye problems, insufficient time for inspection and ineffective visual inspection. These problems caused a huge yearly rejection cost of US 298,240 dollars, poor quality, customer dissatisfaction and poor occupational health and safety. Ergonomics interventions were made to rectify the problems: reduced usage of a magnifying glass, the use of less glaring inspection templates, inspection of only electrically non-tested components and introduction of a visual inspection sequence. The interventions produced savings in rejection cost, reduced operators' eye strain, headaches and watery eyes, lowered the defect percentage at customers' sites and increased the factory's productivity and customer satisfaction.     

Alterations in activities of acid phosphatase, alkaline phosphatase, ATPase and ATP content in response to seasonally varying Pi status in okra (Abelmoschus esculentus)

Phosphorus (P) is the second most important macronutrient for plant growth. Plants exhibit numerous physiological and metabolic adaptations in response to seasonal variations in phosphorus content. Activities of acid and alkaline phosphatases, ATPase and ATP content were studied in summer, rainy and winter seasons at two different developmental stages (28 and 58 days after sowing) in Okra. Activities of both acid and alkaline phosphatases increased manifold in winter to cope up with low phosphorus content. ATP content and ATPase activity were high in summer signifying an active metabolic period. Phosphorus deficiency is characterized by low ATP content and ATPase activity (which are in turn partly responsible for a drastic reduction in growth and yield) and enhanced activities of acid and alkaline phosphatases which increase the availability of P in P-deficient seasons.     

The World Programme of Action: a new paradigm for population policy. The Cairo Conference

There has been considerable national and international debate over the past two years on population-related issues. Women have sought to affirm their right to control fertility and to have access to health services while criticizing current population policies and programs. A new paradigm for population policy has emerged from the debate, one which focuses upon providing broadly defined reproductive health services and acknowledges women's reproductive rights and their need for empowerment. This new population policy is embodied in the World Program of Action (WPOA) adopted September 1994 at the International Conference on Population and Development (ICPD) in Cairo, Egypt. WPOA is the main document emerging from the ICPD. It was developed and negotiated by participating governments during three preparatory committee meetings leading up to the conference and at ICPD itself, where it was adopted. The WPOA is slated for approval by the UN General Assembly during its current session. The WPOA is evidence of how effective women were in making women's rights and health the focus of an international document. The author discusses politics at the ICPD, the WPOA, funding the WPOA's implementation, the road ahead, and the power of women's strategies.     

CFB锅炉SNCR烟气脱硝空预器堵塞原因分析及处理

选择性非催化还原(SNCR)法是目前CFB锅炉常用的烟气脱硝技术。对一台锅炉空气预热器堵塞的原因进行了研究,对堵塞物成分、喷氨、燃煤硫分、空气预热器吹灰等进行了分析。通过煤种调整、喷氨改造、合理投运空预器吹灰等手段,成功解决了SNCR脱硝导致空预器堵塞的问题。     

低强度超声对短程硝化污泥活性的影响

为提高短程硝化反硝化脱氮效率,采用低强度超声对短程硝化反应进行强化,通过对比氨氧化率和亚硝酸盐生产量,考察低强度超声对短程硝化污泥活性影响。首先,通过对超声能量的优化试验,发现低强度超声能够提升短程硝化污泥反应速率,且超声能量为43.20 kJ时氨氧化率和亚硝酸盐生成量最大;然后考察超声能量与污泥浓度的关系。结果表明:1)在相同超声能量(43.20 kJ)条件下,随着污泥质量浓度(0.34~1.03 g VSS/L)增加,能量密度降低,反应速率不断提高;2)保持污泥浓度恒定,增加超声能量,发现在43.20 kJ时短程硝化污泥活性最好,氨氧化速率比对照组提高25.42%,继续增加能量后去除速率开始下降,原因是适宜的能量会增加微生物细胞壁和细胞膜的通透性,加快基质传递和反应速率,提高微生物活性,但当所施加能量超出其所能承受范围,则会对微生物内部产生损害,降低其活性;3)考察超声能量对胞外聚合物浓度和酶活性影响,在43.20 kJ条件下,多糖、蛋白质和胞外聚合物(EPS)浓度分别提高了18.32%、26.54%和22.05%,氨单加氧酶活性增加19.82%。研究表明,由于低强度超声作用加快胞外聚合物分泌,增加生物酶活性,进而促进了短程硝化污泥反应速率。     

亚氨基二琥珀酸修复重金属污染土壤及环境风险削减评估

以亚氨基二琥珀酸（ISA）为洗脱剂,考察ISA投加量、洗脱液pH值、反应时间和土液比对Cd、Pb和Zn去除率影响,通过Box-Behnken多因素设计法优化最佳洗脱条件,并采用涵盖土壤重金属残留量、浸出浓度和毒性的综合环境风险法评估修复效果.结果表明,ISA对Cd、Pb和Zn去除率随其浓度增加而增加;ISA浓度为50mmol/L时,对矿山污染土壤中Cd、Pb和Zn去除率达到11.83%、34.26%和20.96%;对污染农田土壤中Cd、Pb和Zn去除率达到48.89%、57.08%和81.80%.增加反应时间和洗脱液酸性有助于提高ISA对Cd、Pb和Zn去除率.随土液比减低,Cd、Pb和Zn去除率呈上升趋势.ISA去除Cd、Pb和Zn最佳条件为：ISA浓度70mmol/L、洗脱液pH4.0和反应时间120min,预测矿山土壤和污染农田土壤中Cd、Pb和Zn总去除率最大分别为32.58%和93.16%.ISA大幅度降低水溶态、可交换态和碳酸盐结合态Cd、Pb和Zn残留量,从而削减矿山土壤和污染农田土壤中Cd、Pb和Zn总环境风险达50.81%和87.13%.亚氨基二琥珀酸可有效去除污染土壤中重金属并降低残留重金属的环境风险,是一种潜在材料可用于土壤重金属污染修复.     

地下水中重金属污染来源及研究方法综析

查明重金属污染来源是地下水重金属污染防治的前提。近年来随着我国城市化进程的加快和工业的迅猛发展,我国地下水重金属污染也呈现日益严重的趋势。地下水重金属污染来源可分为自然来源和人为来源。地下水重金属污染的来源主要是人为来源,主要包括工业生产、再生水灌溉和生活污染来源。地下水重金属的工业污染主要位于重金属矿山和工业城市附近,其特点是污染元素种类多、浓度高,一般生产历史越长,重金属污染越严重。再生水重金属污染主要位于北方缺水区,运用再生水灌溉首先应该对再生水的重金属污染进行评价。生活来源的重金属污染对地下水正施加着愈来愈重要的影响,当前城市垃圾渗滤液正在成为地下水重金属污染的新源头。根据地下水重金属污染的空间分布、含水层对比、主成分分析、稳定同位素示踪及多元混合模型多种方法手段综合分析,客观准确地判断地下水重金属污染的来源及比例,制定科学合理地下水重金属污染的治理方案,以达到最佳的治理效果。