秸秆还田对水稻镉积累及其亚细胞分布的影响

镉(Cd)是人类一级致癌物,大米食用是以大米为主食人群摄入Cd的主要途径.秸秆还田是秸秆处理中主要方式,在Cd污染稻田被广泛应用,其对水稻Cd吸收及水稻体内Cd的分布产生的影响不可忽视.本研究选用Cd水稻土,通过盆栽和大田试验分析了不同的秸秆还田用量(0.0%、1.0%、2.5%和5.0%)对Cd的亚细胞分布以及在水稻籽粒中积累的影响.结果表明水稻根细胞中的Cd主要分布在细胞壁中,占总Cd的86%~95%,茎叶细胞的细胞壁与可溶部分中的Cd含量相当,分别占总Cd的30%~51%和35%~61%.秸秆按1%和2.5%比例还田能显著提高根中Cd含量,以及细胞壁中Cd含量及其分配比例,并降低水稻体内Cd由根向茎叶转运;但5%的秸秆还田,分蘖期根中Cd含量和细胞壁中Cd含量显著降低,Cd由根向茎叶转运系数提高,灌浆期的根中Cd含量和细胞壁中Cd含量均显著提高,转运系数没有显著变化.大田试验前茬的水稻秸秆和油菜秸秆中Cd含量均较高,分别是0.49 mg·kg~(-1)和0.67 mg·kg~(-1);油菜秸秆单独还田或与石灰一起还田均没有显著影响水稻糙米或秸秆中Cd的积累;水稻秸秆单独还田也没有显著改变水稻糙米或秸秆中Cd的积累,但与石灰一起还田时能显著降低糙米和秸秆中的Cd积累;生物炭添加能显著降低水稻体内的Cd积累,且与石灰一起添加降Cd效果更显著.因此,当用Cd污染稻田前茬所产水稻秸秆还田时,建议与石灰一起添加可达到显著降Cd的效果.该研究将为Cd污染稻田的水稻安全生产与秸秆循环利用提供理论与实践指导.     

导流墙偏置位置对氧化沟性能影响的分析

针对偏置导流墙氧化沟复杂结构的特点,采用计算流体力学数值模型和Fluent计算方法,将导流墙偏置距沿径向从0至1m,间隔0.25m进行偏置距位置变化,对氧化沟流场进行了数值计算模拟。研究结果表明:导流墙的偏置距设置对改善隔墙背后的水流低速区和消除污泥沉积有促进作用,但当导流墙的偏置距增加到一定值时,在隔墙背后径向半宽处会形成第二个水流低速区。在比较不同导流墙偏置距的速度曲线基础上,认为导流墙的偏置距应设置在0.3m～0.4m之间较合适,从而为偏置导流墙的合理设计提供理论依据。     

气瓶充装场所防爆墙安全评价

通过事故案例和对现行国家标准的分析,提出了气瓶充装场所防爆墙安全评价要点,从实践角度为防爆墙设计提出了要求。     

新型波纹板导流墙氧化沟水力特性的数值模拟

提出新型波纹板导流墙氧化沟结构,并基于N-S方程和k-ε紊流模型,采用有限体积法,对新型波纹板导流墙氧化沟的水流流态和水流速度分布进行数值模拟。同时与无延长导流墙和平板导流墙的数值模拟进行比较,研究结果表明:新型波纹板导流墙对降低氧化沟隔墙背后的水流低速区范围和改善污泥沉积有促进作用。     

抗剪强度折减系数法在基坑土钉墙稳定性分析中的应用研究

深基坑土钉墙支护结构由于其经济可靠且施工快速简便,已在许多国家得到迅速的发展和应用。但由于土钉墙支护基坑边坡稳定性分析中土体计算参数的难以确定,常常误导土钉设计,造成众多基坑土钉墙事故的发生。笔者根据抗剪强度折减系数理论,并结合FLAC3D三维动态仿真模拟．分析了基坑土钉墙在开挖与支护作用下的应力场与位移场分布形态特征,据此得出其发生扰动后的综合强度参数,以此综合强度参数计算基坑坡体的安全系数,为基坑土钉墙稳定性分析提供了有效途径。     

光环境污染监测分类与控制值探索

在研究分析国内外现有光污染相关技术规定的基础上,结合我国城市光污染现状,为解决我国城市光污染中危害最严重的典型问题,将我国城市光环境污染划分为玻璃幕墙眩光污染、交通道路眩光污染、居住区光污染、室外光污染源4个重点监测项目,并针对具体项目初步提出了玻璃幕墙反射眩光监测控制值、交通道路眩光监测控制值、居住区光污染监测控制值和室外光污染源监测控制值。     

Prenatal diagnosis and management of anterior abdominal wall defects in the West of Scotland

An attempt was made to identify all the cases of abdominal wall defects occurring in the West of Scotland over a 7-year period to determine the current incidence, prenatal diagnosis, management, and prognosis for fetuses and neonates with abdominal wall defects. Cases were identified because they presented either for prenatal diagnosis, or to the Department of Pathology following termination or spontaneous pregnancy loss, or as neonates to the Neonatal Surgical Department. The incidence of abdominal wall defects was found to be 1 in 2500 births. Exomphalos was diagnosed before birth in 66 per cent of cases, and in 30 per cent of cases it was associated with another major abnormality. There was a 20 per cent intact survival in the cases diagnosed prenatally who had no fetal anomaly and who opted to continue with the pregnancy. Gastroschisis was diagnosed before delivery in 70 per cent of cases, and in the group who continued with the pregnancy there was an intact survival of 77 per cent. Body stalk anomalies were all diagnosed prenatally and terminated. Maternal serum alpha-fetoprotein was elevated in 89 per cent of the cases with exomphalos and in 100 per cent of the cases with gastroschisis and body stalk anomalies in which it was tested.     

渗透性反应墙在地下水污染修复中的应用

渗透性反应墙技术是近年来比较流行的地下水污染原位处理方法。本文综述了渗透性反应墙技术的基本机理、主要结构类型、活性反应介质的选取原则及主要的反应介质,介绍了渗透性反应墙的工程实践应用及存在问题。     

Urban reconciliation ecology: the potential of living roofs and walls

Reconciling human and non-human use of urban regions to support biological conservation represents a major challenge for the 21st century. The concept of reconciliation ecology, by which the anthropogenic environment may be modified to encourage non-human use and biodiversity preservation without compromising societal utilization, potentially represents an appropriate paradigm for urban conservation given the generally poor opportunities that exist for reserve establishment and ecological restoration in urban areas. Two habitat improvement techniques with great potential for reconciliation ecology in urban areas are the installation of living roofs and walls, which have been shown to support a range of taxa at local scales. This paper evaluates the reconciliation potential of living roofs and walls, in particular highlighting both ecological and societal limitations that need to be overcome for application at the landscape scale. We further consider that successful utilization of living roofs and walls for urban reconciliation ecology will rely heavily on the participation of urban citizens, and that a 'citizen science' model is needed to facilitate public participation and support and to create an evidence base to determine their effectiveness. Living roofs and walls are just one aspect of urban reconciliation ecology, but are particularly important 'bottom-up' techniques for improving urban biodiversity that can be performed directly by the citizenry.     

Instream-Flow Needs for Anadromous Salmonids and Lamprey on the Pacific Coast, with Special Reference to the Pacific Southwest

This paper addresses differences in instream-flow needs (IFNs) of Pacific salmonids and lamprey across species, life stages, and stream sizes on the Pacific coast, with additional consideration of salmonid-IFN data from northern Europe. The Pacific Southwest data set was for various life stages of coho salmon and steelhead trout in small coastal streams of central and southern California. These data showed that younger life stages required less flow than adults. The Pacific Northwest data set was for spawning adults of all five salmon species and steelhead trout in Washington or northern California. These data showed that spawning salmonids required more flow, relative to mean annual flow, in smaller streams. Although these IFNs varied by species, all were much higher than IFNs to protect wetted perimeters (rearing habitat) and water quality in these streams. The high-flow guild included chinook, pink, and chum salmon, whereas the low-flow guild included coho and sockeye salmon. Steelhead were unique in showing relatively high spawning IFNs for creeks and small rivers, unlike large rivers, such that IFNs were more affected by stream size for this species than salmon.