重庆主城区空气降尘中重金属的特点及其在表层土壤中的累积量研究

探索不同功能区空气降尘中重金属通量特征并对其进行污染评价,对于了解空气降尘输入对土壤中重金属累积影响具有重要意义。对重庆主城的居住区(JZ)、文教区(WJ)、商业区(SY)、郊区(JQ)、交通区(JT)和工业-居住混合区(GJ)逐月进行空气降尘通量和Cr、Ni、Cd、Pb含量的测定。结果表明,工业–居住混合区的空气降尘通量平均值最高,文教区的最低。6类功能区秋季的降尘量相对较低。Cd、Cr、Ni和Pb的平均降尘量在不同功能区分布存在差异。空气降尘中4种重金属元素的平均含量为:Cd 2.14 mg/kg、Cr 66.36 mg/kg、Ni 27.69 mg/kg、Pb 98.33 mg/kg。6类功能区降尘中Cd、Cr、Ni和Pb 4种重金属含量一般冬季较高。地积累指数法的分析表明降尘中Cd污染最严重。经推算,以空气降尘的方式向土壤中输入的重金属,使重庆主城区土壤中Cd、Cr、Ni和Pb等4种重金属元素的浓度在累积100a后仍将低于《土壤环境质量标准》中的二级标准。土壤中重金属元素增加速度最快为Cd,其次为Pb和Cr,Ni的增长为负值。     

温室分层土壤条件下滴头流量和间距对湿润体的影响

基于温室田间土壤大多容重分层和不均匀的特点,进行了原状分层、分层筛分均质和筛分均质3种土壤对湿润体影响的对比研究。试验地土壤为粉土(中国制分类),原状分层和分层筛分均质土壤0~20 cm容重为1.44 g/cm3,20~40 cm为1.63 g/cm3,40~60 cm为1.55 g/cm3,筛分均质土壤采用0~60 cm平均容重1.54 g/cm3。滴头流量设2.7 L/h和1.4 L/h二种,滴头间距有30,50,70,100 cm四种,采用剖面法观测土壤含水率和湿润体发展。试验结果表明:①湿润体在现场原状分层土壤、分层均质和均质土壤中有很大的区别,分层筛分均质和筛分均质土壤中均为碗状原状,而分层土壤的湿润体形状在灌水量较小时为碗状,随灌水时间的延长,其形状逐渐变为椭柱体;②土壤容重分层情况对湿润锋的运移影响很大,分层土壤由于20~40 cm容重较大纵向湿润锋发展缓慢,灌水历时8 h时最大纵向湿润锋分别为27 cm和25 cm,且原状分层土壤灌水量较大时出现0 cm深度处横向湿润锋小于-7~-13 cm深度处湿润锋现象;而筛分均质土壤中纵向湿润锋明显大于分层土壤,灌水历时8 h时最大纵向湿润锋为32 cm;③原状分层土壤湿润体内平均含水率高于分层筛分均质和筛分均质土壤,但各组均高于田持,土壤含水率均匀度均在82%以上。基于这种结果,建议设计湿润比应根据温室土壤特点和设计灌水量进行现场测试确定,这样更符合实际情况。     

不同改良剂对铅污染砖红壤的修复效果

在未污染的花岗岩砖红壤中加入重金属Pb，平衡两周后在污染土壤上施用不同水平的钙镁磷肥、牛粪、钙镁磷肥＋牛粪等改良剂，以小白菜作为指示作物，根据小白菜生长动态变化和收获后生物量、Pb吸收量、土壤pH、土壤中有效Pb含量等理化性质的差异，来评价各种改良剂对Pb污染砖红壤的改良效果，以便为海南花岗岩砖红壤Pb污染修复提供理论依据。实验结果表明：各改良剂对Pb污染土壤都有一定的修复效果，不同程度的减轻了小白菜的毒害症状，其中钙镁磷肥与牛粪配施处理效果最好，该处理的小白菜不仅生物量高，而且Pb含量较低；其次是钙镁磷肥处理，而改良效果最差的是牛粪，其植株叶片不仅稍有黄化症状，且Pb含量较高     

Production protocol development for greenhouse cut Linaria, Lupinus, and Papaver flowers

Linaria maroccana Hook. f. Ann., ‘Lace Violet’, Lupinus hartwegii ssp. cruikshankii Lindl. ‘Sunrise’ and Papaver nudicaule L. ‘Meadow Pastels’ seeds were directly sown into 105 cell plug trays and received either ambient light or supplemental high intensity discharge (HID) lighting. For each species, a 2 × 3 × 3 factorial was used with two light intensities during propagation, three transplant stages, and three night temperatures. Seedlings were transplanted at the appearance of 2–3, 5–6, or 8–9 true leaves. Transplanted Linaria and Papaver seedlings were placed at 5/11, 10/16, or 15/21 ± 1 °C night/day temperatures and Lupinus seedlings were placed at 15/24, 18/25, or 20/26 ± 2 °C night/day temperatures. For this study, the optimum production temperature for Linaria was 10/16 °C as the cut stems produced at 15/21 °C were unmarketable and production time was excessively long at 5/11 °C. At 10/16 °C, Linaria seedlings should be transplanted at the 2–3 leaf stage to maximize stem number, stem length and profitability. For Lupinus the optimum temperature was 15/24 °C due to long stems and high profitability per plant. Lupinus seedlings should be transplanted at the 2–3 leaf stage when grown at 15/24 °C to obtain the longest and thickest stems; however, $/m² week was higher for plants transplanted at the 8–9 leaf stage due to less time in finishing production space. For Papaver, the 15/21 °C temperature was optimal as that temperature produced the longest stems in the shortest duration, resulting in the highest $/m² week. At 15/21 °C Papaver plants should be transplanted at the 2–3 leaf stage. Supplemental HID lighting had no effect on any of the species.     

插入式地下滴水器的研制与水力性能试验分析

在对现有滴头、滴箭等产品结构改进与优化设计的基础上,研制开发出一种具有快速装拆、移动灵活、抗堵塞功能的插入式地下滴水器产品,通过产品的具体结构组成与工作原理分析,进行了其流量均匀性、压力-流量关系的试验研究,结果表明:插入式地下滴水器所需起始工作压力低,额定流量小,具有较稳定的水力性能,适合用于对缺水区非密植作物的补充性抗旱灌溉,起到提高设备利用率、有效降低灌溉系统投资的作用,且能成功地把地表滴灌转化为地下滴灌的应用模式.     

Condition assessment of lamprey populations in the Yorkshire Ouse catchment,north‐east England,and the potential influence of physical migration barriers

• 1. River lamprey (Lampetra fluviatilis) and sea lamprey (Petromyzon marinus) are designated features of the River Derwent Special Area of Conservation (SAC) and the Humber Estuary (a possible SAC). This study determined the condition of lamprey populations in the Yorkshire Ouse catchment by assessing the species composition, distribution, abundance and size‐structure of larval (ammocoete) populations in five major tributary rivers (Derwent, Swale, Ure, Nidd and Wharfe).
• 2. According to EU condition assessment criteria, Lampetra populations (assumed to be mostly river lamprey) are at present in favourable condition, with site mean (±SE) densities ranging from 2.7 (±1.2) to 160.3 (±50.5) individuals m^?2 (all river means >2 individuals m^?2), and at least two size (≈age) classes present in optimal microhabitats. By contrast, no sea lamprey larvae were recorded, suggesting that populations of this species are in unfavourable condition.
• 3. Actions to protect and enhance nationally or internationally important stocks must be implemented from at least a catchment perspective, because many of the issues affecting such species are not localized. With respect to lampreys, particular attention should be given to protecting spawning and nursery habitats, improving water quality, reducing impingement at abstraction points, preventing exploitation at spawning grounds and increasing passage at potential physical obstructions.

Copyright © 2007 John Wiley & Sons, Ltd.     

矩形薄壁侧堰水力特性试验研究

侧堰作为一种量水设施,精度较高、结构简单、安装和拆卸方便,较易在灌区应用和推广,有很大的研究价值。对不同宽度和高度的矩形侧堰在缓流条件下进行了试验,分析了各工况下矩形渠道侧堰上、下游水面线、能量分布、流量系数等水力因素。结果表明,主渠道侧堰段能量基本保持不变,符合De Marchi的恒定能量假定;主渠道靠近侧堰边壁、中心线以及另一边壁三处的水面波动程度不同,说明侧堰对堰前水流产生影响;基于De Marchi假定和无量纲分析原理得到的流量公式最大相对误差均在±10%以内,满足灌区量水精度要求。     

涌泉根灌灌水器抗堵性能试验研究

为了研究大流道涌泉根灌灌水器的水力性能及抗堵性能,在微灌产品测试平台上对其进行了水力性能和短周期抗堵测试,并与常规迷宫流道灌水器进行比较。结果表明,涌泉根灌灌水器流态指数为0.517,制造偏差为3.5%,属优等产品;在含沙水条件下,其出水均匀性高于95%;经强制加沙试验验证,涌泉根灌灌水器与常规迷宫流道灌水器相比,具有较强的抗堵塞能力,并且该灌水器流量大,适合旱地经济林灌溉。     

喷灌水量分布动态模拟与均匀性研究

为研究压力、喷头组合方式和插值方法对喷灌均匀系数CU和分布均匀系数DU这两个评价指标计算结果的影响规律,利用雨量筒径向间隔为1 m的FY RB-471型喷头无风喷洒试验数据,模拟出了喷头在不同压力下的水量分布情况。在喷头矩形组合方式和正三角形组合方式下,采用线性插值、立方插值、三次样条插值、距离插值和平面插值法计算了不同压力下的喷灌均匀系数和分布均匀系数。结果表明,采用三角形组合方式比矩形组合方式计算的喷灌均匀系数CU高1.56~4.77个百分点,同样,三角形组合方式比矩形组合方式计算的分布均匀系数DU高4.26~9.19个百分点;不同的插值方法对喷灌均匀系数与分布均匀系数的计算结果影响不明显,而压力是影响喷灌均匀系数的一个重要因素。     

改进暗管排水结构型式对排水性能的影响

提出一种占用耕地少、排水流量较常规暗排大且环境友好的改进暗排。基于室内土柱试验,分析改进暗排在地表积水、土体饱和条件下的排水除涝性能及其机理,提出地表积水土体饱和入渗条件下改进暗排排水流量的理论计算公式。结果表明,改进暗排可以有效提高暗管排水能力,试验条件下,反滤体宽度为2~6 cm的改进暗排在自由出流条件下的排水流量为常规暗排排水流量的2~3倍;积水层深度相同时,改进暗排排水性能随反滤体宽度的增加而增大,但增幅逐渐减小;土体介质和反滤体的渗透系数差别越大,改进暗排的排水作用越明显。理论方法计算结果与试验结果相吻合,证明提出的理论计算公式是合理可行的。