Optimum ridge-to-furrow ratio in ridge-furrow mulching systems for improving water conservation in maize (Zea may L.) production

Environmental Science and Pollution Research - Water-saving cultivation techniques have been attracting increased attention worldwide. Ridge-furrow mulching system (RFMS), as a prospective...     

江苏省空气质量预报准确度及改进方法分析

介绍了江苏省重污染天气监测预报预警系统以及大气重污染预警会商流程,将2015年13个地级市的模式预报、人工预报结果分别与实际观测值进行比较。结果表明:人工预报更准确,PM_(2.5)日均值、臭氧日最大8 h平均值、AQI 3个指标人工预报和实况的相关性分别比模式预报高出12.8%、0.3%、11.4%,平均标准误差(MNE)分别低20.7%、3.1%、23.1%。依据国家空气质量预报技术指南评分办法,对各市2015年全年空气质量级别为"良"时进行评分。通过开展07∶00预报更新,使2015年上半年空气质量预报级别得分平均提高了0.9分,全年级别得分平均提高了2.6分;通过改进模式预报参数,使PM_(2.5)日均预报值、臭氧日最大8 h平均预报值、AQI预报值和实际观测值的相关性比上年同期分别提高26.0%、5.0%、33.9%,MNE分别降低3.6%、31.3%、7.6%。     

Histopathological changes in zebrafish embryos exposed to DLPCBs extract from Zhanjiang coastal sediment

Dioxin-like polychlorinated biphenyls (DLPCBs) are ubiquitous persistent pollutants that cause adverse effects in many environmental organisms. DLPCBs in marine sediments can be absorbed by benthic organisms, bioaccumulate, and biomagnify through the food chain and threaten animal and human health. There are no reports of DLPCBs concentrations in the Zhanjiang Gulf seabed. This study was designed to investigate the concentration of DLPCBs in the Zhanjiang coastal sediment and histopathological changes in zebrafish (Diano rerio) embryos exposed to environmentally relevant concentrations of DLPCBs. Of the five sites selected, two sites TS and JSW contained DLPCBs at concentrations of 0.08 and 22.54 ng/g dry sediment, respectively. Two groups of zebrafish embryos were used. One group was exposed to 3.75, 7.5, 15, 30, and 60 mg/ml of DLPCBs extracted from the sediments sampled from the TS site and the second group to 4.375, 8.75, 17.5, 35, and 70 mg/ml of DLPCBs from JSW site from 0.75 h post-fertilization (hpf) to 96 hpf. The zebrafish exposed to 60 and 70 mg/ml of DLPCBs at 96 hpf displayed gross histopathological changes with cardiac lesions including pericardial edema being the most deleterious. Other changes observed were hydropic degeneration of gill filaments and hepatocytes, loss of intestinal folds, and uninflated swim bladder. It appears that only a few sites of the Zhanjiang gulf are contaminated with DLPCBs. This is the first report of histopathological changes in the gills, hepatocytes, intestines, heart, and the swim bladder in zebrafish embryos exposed to DLPCBs from a coastal sediment. Further studies with sampling at different stages of development are required to identify which organ/tissue is most sensitive to DLPCBs.     

Concentrations,atmospheric partitioning,and air–water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin,North China

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient air, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their concentrations, profiles, and to understand the processes of gas–particle partitioning and air–water/soil exchange. The following results were obtained: (1) The average concentrations (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in air, water, sediment, and soil samples were 4,855 fg/m³, 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m³, 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the gas–particle partition coefficient (K _p) and the subcooled liquid vapor pressure (P _L ⁰) and octanol–air partition coefficient (K _oa). (4) Fugacity fraction values of air–water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into air. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into air, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for air–soil exchange.     

镍渣的重金属浸出特性

在分析镍渣的矿物相组成和重金属元素含量的基础上,鉴定了镍渣样品的浸出毒性,并考察了pH、液固比和浸出时间等条件对镍渣样中铬、铅、铜和锌等重金属浸出特性的影响。结果表明,镍渣中的重金属总量约为渣样的0.9%,且铬、铜和锌的含量较高,需进行安全管理。实验所用镍渣样品为第Ⅰ类一般工业固体废物。在强酸条件下镍渣中重金属浸出浓度较大,pH3后浸出浓度显著降低;液固比40 L/kg时,镍渣中重金属不断溶出,液固比40 L/kg后,浸出达到饱和,浸出浓度趋于平衡;随着浸出时间的增加,重金属离子的浸出浓度先增加后减少,但由于各重金属性质不同,各重金属达到最大浸出浓度的时间不同。     

优势菌种对餐厨垃圾高温好氧消化的促进

为研究优势菌种对餐厨垃圾高温好氧消化(TAD)的促进作用,本研究通过淀粉水解、油脂降解及明胶液化等生化实验,从餐厨垃圾中筛选出若干对其主要成分具有显著降解效果的优势菌种。通过对样品水溶性TOC(TOCw)、水溶性凯氏氮(KNw)、水溶性C/N(KNw)、pH以及含水率等指标的分析,考察优势菌种对餐厨TAD的促进作用。研究表明,优势菌种制剂最优添加量为1%。在此剂量下,好氧消化60 h,TOCw由8.53%降低为2.49%,C/Nw由18.71降低至6.14,以上指标说明加入优势菌种可加速TAD反应。添加量1%样本的水溶性凯氏氮和pH在反应48 h后开始回升,而未添加生物制剂的样本相关参数回升时间需96 h以上,由此推断优势菌种对TAD的促进机制是加快了蛋白质等大分子有机物的降解速度。     

基于环境一号卫星的PM2.5浓度遥感反演研究

2014年12月29—30日,青岛市发生了一次空气污染过程,利用环境一号卫星CCD遥感影像数据和实测PM_(2.5)浓度数据,分析了该过程前后5 d的实测PM_(2.5)浓度与环境一号卫星CCD遥感影像的DN值之间的相关性,分别按日期和区域建立了反演模型。结果表明,按日期拟合反演模型相关系数为0.02~0.51,按区域拟合反演模型相关系数为0.01~0.80,总体来说,区域拟合结果较好。     

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO₂ fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO₂ in the gases. The gases contained 5–55 ppm NO₂ and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO₂ of 54 ppm could be removed, and 47% of the removed NO₂ was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO₂ adsorption. Within EBRTs of 0.076–0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design.

Implications: Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO₂ fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO₂ in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO₂ (kg GAC)^?1 with an influent NO₂ of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.     

道路交通噪声预测声源简化研究

为了分析《环境影响评价技术导则声环境》(HJ 2.4—2009)中将道路声源简化为1条位于道路中心线处的线声源与按照车道数简化为多条线声源之间的误差,针对不同宽度的道路,推导了多条线声源与1条线声源在接收点噪声影响的误差计算公式,并基于Predictor-lima预测软件预测和现场噪声衰减规律实测进行了验证。研究结果表明,对于接收点到道路边缘的距离大于道路宽度的情况,可简化为1条线声源;对于接收点到道路边缘的距离小于道路宽度的情况,应按照车道数简化为多条线声源。     

阿什河底栖动物群落特征及影响因子

阿什河作为松花江的一级支流,全境包含了从Ⅰ类到劣Ⅴ类的各种类型水质。通过对阿什河沿线底栖动物群落构成进行调查,结合典范对应性分析(CCA)对底栖动物群落与环境因子进行相关性分析得出结论,溶解氧和高锰酸盐指数为研究区域内底栖动物群落构成的主要限制因子。为分析不同水质条件下底栖动物种群变化成因和从生物学角度提出阿什河治理方法提供技术依据。