Freeze-thaw effects on phosphorus loss in runoff from manured and catch-cropped soils

Concern over nonpoint source P losses from agricultural lands to surface waters in frigid climates has focused attention on the role of freezing and thawing on P loss from catch crops (cover crops). This study evaluated the effect of freezing and thawing on the fate of P in bare soils, soils mixed with dairy manure, and soils with an established catch crop of annual ryegrass (Lolium multiflorum L.). Experiments were conducted to evaluate changes in P runoff from packed soil boxes (100 by 20 by 5 cm) and P leaching from intact soil columns (30 cm deep). Before freezing and thawing, total P (TP) in runoff from catch-cropped soils was lower than from manured and bare soils due to lower erosion. Repeated freezing and thawing significantly increased water-extractable P (WEP) from catch crop biomass and resulted in significantly elevated concentrations of dissolved P in runoff (9.7 mg L(-1)) compared with manured (0.18 mg L(-1)) and bare soils (0.14 mg L(-1)). Catch crop WEP was strongly correlated with the number of freeze-thaw cycles. Freezing and thawing did not change the WEP of soils mixed with manures, nor were differences observed in subsurface losses of P between catch-cropped and bare soils before or after manure application. This study illustrates the trade-offs of establishing catch crops in frigid climates, which can enhance P uptake by biomass and reduce erosion potential but increase dissolved P runoff.     

Incinerating volatile organic compounds with ferrospinel catalyst MnFe2O4: an example with isopropyl alcohol

This paper concerns the incineration of isopropyl alcohol (IPA) using the ferrospinel catalyst MnFe2O4. It covers the preparation of the ferrospinel catalyst, the screening of catalytic activity, catalytic incineration testing, and 72-hr decay testing of the catalyst. The experimental results of catalyst screening reveal that the Mn/Fe catalyst is the best of five prepared catalysts (chromium/iron [Cr/Fe], manganese/iron [Mn/Fe], zinc/iron [Zn/Fe], nickel/iron [Ni/Fe], and pure magnetite [Fe3O4]). In tests of the catalytic incineration system used to convert IPA, 98% conversion was obtained at a space velocity of 24,000 hr(-1), an oxygen (O2) content of 21%, 1700 ppm of IPA, and a reaction temperature of 200 degrees C.     

Deciphering urban traffic impacts on air quality by deep learning and emission inventory

Air pollution is a major obstacle to future sustainability, and traffic pollution has become a large drag on the sustainable developments of future metropolises. Here, combined with the large volume of real-time monitoring data, we propose a deep learning model, iDeepAir, to predict surface-level PM_2.5 concentration in Shanghai megacity and link with MEIC emission inventory creatively to decipher urban traffic impacts on air quality. Our model exhibits high-fidelity in reproducing pollutant concentrations and reduces the MAE from 25.355 µg/m³ to 12.283 µg/m³ compared with other models. And identifies the ranking of major factors, local meteorological conditions have become a nonnegligible factor. Layer-wise relevance propagation (LRP) is used here to enhance the interpretability of the model and we visualize and analyze the reasons for the different correlation between traffic density and PM_2.5 concentration in various regions of Shanghai. Meanwhile, As the strict and effective industrial emission reduction measurements implementing in China, the contribution of urban traffic to PM_2.5 formation calculated by combining MEIC emission inventory and LRP is gradually increasing from 18.03% in 2011 to 24.37% in 2017 in Shanghai, and the impact of traffic emissions would be ever-prominent in 2030 according to our prediction. We also infer that the promotion of vehicular electrification would achieve further alleviation of PM_2.5 about 8.45% by 2030 gradually. These insights are of great significance to provide the decision-making basis for accurate and high-efficient traffic management and urban pollution control, and eventually benefit people's lives and high-quality sustainable developments of cities.     

老港填埋场渗滤液性质随工艺变化研究

经老港填埋场渗滤液处理系统的各处理单元处理后的流出液,用不同孔径的系列膜进行了梯度分离。分离前后的渗滤液进行了TOC、TP、TN、氨氮和可溶性P等参数的测定,并建立了各参数与不同孔径膜的关系。结果表明,此工艺对老港填埋场渗滤液的处理具有一定的功效;随着处理工艺的进行,渗滤液的组成发生了较大的改变,其中细胶体部分的百分含量增加,而可溶性部分降低;渗滤液的绝大部分污染物质集中于可溶性部分,而渗滤液中的P主要与大分子的悬浮物和粗胶体结合。     

五氯酚废水生化处理技术研究进展

五氯酚是氯酚族中最具毒性和最难降解的有机污染物,其废水的处理一直受人关注.文章概述了五氯酚的生物降解规律和近年来国内外有关五氯酚废水生化处理技术的最新研究进展,对各种方法的优缺点进行了评述,对未来的研究方向提出了建议.     

废水毒性鉴别评价方法

废水毒性鉴别评价是１９８４年发展起来的一项新技术，目的是快速，简便地鉴别引起毒性的化学物质。包括毒物的分离，浓缩，样品分级，仪器分析，毒性追踪，相关性等技术，本方法分三个阶段：毒物特征，毒物鉴别、毒物确证。     

农田土壤重金属污染状况及修复技术研究

重金属污染因具有毒性、易通过食物链在植物,动物和人体内累积,对生态环境和人体健康构成严重威胁。随着工业快速发展、农药及化肥的广泛使用,农田土壤重金属污染越来越严重,研究农田土壤重金属污染现状及修复技术对农产品安全具有重要意义。综合国内外农田土壤重金属污染状况,农田土壤重金属污染主要来源于固体废弃物堆放及处置、工业废物大气沉降、污水农灌和农用物质的不合理施用。该文综述了国内外有关农田重金属污染土壤修复技术（物理修复、化学修复、生物修复、农业生态和联合修复）的研究进展,并针对各种修复方法,阐述了其原理、修复条件、应用实例及其优缺点,重点论述了植物修复的机理和应用,提出了草本与木本联合修复可有效提高农田土壤重金属复合污染的修复效率,为农田土壤土壤重金属复合污染修复提出了新的途径。最后在对已有研究分析的基础上,提出了联合修复技术（如生物联合技术、物理化学联合技术和物理化学-生物联合技术）可以在一定程度上克服使用单一修复手段存在的缺点,可提高复合污染的修复效率、降低修复成本,未来应深入探索联合修复技术间的相互作用机理,以期为农田土壤重金属综合治理与污染修复提供科学依据。     

老港填埋场新鲜渗滤液性质研究

用系列滤膜对老港填埋场2003年3月份新鲜渗滤液进行了梯度分离．并研究了其CODcr、氨氮、TOC、IC、TC、TS、FS、电导率、pH、色度,浊度的变化趋势与不同孔径膜之间的关系。结果表明,随着膜孔径的减小,CODcr、氨氮、TOC、IC、TC、TS、FS、色度、浊度等都有不同程度的降低,但降低不大,说明可溶性部分物质对新鲜渗滤液的污染性贡献最大;电导率、pH则先增大后减小。     

外置双U型静钻根植工法能源桩换热性能研究∗

为探究外置双U型静钻根植工法能源桩换热性能,通过现场热响应试验,利用热源理论初步分析其岩土综合导热系数,建立三维传热数值模型并进行验证。利用三维传热数值模型分析换热管间距及其导热系数、换热液流速和桩周水泥土导热系数等因素对该新型桩换热性能的影响。分析结果表明,试桩区域岩土综合导热系数为1.64W(m·K)-1。提高换热管间距、换热管导热系数、换热液流速和桩周水泥土导热系数均能提高能源桩的换热性能,但当换热管间距大于0.25 m,换热液流速达到紊流态,换热管和桩周水泥土导热系数高于岩土综合导热系数后,提高上述参数对能源桩换热性能的提高贡献不大。     

南京市夏季青菜中有机磷农药残留量调查

１９９４年夏季调查和测定了南京市市售青菜中甲胺磷、乐果、甲基－１６０５等５种有机磷农药残留量。结果表明，夏季青菜（包括青菜秧）中有机磷农药残留量有超标现象，其中甲胺磷在青菜中的平均残留量为０．０６３ｍｇ／ｋｇ，超标率为１１．５％，其余４种有机磷农药在青菜中未检出。