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101.
102.
Combined effects of two sulfonylurea herbicides on soil microbial biomass and N-mineralization 总被引:1,自引:0,他引:1
IntroductionAgrochemicalshavebeenactedaveryimportantroleinagriculturalproduction .Foravoidingdamageofcrops,manykindsofpesticidesareappliedforthereasonofinsect,diseasesandweedcontrolinChina .Scientistshavedonealotofworkonthefateandmetabolismofpesticides,… 相似文献
103.
为探究溶解性有机质(DOM)不同相对分子质量组分在矿物质上的吸附特征及其与药物和个人护理品(PPCPs)类污染物的结合作用对两者吸附过程的影响,以卡马西平作为目标污染物,用商用腐殖酸制备DOM,以石英砂代表无机矿物,开展吸附实验,并采用透析实验和红外光谱表征等手段,探讨了不同相对分子质量腐殖酸(HA)的结构特征及其与卡马西平(CBZ)的结合作用对HA或CBZ在固相介质上吸附作用的差异及产生机制.结果表明,大分子量HA有更多的羟基、芳香烃和脂肪烃,以疏水物质为主;而小分子量HA有更多的醇和羧基,以亲水物质为主.HA与CBZ的结合主要通过CBZ的氨基与小分子量HA中极性官能团的结合,以及CBZ疏水基团与大分子量HA中脂肪族与芳香族的疏水作用.CBZ与HA之间的相互作用对腐殖酸或卡马西平的吸附产生明显差异.当CBZ不存在时,石英砂主要通过疏水作用结合HA中疏水性大分子或与HA的羟基、羧基等发生交换配位反应,且石英砂更倾向于吸附HA中的脂肪性及疏水性大分子组分.当CBZ存在时,石英砂转而吸附HA中的小分子量部分,且HA在石英砂上的最大吸附量减小.当HA不存在时,CBZ可通过疏水作用,范德华力和极性相互作用使其在石英砂上有一定量的吸附.加入HA后,石英砂吸附增加的CBZ归因于部分HA分子与CBZ结合后共吸附或累积吸附于石英砂上. 相似文献
104.
Rapid growth in marine sand mining for construction and other uses poses environmental challenges to coastal nations virtually
worldwide. Yet the development of management policies, such as a system of fees imposed on operators for damage caused by
mining, has been frustrated by a lack of studies to support such measures. Adapting a Beverton-Holt bioeconomic model, this
paper attempts to contribute to the estimation of external costs to commercial fisheries due to marine mining. Using the major
mining area of Ongjin in Korea as a case study, we estimate economic losses in use value of commercial fisheries through the
time to recovery of the injured resource stocks. Present value of lost catch over a 1-year period from mining to resource
recovery is estimated at $38,851 for a single “prototype” mining site. Estimated cumulative damages due to recurring mining
for 5 and 10 years are $1.5 million and $2.2 million, respectively, at 20 mining sites. Sensitivity analyses are used to examine
the effects of alternative assumptions to assess the many sources of uncertainty. Using a form of meta-analysis, dose-response
information is used to assess the excess mortality the mining sediment plume has on eggs and larvae and, ultimately, on the
value of lost catch ($841). Also addressed is the importance of specifying the appropriate “premining” conditions against
which to assess environmental losses at the mining site. Damages estimated with premining fish populations are $23,066 higher
than is the case using postmining conditions. Overall, the illustrative results suggest the variety of complex conditions
which influence damage to fisheries from mining and which can benefit from further study to improve management guidelines.
An erratum to this article can be found at 相似文献
105.
Zero-valent iron and iron oxide-coated sand as a combination for removal of co-present chromate and arsenate from groundwater with humic acid 总被引:1,自引:0,他引:1
The combination of zero-valent iron (Fe0) and iron oxide-coated sand (IOCS) was used to remove Cr(VI) and As(V) from groundwater in this study. The efficiency and the removal mechanism of Cr(VI) and As(V) by using this combination, with the influence of humic acid (HA), were investigated using batch experiments. Results showed that, compared to using Fe0 or IOCS alone, the Fe0-IOCS can perform better on the removal of both Cr(VI) and As(V). Metal extraction studies showed that As(V) was mainly removed by IOCS and iron corrosion products while Cr(VI) was mainly removed by Fe0 and its corrosion products. Competition was found between Cr(VI) and As(V) for the adsorption sites on the iron corrosion products. HA had shown insignificant effects on Cr(VI) removal but some effects on As(V) removal kinetics. As(V) was adsorbed on IOCS at the earlier stage, but adsorbed/coprecipitated with the iron corrosion products at the later stage. 相似文献
106.
107.
This paper shows the results of a survey carried out at some refractory manufacturing plants. During the first part of the survey, the concentration of natural radioactivity in raw materials and end-products, coming from four plants, was assessed. Several raw materials and, as a consequence, some end-products as well have shown activity concentrations exceeding a few hundreds of Bq kg−1 of 238U and 232Th. In some important raw materials, such as bauxite and corundums, a remarkable radioactive disequilibrium was observed; this is probably due to the high temperature processes undergone by these materials. The second part of the survey focussed on the measurements of ambient equivalent dose rates, airborne dust concentrations and radon indoor. On the basis of results obtained, the effective dose for the standard worker was estimated. Two different types of refractory plants were investigated. Effective doses for both plants were lower than 1 mSv y−1. 相似文献
108.
109.
Abdolreza Mirmohseni Mehrdad Rastgouy-Houjaghan 《Journal of environmental science and health. Part. B》2013,48(7):677-686
Quartz crystal nanobalance (QCN) technique is considered as a powerful mass sensitive sensor for monitoring of materials in the sub-nanogram level. In the current study, a method based on QCN technique developed to determine Telone in air. Various coating materials including methyl phenyl silicon, 75% phenyl (OV25) and molecularly imprinted polymer (MIP) were employed. The frequency shift of OV25-modified quartz crystal was found to be linear against organohalogen compounds [Telone (soil fumigant), Koril (Herbicide), Endosulfan (organochlorine insecticide) and Chloroform (solvent)] concentrations in the range of 2.4 to 48 mg L?1 for Telone vapor and 4.8–24 mg L?1 for three other vapors. The correlation coefficients for Telone, Koril, Endosulfan and Chloroform were 0.992, 0.996, 0.989 and 0.991, respectively. The principal component analysis was also utilized to process the frequency response data of the organic vapors. Using principal component analysis, it was found that more than 93.85% of the data variance could still be explained by use of two principal components (PC1 and PC2). Subsequently, the successful discrimination of Telone and other compounds was quite possible through the principal component analysis of the transient responses of the OV25-modified electrode. In the second method, a molecularly imprinted polymer-coated sensor for Telone was developed. Molecularly imprinted polymer coated quartz crystal (MIP-QCN) showed a selective response to Telone and gave a linear relationship between frequency shift and amount of Telone from 1 to 48 mg L?1. In this investigation, the proficiency of MIP-QCN and OV25-modified QCN sensors were compared. 相似文献
110.
Dissipation of terbuthylazine,metolachlor, and mesotrione in soils with contrasting texture 总被引:1,自引:0,他引:1
Laura Carretta Ester Marotta Giuseppe Zanin Roberta Masin 《Journal of environmental science and health. Part. B》2013,48(10):661-668
ABSTRACTThis study evaluates the dissipation of terbuthylazine, metolachlor, and mesotrione at different depths in soils with contrasting texture. The field trial was conducted at the Padua University Experimental Farm, north-east Italy. The persistence of three herbicides was studied in three different soil textures (clay soil, sandy soil, and loamy soil) at two depths (0–5 and 5–15 cm). Soil organic carbon content was highest in the clay (1.10%) followed by loam (0.67%) and sandy soil (0.24%); the pH of soils was sub-alkaline. Terbuthylazine, metolachlor, and mesotrione were applied on maize as a formulated product (Lumax®) at a dose of 3.5 L ha?1. Their dissipation in the treated plots was followed for 2 months after application. The concentrations of herbicides were analyzed by liquid chromatography-mass spectrometry. The dissipation of terbuthylazine, metolachlor, and mesotrione could be described by a pseudo first-order kinetics. Terbuthylazine showed the highest DT50, followed by metolachlor and mesotrione. Considering the tested soil, the highest DT50 value was found in clay soil for terbuthylazine and metolachlor, whereas for mesotrione there was no difference among soils. Significant differences were found between the two soil depths for terbuthylazine and metolachlor, whereas none were found for mesotrione. These results suggest that soil texture and depth have a strong influence on the dissipation of terbuthylazine and metolachlor, whereas no influence was observed on mesotrione because of its chemical and physical properties. 相似文献