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471.
472.
如何从源头做到城市生活垃圾减量化、资源化和无害化,实现物资回收再利用,获得物资回收在经济和环境效益的和谐统一,一直是理论界和现实生活中一个长期争论的问题。从政策管理的角度出发,尝试找到一个实现个人利益和政府管理角色和谐统一的方法,以期能通过政策管理,利用经济手段,从源头实现城市生活垃圾的减量化、资源化和无害化。 相似文献
473.
农药杀虫单的稻田流失规律研究 总被引:2,自引:0,他引:2
通过测坑、人工降雨等手段,对水溶性农药杀虫单的稻田消解动态、渗漏流失和径流流失等进行了研究。结果表明,(1)无水稻时,杀虫单在稻田水中消解的半衰期为0.76d;分蘖初期,杀虫单在稻田水中降解的半衰期为1.02d;平均为0.89d。(2)杀虫单的渗漏流失量在用药后8d内可达总用药量的7%—10%,平均为8.48%。(3)极端情况下,用药当天如果遇暴雨(50mm雨量),杀虫单的径流流失量将达到用药量的30%左右。杀虫单的渗漏损失不可避免,故其流失控制应从径流损失着手,尽量避免在可能有暴雨的当天或雨前1—2d用药。 相似文献
474.
介绍了我国水污染方面的情况、水污染治理的常用技术及基本工艺流程、水治理技术发展的新趋势和几种水处理的新技术。对这些新技术的基本原理、研究方向与前景作了阐述。 相似文献
475.
The application of ultrasonic-electrolysis process for the removal of copper is studied.In the ultrasonic field cavitation acts as jets and agitates the solution and breaks the barrier layer between the cathode surface and the bulk of the solution.Thus increases metal deposition on the cathode surface.The results show that an ultrasonic field is successful for the removal of low copper concentrations in solution. 相似文献
476.
To gain an understanding of the characteristics of the needle surfaces of naturally regenerated Scots pine (Pinus sylvestris L.) and their geographical distribution, eight physicochemical variables were investigated within the north boreal forest area. The visibly undamaged needles were collected in autumn 1990 from 114 plots (3-5 pines per plot) along radial transects from the Monchegorsk and Nikel smelters, emitting SO2 and heavy metals, on the Kola Peninsula, Russia, to Finnish Lapland. The needles were examined by scanning electron microscopy (SEM) and measured for surface wettability using the droplet contact angle (DCA) method. Significant geographical south-north and west-east patterns could be observed in needle surface characteristics, correlating with emissions from the smelters and to climate. Despite the slightly higher initial DCAs (61.4-87.6 degrees) towards the north, the pine needle surfaces of the northernmost transects exhibited higher annual needle wettability change (ANWC) and wax erosion rate (AWER), expressed as the reduction in DCAs and epistomatal wax tube distribution (WTD) during one year, respectively, but a lower occurrence of particles and fungal hyphae than those of more southern transects. The higher ANWC was related to higher atmospheric SO2 concentration, and to the lower long-term temperature sum, but not clearly to annual precipitation. In the Monchegorsk smelter area, the current needles exhibited, on average, a 15% higher WTD and seven degree larger DCA, resulting in more hydrophobic needle surfaces than in Finnish Lapland, but during their first year, both the AWER and ANWC, were greatly increased. In Finnish Lapland, 30%, of all the epistomatal wax tubes disappeared from the needle surface during the first year, the value being 70% for the pines located 8 km from the smelter. The mineral composition of the particles deposited on the needle surfaces mirrored that of the minerals being produced by the smelters (e.g. FexSx, CuFeS2, NixSx, FexOx). Stomatal densities were in the range of 71.1-141.7 stomata mm(-2). The lower densities of stomata on needles close to the smelters correlated with reduced number of needle age classes of the pines, higher dry weights, higher pollutant accumulation and lower Mn and Zn concentrations in the needles. The AWER and ANWC were able to indicate the most seriously deteriorated needle surfaces on a regional scale, e.g. including the surroundings of both smelters, although the plot-specific relationships between 'needle surface variables' and 'pollution variables' were generally weak. The present study showed that the exposure of pine needles to the combined effects of ambient pollutants and harsh climate led to a deterioration in the physicochemical characteristics of the epicuticular wax, which may have serious ecophysiological consequences in the long term. 相似文献
477.
Skelly JM Fredericksen TS Savage JE Snyder KR 《Environmental pollution (Barking, Essex : 1987)》1996,94(2):235-240
Ambient concentrations of ozone (O(3)) and carbon dioxide (CO(2)) were measured at locations from the forest floor to the top of the canopy in a deciduous forest at the Moshannon State Forest in northcentral Pennsylvania. O(3) concentrations were measured from May-September for three years (1993-1995) while CO(2) concentrations were measured only during July and August of 1994. O(3) concentrations increased steadily during the day at all locations, peaking during the middle to late afternoon hours. O(3) concentrations then steadily declined to their lowest point, just before dawn. Vertical O(3) concentration gradients varied seasonally and among years. However, O(3) concentrations were highest within the forest canopy and lowest at the forest floor, with an average difference of approximately 13%. Differences in O(3) concentrations between the canopy and forest floor were greatest at night. O(3) concentrations were slightly higher at locations within the canopy than above the canopy. CO(2) concentrations were consistenly higher near the forest floor and were higher above the canopy than within the canopy. CO(2) concentrations were higher at night than during the day at all locations, especially near the forest floor. 相似文献
478.
Bottrell SH 《Environmental pollution (Barking, Essex : 1987)》1996,91(3):325-332
Recent (<7 years old) cave sediments in Speedwell Cavern, Derbyshire, show an approximately exponential decay of organic carbon with depth. This phenomenon was thought to be due to one of two causes: (i) changing agricultural practice within the catchment feeding the cave, especially the increased use of sewage sludge and animal slurry as fertilizer; (ii) a relatively constant organic carbon concentration over time in the input sediment, with subsequent carbon mineralization during diagenesis. Carbon isotope composition of the organic material and the evolution of H/C ratio with depth indicate that the latter hypothesis is correct and that the profiles result from microbial diagenesis, not increased organic carbon inputs. By comparison with sediment of known (7 years) age, temporal decay constants for organic matter can be derived; these lie between rates previously determined for organic matter decomposition in marine sediments and soils. The H/C ratio of organic matter can be modelled as a function of time and proceeds in a similar fashion to soil organic material. 相似文献
479.
A model describing the complexing effect in the leaching of aluminum from cooking utensils 总被引:1,自引:0,他引:1
Bi S 《Environmental pollution (Barking, Essex : 1987)》1996,92(1):85-89
A simple model describing the complexing effect in the leaching of aluminum from cooking utensils is presented in this paper. Some experimental results obtained by previous workers may be explained by this model, which demonstrates that the complexing effect takes a very important role in the process of aluminum liberated from cooking utensils. Increased concentrations of complexing ions (organic acids, fluoride ion, OH-, etc.) significantly enhance the release of aluminum. The speciation of aluminum in simulated food solution is also investigated. The model suggests that in the pH range of most food (pH 4-8) aluminum present is predominantly in the form of organic Al-complexes, which is harmful to the human body. 相似文献
480.
Johnstone RM Court GS Fesser AC Bradley DM Oliphant LW MacNeil JD 《Environmental pollution (Barking, Essex : 1987)》1996,93(2):109-120
Levels of eggshell thinning, and organochlorine residues in egg contents, blood plasma of adults and juveniles, tissue samples, and prey species were determined for a population of migratory Peregrine Falcons (Falco peregrinus tundrius) breeding in the Canadian Arctic. Temporal trends were assessed by comparing data collected during 1991-1994, with data from 1982-1986, for the same population. Shells (n=54) from 1991-1994 averaged 15% thinner than eggs produced prior to the introduction of DDT. No improvement in shell thickness was detected between decades. Mean DDE residue levels in eggs showed a decline from 7.6 mg kg (1982-1986) to 4.5 mg kg (1991-1994), but there was no significant change in SigmaPCB residues. Moreover, the proportion of clutches with eggs exceeding critical SigmaPCB, DDE, and dieldrin residue levels (10%) did not change between decades. Relative to Greenland and Alaskan populations, F. p. tundrius at Rankin Inlet show high levels of organochlorine contamination and little reduction in residues over the last decade. These Tundra Peregrines continue to be exposed to organochlorines in Latin America; however, results also link relatively high levels in the study population with waterfowl species that do not leave Canada in winter. 相似文献