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261.
In this study, the surface chemical functional groups of Bacillus cereus biomass were identified by Fourier transform infrared (FTIR) analytical technique. It had been shown that the B. cereus cells mainly contained carboxyl, hydroxyl, phosphate, amino and amide functional groups. The potentiometric titration was conducted to explain the surface acid-base properties of aqueous B. cereus biomass. The computer program FITEQL 4.0 was used to perform the model calculations. The optimization results indicated that three sitesthree pKas model, which assumed the cell surface to have three distinct types of surface organic functional groups based on the IR analysis results, simulated the experimental results very well. Moreover, batch adsorption experiments were performed to investigate biosorption behavior of Cu(Ⅱ) and Pb(Ⅱ) ions onto the biomass. Obviously, the adsorption equilibrium data for the two ions were reasonably described by typical Langmuir isotherm. 相似文献
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盐碱池塘底栖动物的初步研究 总被引:9,自引:0,他引:9
研究了不同放养模式的高青盐碱池塘底栖动物的种类组成、生物量及其季节变动。结果表明,盐碱池塘底栖动物群落结构简单,主要优势种是羽摇蚊幼虫和奥特开水丝蚓,底栖动物密度和生物量无鱼对照池比养鱼池高得多,平均密度(nar/m^-2)和生物量(ρA/g m^-2)分别为1103(40-2085)m^-2和4.61(0.15-12.91)g m^-2,养地池底栖动物nar/m^-2和ρA/g m^-2分别为54-161m^-1和0.14-0.54g m^-2。底栖动物密度和生物量在春夏之交有一高峰,对盐碱池塘底栖动物种、量特点及其与鱼类捕食和一些生态因子的关系进行了讨论。 相似文献
264.
An incubation experiment lasting 111 d was carried out to study the effect of the addition of three clay minerals (Na-bentonite, Ca-bentonite, and zeolite) to soil derived from sewage sludge on water-extractable and exchangeable forms of four heavy metals (Zn, Cd, Cu, and Ni), as well as on soil organic matter mineralization, microbial biomass C and the release of inorganic N. The addition of clay minerals led to a significant decrease in water-extractable and exchangeable forms of heavy metals. The extent of decrease ranged from 14 to 75% for the water-extractable heavy metals and from 12 to 42% for the exchangeable form over the incubation time, as compared with untreated soil. The reduction in extractability of heavy metals was greater due to the addition of Na-bentonite and Ca-bentonite than that due to the addition of zeolite. Addition of clay minerals did not affect any of the following microbiological parameters in the soil: microbial biomass C, organic C (Corg) mineralization, and metabolic quotient (qCO2), and release of inorganic N during the first 3 weeks of incubation. However, as the incubation period increased, these parameters were significantly increased by the addition of clay minerals, especially by the addition of Na-bentonite and Ca-bentonite. This result is explained by a strong reduction in extractability of heavy metals after the addition of Na-bentonite and Ca-bentonite. 相似文献
265.
Parameters of the production and destruction processes in different types of tundras are compared. It is shown that there is a fairly high degree of correspondence between the structure of tundra communities and the ecotopes occupied by them. On the other hand, typologically similar lowland and mountain tundras markedly differ in the functional respect. The rate of decomposition processes is higher under environmental conditions of the mountain tundra belt. 相似文献
266.
梦清园芦苇湿地根际微生物特性研究 总被引:1,自引:0,他引:1
本文通过对上海市梦清园芦苇湿地净化苏州河污染水体的示范工程采样分析,结果表明芦苇根际的微生物数量、酶的活性高于非根际的土壤。根际细菌、真菌和放线菌的数量均比非根际多,R/S平均值分别为70.3、9.5、2.9。相对于硝酸细菌而言亚硝酸细菌的根际效应较为明显,无论根际还是非根际的亚硝酸细菌数量均高于硝酸细菌的数量。根际细菌和硝化细菌数量随着水力停留时间增加而增加,而根际反硝化细菌数量则减少。菌剂和酶制剂的加入使得非根际泥样异养细菌、真菌、放线菌和亚硝酸细菌比对照组稍高,硝酸细菌和反硝化细菌则较少;而根际泥样中加菌剂和酶制剂组微生物数量比空白组高出1—2个数量级,在投加菌和酶制剂后酶活性无论在根际还是非根际都得到提高,高于对照组约5—6个酶活单位。 相似文献
267.
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270.
Many marshes in the Gulf Coast Chenier Plain, USA, are managed through a combination of fall or winter burning and structural
marsh management (i.e., levees and water control structures; hereafter SMM). The goals of winter burning and SMM include improvement
of waterfowl and furbearer habitat, maintenance of historic isohaline lines, and creation and maintenance of emergent wetlands.
Although management practices are intended to influence the plant community, effects of these practices on primary productivity
have not been investigated. Marsh processes, such as vertical accretion and nutrient cycles, which depend on primary productivity
may be affected directly or indirectly by winter burning or SMM. We compared Chenier Plain plant community characteristics
(species composition and above- and belowground biomass) in experimentally burned and unburned control plots within impounded
and unimpounded marshes at 7 months (1996), 19 months (1997), and 31 months (1998) after burning. Burning and SMM did not
affect number of plant species or species composition in our experiment. For all three years combined, burned plots had higher
live above-ground biomass than did unburned plots. Total above-ground and dead above-ground biomasses were reduced in burned
plots for two and three years, respectively, compared to those in unburned control plots. During all three years, belowground
biomass was lower in impounded than in unimpounded marshes but did not differ between burn treatments. Our results clearly
indicate that current marsh management practices influence marsh primary productivity and may impact other marsh processes,
such as vertical accretion, that are dependent on organic matter accumulation and decay. 相似文献