水泥粉尘对夹江城区降雨pH值的影响

本文通过实验测试和理论计算，说明了夹江县城区降雨pH值偏高是由于水泥粉尘影响造成的，通过测试数据计算了水泥厂周围区域每天承受水泥污染的数量。     

《地面水质量标准(GB3838—88)》中非离子氨浓度的计算方法

本文分析了《地面水质量标准》(GB3838—88)中非离子及氨查表换算法可能的缺点,介绍了一种仅用计算式可快速、准确计算5—30℃水温,pH=6.0～10.0范围内任意温度、任意pH值时非离子氨百分比、允许总氨浓度,非离子氨浓度的方法,并具体计算与文献值比较,结果表明此计算式是正确和简便实用的。     

xDLVO理论解析腐殖酸微滤膜污染机理

运用extended Derjaguin-Landau-Verwey-Overbeek(xDLVO)理论定量解析不同pH值下腐殖酸微滤膜污染机理。理论计算表明,随着pH升高,膜污染趋势会降低,这主要是通过改变极性相互作用而实现的,并且过滤初期的膜污染比后期更严重。过滤实验验证了xDLVO理论预测膜污染趋势的准确性。不同阶段下界面相互作用能和膜污染趋势的线性拟合表明,在粘附阶段膜污染趋势对界面作用能更敏感。     

环境质量评价模糊集理论与模式研究

探讨了模糊集理论方法对环境质量评价的可行性，以大气环境质量评价为例，叙述了这种方法的研究程序及计算步骤。研究表明，采用模糊集理论方法对大气环境质量进行评价，结果结果合理，方法可行，有一定的参考价值。     

用灰色系统理论GM(1,1)建立大气降水中酸雨pH值的预测模型

本文用灰色系统理论GM(1,1)建立了大气降水中pH值的预测模型。经三种不同方法检验。对我市1990—1993年大气降水中酸雨pH值进行了预测,结果令人满意。     

酸雨pH预测的偏最小二乘回归模型

酸雨pH值受酸性离子[SO4^2-]、[NO3^-]和碱性离子[Ca^2 ]、[NH4^ ]等的影响。这些影响因素之间存在多重相关性。用一般最小二乘回归法建模预测pH值，估计参数存在着很大的误差且物理意义明显不足。应用偏最小二乘回归技术建立pH值预测模型，克服了自变量之间的多重相关性的问题，因而更具有先进性，计算结果更为可靠。以我国17个城市pH值预测为例，探讨偏最小二乘法的优势，并与最小二乘回归法进行了比较。     

壳聚糖对酸性染料的吸附性能

在不同的壳聚糖浓度、pH和温度条件下，采用分光光度法测得吸附后的染料浓度，得到了壳聚糖对酸性染料的最佳吸附条件，即在固定染料浓度和体积的情况下，壳聚糖的投入量在500mg、pH值为6、温度为室温、吸附时间为2h左右条件下吸附最佳，其结果将为利用壳聚糖处理印染废水提供一定的理论根据。     

壳聚糖处理印染废水的研究

在不同的壳聚糖浓度、pH和温度条件下，采用分光光度法测得吸附后染料的浓度，得到了壳聚糖对染料的最佳吸附条件，结果为：壳聚糖的投入量在红3B为2％，兰2BG和黄3GE为3％时，pH8．4在碱性范围内，温度为50℃效果最佳。其结果将为壳聚糖在印染废水处理提供一定的理论基础。     

正交化方法在水质模型参数确定中的应用

本文根据常微分方程参数反问题的数学理论，将正交化方法同有限差分法结合用于确定水质模型参数，并与正则化方法、最速下降法和共轭梯度法作了比较。其计算结果对比表明，正交化方法具有快速、简便、可靠的特点。更适合于水质模型参数的确定。     

石灰—石膏法在烧结烟气脱硫中的应用

介绍了钢铁企业烧结机烟气采用湿式石灰—石膏法进行脱硫的基本原理和工艺方法,结合已投入使用的系统进行了分析和探讨,对影响脱硫效率的诸多因素,如烟气中SO2浓度、液气比、pH值、吸收反应过程、特性、最终产品石膏的形成进行了理论分析和研究。通过对系统设备、特性的研究,提出了控制液气比、调节浆液pH值和烟气性质等保障系统高效稳定运行的措施。     

Rhamnolipid morphology and phenanthrene solubility at different pH values

The effect of pH and rhamnolipids on the solubility of phenanthrene was investigated in a sand-water system. Batch phenanthrene solubilization experiments in this system showed that the highest phenanthrene solubility occurred at pH 5 in the presence of 240 and 150 mg L(-1) rhamnolipids. As the pH was increased from 5 to 7, the apparent solubility of phenanthrene decreased and then stabilized from pH 7 to 8. At pH 4, a dramatic decrease in phenanthrene solubility was observed. This result is in contrast to previous findings obtained in an aqueous system without soil particles. To investigate the reason for this decrease, the critical micelle concentrations (CMCs) were measured in the presence or absence of sand particles, and the maximum amount of sorbed biosurfactant at each pH was calculated based on the differences of the two CMC values. More rhamnolipid molecules were lost by the sorption into sand particles at pH 4 than at other pH values; this explains the dramatic decrease of solubility at pH 4 in the sand-water system. To confirm the explanation for the different solubilizing capacity that results from the structural change of biosurfactant aggregate, cryo-transmission electron microscopy was used. Micrographs showed that the rhamnolipid morphology changed from large lamellar sheets, to vesicle, and then to micelle as the pH increased. The large and multilamellar vesicles at pH 5 were considered to be the most effective structure for the solubilization of phenanthrene.     

Zinc fractionation in contaminated soils by sequential and single extractions: influence of soil properties and zinc content

We studied the fractionation of zinc (Zn) in 49 contaminated soils as influenced by Zn content and soil properties using a seven-step sequential extraction procedure (F1: NH4NO3; F2: NH4-acetate, pH 6; F3: NH3OHCl, pH 6; F4: NH4-EDTA, pH 4.6; F5: NH4-oxalate, pH 3; F6: NH4-oxalate/ascorbic acid, pH 3; F7: residual). The soils had developed from different geologic materials and covered a wide range in soil pH (4.0-7.3), organic C content (9.3-102 g kg(-1)), and clay content (38-451 g kg(-1)). Input of aqueous Zn with runoff water from electricity towers during 26 to 74 yr resulted in total soil Zn contents of 3.8 to 460 mmol kg(-1). In acidic soils (n = 24; pH <6.0), Zn was mainly found in the mobile fraction (F1) and the last two fractions (F6 and F7). In neutral soils (n = 25; pH > or =6.0), most Zn was extracted in the mobilizable fraction (F2) and the intermediate fractions (F4 and F5). The extractability of Zn increased with increasing Zn contamination of the soils. The sum of mobile (F1) and mobilizable (F2) Zn was independent of soil pH, the ratio of Zn in F1 over F1+F2 plotted against soil pH, exhibited the typical shape of a pH sorption edge and markedly increased from pH 6 to pH 5, reflecting the increasing lability of mobilizable Zn with decreasing soil pH. In conclusion, the extractability of Zn from soils contaminated with aqueous Zn after decades of aging under field conditions systematically varied with soil pH and Zn content. The same trends are expected to apply to aqueous Zn released from decomposing Zn-bearing contaminants, such as sewage sludge or smelter slag. The systematic trends in Zn fractionation with varying soil pH and Zn content indicate the paramount effect of these two factors on molecular scale Zn speciation. Further research is required to characterize the link between the fractionation and speciation of Zn and to determine how Zn loading and soil physicochemical properties affect Zn speciation in soils.     

THROUGHFALL pH: EFFECT OF PRECIPITATION : TIMING AND AMOUNT1

ABSTRACT: Precipitation, throughfall, and stream pH were measured weekly over a 27-week period in 1982 on the Little Millseat watershed in eastern Kentucky. The average pH values over the study period were 4.3, 4.9, and 6.4, respectively, indicating significant buffering as water moved from the atmosphere, through the deciduous canopy, and through or over the soil to the stream. Regression analysis demonstrated that the timing and amount of precipitation were important factors influencing the pH of the throughfall. Weekly precipitation and the three-week average precipitation were statistically significant variables, explaining 53 percent of the variance in the observed through- fall pH. Precipitation pH was not a statistically significant variable for this watershed and sampling period.     

PERIVITELLINE pH OF SALMONIDE EGGS IN RELATION TO AMBIENT pH1

ABSTRACT: Eggs from salmon and brown trout were reared at 6 pH levels in the pH range 4.1–7.5. By micropuncture, the pH of the perivitelline fluid (PVF) was measured at different stages of development with an antimony microelectrode system. The pH of the PVF falls with decreased pH of the ambient media, although no point of equilibrium was found at the lower pH levels. When eggs were reared at pH levels 4.1–4.7, the pH of the PVF in salmon eggs was 0.4 units above the ambient media, while that in trout eggs was 1.0 pH units above. Decreased pH of the PVF during the later, actively ion accumulation, embryonic stages will subject the embryos to ion regulating stresses similar to those registered for adult fishes.     

Physiological and Biochemical Effects of Simulated Acid Rain on Phaseolus Vulgaris Var. HUR-15

Pot experiments were performed to determine the effects of simulated acid rain on Phaseolus vulgaris var. HUR-15. Seeds of Phaseolus vulgaris var. HUR-15 were exposed to simulated acid rain at pH values of 5.1, 4.1, 3.1, 2.1 and 1.1 and a control level of pH 6.8. Plants were harvested at three stages, i.e. pre, peak and post-flowering stages. Seedlings succumbed at pH 1.1. Necrosis developed on the leaves of plants treated with water of pH 2.1, resulting in adverse effect on chlorophyll content. They died after peak-flowering. Root and shoot length and dry weight were reduced with the lowering in pH. Carbohydrate, nitrogen and protein contents decreased with the decrease in pH level, adversely affecting their nutrient value.     

Betaine removal during thermo- and mesophilic aerobic batch biodegradation of beet molasses vinasse: influence of temperature and pH on the progress and efficiency of the process

The key issue in achieving a high extent of biodegradation of beet molasses vinasse is to establish the conditions for the assimilation of betaine, which is the main pollutant in this high-strength industrial effluent. In the present study, aerobic batch biodegradation was conducted over the temperature range of 27-63°C (step 9°C), at a pH of 6.5 and 8.0, using a mixed culture of bacteria of the genus Bacillus. Betaine was assimilated at 27-54°C and the pH of 8.0, as well as at 27-45°C and the pH of 6.5. The processes where betaine was assimilated produced a high BOD(5) removal, which exceeded 99.40% over the temperature range of 27-45°C at the pH of 8.0, as well as at 27°C and the pH of 6.5. Maximal COD removal (88.73%) was attained at 36°C and the pH of 6.5. The results indicate that the process can be applied on an industrial scale as the first step in the treatment of beet molasses vinasse.     

Responses of herbaceous mimosa (Mimosa strigillosa), a new reclamation species, to soil pH

Growth responses of herbaceous mimosa (Mimosa strigillosa Torr. and Gray), a potential new reclamation species in the SE USA and Mexico, to nine soil pH scales were studied under a controlled environment at Nacogdoches, TX, USA. Twenty seeds were planted in each of 40 (nine scales plus one control in four replicates) 20.3-cm pots filled with Tonkawa sandy soil. These pots were treated with H₂SO₄ or Ca(OH)₂ to adjust each pot to its designated pH level. After 15 days of seeding, the emergence rate was at best about 50–70% for pH 4.7–6.6. The plant can survive and grow at soil pH as low as 4.7, but the optimum growth seems to be on soils with pH ranging from 6.2 to 7.1. At this pH range, the plant exhibits higher values of green and dry biomass, longer shoot growth and lower root/shoot weight and length ratios. The survival rate was greater than 90% for all treatments, except for pH 4.1. There were no nutrient deficiencies in plant tissues on soil pH 4.7 or higher. The plant allocated more growth to the shoot under optimum conditions, but more growth to the roots under environmental stress. It is not suitable for herbaceous mimosa to grow on soils with pH 4.1 or less.     

The leaching characteristics of selenium from coal fly ashes

The leaching characteristics of selenium from several bituminous and subbituminous coal fly ashes under different pH conditions were investigated using batch methods. Results indicated that pH had a significant effect on selenium leaching from bituminous coal ash. The minimum selenium leaching occurred in the pH range between 3 and 4, while the maximum selenium leaching occurred at pH 12. The release of selenium from subbituminous coal ashes was very low for the entire experimental pH range, possibly due to the high content of calcium which can form hydration or precipitation products as a sink for selenium. The adsorption results for different selenium species indicated that Se(VI) was hardly adsorbable on either bituminous coal ashes or subbituminous coal ashes at any pH. However, Se(IV) was highly adsorbed by bituminous coal ashes under acidic pH conditions and was mostly removed by subbituminous coal ashes across the entire pH range. This result suggests that the majority of selenium released from the tested fly ashes was Se(IV). A speciation-based model was developed to simulate the adsorption of Se(IV) on bituminous coal fly ash, and the pH-independent adsorption constants of HSeO3* and SeO3 2* were determined. The modeling approach is useful for understanding and predicting the release process of selenium from fly ash.     

The effect of pH on metal accumulation in two Alyssum species

Nickel phytoextraction using hyperaccumulator plants offers a potential for profit while decontaminating soils. Although soil pH is considered a key factor in metal uptake by crops, little is known about soil pH effects on metal uptake by hyperaccumulator plants. Two Ni and Co hyperaccumulators, Alyssum murale and A. corsicum, were grown in Quarry muck (Terric Haplohemist) and Welland (Typic Epiaquoll) soils contaminated by a Ni refinery in Port Colborne, Ontario, Canada, and in the serpentine Brockman soil (Typic Xerochrepts) from Oregon, USA. Soils were acidified and limed to cover pH from strongly acidic to mildly alkaline. Alyssum grown in both industrially contaminated soils exhibited increased Ni concentration in shoots as soil pH increased despite a decrease in water-soluble soil Ni, opposite to that seen with agricultural crop plants. A small decrease in Alyssum shoot Ni concentration as soil pH increased was observed in the serpentine soil. The highest fraction of total soil Ni was phytoextracted from Quarry muck (6.3%), followed by Welland (4.7%), and Brockman (0.84%). Maximum Ni phytoextraction was achieved at pH 7.3, 7.7, and 6.4 in the Quarry, Welland, and Brockman soils, respectively. Cobalt concentrations in shoots increased with soil pH increase in the Quarry muck, but decreased in the Welland soil. Plants extracted 1.71, 0.83, and 0.05% of the total soil Co from Welland, Quarry, and Brockman, respectively. The differences in uptake pattern of Ni and Co by Alyssum from different soils and pH were probably related to the differences in organic matter and iron contents of the soils.     

Adsorption and degradation of the weak acid mesotrione in soil and environmental fate implications

The ability of soils to adsorb and degrade pesticides strongly influences their environmental fate. This paper examines the adsorption and degradation of a weak acid, a new herbicide mesotrione 12-[4-(methylsulfonyl)-2-nitrobenzoyl]-1,3-cyclohexanedione], in 15 different soils from Europe and the USA. Experiments were conducted to understand the influence of soil properties, covering a wide range of soil textures, soil pH values (4.4 to 7.5), and organic carbon contents (0.6 to 3.35%). Mesotrione adsorption (Kd values ranged from 0.13 to 5.0 L/kg) was primarily related to soil pH, and to a lesser extent by percent organic carbon (%OC). As soil pH rose. mesotrione Kd values got smaller as mesotrione dissociated from the molecular to anionic form. Mesotrione degradation (half-lives ranged from 4.5 to 32 d) was also related to soil pH, getting shorter as soil pH rose. Simple regression of mesotrione adsorption against soil pH and %OC and against degradation provided a close fit to the data. The correlation between mesotrione adsorption and degradation means that Kd and half-life values are only relevant for use in environmental fate assessment if these values are "paired" for the same soil pH and %OC. The implications were as illustrated for leaching, raising important issues about combining pesticide adsorption and degradation behavior in environmental fate assessments.