Estimating organic acid contributions to surface water acidity in Quebec (Canada)

Inorganic ion balances for lake waters lying on the Canadian Shield in the province of Quebec, Canada, consistently show significant anion deficits (mean deficit 70 to 90 μeq L^?1). Models taking into account organic anions have been tested for their ability to eliminate this anion deficit. The data set consisted of the chemical composition (pH, all major ions, major trace metals, dissolved organic and inorganic C, total alkalinity) of ≈1200 lakes from four hydrographic regions. The relative performances of three models (the 1983 Oliver et al. model and two derived models) were evaluated by comparing the capacity of each model to compensate fully for the anionic deficit of the waters. The study showed that without calibration all models systematically underestimated the anionic deficit. The two derived models were recalibrated and validated by regional discrimination of the data; charge balances calculated with the recalibrated models were markedly improved. Based on calculated anion deficits, the contribution of natural organic acids to Quebec surface water acidity increases from southwest to northeast and greatly exceeds that previously reported.     

Effects of acidity on fish communities in southwestern Québec (Canada)

Surveys of fish populations were conducted on 74 lakes of the Outaouais hydrographic region during the summers of 1985 and 1986 to assess the potential impact of acidity on ichtyologic fauna. Results show that species diversity declined with the increasing acidity. The color of water does not seem to mitigate the adverse effects of acidity. On the contrary, the number of species decreased similarly in both brown lakess (>30 Hazen) and clear lakes (≤30 Hazen) with the increase of acidity. The species tolerance threshold levels to acidity show that 72% of fish species are no longer captured when pH reaches 5.0, compared to 32% at pH ≤5.5. The pH range 5.0 to 5.5 can possibly be regarded as the break point for the occurrence of most fish species in this area. Analysis of the size frequency distributions show that recruitment failures have occurred in acidic waters for walleye and lake trout. We have estimated that anthropogenic acidification is responsible for the loss of more than 10000 fish populations in the Outaouais area.     

Relationships between buffer acidity and exchangeable acidity in lime trials with Ultisols and Histosols

Abstract

Lime requirements ordinarily are based on buffer methods but could be based on unbuffered salt‐exchangeable acidity. The relationships between exchangeable acidity (EA) and buffer acidity (BA) were studied across a range of pH levels established through lime trials in four Ultisols and one Histisol in North Carolina Coastal Plain and Piedmont regions. Buffer acidity was proportionately higher than EA in all soils at any pH level. Linear regression slopes between either BA or EA and pH, within each soil, were not significantly different when the latter relationship included samples with pH less than or equal to 5.4. Variations in EA accounted for by BA ranged from 41 to 67% among the soils investigated. Buffer acidity alone accounted for 64% of the variation in EA for samples from all soils with pH less than or equal to 5.4. Including a squared BA term and either HM or CEC increased the R² to 0.79 and 0.86, respectively, but neither equation provided a completely suitable prediction of EA across all five soils investigated.     

中性盐和pH对红壤、砖红壤胶体交换性酸的影响

In the present work, the exchangeable acidity of a red soil colloid and a latosol colloid at different pH during reacting with four neutral salts was measured. The results show that the exchangeable acidity increased with increasing amounts of the neutral salts added, and the relation between them was almost linear. When the amount of the neutral salt added was lower than a certain value, the slope of the line was high, and the slope turned low when the amount exceeded that value, so there was a turning point in each line. The addition amounts of the neutral salts for the turning points were affected by the cation species of the neutral salts, but pH had less effect on them. After the turning points occurred, the exchangeable acidity of the red soil colloid still gradually increased with the addition amounts of the neutral salts, but that of the latosol colloid did not increase any more. The exchangeable acidity in NaClO₄, KClO₄ and NaCl solutions increased at first, and then decreased with increasing pH, that is to say, peak values appeared. The peak positions of the exchangeable acidity in relation to pH changed with neutral salt solutions and were affected by the surface characteristics of the soil colloids, but not affected by the amounts of the neutral salts added. The exchangeable acidity in the Ba(NO₃)₂ solution increased continuously with increasing pH. The exchangeable acidity of the red soil colloid was obviously larger than that of the latosol colloid.     

喉管与喷嘴截面积比对射流式鱼泵输送性能及鱼损的影响

为探究喉管与喷嘴截面积比对射流式鱼泵输送性能及鱼损的影响规律,该文设计了喉管与喷嘴截面积比分别为1.75和3的射流式鱼泵,以鲫鱼为试验对象进行鱼类输送试验,获得了不同喉管与喷嘴截面积比射流式鱼泵的输送能力及单位质量能耗,并采用表观损伤统计、解剖和血清指标检测等方法分析了射流式鱼泵喉管与喷嘴截面积比对鲫鱼损伤的影响。研究结果表明:在相同被吸流体流量工况下,喉管与喷嘴截面积比较小的射流式鱼泵输送鱼类能力较强,且单位质量能耗较低。试验中喉管与喷嘴截面积比为1.75的射流式鱼泵输送鱼类能力达到1913kg/h,而单位质量能耗仅为1.51 kW?h/t。鱼类损伤的主要类型是局部鳞片少量脱落(轻度损伤),约占所有过泵鱼类的10%。在相同被吸流体流量下,喉管与喷嘴截面积比较小的射流式鱼泵中鱼类轻度损伤率较高,而喉管与喷嘴截面积比对重度损伤率影响较小;喉管与喷嘴截面积比较大的射流式鱼泵在输送过程中对少数鲫鱼肝脏造成的损伤较严重;而不同喉管与喷嘴截面积比射流式鱼泵输送过程均会对鲫鱼肾脏造成影响,但是这种影响在24 h内可以恢复到未过泵时的水平。综合考虑输送能力及鱼损情况,喉管与喷嘴截面积比为1.75的射流式鱼泵更适合鱼类输送。研究结果可为射流式鱼泵推广应用提供支持并可作为其优化设计的参考。     

石灰对酸化黄壤整治烟田土壤酸度的影响及其应用效果

采用室内培养试验和田间试验相结合的方法,研究土壤酸度对石灰施用量的动态响应规律,以及石灰施用量对烤烟农艺性状及经济性状的影响。结果表明：酸化黄壤在室内培养环境下对石灰的响应可分为3个阶段,即快速变化阶段,土壤pH值急剧升高,持续时间较短;缓慢变化阶段,土壤pH值的变化速度以及持续时间受石灰施用量的影响,石灰施用量低于3.00 t/hm2时该阶段持续时间约60 d,石灰施用量高于4.50 t/hm2时该阶段持续时间为15~30 d;稳定阶段,石灰施用量与土壤pH值间呈显著的非线性正相关关系。田间试验研究表明,土壤pH值随石灰施用量的变化规律基本与室内试验研究结果相吻合。综合石灰施用量对烤烟影响发现,在pH值为5.0左右的酸性黄壤整治烟田中,推荐提前移栽期60 d向烟田垄体中施入1.50 t/hm2的石灰以矫正土壤酸度,促进烤烟生产。     

Influence of herbicide structure,clay acidity,and humic acid coating on acetanilide herbicide adsorption on homoionic clays

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.     

Effects of acidity in precipitation on terrestrial vegetation

Over the last several decades rain in the Northeastern United States has become more acidic presumably as a result of anthropogenic inputs of SO_x and NO_x to the atmosphere and their conversion to H₂SO₄ and HNO₃. Present experimental results suggest that acidic precipitation would initially affect organisms on leaf surfaces and epidermal cells of leaves of higher plants. More internal cell layers would be affected with increasing duration or frequency of exposure. Differences in responses of plant foliage among plant species to acidic precipitation appear to be due to the degree of leaf wetting and differences in responses of leaf cells to low pH rain. Moreover, within the same plant, particular structures or cell types may be more sensitive than others. If the United States is to utilize coal reserves for electric power generation that might increase rainfall acidity in the future, an assessment of the impact that acidic rain might have on terrestrial vegetation is necessary. In one experiment, field-grown soybeans were exposed to short duration rainfalls of either pH 4.0, 3.1, 2.7, or 2.3 to provide inputs of 50, 397, 998, or 2506 μeq of H⁺, respectively, above ambient levels throughout the growing season. Control plots received only ambient rainfalls. These additional H⁺ decreased seed yield, 2.6, 6.5, 11.4, and 9.5%, respectively. A treatment response function determined between H⁺ treatments and seed yield wasy=21.06?1.01 logx had a correlation coefficient of ?0.90. Researchers must design additional experiments with adequate experimental controls to assess the impact that acidic rain, at the present pH levels of 3.0 to 4.0 or at anticipated worst-case levels, that could occur if the acidity of rain should increase. Only a holistic view of the impacts that acid precipitation may have on vegetation will enable optimal energy and environmental policy decisions to be made.     

Correlates of diet quality in the Quebec population

OBJECTIVE: To determine the correlates of a high-fat diet in urban, suburban and rural areas of Quebec, Canada. DESIGN: A secondary analysis of data collected as part of a 5-year multi-factorial, multi-setting, community-intervention project. SETTING: Urban, suburban and rural settings of the province of Quebec, 1997. SUBJECTS: Data were analysed from a sample of 5214 participants (2227 males, 2987 females). A food-frequency questionnaire was completed and a global index of food quality was calculated. Logistic regression was used to identify correlates of a diet high in total fats, saturated fat and cholesterol. RESULTS: In both genders, lower level of education, smoking status, French and English languages compared with other languages spoken at home, and a rural environment were associated with poor diet quality. Having no intention to eat low-fat dairy products more often was associated with a high-fat diet. In men, obesity (body mass index >/=30 kg m(-2)) and absence of reported health problems were correlates of a high-fat diet, while, in women, lower physical activity was a correlate. CONCLUSIONS: Future health interventions in Quebec should target people with low education, smokers and those living in a rural environment. Obese men and sedentary women should have access to specific dietetic resources.     

Influence of clay content and acidity of soil on development of the earthworm <Emphasis Type="Italic">Lumbricus rubellus</Emphasis> and its population level consequences

In this paper we report on the influence of clay content and acidity of soil on growth and reproduction of the epigeic earthworm species Lumbricus rubellus (Hoffm.), which is common in most temperate soils and abundant in grasslands. Growth, cocoon production and survival of L. rubellus were tested in 12 Dutch soils which differed in soil properties. A matrix model was used to assess the population-level consequences of changes in growth and reproduction. Soil acidity had a strong negative effect on earthworm survival, and the maturation weight decreased with clay content. Individual weight gain in L. rubellus decreased with both acidity and clay content. The acidity of soils had a larger influence on population growth rate than the clay content. The acidity of the soil also changed the population composition towards younger age classes, whereas in soils rich in clay, the population composition did not change. The average individual weight of L. rubellus in clayey soils, however, was lower compared with that in soils low in clay, a result that agrees with literature data.     

Rapid determination of methyl mercury in fish and shellfish: method development

The AOAC official first action method for methyl mercury in fish and shellfish was modified to provide more rapid determination. Methyl mercury is isolated from homogenized, acetone-washed tissue by addition of HCl and extraction by toluene of the methyl mercuric chloride produced. The extract is analyzed by electron capture gas chromatography (GC) on 5% DEGS-PS treated with mercuric chloride solution. The quantitation limit of the method is 0.25 micrograms Hg/g. Swordfish, shark, tuna, shrimp, clams, oysters, and NBS Research Material-50 (tuna) were analyzed for methyl mercury by the AOAC official first action method. All products also were analyzed by the modified method and the AOAC official method for total Hg. In addition, selected extracts obtained with the modified method were analyzed by GC with Hg-selective, microwave-induced helium plasma detection. There was no significant difference between the results for the various methods. Essentially all the Hg present (determined as total Hg) was in the organic form. Coefficients of variation from analyses by the modified method ranged from 1 to 7% for fish and shellfish containing methyl mercury at levels of 0.50-2.30 micrograms Hg/g. The overall average recovery was 100.5%.     

Influence of surface‐applied poultry manure on topsoil and subsoil acidity and salinity: A leaching column study

It has been suggested that surface applications of animal manure can ameliorate both top and subsoil acidity. For that reason, the effects of surface incorporation (0–5 cm) of a high rate of poultry manure to an acid soil on pH and exchangeable and soluble Al in the top‐ and subsoil were investigated in a leaching column study. During the experimental period of 108 d, columns received a total of 875 mm with leaching events occurring after 9, 37, 58, and 86 d. Incorporation of poultry manure into the surface 5 cm resulted in a large rise in pH measured in both 1M KCl and in soil solution. This liming effect was attributed primarily to the substantial CaCO₃ content of poultry manure. In the 15–45 cm layer, pH_KCl was not significantly different between poultry manure and control treatments but surprisingly, soil‐solution pH was substantially less in the poultry‐manure treatments. Exchangeable Al was significantly less in poultry manure than in control in all soil layers although the effect was most marked in the 0–5 cm layer. However, although concentrations and activities of monomeric Al (Al_mono), and the proportion of total Al present as Al_mono, in soil solution were lower under poultry manure than in control in the 0–5 cm layer, the reverse was, in fact, the case in lower soil horizons. This was attributed to a soluble‐salt effect, originating from the large cation content of poultry manure, displacing exchangeable Al³⁺ and H⁺ back into soil solution. Indeed, electrical conductivity and concentrations of Ca²⁺, Mg²⁺_, K⁺, and Na⁺ in soil solution were substantially higher in the poultry‐manure than in the control treatments at all soil depths. Poultry‐manure applications also resulted in substantial increases in the concentrations of Ca²⁺_, Mg²⁺_, K⁺, Na⁺, Al_mono, NH , and NO in leachates, particularly at the fourth leaching. It was concluded that although surface application of poultry manure can raise soil pH in the topsoil, increases in soluble‐salt concentrations in soil solution can greatly modify this effect in the subsoil.     

Influence of competition by sown grass, disturbance and litter on recruitment of rare flood-meadow species

As a response to the sharp decline in species-rich flood-meadows along the northern Upper Rhine during the past decades, large-scaled restoration projects have been started recently. For the implementation of restoration measures knowledge about the effects of topsoil disturbance, litter and simultaneously sown grasses on seedling recruitment are of special interest. This applies in particular to the role of sown of grasses that may accelerate sward development and ease the incorporation of newly created meadows into local farming systems. As study species we selected six typical, but rare or declining flood-meadow species which differed in seed size, since this may influence the impact of the applied treatments. We studied effects of simultaneously sown grasses on germination and recruitment success of these flood-meadow species in two former arable fields situated in the functional and fossil floodplain along the northern Upper Rhine. The effects of litter and topsoil disturbance in an existing grass sward on the recruitment of the six flood-meadow species were experimentally assessed in a species-poor grassland in the functional floodplain. The individual fate of emerging seedlings was followed over two years. The effects of the applied treatments were species-specific and rather inconsistent. Responses towards disturbance and litter application corresponded to differences in seed size, with large-seeded species showing a lower susceptibility to the influence of treatments. In addition, simultaneous sowing of grass did not hamper seedling recruitment in most cases, and thus seems to be a feasible measure to accelerate the integration of newly created flood-meadows into farming systems.     

Effects of soil acidity on the growth of sericea lespedeza

Field experiments were conducted in 1992 and 1993 to examine effects of soil acidity on growth and N₂ fixation by “Serala”; sericea lespedeza [Lespedeza juncea (L.F.) var. sericea (Mig.)]. Effects of acidified soil on N₂ fixation could not be determined because nodulation was suppressed, apparently by sufficient availability of N. Apparently‐suppressive, mean 1993 levels of KCl‐extractable NH₄ and NO₃ in zero nitrogen (N) control treatments were 20 and 13 mg‐kg^‐1, respectively. In soil acidified with sulfur (S), growth of sericiea lespedeza was significantly reduced (PO.05) when the concentration of water‐extractable Mn exceeded 1.3 mM or calculated Mn²⁺ activity exceeded 0.4 mM. This occurred at pH values of 4.1 to 4.3 depending on S treatment. At a given value of pH, shoot dry weight production was greater in S‐amended soil than in Al₂SO₄‐amended soil. Reduced growth in the latter did not appear to be directly related to higher measured levels of toxic Al but may have been caused by a combination of aluminum (Al), hydrogen (H), manganese (Mn), and phosphorus (P) effects. Lespedeza growth was lowest in nonacidified soil with pH values near 6.0, indicating a preference for acid soils by the variety “Serala.”; The demonstrated tolerance of sericea lespedeza to acid soils make it a valuable reclamation species. However, Mn may inhibit growth in acidic soils when the activity of water‐extractable Mn²⁺ exceeds 0.4 mM, and it may not fix appreciable N₂ unless available soil N is quite low.     

聚甲基硅氧烷改性有机硅对土壤酸碱调节的作用及机理研究

碱性条件下,将聚甲基硅氧烷改性,得到改性有机硅。将其与路易斯酸、质子碱、强酸和强碱按一定比例混溶于甲醇中,常温搅拌30 min。X射线光电子能谱(XPS)结果表明,路易斯酸中金属离子电子结合能均向高结合能方向位移,改性有机硅的氧原子电子结合能均不同程度降低。在不同pH值的路易斯酸、质子碱、强酸和强碱溶液中加入改性有机硅,测定其pH值。结果显示,不同易斯酸和强酸溶液pH值均有升高,质子碱和强碱溶液pH值降低。结论:改性有机硅主链结构由Si—O—Si键构成,其中氧原子的孤对电子具有路易斯碱的性能;而改性有机硅中的多羟基结构具有质子酸的性能。所以有机硅材料与普通复合肥以一定比例混合复配制得的有机硅复合肥具有调控土壤酸性和盐碱性的作用。     

Influence of O3, rainfall acidity,and soil Mg status on growth and ectomycorrhizal colonization of loblolly pine roots

Root biomass, length, and branching frequency, and number and type of mycorrhizal short roots were determined for loblolly pine seedlings grown at two levels of soil Mg and exposed to chronic levels of O₃ and simulated acidic rainfall. Seedlings were planted in a sandy loam soil having approximately 15 or 35 mg kg^?1 Mg and were exposed to subambient; ambient, or twice ambient concentrations of O₃ in open top chambers from May through October. Seedlings also received ambient amounts of simulated rainfall at pH 3.8 or 5.2. Root biomass, length, and branching frequency were not significantly affected by O₃, rainfall acidity, or soil Mg treatments. Seedlings grown in the subambient O₃ treatment had a greater number of short roots infected with mycorrhizae than seedlings grown in ambient or twice ambient O₃ treatments, but trends were not statistically significant. Increasing rainfall acidity and soil Mg concentration resulted in a significantly (P = 0.07) greater number of mycorrhizal short roots, due primarily to an increased occurrence of one corraloid mycorrhizal type. Results suggest that mycorrhizal fungi differ in their response to O₃, rainfall acidity, and soil Mg status, and suggest that mycorrhizal infection is more sensitive than seedling root growth to O₃, acidic rainfall, and soil Mg status.     

Influence of stage of development in the efficiency of nitrogen fertilization on poplar

Poplar cuttings (Populus x euroamericana) were planted in pots and grown in a greenhouse for four months with drip irrigation. Two nitrogen (N) doses of 60 and 120 kg nitrate (N-NO₃^?) ha^?1 (labeling with ¹⁵N stable isotopes) were applied at one (time I), two (time II) and three months after of the plantation (time III). The aim of this study was to determine the N-fertilizer application method that resulted in optimal N-uptake by a short-rotation of poplar crop during first year of growth. Our data revealed that NUE (N use efficiency) was largest in the last part of the experiment. The larger development of those plants at this stage enabled the improved absorption and assimilation of N. Furthermore, ¹⁵N also revealed that supply of N at three months post-planting generated more biomass and increased the N reserves in the stem; a key factor for ensuring the optimum regrowth during the second year.     

Influence of calcium on vegetative and reproductive development of Pelargonium

Cloned stem cuttings of geranium (Pelargonium peltatum) were maintained in control and mineral deficient solutions for five weeks. Hydroponic solutions were formulated to be deficient in a single mineral; e.g., ‐Ca, ‐Fe, ‐Mg, ‐N, and ‐P. Positive control solutions contained all macro and micronutrients, while negative controls consisted of double distilled water. Weights and numbers of all organs of the shoot were determined, as was an analysis of adventitious roots. Plants grown in ‐Ca solutions characteristically manifested reduced organ weights and numbers as compared to plants grown in other mineral deficiencies and both controls. Examples of reduced values recorded in ‐Ca plants, as compared to the negative control plants, were: (i) a 60% decrease in overall plant weight, (ii) a 40% reduction in the total weight of leaves per plant, (iii) a 50% reduction in stem weight, (iv) a 60% drop in the weight of the stem base and associated adventitious roots, (v) a 30% decline in inflorescence weight, (vi) a 20% reduction in the number of leaves produced per plant, and (vii) a 20% decrease in the weight of individual leaves. Perhaps the most striking developmental distinction was the absence of adventitious roots in ‐Ca plants. Cuttings in distilled water produced an average of nearly 30 roots near the stem base. Anatomical examination of stem bases from plants grown in Ca‐deficient nutrient solutions revealed a few initiated roots in only one instance, but all roots were poorly developed and few in number. Most stem bases in ‐Ca did not have any initiated root primordia. It is believed that Ca has the capability of ameliorating mineral toxicity induced by other elements in the nutrient solution.