Temporal Trends in Water Chemistry in the Turkey Lakes Watershed Ontario,Canada, 1982-1999

The Turkey Lakes Watershed (TLW) was established in 1980 as asite for study of the ecosystem effects of acidic deposition, andsince then there has been 40% reduction in North AmericanSO₂ emissions. Monitoring records for bulk deposition,shallow and deep ground water, two headwater streams and two lakeoutflows have been tested to identify statistically significantmonotonic trends. The TLW appears to be responding to decliningacidifying emissions because the most prevalent chemical trendacross sample types/stations was decreasing SO₄ ^2-. Increasing pH was detected in four of the seven data sets, butonly the H⁺ decrease in bulk deposition was of a magnitudeto be an important ionic compensation for the SO₄ ^2-decline. There is little evidence of acidification recovery inTLW waters however. Increasing alkalinity was found only in theoutflow of the penultimate lake of the basin, and in fact, deepground water and the other lake outflow had decreasing alkalinitytrends (i.e., continuing acidification). For the surface waterstations, the greater part of the ionic compensation fordeclining SO₄ ^2- was decreasing base cations, and as aresult, these waters are probably becoming more dilute with time,although only the headwater streams exhibited decliningconductivity. Five of seven data sets had increasing dissolvedorganic carbon concentrations. Increasing NO₃ ^- wasimportant in ground waters. Drought has strongly influencedtrends and delayed recovery by mobilizing S stored in catchmentwetlands and/or soils.     

水解酸化-好氧生物滤池处理炼油废水

以高炉水渣为填料,采用水解酸化-好氧生物滤池处理炼油废水。考察了好氧区气水比、水力停留时间对炼油废水处理效果的影响。实验结果表明：在水力停留时间为6h、温度为20～35℃、废水pH为6～9、好氧区气水比为10：1的条件下,该生物滤池对NH3-N,Ar-OH,COD的总去除率分别为100％,97％,85％,处理后出水水质达到国家《污水综合排放标准》一级标准。     

An Analysis of the Structure of the Simple Mass Balance Equation: Implications for Testing National Critical Loads Maps

The critical loads concept is used by the UN-ECEConvention on Long Range Transboundary Air Pollution(CLRTAP) for setting pollution reduction targets.Increasing numbers of countries are adopting the SimpleMass Balance equation (SMB) to calculate critical loads ofacidifying S and N for forest soils. The equation is madeup of a series of mass balances each of which is used tocalculate a leaching flux. The assumptions in the SMBequation were investigated by testing its ability topredict current sulphur load and by comparing each of thecalculated leaching fluxes to measured rates. It was notpossible to predict current sulphur load at our sites usingthe SMB equation. The leaching tests demonstrated that,primarily due to its steady state assumptions, the SMBequation generates critical loads that are theoretical longterm estimates of risk, and are untestable. Thesimplifying assumptions sometimes lead to illogicalresults. Some of these can be improved by adding a final,simple but dynamic, calculation step to determine theexpected time until effects are observed. Theacceptability of combining annual average data, which bestapproximates steady state, with a biological indicator isquestionable. It is not possible to test critical loadscalculated using the SMB equation when applied with all ofits assumptions but it is possible to test its fundamentalapproach using non steady state data.     

The Importance of Selecting Appropriate Criteria for Calculating Acidity Critical Loads for Terrestrial Ecosystems Using the Simple Mass Balance Equation

The Simple Mass Balance (SMB) equationis commonly used throughout Europe for thecalculation of acidity critical loads for forestsoils. Different criteria can be set in themodel depending on whether the receptor (e.g. treeroots) is more sensitive to the toxic effects ofaluminium or to unfavourable pH conditions. Thispaper examines the effects on critical loadscalculations of using different criteria andcritical limits, and demonstrates the importanceof selecting the most appropriate and justifiablecriteria for the chosen receptor, since they caneffect the critical loads values obtained. Abrief review of the range of different criteriaand limits used throughout Europe is included. In addition, the gibbsite equilibrium constant,used in the SMB equation to represent therelationship between dissolved aluminium andhydrogen ions in soil solution, is discussed. This relationship is not generally described inthe literature as a criterion in the equation,but this work highlights the effects differentgibbsite values have on critical loadcalculations and the importance of applying themost appropriate value for the soil in therooting zone of the receptor.     

Aluminium: The Need for a Re-Evaluation of Its Toxicity and Solubility in Mature Forest Stands

Aluminium (Al) is a key element in critical loadcalculations for forest. Here, we argue for re-evaluating theimportance of Al. Effects of two levels of enhanced Alconcentrations and lowered Ca:Al ratios in the soil solutionin a field manipulation experiment in a mature spruce stand(1996–1999) on tree vitality parameters were tested. Inaddition, Al solubility controls were tested. Various loads ofAl were added to forest plots by means of an irrigationsystem. Potentially toxic Al concentrations and criticalratios of Ca to inorganic Al were established. The ratio of Cato total Al was not a suitable indicator for unfavourableconditions for plant growth. No significant effects on crowncondition, tree growth and fine root production were observedafter three years of treatment. In 1999, foliar Mg content inthe highest Al addition treatment had declined significantly.This agreed with the known response to Al stress of seedlingsin nutrient solution experiments. No support was found forusing the chemical criterion Ca:Al ratio in soil solution,foliar and root tissue as an indicator for forest damage dueto acidification. Al solubility was considerably lower thanimplied by the assumption of equilibrium with gibbsite,particularly in the root zone. The gibbsite equilibrium iscommonly used in critical load models. Substitution of thegibbsite equilibrium with an Al-organic matter complexationmodel to describe Al solubility in soil water may have largeconsequences for calculation of critical loads. The resultsindicate that critical load maps for forests should bereconsidered.     

Recovery of Acidified Lakes: Lessons From Sudbury, Ontario, Canada

Over 7,000 lakes around Sudbury, Ontario, Canada were acidified by S deposition associated with emissions from the Sudbury metal smelters and more distant S sources. Air pollution controls have led to widespread changes in damaged Sudbury lakes, including increased pH and decreased concentrations of SO₄, metals and base cations. While chemical improvements have often been substantial, many lakes are still acidified, although water quality recovery is continuing. Biological recovery has been observed in some lakes among various groups of organisms including fish, zooplankton, phytoplankton and zoobenthos. Generally, however, biological recovery is still at an early stage. Lakes around Sudbury are also showing that the recovery of acid-damaged lakes is closely linked to the effects of other major environmental stressors such as climate change, base cation depletion and UV-B irradiance. Future studies of the recovery of acid-damaged lakes around Sudbury, and in other regions, will need to consider the interactions of these and other stressors.     

Effects of Lime and Ash Treatments on DOC Fractions and Low Molecular Weight Organic Acids in Soil Solutions of Acidified Podzolic Soils

Dissolved organic carbon (DOC) fractions and different low molecular weight organic acids (LMWOAs) were determined in soil solutions from two lime or ash treated Norway spruce sites in the south of Sweden. At Hasslöv, 3.45 t ha^-1 or 8.75 t ha^-1 dolomite were applied 15 years before sampling. Horröd was treated with 4.28 t ha^-1 ash and 3.25 t ha^-1 dolomite and sampled four years later. Propionate (7–268 M) and malonate (2–34 M) were the LMWOAsfound in the highest concentrations at Hasslöv. Two other LMWOAs dominated at Horröd, namely citrate (18–64 M)and fumarate (5–31 M). The differences in concentration of most of the determined LMWOAs at Hasslöv were significantly increased due to treatment. The LMWOAs comprised between 1.1–6.3% of the DOC at Hasslöv and 4.5–17.6% at Horröd. At Hasslöv normally 3–10% of the total acidity (TA) was due to LMWOAs and the average specific buffer capacity was 74 ± 22 mmol mol^-1C.The total DOC concentration in the mor layer solution was 16 mM for the dolomite treated plots compared to 10 mM at the untreated plot. A major part of the increase in DOC at the treated plots apparently had a hydrophobic character and was of high molecular weight corresponding to 3–10 kDa. The concentration of DOC < 1 kDa in the control and treated plots was similar.     

酸沉降下加速土壤酸化的影响因素

酸沉降对土壤和水域的酸化影响是土壤环境化学研究前沿的热点问题之一。酸沉降的化学组成对酸性土壤的进一步酸化起着催化剂的作用。在酸雨影响下,SO42-、NO-3、有机阴离子是加速土壤酸化和盐基淋溶损失的主要阴离子,外源H+的进入会加速铝离子水解。自然因素与人为因素导致土壤酸化的实际酸化速率差异表明:HCO3-、RCOO-在土壤剖面中的淋失状况可反映自然土壤的酸化速率,而SO42-和NO-3淋溶产生的质子负荷揭示土壤受人为因素影响的酸化速率。通过计算酸沉降的主要化学成分进入土壤前后的质子负荷平衡,与酸中和容量(ANC)相结合,反映酸沉降加速土壤酸化的进程。     

石化废水微好氧水解酸化与厌氧水解酸化的运行对比

以石化废水为研究对象,采用微好氧水解酸化与厌氧水解酸化进行对比试验,探讨微好氧条件对难降解工业废水水解酸化的影响。维持微好氧的溶解氧(DO)浓度为0.5 mg/L左右,厌氧反应器的ORP低于-300 mV。微好氧水解酸化对COD_Cr的平均去除率为25.0%,厌氧水解酸化对COD_Cr的平均去除率为23.5%;相对于厌氧水解酸化,微好氧水解酸化的UV₂₅₄/COD_Cr低一些,对难降解的芳香有机物和含有共轭双键化合物的大分子处理效果更好。厌氧水解酸化的产酸量与酸化度稍高,这是由于微好氧水解酸化的传质效率高,氧气的存在使得产生的部分VFA同时被异养菌降解;厌氧水解酸化废水中SO₄^2-浓度降低明显,而微好氧水解酸化的SO₄^2-还原在一定程度上被抑制,SO₄^2-浓度没有显著降低,比厌氧水解酸化更能降低恶臭有毒气体H₂S的产生。在溶解氧控制适当的情况下,微好氧水解酸化更适合用于高含盐难降解石化废水的处理。     

三氯乙烯对厌氧水解酸化菌的抑制作用及去除特性

三氯乙烯（TCE）是石化废水中典型的有机污染物,对微生物具有极强的毒性。通过对挥发性脂肪酸批次试验进行生物测定,探讨TCE对厌氧水解酸化菌的产酸抑制作用,在TCE作用下水解酸化菌的胞外聚合物（EPS）和污泥zeta电位的变化以及TCE的去除特性。结果表明：TCE浓度为75 mg/L（半抑制浓度,EC₅₀）时,对水解酸化菌的产酸量有抑制作用;随着TCE浓度升高,水解酸化菌的EPS中蛋白质浓度先增大后减少,其中TCE浓度为50 mg/L时EPS中蛋白质浓度达到最大值,为（33.94±0.25）mg/L;zeta电位的结果显示,污泥的凝聚性能随TCE浓度增大（0~100 mg/L）而增大;厌氧水解酸化菌对TCE的脱氯能力随TCE浓度的升高而降低,水解酸化菌转化TCE的脱氯率由TCE浓度为10 mg/L时的77.83%降为200 mg/L时的6.67%。TCE对水解酸化菌具有强烈的抑制作用,TCE主要是通过抑制细胞的蛋白质合成来抑制微生物活性,进而限制水解酸化菌降解TCE的能力。