Tolerance of calluna vulgaris and peatland plant communities to sulphuric acid deposition

Critical loads offer a unique way of evaluating impacts of acid deposition by quantifying environmental sensitivity. The critical loads of acidity for UK peat soils have been based upon an arbitrary reduction in pH of 0.2 units. This chemical shift needs to be better related to adverse effects on sensitive biological receptors. It is known that effective precipitation pH equates closely to soil solution pH, and the latter is directly linkable to biotic effects of pH change. On continuation of a long-term experiment assessing impacts of simulated acid rain on peat microcosms in a realistic outdoor environment, Calluna vulgaris continued to flourish at acid deposition loads well above the existing critical load. Calluna plants were harvested and analysed, and acid deposition treatments to the microcosms continued to allow natural vegetation to regenerate. A diverse mixture of moorland plants and bryophytes established at acidity treatments well above the existing critical load, and only a very high acid load resulted in no natural regeneration. A critical effective rain pH value of 3.6 is suggested as a basis for setting critical loads. At this pH, Calluna grows well, and a healthy diverse vegetation community re-establishes when harvested. It is suggested that the peat critical load should be set at the acid load that, at any specific site, would result in a mean effective precipitation pH of 3.6.     

大麻茎腐病菌的分离及其对土壤环境影响的研究

从病变部位分离出两株病原真菌DN1和DN2,通过茵丝及孢子形态的观察,初步确定其分别为半知菌亚门链格孢属（Altemaria altemata）及轮枝孢属（M．Verticillium）。在pH值4～14之间,两株菌都能正常生长,对环境的适应能力较强。通过盆栽试验确定大麻对土壤pH的影响,结果表明大麻能修复弱碱性土壤。     

海水酸化对中肋骨条藻的影响

为探讨海水酸化对中肋骨条藻（Skeletonema costatum）的影响,本文选择pH和pCO₂两个影响海水酸化的主要因素对中肋骨条藻进行处理,测定了不同条件下该藻的生长速率、叶绿素荧光参数、颗粒有机碳（particulate organic carbon, POC）、颗粒有机氮（particulate organic nitrogen, PON）含量以及C/N。结果表明,海水酸化显著抑制中肋骨条藻生长,酸化组的生长速率为0.86/d,对照组的生长速率为0.99/d,这种抑制效应主要来自pCO₂的影响。海水酸化对中肋骨条藻的光合效率无显著影响。海水酸化使中肋骨条藻细胞的POC含量显著提高37.1%,PON含量显著提高43.3%,其中,POC含量受pH和pCO₂的共同影响,而PON含量主要受pCO₂影响,推测这种效应是pCO₂升高影响关键的代谢过程所致。海水酸化对中肋骨条藻C和N的积累具有促进作用,但藻细胞中C/N无显著性变化。     

Specific Conductance and pH as Indicators of Watershed Disturbance in Streams of the New Jersey Pinelands, USA

/ We used linear regression to independently and jointly relate specific conductance and pH measured at New Jersey Pinelands stream sites to the percentage of altered land in a watershed. Percentage altered land included developed and agricultural land uses and represented watershed disturbance for a given site. Median values calculated for a 2-year period (September 1992 through August 1994) characterized pH and specific conductance at the study sites. We found the relationships between the median values for both water-quality measures and percentage altered land for a site to be consistent across subregion and dominant altered-land use. Our results also demonstrated that the water-quality/altered-land relationships developed using median values were similar to relationships developed using data from any single-sample period within the entire study period. Individually, pH and specific conductance explained 48% and 56%, respectively, of the variability in watershed disturbance among study sites. The joint use of pH and specific conductance explained 79% of the watershed disturbance variability among sites. The joint use of these easily obtained water-quality measures can provide a quick assessment of instream water-quality impacts from upstream watershed disturbance at any Pinelands stream site. Additionally, a range in pH and specific conductance, and hence a range in ambient water quality, can be predicted for a given altered-land percentage or a change in existing altered-land conditions.     

Variability of soil-water quality due to Tsunami-2004 in the coastal belt of Nagapattinam district, Tamilnadu

In this study, the Tsunami-caused deterioration of soil and groundwater quality in the agricultural fields of coastal Nagapattinam district of Tamilnadu state in India is presented by analyzing their salinity and sodicity parameters. To accomplish this, three sets of soil samples up to a depth of 30cm from the land surface were collected for the first six months of the year 2005 from 28 locations and the ground water samples were monitored from seven existing dug wells and hand pumps covering the study region at intervals of 3 months. The EC and pH values of both the soil and ground water samples were estimated and the spatial and temporal variability mappings of these parameters were performed using the geostatistical analysis module of ArcGIS((R)). It was observed that the spherical semivariogram fitted well with the data set of both EC and pH and the generated kriged maps explained the spatial and temporal variability under different ranges of EC and pH values. Further, the recorded EC and pH data of soil and ground water during pre-Tsunami periods were compared with the collected data and generated variability soil maps of EC and pH of the post-Tsunami period. It was revealed from this analysis that the soil quality six months after the Tsunami was nearing the pre-Tsunami scenario (EC< 1.5dSm(-1); pH<8), whereas the quality of ground water remained highly saline and unfit for irrigation and drinking. These observations were compared with the ground scenarios of the study region and possible causes for such changes and the remedial measures for taking up regular agricultural practices are also discussed.     

经典化学法结合pH/ORP自控系统处理电镀废水的工程应用

电镀废水是我国三大工业污染废水之一,该废水污染严重、水质复杂、水量大。针对该废水的特点,实行清污分流,各类废水先预处理再综合处理的原则,并采用经典化学法结合pH/ORP自控系统处理技术,废水经处理后可达GB8978-1996《污水综合排放标准》一级排放标准。     

pH对煤泥水絮凝沉降的影响

选择聚合氯化铝(PAC)/阴离子型聚丙烯酰胺(PHP)、氯化钙(CaCl2)/非离子型聚丙烯酰胺(NPAM)组合与NPAM、PHP、两性离子型聚丙烯酰胺(ZPAM)作为絮凝剂,在对道清选煤厂水采筛下原生煤泥和浮选尾矿的煤泥水进行组合药剂絮凝实验的基础上,考察了pH对煤泥水絮凝沉降的影响。实验结果表明,在不同的pH下,煤泥水的絮凝效果不同:在酸性条件下,宜单独使用有机高分子絮凝剂;在中性至碱性条件下,无机凝聚剂和有机絮凝剂联合使用效果较好。     

生物滴滤塔处理模拟甲硫醚废气

在常温条件下,采用生物滴滤塔处理模拟甲硫醚废气,考察了气体空床停留时间(EBRT)、容积负荷、喷淋密度及营养液pH对生物滴滤塔性能的影响。实验结果表明:当EBRT为90 s、进气甲硫醚质量浓度为150 mg/m~3、喷淋密度为0.65 m~3/(m~2·h),营养液pH为6.8时,甲硫醚去除率为90%;容积负荷高于15 g/(m~3·h)时,对生物滴滤塔的性能产生抑制作用;EBRT为90 s及60 s时,最佳喷淋密度分别为0.56~0.65 m~3/(m~2·h)及0.65~0.75 m~3/(m~2·h);降解甲硫醚的微生物对pH的变化较敏感,最适营养液pH为6~7。     

抗坏血酸和铁系还原剂修复铬污染土壤

通过投加抗坏血酸(C₆H₈O₆)或铁系还原剂(FeCl₂,(NH₄)₂Fe(SO₄)₂,FeS)对重庆某化工厂的Cr污染土壤进行修复。除FeS外,其余3种还原剂对土壤中Cr(Ⅵ)的还原率均达80%以上,稳定效率均超73%,且投加量为理论值3倍和4倍时的效果相差不大。C₆H₈O₆相比于铁系还原剂表现出更好的长期稳定性,4~30 d的Cr(Ⅵ)浸出质量浓度均低于《生活垃圾填埋场污染控制标准》(GB 16889—2008)中Cr(Ⅵ)的浸出限值(1.5 mg/L)。投加3倍理论值C₆H₈O₆的土壤在30 d时的Cr(Ⅵ)浸出质量浓度仅为0.83 mg/L,稳定效率高达98.3%。除FeS外,其余3种还原剂均显著增加了土壤中Cr的残渣态占比。FeCl₂和(NH₄)₂Fe(SO₄)₂会导致土壤pH降低。4种还原剂均未对土壤晶体结构产生明显影响。