Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

FACTORS INFLUENCING ACUTE TOXICfrY OF COAL ASH TO RAINBOW TROUT (SALMO GAIRDNERI) AND BLUEGILL SUNFISH (LEPOMIS MACROCHIRUS)1

ABSTRACT: The potentially toxic components in coal ash (ash particles, heavy metals) were evaluated in laboratory static, acute (96 hr) bioassays, both separately and in various combinations with extreme pH (5.0 and 8.5), using rainbow trout (Salmo gairdneri) and bluegifi sunfish (Lepomis macrochirus). Ash particle morphology and metal distribution anlaysis, using electron microscopy and surface-subsurface analysis by ion microscopy, showed that metals could be either clumped or evenly distributed on the surface of fly ash. Surface enrichment on fly ash particles from electrostatic precipitators, as measured by ion microscopy, was found for cadmium, copper, chromium, nickel, lead, mercury, titanium, arsenic, and selenium. Bottom (heavy) ash was not acutely toxic to either fish species at concentrations of up to 1500 mg/l total suspended solids (TSS) at pH 5.0, 7.5, or 8.5. Fly ash particles were not acutely toxic to blue-gill at levels up to 1360 mg/l TSS. Rainbow trout were highly sensitive to fly ash (25 to 60 percent mortality) at concentrations of 4.3 to 20.5 mg/I TSS when dissolved metal availability was high but were not sensitive at higher particulate concentrations (58 to 638 mg/I TSS) when dissolved metals were low. When metals were acid-leached from fly ash prior to testing, no rainbow trout mortality occurred at TSS concentrations of up to 2,350 mg/l TSS. When the percent of dissolved metal was high (e.g., 50–90 percent of the total), fish mortality was increased. Rainbow trout were nearly two orders of magnitude more sensitive than bluegill when subjected to a blend of cadmium, chromium, copper, nickel, lead, and zinc. The two species were similar in their acute sensitivity to acidic pH at levels at or below 4.0 and alkaline pH of 9.1. If the pH of coal ash effluent is contained within the range 6.0 to 9.0, acute toxicity to fish can be attributed to trace element availability from fly ash but not heavy ash. Control of holding pond and effluent pH and maximizing pond residence time are important strategies for minimizing effects of ash pond discharges on fish.     

绵阳市大气降水pH值时空分布及酸雨成因研究

通过对绵阳市9个测点1998－1999年大气降水监测数据的统计分析，并结合历史数据，对大气降水pH值的时空分布及酸雨成因进行了研究。结果表明：绵阳市大气降水酸化严重，除主要受本地区大气污染影响外，还受大气中、长距离输送的影响。     

Physiological Age of Host Plant Foliage and Survival of Gypsy Moth Larvae

The pH of leaf homogenates of common birch (Betula verrucosa L.), a food plant of gypsy moth (Lymantria dispar L.) larvae, was measured at different times of day in the course of leaf organogenesis, and midgut pH was measured in gypsy moth larvae phenotypically differing in the color of the hypodermis at the fifth instar. A possible relation between these parameters is discussed.     

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.     

High acidity tolerance in lichens with fumarprotocetraric, perlatolic or thamnolic acids is correlated with low pKa1 values of these lichen substances

The depsidone fumarprotocetraric acid as well as the depsides perlatolic and thamnolic acids are lichen secondary metabolites. Their first dissociation constants (pK_a1) in methanol were determined to be 2.7 for perlatolic acid and 2.8 for fumarprotocetraric and thamnolic acids by UV spectroscopy. Lower pK_a1 values are, so far, not known from lichen substances. Several lichens producing at least one of these compounds are known for their outstanding tolerance to acidic air pollution. This is demonstrated by evaluating published pH preferences for central European lichens. The low pK_a1 values suggest that strong dissociation of the studied lichen substances is a prerequisite for the occurrence of lichens with these compounds on very acidic substrata, as protonated lichen substances of different chemical groups, but not their conjugated bases, are known to shuttle protons into the cytoplasm and thereby apparently damage lichens.     

油田井场废水配制压裂液处理技术实验研究

针对油田井场废水高悬浮物、高色度、高金属离子浓度的特征,以处理后配制压裂液为目标,通过p H值调节及无机高分子絮凝法对井场废水进行了处理实验。结果表明,碳酸钠作为优选的p H值调节剂,可以在较低的p H值条件下有效去除废水中的高价金属离子;无机絮凝剂聚合硫酸铁在强碱性条件下对于悬浮物、色度的去除效果明显优于聚合氯化铝。聚合硫酸铁絮凝法可以使井场废水达到配制压裂液用水的要求。     

土壤及铁锰结核中锰氧化菌的氧化特性分析

利用从土壤铁锰结核及其附近土壤中分离筛选得到的4株锰氧化菌,研究了不同pH、Mn(Ⅱ)初始浓度下菌株的锰氧化效率及生长情况,并用SEM-EDS及TEM对菌株WHS26、GY16形成的生物氧化锰及水羟锰矿进行了表征.结果表明,pH及Mn(Ⅱ)初始浓度对菌株的锰氧化效率均有影响,4株菌在pH 7~8、Mn(Ⅱ)初始浓度为10~20 mmol·L-1时,锰氧化效率最高;GY16、WHS26形成的生物氧化锰的形貌与化学合成的水羟锰矿存在明显差异,前者呈胶膜状附着在菌株表面,后者呈结晶态.该结果可为生物氧化锰应用于重金属污染修复提供技术支撑.     

初始pH对厌氧环境下污泥中抗生素抗性基因行为特征的影响

污水处理厂产生大量的剩余污泥中含有丰富的抗性基因,给环境带来了潜在风险。以城市污水处理厂的剩余污泥为研究对象,在不同初始p H(对照组、初始p H=3、5、7、9、11)下观察厌氧条件下,8种抗生素浓度以及四环素类抗性基因(tet A、tet G、tet L、tet M、tet O、tet Q、tet W、tet X)、磺胺类抗性基因(sul I、sul II)和Ⅰ类整合子(int I 1)的行为特征。研究结果显示,初始p H对抗生素的降解影响较小,污泥中总抗生素的平均去除率为42%。对照组及初始p H为3、5、7、9、11下的总四环素类抗性基因分别削减0.65 log、0.96 log、0.75 log、0.62 log、0.86 log和0.98 log。不同四环素类抗性基因表现相似,在初始p H=3和初始p H=11下部分抗性基因削减较多,特别是tet A、tet G、tet L、tet O和tet X。2种磺胺类抗性基因均无削减,浓度平均上升0.18log。相关性分析显示,总抗性基因与TN、NH3-N、TP、SCOD(溶解性COD)均存在显著相关性(P0.05)。上述研究结果为污泥厌氧消化中抗生素抗性基因减量条件提供参考依据。     

pH值及温度对杂色云芝漆酶活性的影响

以3-乙基苯并噻唑-6-磺酸(简称ABTS)为底物,研究pH值和温度对杂色云芝漆酶活性的影响。实验结果表明,漆酶的活性受pH的影响较大;温度不同,漆酶活性不同。