Single and joint acute toxicity of isocarbophos enantiomers to Daphnia magna

Although enantioselectivity in the toxicity of chiral pesticides has received considerable attention over recent years, how coexisting enantiomers interact with each other during their toxic action remains unknown. In this study, we attempted to resolve the enantiomers of a chiral organophosphate insecticide, isocarbophos, and investigated the acute toxicity of individual enantiomers and various enantiomer mixtures. Baseline enantiomeric separation of isocarbophos was achieved on a Chiralcel OD column with the mobile phase of n-hexane/isopropanol (90/10, v/v) at a flow rate of 0.8 mL/min. The resolved enantiomers were differentiated by their responses on a circular dichroism detector. The median lethal concentrations (LC 50) of racemate, (+)-enantiomer, and (-)-enantiomer of isocarbophos toward Daphnia magna were 13.9, 7.08, and 353 microg/L, respectively, after 48 h of static exposure, displaying a 50-fold difference between the enantiomers. Toxic unit (TU) analysis was employed to evaluate the joint toxicity of isocarbophos enantiomer mixtures. The calculated TU mix for the acute toxicity (48 h test) of various binary mixtures ranged from 0.83 to 1.04, suggesting a mode of additive effect. Further evaluation of available literature data for chiral organophosphorus insecticides showed that the joint toxicity of enantiomers may be additive, synergistic, and antagonistic. Therefore, when significant enantioselectivity exists for a chiral pesticide, it is important to also evaluate the interaction of enantiomers in the joint toxicity effect when enantiomers are present in a mixture.     

Chronic effects of reduced dissolved oxygen on Daphnia magna

Daphnia magna, initially exposed when less than 48 h old, were maintained at reduced dissolved oxygen (DO) concentrations for 26 days. Exposure was accomplished in a continuous flow recirculating water system. Number of days to first brood, number of young in the first brood, total number of young produced, and dry weight were parameters measured. Statistical analyses show the Daphnia exposed to the lowest DO concentration tested (1.8 mg l^?1) had significantly reduced responses for all parameters measured. In addition, the organisms exposed to 2.7 mg l^?1 O₂ gained less weight than did the controls.     

Toxicity of uranium to Daphnia magna

The toxicity of U to Daphnia magna was determined in acute and chronic tests. The 48-hr LC₅₀ of U (VI) in Columbia River water was 6 mg L^?1. Acute toxicity diminished by a factor of 7.5 as mean water hardness and alkalinity values increased from 70 mg L^?1. and 57 mg L^?1. to 195 mg L^?1. and 130 mg L^?1. respectively. This effect was most likely the result of complexation of uranyl ion with carbonate ions. D. magna reproduction was suppressed in Columbia River water at U concentrations between 0.5 and 3.5 mg L^?1. Potential hazards of U to aquatic life are discussed as they relate to mining practices.     

5种杀虫剂在水-人工底泥系统中对大型溞的急性毒性及其比较

建立了包含＂水＂和＂底泥＂两相的水蚤毒性测试系统（水相为全人工培养液,＂底泥＂为OECD配方标准化人工土）,并通过该系统测得毒死蜱（chlorpyrifos）、氟虫腈（fipronil）、氰戊菊酯（fenvalerate）、氟氯氰菊酯（cyfluthrin）、联苯菊酯（bifenthrin）对大型溞（Daphnia magna）的急性毒性（48 h-LC50）分别为9.01、88.1、0.142、0.097 6、0.050 4μg.L-1。对比水相的急性毒性测定结果发现,在有底泥的条件下,所测得的联苯菊酯、氟氯氰菊酯、毒死蜱的大型溞毒性低于水相的测定结果,而氰戊菊酯、氟虫腈的毒性则比水相中的测定结果要高。研究结果反映出药剂和受试生物在＂水-底泥＂系统内相互作用的复杂性和难以预见性,从而在为相关农药生态安全评价提供科学依据的同时,为在更接近实际暴露状态下开展评价试验提供了一种简便有效的方法。     

多氯联苯（PCB_（153）与PCB_（28））对大型溞的毒性效应研究

选用大型溞作为受试生物,探讨多氯联苯（PCB153与PCB28）对浮游动物的急性和慢性毒性反应,初步评价多氯联苯（PCBs）对浮游动物的毒害效应。急性毒性试验中,PCB28和PCB153对大型溞的48h-LC50分别为27.08μg·L-1和579.16μg·L-1。实验表明,大型溞对PCB28的敏感性高于对PCB153的敏感性。慢性毒性试验显示,PCB28和PCB153对大型溞的生长、生殖均有不利影响,PCB28的影响表现为随浓度的升高,生长和生殖抑制效应加强;PCB153对大型溞生长的影响表现为随浓度升高而抑制效应增强,但其对大型溞的繁殖则表现为低浓度抑制而高浓度促进的现象虼耍团ǘ榷嗦攘剑≒CB153、PCB28）长期暴露的潜在毒性和高浓度多氯联苯的急性毒性在环境生态安全研究中值得高度关注。     

氨基酸对甘蓝硫代葡萄糖苷的影响

以中甘21(ZG21)、06-115两个甘蓝品种为试验材料,研究叶面喷施6种氨基酸对甘蓝硫代葡萄糖苷组分及其含量的影响。结果表明,不同种类氨基酸处理甘蓝硫代葡萄糖苷组分相同,均含有9种硫苷。氨基酸对甘蓝硫苷含量有一定的影响,半胱氨酸和甲硫氨酸显著提高06-115硫苷的总含量、脂肪族硫苷的含量和4-甲基硫氧丁基硫苷含量,其中半胱氨酸处理含量最高,与对照相比分别提高63.0％、69.6％和69.1％;半胱氨酸处理提高了3-吲哚基甲基硫苷含量,达到725.6 μmol/kg, FW;半胱氨酸处理也显著提高了中甘21硫苷的总含量、脂肪族硫苷的含量、吲哚族硫苷含量和4-甲基硫氧丁基硫苷含量,与对照相比分别提高了27.2％、39.6％、15.3％和26.2％。半胱氨酸、苯丙氨酸、甘氨酸和谷氨酸处理都提高了3-吲哚基甲基硫苷的含量,其中半胱氨酸处理最高,达到292.7 μmol/kg, FW,其次是谷氨酸和甘氨酸处理。     

Physiological Response of Daphnia magna to Linear Anionic Polyacrylamide: Ecological Implications for Receiving Waters

Linear anionic polyacrylamide (LA-PAM) is being considered as a soil amendment to reduce seepage and infiltration in unlined earthen canals. While polyacrylamides have been extensively used for potable water treatment, dewatering sewage sludge, coal and mine processing, paper manufacturing, and agriculture, little is known about its ecological impact to aquatic ecosystems. Acute toxicity (LC₅₀, 24 and 48 h) and chronic exposure tests (limited and continuous exposures) were conducted on Daphnia magna. In the chronic limited exposure experiments, Daphnia were exposed to LA-PAM for only 24 h whereas for the chronic continuous exposure the concentrations of 0, 0.5, 1, 5, 10, and 100 mg/L were tested and the endpoints of growth, onset to reproduction, fecundity, and mortality were measured for the duration of 32 days. There was no significant difference among the chronic, limitedly exposed organisms. The acute toxicity for LA-PAM was measured at 100, 150, 200, 250, and 300 mg/L. The acute test showed that the LC₅₀ for LA-PAM was at 152 mg/L. Overall in the chronic, continuous exposure test, D. magna was negatively impacted by LA-PAM at levels as low as 1 mg/L. Growth was reduced by 37% and 89% at 1 and 100 mg/L, respectively. Fecundity and onset to reproduction was impaired at 10 and 100 mg/L. Kinematic viscosity ranged from 0.98 cSt at 1 mg/L to 2.9 at 100 mg/L. At these levels, mechanical and physiological impairments due to the viscous properties of LA-PAM are the proposed mechanisms of reduction in the life history traits of D. magna.     

香蕉减量施肥与氨基酸水溶性肥配施效果研究

通过大田试验,研究减量施肥对香蕉生长、产量、品质及土壤养分、肥料利用的影响,以期为广东珠江三角洲新植香蕉产区化肥减量与提质增效提供技术和依据.以常规施肥为对照,采用减施化肥总量26％(减氮25％、减磷33％、减钾25％)和减施化肥总量40％(减氮50％、减磷50％、减钾25％)+氨基酸水溶性肥2种减施方式对香蕉生长势、...     

重金属铜、镉对蝌蚪毒性的研究

试验研究铜、镉对蝌蚪的急性毒性和联合毒性结果表明,Cu~(2 )对蝌蚪24h、48h、96h的半致死浓度LC_(50)分别为0.201mgg/kg、0.138mg/kg和0.118mg/kg,Cd~(2 )对蝌蚪24h、48h和96h的LC_(50)分别为32.1mg/kg、23.3mg/kg和18.9mg/kg。Cu~(2 )和Cd~(2 )共存对蝌蚪24h、48h和96h联合毒性的相加指数AI分别为1.03、1.2和1.20,均为协同作用。     

Priming effects of sugars,amino acids,organic acids and catechol on the mineralization of lignin and peat

The ¹⁴C‐labeled substrates glucose, fructose, alanine, glycine, oxalic acid, acetic acid, and catechol were incubated at 20 °C in a model system that consisted of sand mixed with lignin or peat (3 % C_org). Each substrate was added at either 80 or 400 μg C (g sand)^—1. During 26 days of incubation with an inoculum extracted from forest soil, the amount of CO₂ evolved was measured hourly. The amount of ¹⁴CO₂ was determined after 4, 6, 12, 19, and 26 days. After 26 days of incubation, each substrate showed priming effects, but not in all examined treatments. Most substrates stimulated the degradation of the model substances (positive priming effects). Negative priming effects only were found in the lignin system with oxalic acid and catechol addition at both concentrations. The strongest positive priming occurred in the peat system with the oxalic acid addition of 80 μg C g^—1 where 1.8 % of the peat were mineralized after 26 days, compared to 0.7 % in the control. The addition of 400 μg alanine‐C g^—1 caused the strongest increase in lignin mineralization, amounting to 3.9 % compared to 2.8 % in the control. During the incubation the extent of priming changed with time. Most substrates caused the strongest effects during the first 4 to 10 days of incubation. The extent of priming depended on substrate type, substrate concentration, and organic model substance. Possibly this is due to the activation of different microorganisms.     

铜污染对高等植物的生理毒害作用研究

本文综述了当前国内外Cu污染对高等植物生理毒害的研究近况,探讨了Cu过量对植物光合作用、细胞结构、细胞分裂、酶学系统和其他营养元素的吸收等的影响,并探讨了该方面研究存在的不足及其展望。     

植物对氨基酸的吸收利用及氨基酸在农业中的应用

植物对氨基酸的吸收、转运、代谢以及氨基酸在肥料和农药上的应用国内外已有报道。已有研究证明,植物可直接吸收土壤中的氨基酸分子,其吸收后的转运、分配、代谢因氨基酸种类而异,产生的生理效应也不相同;氨基酸农药易被日光分解或被自然界微生物降解,在土壤中、植物体内不留残毒,其降解产物还可作为农作物的营养物质,提高农作物的品质和产量,施用这类农药,人畜安全,没有公害;氨基酸肥具有促进植株生长发育、增强抗逆性、改善土壤状况和提高作物产量的作用。     

The effects of different amendments on the mobility and toxicity of nickel and copper in polluted soils

The efficiency of different amendments for the remediation of acidic sandy soils contaminated with heavy metals was assessed in a model laboratory experiment with podzols from the Kola Peninsula. The addition of SLOVAKITE®, lime, and vermiculite leads to significant reduction of the acidity and mobility of nickel and copper in polluted soils, as well as an increase in the length and phytomass of shoots and roots of Festuca rubra. The application of superphosphate for the remediation of soils that were polluted with nickel and copper was less helpful, while the apatite and zeolite additives were inefficient.     

添加酸解氨基酸对植物源废弃物好氧堆肥品质及其应用效果的影响

[目的]探究添加酸解氨基酸 (AA) 对不同植物源废弃物堆肥进程、氮素损失阻控、堆肥品质和产品效果的影响.[方法]分别向3种含碳量不同的植物源废弃物 (中药渣、木薯渣和蘑菇渣) 中添加5％、10％和15％(体积质量比) 的酸解氨基酸,以不添加酸解氨基酸处理作为对照,监测堆肥过程中的温度和理化指标.堆肥结束后,以辣椒和茄...     

Amelioration of copper toxicity by iron on Spinach physiology

The effect of excess copper (Cu) on young spinach (Spinacia oleraced) as well as the role of iron (Fe) for amelioration of toxicity on growth and photosynthesis in Cu‐treated plants was evaluated. Plants treated with 160 μM Cu showed symptoms of heavy metal toxicity, while addition of Fe (40 μM) ameliorates to a certain extent toxic effects of Cu, due to antagonistic action between Cu and Fe. Root length and biomass revealed a lower decrease under Cu+Fe than under Cu treatment. Copper accumulation in plant tissues increased, while Fe, sodium (Na), potassium (K), calcium (Ca), and magnesium (Mg) declined under Cu treatment. The significant increase in chlorophyll fluorescence (F_o) under 160 μM Cu, possibly reflects the more severe damages suffered at the membrane level with respect to Cu+Fe treatment. Copper decreased the efficiency of excitation energy capture by PSH reaction centers and negatively affected the effective antenna size of PSH. Changes in the rate of carbon dioxide (CO₂) assimilation were associated with changes in both stomatal conductance (gs) and mesophyll capacity for photochemistry as well as with lower pigment content. Net CO₂ assimilation, transpiration rate, and stomatal conductance were reduced. These changes at PSII are characteristic of a saturation of photosynthetic metabolic activity. The results suggest a tight linkage between PSII activity and CO₂ fixation under Cu treatment. Amelioration of Cu toxicity was obvious under Fe application.     

Silicon effects on aluminum toxicity to mungbean seedling growth

The effects of silicon (Si) on the toxicity of aluminum (Al) to mungbean (Phaseolus aureus Roxb.) seedlings were studied in a growth chamber. Mungbean seedlings were grown in a nutrient solution with combinations of three concentrations of Si (0,1, and 10 mM) and three concentrations of Al (0, 2, and 5 mM) in randomized completely block design experiments for 16 days. Silicon at 1 mM in the solution decreased root length, fresh and dry weights, and chlorophyll content, and showed no significant effect on epicotyl length and seedling height, and protein contents of shoots or roots in mungbean seedling under no Al stress. But, Si at 10 mM showed marked toxic effects on mungbean seedling growth and increased protein contents of the shoots or roots. In contrast, under 2 mM Al stress, Si addition at 1 mM had significant increasing effect on root length, fresh and dry weights, and chlorophyll content. It also had decreasing effect on protein contents of the shoots or roots, and had no effect on epicotyl length and seedling height. Silicon addition at 10 mM showed no effect on morphological and physiological measurements of mungbean seedling. However, Si at 1 mM added to solution only increased seedling height, epicotyl length, fresh weight, and chlorophyll content, but decreased dry weight and protein content of the roots under 5 mM Al stress, significantly. Silicon addition at 10 mM showed similar toxic effects on mungbean seedling growth under 5 mM Al stress to that under no Al stress.     

土壤弹尾目昆虫对铜污染的急性毒理初步研究

随着土壤环境重金属污染的加剧,有关重金属污染土壤的风险评估受到关注。对土壤质量评价的方法长期以来集中在检测重金属污染物质在土壤中的浓度及化学形态等方面,而对于重金属、土壤和生物之间的相互作用很少考虑,因而难以全面评估重金属对土壤环境的生态毒性效应。重金属污染土壤的     

Gas chromatographic analysis of amino acids from the action of proteolytic enzymes on soil humic acids

Six proteases released more amino compounds from albumin than from a humic acid. Pronase and thermolysin released about one-sixth of the acid-hydrolysable amino acids from a humic acid, papain had slight activity while chymotrypsin, trypsin and subtilopeptidase did not attack humic acid. Thermolysin hydrolysates of four humic acids contained peptides which on acid hydrolysis broke down to increase three fold the yield of α-amino N. Net amounts of amino compounds released on incubation of thermolysin and humic acids were directly related to incubation time, substrate concentration and enzyme concentration.