定性与定量评估4种重金属及2种农药混合物对费氏弧菌的毒性相互作用

重金属与农药共同暴露产生的联合毒性作用可以对实际环境产生潜在的风险。为了研究重金属与农药混合物在不同浓度比毒性相互作用(协同、拮抗与加和)及其定量评估相互作用大小,根据单个物质无观测浓度(NOEC)、5%效应浓度(EC5)、10%效应浓度(EC10)和50%效应浓度(EC50),设计3组混合物体系(即农药-农药、重金属-重金属和农药-重金属)分别按NOEC、EC5、EC10和EC50浓度比的12条混合物射线,测试单个化合物及混合物对以费氏弧菌的发光抑制急性毒性,利用浓度加和(CA)、独立作用(IA)、模型偏差比(MDR)及其观测值置信区间定性和定量评估12条混合物射线的毒性相互作用。结果表明,农药-农药二元混合物体系和农药-重金属六元混合物体系均产生明显的协同作用,其中农药-农药混合物体系中,混合物射线EE-NOEC在50%效应下协同作用大小达到30.6(MDRCA和MDRIA数值);混合物射线EE5、EE10的协同作用大小接近于混合物射线EE-NOEC,混合物射线EE50的效应大于15%时CA和IA计算的MDR值均在置信区间上限的上方,即混合物发生协同作用;农药-重金属混合物体系的4条混合物射线EE-NOEC、EE5、EE10和EE50在所有测试浓度水平的MDR值均在置信区间上限的上方,呈现出明显的协同作用;在50%效应下,混合物射线EE-NOEC、EE5、EE10和EE50的MDRCA和MDRIA值分别为4.05和4.91、6.12和7.98、3.70和4.60、2.62和2.59。重金属-重金属四元混合物体系除了EC50浓度比混合物表现出拮抗作用,其余混合物在所有测试浓度范围的MDR值均在置信区间范围内,均为加和作用。因此,混合物的毒性相互作用大小随着组分浓度比变化而发生变化。     

Determination of aflatoxin-B1 in poultry feed and its components employing enzyme-linked immunosorbent assay (ELISA)

A highly sensitive enzyme immunoassay was standardized for aflatoxin B₁ determination in poultry feed and its components using Riedel-de-Haen, ELISA Systems_. A microtitration plate method was optimized using anti-aflatoxin B₁ antibodies and peroxidase – aflatoxin B₁ conjugate, based on competitive enzyme immunoassay principle. Standards of concentrations of 5, 10, 20, 50, 100, 500?ng/L aflatoxin B₁, prepared in phosphate-buffered saline, were used. Standard curves showed that as the concentration of antigen decreased, absorbance values increased. Fifty percent inhibition was observed at 37?ng/L. Regression analysis showed that log concentration was inversely related to %B/B₀, with a highly significant negative correlation (?0.980). The lowest detection limit for aflatoxin B₁ was 5?ng/L. Using this standardized ELISA, aflatoxin B₁ was detected in most of the commercially available poultry feed samples and their components.

The data suggest that this test is suitable for the accurate determination of aflatoxin B₁ concentrations in poultry feed and its components.     

Adsorption and movement of carbaryl in soils: A verification of cosolvent theory and comparison of batch equilibrium and soil thin layer chromatography results

Batch equilibrium and soil thin layer chromatography (TLC) techniques were used to investigate the influence of different volume fractions of organic cosolvents (acetone and methanol) on the adsorption and movement of carbaryl in four different types of Indian soils. L-shaped isotherms were obtained for both the cosolvent–water mixtures at all f _s values and were in close agreement with the Freundlich equation. Higher adsorption was observed on F.R.I. soil (FSL) followed by Alampur soil (ASL), Kalai soil (KL), and Bhoran soil (BSL) at all f _s values for both the cosolvent systems as was anticipated from the K and K _D values. The K and K _D values also confirmed that carbaryl adsorption was higher in methanol–water mixture than acetone–water mixture and decreased with increasing f _s values. The frontal R _f values obtained from soil TLC studies were inversely proportional to the K and K _D values for both the cosolvent systems. The higher K and K _D values and lower R _f values in methanol–water mixtures relative to acetone–water mixtures for all the soils indicated that acetone had a greater potential for ground water contamination compared to methanol. The adsorption data were used to evaluate the cosolvent theory for describing adsorption of carbaryl in acetone–water and methanol–water mixtures. The aqueous phase partition coefficients, K _DW (mol g^?1), normalized with respect to f _oc for carbaryl was evaluated by extrapolating f _s → 0.     

The influence of storage on antibacterial activity of sea water. I. Experiments with sea water stored at 18°C

Three sea-water samples of about 25 l each, stored at 18°C in the dark, were examined for antibacterial activity and bacterial content. Serratia marinorubra mainly was used as test bacterium. During storage for 197 to 454 days, bactericidal capacity varied considerably. In raw sea water, extreme log (N ₃–N ₀) values (N: number of colony-forming test bacteria/ml after 0 and 3 days of any test) were higher than-1 and lower than-4. Antibacterial activity of filtersterilized and autoclaved, stored, sea water likewise varied, but to a lesser degree. The number of colony-forming marine bacteria fluctuated about 3 orders of magnitude. Variations in bacterial content and in bactericidal action of stored sea water were positively correlated during the first months of storage; later, this correlation became negative. From these results it is concluded that variations in nutrient concentration — due to successive periods of growth and autolysis of marine bacteria — were the primary reason for the changes observed in antibacterial activity of stored sea-water samples.     

Determination of types of interactions exhibited by binary mixtures of heavy metals tested against the hermit crab,Clibanarius africanus

Single and joint action toxicity of heavy metal compounds (ZnCO₃, CuSO₄ and CdSO₄) were carried out against the hermit crab, Clibanarius africanus in laboratory bioassays. On the basis of 96?h LC₅₀ values, CuSO₄ (96?h LC₅₀?=?0.03?mM) was found to be the most toxic followed by CdSO₄ and ZnCO₃ (96?h LC₅₀?=?0.24?mM) in decreasing order of toxicity. The evaluation of the metal compounds in mixtures of ZnCO₃–CuSO₄, ZnCO₃–CdSO₄ and CdSO₄–CuSO₄ in pre-defined molar ratios revealed that interactions between Zn–Cu and Zn–Cd test mixtures were in conformity with the models of antagonism (reduction in toxicity of constituent metals). The synergistic ratios (S.R.s) and relationship between observed/predicted 96?h LC₅₀ values (relative toxic unit, RTU) were consistently below 1, indicating antagonistic interactions. Analysis using isobolograms also indicated the interactions between the mixture components to be antagonistic. However, with regards to CdSO₄–CuSO₄ test mixtures, the interactions between these metals were mainly in conformity with the model of synergism. The S.R. and RTU values were largely above 1, indicating synergistic interactions. The importance of the joint action evaluations for the management and protection of aquatic ecosystems, particularly in the setting up of water quality criteria was discussed.     

Reproduction and growth of Euterpina acutifrons (Copepoda: Harpacticoida) under experimental conditions

Individual specimens of Euterpina acutifrons (Copepoda: Harpacticoida) taken from the mass cultures of the C.N.E.N.-EURATOM Laboratory at Fiascherino, Italy, were reared in new culture media prepared with suspensions of several species of algae in filtered and sterilized sea water. All the experiments were carried out at a temperature of 18°C±1 C°. The influence of food concentrations on adult life-span and reproductive activity of E. acutifrons was analyzed. A good correlation was found between concentration of algal suspension and egg production. Maximum life-span was observed at intermediate values of food concentration. Other experiments were carried out to determine egg fertility and duration of the various embryonic and postembryonic development stages. Embryonic development time was calculated as approximately 2 days; the adult females appeared 10 to 12 days after hatching of Nauplius I. Production of nauplii by 6 females reared under conditions of excess food supply was also studied. These conditions were achieved by supplying high concentrations of a mixture of 4 different algal species and by completely renewing the culture medium at frequent intervals. Under these conditions, each female laid an average of 12.5 sacs and produced an average of 294.3 nauplii. An average production of 355.5 eggs per female was estimated. An analysis was made of growth in size and weight of the females: the average daily egg production in terms of dry weight corresponded to about 32% of the biomass of the adult female. Birch's (1948) method was used to calculate net reproduction rate (R _o=70.89), intrinsic rate of increase (r _m=0.161) and mean generation time (T=26.5 days).This study was performed at: Laboratorio per lo Studio della Contaminazione Radioattiva del Mare, C.N.E.N.-EURATOM, Fiascherino, I-19030 La Spezia, Italy.     

南方某铀矿山废水对生物的急性毒性研究

为探明铀矿山对周围环境的联合毒性机制,本研究以常用生物毒性测试菌种——发光细菌青海弧菌Q67和费氏弧菌以及禾花鲤为受试生物代表,实地采集的铀矿山废水为目标废水,研究铀矿山废水对发光细菌和禾花鲤的急性毒性。实验结果表明,矿山废水对3种生物的急性毒性存在显著的剂量-效应关系,毒性效应浓度EC_(50)(LC50)的大小顺序为禾花鲤幼鱼费氏弧菌青海弧菌Q67,Pb~(2+)/U~(6+)浓度分别为6.052/3.026 mg·L~(-1)、2.284/1.142 mg·L~(-1)、1.339/0.669 mg·L~(-1),均可有效指示矿山废水的毒性水平,其中发光细菌更为灵敏、快速;且青海弧菌Q67的EC_(50)值最小,灵敏度最高,可作为表征矿山废水毒性风险的首选指示物。研究结果能够为放射性矿区废水生态风险预警、安全处理处置、水质基准制定及流域水环境管理提供依据。     

Metal inclusion in expanded clays

The possibility to include in expanded clay little amounts of metallic ions present in waste material, without significant influence on the environment, was investigated. In this article, known quantities of cadmium(II), lead(II), chromium(III), and chromium(VI) were added to a mixture of raw pit clay, adding a small amount of mineral oil. The resultant paste was heated at 1200°C, in conditions to provide the commercial product with the best characteristics of lightness. The obtained pellets were analyzed in two ways. A sample of expanded clay was crushed, added to with KNaCO₃ and melted. The melted mass, after cooling, was dissolved in HCl or in water and analyzed. The composition of the raw pit clay was analyzed as a blank. In parallel, pellets were subjected to a leaching process and the eluate was analyzed for the added cations. The concentration of the metal ions in the leached water is negligible compared with that generally admitted in drinking water.     

Temperature effects on the toxicity of four trace metals to adult spotted Babylonia snails (Babylonia areolata)

A study was conducted to determine the median lethal toxicity of four heavy metals on the marine gastropod Babylonia areolata. Median lethal toxicity tests were conducted to observe the sensitivity of this gastropod to metals and how variations in temperature might affect toxicity of test elements. Four heavy metals were used in the study. It was observed that the 96-hr LC₅₀ (in mg/L) for the different metals was found to be nickel (Ni) 33.53 (35.22–28.43), copper (Cu) 44.59 (46.43–41.53), cadmium (Cd) 21.53 (23.43–18.37), and zinc (Zn) 27.34 (28.81–24.24) at room temperature 24 °C. With temperature as a variable, median lethal concentration (LC₅₀) values were observed to increase from 22.41 mg/L at 10 °C to 27.34 mg/L at 28 °C and reduce to 18.43 mg/L at 30 °C and a further rise in toxicity was observed at 35 °C where LC₅₀ value was 12.7 mg/L as seen in the case of Zn. It was also observed that at 40 °C thermal and chemical toxicity overlapped as 100% mortality was observed in controls. This trend was noted in all metals for Babylonia areolata indicating that temperature played an important role in determining LC₅₀ values of toxicants.     

Adsorption of arsenic using high surface area magnetites

Magnetites (MEBWx) were prepared by precipitation in 1-butanol/water mixtures of various mole ratios of 1-butanol to water. It was found that the magnetites prepared in the mixture with high mole ratio of 1-butanol to water have high specific surface area. The adsorption isotherms of As(III) and As(V) with the magnetites at 303 K fitted the Langmuir model well. The adsorption capacities of the magnetite prepared in the mixtures were higher than those of the magnetite prepared without 1-butanol. Their adsorption capacities increased with increasing specific surface area.     

Influence of algal concentration and temperature on the filtration rate of Mytilus edulis

The filtration rates of Mytilus edilis (=galloprovincialis; 40 mm) were determined in relation to food concentration and temperature, using pure suspensions of the unicellular alga Platymonas suecica in concentrations ranging from 3x10⁵ cells/l to 1.5x10⁸ cells/l. The rate of filtration (ml/h/mussel) generally decreased as cell concentrations increased, and dropped to low values when concentrations above 5x10⁷ cells/l were supplied. The amount of water swept clear varied continuously, and noticeable differences in the filtration activity of M. edulis were observed over short time intervals (5 min). Fluctuations of filtered volumes per unit time were greater with lower than with higher concentrations of algae. The influence of temperature on filtration activity was highest between 5°–15°C and 25°–30°C. A temperature increase from 15° to 25°C resulted in only a slight increase in filtration rate. At 5° and 30°C, filtration dropped to very low values, namely 350 and 100 ml/h, respectively. The temperature coefficients for the filtration rates of M. edulis were determined as: Q₁₀ (5° to 15°C)=4.96; Q₁₀ (10° to 20°C)=1.22. The amount of algae cells ingested per mussel per hour is directly related to food concentration. The maximum number of cells filtered/mussel/h in an algal suspension of 70x10⁶ cells/l was 21.5x10⁵ cells/h. Cell concentrations of up to 40x10⁶ cells/l were swept clear without producing pseudofaeces. The critical cell density for M. edulis was reached at algal concentrations of 70 to 80x10⁶ cells/l. Above these concentrations no normal filtration activity was observed.     

Influences of Suspended Particles on the Runoff of Pesticides from an Agricultural Field at Askim, SE-Norway

Field and laboratory experiments were conducted to study the loss of particles from agricultural fields, and the role of suspended particles in carrying pesticides in surface runoff and drainage water. Propiconazole, a widely used fungicide was applied to experimental fields located at Askim, SE-Norway. Samples from surface runoff and drainage water were collected and analyzed for sediment mass, pesticides, particulate and dissolved organic carbon through a whole year. The surface soil and the runoff material were characterized by its particle size distribution, organic carbon content in size fractions and its ability to bind propiconazole. The results show that (1) particle runoff mostly occurred during the rainfall event shortly after harrowing in autumn. The highest particle concentration observed in the surface runoff water was 4600 mg l^–1, and in the drainage water 1130 mg l^–1; (2) the erosion of surface soil is size selective. The runoff sediment contained finer particle/aggregates rich in organic matter compared to its original surface soil; (3) the distribution coefficient (K _d) of propiconazole was significantly higher in the runoff sediment than in the parent soil. According to our calculation, particle-bound propiconazole can represent up to 23% of the total amount of propiconazole in a water sample with a sediment concentration of 7600 mg l^–1, which will significantly influence the transport behavior of the pesticide.     

Development and characterization of complex particles for delivery of amino acids to early marine fish larvae

Complex particles (CP), zein microbound particles and lipid-spray beads (LSB) were prepared and their performances were compared for delivering glycine and a mixture of free amino acids (FAA; alanine, glycine, leucine, serine and tyrosine) to early fish larvae. Measures of performances of microparticles included inclusion, encapsulation, retention and delivery efficiencies in addition to T50 (time to 50% retention) values. CP were prepared containing LSB and a defined dietary mixture that were bound together with zein. CP had significantly higher retention and delivery efficiencies for FAA compared to those of zein microbound particles. Free LSB had higher retention efficiencies for particulate glycine compared with CP, possibly due to differences in suspension characteristics. Free LSB clumped and floated when suspended in water, negatively affecting their acceptability by fish larvae; therefore, LSB should be incorporated into CP for more effective delivery of amino acids. There was a significant inverse correlation between retention efficiencies and solubilities of FAA encapsulated in CP. After 1 h of aqueous suspension, highest retention (44%) and delivery efficiencies (20.3 mg tyrosine g^–1 particle) were achieved with tyrosine. T50 values indicated 50% of the initial tyrosine in CP was still available after 36.7 min of suspension in water. Furthermore, CP can deliver FAA to marine fish larvae based on the results of feeding studies in which CP were digested by 3-day-old clownfish larvae; therefore, this particle type could be a valuable tool in studies of larval fish nutrition.Communicated by R.J. Thompson, St. Johns     

Passives Monitoring von Stickstoffeinträgen in Kiefernforsten mit dem Rotstengelmoos (Pleurozium schreberi (Brid.) Mitt.)

Investigations in 23 pine stands, a widespread type of forest on sandy soils in Northern Germany, were made to compare the concentration of the total N in pine needles, the overall rates and concentrations of nitrogen in precipitation water (NH₄?N+NO₃?N) to concentrations of total N in shoots ofPleurozium schreberi (Brid.) Mitt., a common bryophyte in these forests. Within the investigation period from 1996 to 1998, a total deposition of nitrogen in a range from 10 to 32 kg ha^?1a^?1 and mean values of nitrogen concentrations in the precipitation water between 2.8 and 6.9 ppm were observed. N concentrations in both bryophytes and pine needles also varied in a large scale from 1.3 to 2.3% d.wt. High correlations between concentrations of total N in moss tissue and total N concentrations in pine needles (r²=0.75, p<0.001) as well as N concentrations in the precipitation water (r²=0.81, p<0.001) were found. Lower correlations of N concentrations inPleurozium with overall rates of nitrogen calculated for the year before moss sampling in 1997 until 1999 can be attributed to temporary variations of N concentrations in precipitation due to different amounts of rainfall. Comparing the results of only one year (1998), the correlation was higher (r²=0.86). The role of other effects, e.g. growth rate and dry deposition, is discussed as well. Aside from the monitoring of heavy metals and organic compounds,Pleurozium schreberi is seen to be a useful indicator for estimating the amount of N deposition.     

氯霉素对大型溞的急性和慢性毒性效应研究

氯霉素是一种具有广谱杀菌作用的抗生素,曾在水产养殖中广泛使用,虽然目前已被列入我国渔药禁用清单,但在水环境中仍被大量检出。为探究氯霉素对水生生物的毒性作用,选择大型溞(Daphnia magna)作为受试生物,研究氯霉素对其急性毒性和慢性毒性效应,同时建立了氯霉素的高效液相色谱(HPLC)分析方法,通过实测浓度分析确保实验过程中氯霉素浓度保持在可接受范围内。结果表明:氯霉素对大型溞的48 h半数抑制浓度(EC50)为129.5 mg·L~(-1),95%置信区间为124.4!150.9mg·L~(-1),对溞类的急性毒性为低毒;长期暴露能抑制大型溞的产溞数量,以繁殖量为毒性指标,21 d无可观察效应浓度(NOEC)为1.25 mg·L~(-1),最低可观测效应浓度(LOEC)为2.50 mg·L~(-1);各暴露组实测浓度范围在配制浓度的80%～110%,保证了实验的有效性。同时,利用实验获得的急慢性毒性数据,计算氯霉素对大型溞的急慢性毒性比(ACR),发现利用慢性毒性求得的ACR值比利用急性毒性EC10求得的ACR值更接近推荐值。研究表明氯霉素对大型溞的急性毒性低,但具有慢性毒性效应,其环境风险不容忽视。     

PAH depositional history and sources in recent sediment core from Ukwa Ibom Lake, S. E. Nigeria

Analyses of recent sediment core from the Ukwa Ibom Lake show evidence of aquatic production, terrigenous, combustion and petroleum inputs. Total organic carbon/total nitrogen values (>10) for the sediments indicate greater wash-in of land-plant organic matter relative to algal production. The characteristic combustion ratios, fluoranthene/fluoranthene + pyrene (>0.50), anthracene/anthracene + phenanthrene (>0.10), benzo(a)anthracene/benzo(a)anthracene + chrysene (>0.35) as well as 1,7/1,7 + 2,6-dimethylphenanthrene (>0.70) were observed for the top section only. These results coincided with the most recent pave-road extension exercise involving tree logging and burning of bush. The highest total PAH concentration (91.13 ng/g dry weight (dw)) observed for the bottom section coincided with the period of inhabitation of the lake catchments (~5 decades ago) when discharge to the Lake water of domestic sewage and mill waste water were prevalent. The regular decline in total PAH concentrations upcore is a reflection of the ban placed on indiscriminate dumping of wastes following relocation of the inhabitants of the catchments. Besides the local depositional history, the irregular decrease in unresolved complex mixture (UCM) profiles suggests regional contaminant influx from the adjacent upper Cross River estuary, especially during intense rainfall event. The non-uniformity in methylphenanthrene indices (MPI-1 and MPI-2) shows evidence of importation and utilization of petroleum products of different thermal maturity histories into the Nigerian economy.     

Ti-montmorillonite as photocatalyst to remove 4-chlorophenol in water and methanol in air

We studied the photocatalytic activity of Ti-montmorillonite. The highest activity was found for a Ti/bentonite ratio of 10 mmol/g, prepared using HCl and calcined by microwaves. This mixture is less active than TiO₂ P-25 for 4-chlorophenol removal in water, but more active for methanol removal in air.     

吡啶类离子液体对青海弧菌Q67的混合毒性评估

合污染物产生的累积与毒性相互作用具有潜在的环境与健康风险。以6种吡啶类离子液体(IL)：丁基溴化吡啶([Bpy]Br)、己基溴化吡啶([Hpy]Br)、辛基溴化吡啶([Opy]Br)、丁基氯化吡啶([Bpy]Cl)、己基氯化吡啶([Opy]Cl)和辛基氯化吡啶([Opy]Cl)为混合物组分,应用直接均分射线法(EquRay)和均匀设计射线法(UD-Ray)分别设计4组二元IL混合物和2组三元混合物,每组混合物包括5条具有不同浓度配比的混合物射线。应用微板毒性分析法测定6种IL及其30条混合物射线对青海弧菌Q67的发光抑制毒性,以浓度加和(CA)为加和参考模型分析混合物毒性相互作用。结果表明,Logit函数能有效地拟合6种吡啶IL及其30条混合物射线的浓度-效应数据。若以半数效应浓度的负对数(pEC₅₀)为毒性指标,6个吡啶IL对Q67的毒性与烷基链上碳原子数目正相关,且每增加2个碳原子,其毒性约增加1。IL的阴离子(Br^-或Cl^-)对毒性没有影响。除己基氯化吡啶([Hpy]Cl)和辛基氯化吡啶([Opy]Cl)的二元混合物呈现明显拮抗作用外,其他二元及三元混合物都为加和作用。