Microbial community structure and function in sediments from e-waste contaminated rivers at Guiyu area of China.

The release of toxic organic pollutants and heavy metals by primitive electronic waste (e-waste) processing to waterways has raised significant concerns, but little is known about their potential ecological effects on aquatic biota especially microorganisms. We characterized the microbial community composition and diversity in sediments sampled along two rivers consistently polluted by e-waste, and explored how community functions may respond to the complex combined pollution. High-throughput 16S rRNA gene sequencing showed that Proteobacteria (particularly Deltaproteobacteria) dominated the sediment microbial assemblages followed by Bacteroidetes, Acidobacteria, Chloroflexi and Firmicutes. PICRUSt metagenome inference provided an initial insight into the metabolic potentials of these e-waste affected communities, speculating that organic pollutants degradation in the sediment might be mainly performed by some of the dominant genera (such as Sulfuricurvum, Thiobacillus and Burkholderia) detected in situ. Statistical analyses revealed that toxic organic compounds contributed more to the observed variations in sediment microbial community structure and predicted functions (24.68% and 8.89%, respectively) than heavy metals (12.18% and 4.68%), and Benzo(a)pyrene, bioavailable lead and electrical conductivity were the key contributors. These results have shed light on the microbial assemblages in e-waste contaminated river sediments, indicating a potential influence of e-waste pollution on the microbial community structure and function in aquatic ecosystems.

[Rhizospheric Mechanisms of Hemerocallis middendorfii Trautv. et Mey. Remediating Petroleum-contaminated Soil and Metabonomic Analyses of the Root Systems].

The effects of a special ornamental plant Hemerocallis middendorfii Trautv. et Mey. on remediating petroleum-contaminated soil from the Dagang Oilfield in Tianjin, China, was studied by a greenhouse pot-culture experiment and the gradients of TPHs were 0, 10,000 and 40,000 mg · kg⁻¹. The results suggested that H. middendorfii had a high tolerance to TPHs (≤ 40,000 mg · kg⁻¹). And H. middendorfii significantly (P < 0.05) promoted the removal rate of TPHs (53.7% and 33.4%) compared with corresponding controls (31.8% and 12.0%) by natural degradation, respectively. The relative abundance of amino acids, organic acids and sugars and others in soil were analyzed by gas chromatography-mass spectrometry (GC-MS), and PCA and PLS-DA models were to investigate the rhizospheric mechanisms. The results suggested that H. middendorfii changed the distribution characteristics of each component in soil, and the glucopyranoside played a key role in the removal of TPHs. Furthermore, the results about comparative metabolic profile showed that some special metabolites were only found in the contaminated groups, including alanine, tetradecanoic acid, hexadecanoic acid and 9,12-octadecadienoic acid. Additionally, the exposure of TPHs changed the primary metabolic flux of roots, and caused the significant (P < 0.01) change of metabolites. In conclusion, H. middendorfii might be an enduring ornamental plant for effective remediating TPHs (≤ 40,000 mg · kg⁻¹) in soil. But the exposure of TPHs had changed the metabolic profile of H. middendorfii in roots, which might be the metabolic response of H. middendorfii to petroleum-contaminated soil.

[Phytoremediation of Petroleum Contaminated Soils with Iris pseudacorus L. and the Metabolic Analysis in Roots].

In this study, we performed a greenhouse pot-culture experiment to investigate the potential of a wild ornamental plant Iris pseudacorus L. in remediating petroleum contaminated soils from the Dagang Oilfield in Tianjin, China. The results suggested that Iris pseudacorus L. had great resistance to ≤ 40,000 mg · kg(⁻¹ of total petroleum hydrocarbons (TPHs). The removal rate of TPHs with concentrations of 10,000 mg · kg⁻¹, 20,000 mg · kg⁻¹ and 40,000 mg · kg⁻¹ in soils by Iris pseudacorus L. was 42.1%, 33.1% 31.2%, respectively, much higher than those in the corresponding controls (31.8%, 21.3% 11.9%, respectively) (P < 0.05). The root specific surface area of Iris pseudacorus L. was determined by the root scanner. The results suggested that TPHs with concentrations of 10,000 mg · kg⁻¹, 20,000 mg · kg⁻¹ and 40,000 mg · kg⁻¹ in soils increased the root specific surface area comparing with the controls. Additionally, the metabolic analysis showed that root metabolism changed to different degrees under the stress of TPHs, and the levels or species of metabolites had a significant change (P < 0.001). Furthermore, the results showed that 5 of 11 metabolites (VIP value > 1.2) with the root specific surface area from the PLS-DA model analysis, including ethanedioic acid, lactic acid, 2-butenedioic acid, phosphate and propanedioic acid, were positively correlated with the root specific surface area, but the others, gluconic acid, uridine, butanoic acid, maltose, 9,12-octadecadienoic acid, phenylalanine, were negatively correlated with it. In conclusion, using Iris pseudacorus L. to remediate petroleum contaminated soils is feasible, and the metabolic analysis in roots is useful to better understand the metabolic response of plants exposure to petroleum contaminated soils, and then reveals its remediated mechanisms.

[Competence of Cd Phytoremediation in Cd-OCDF Co-contaminated Soil Using Mirabilis jalapa L].

Soil contamination by heavy metals and persistent organic pollutants tends to be severe. Pot experiment was conducted to investigate the phytoremediation of cadmium (Cd) in Cd-OCDF Co-contaminated Soil by Mirabilis jalapa L., using OCDF and Cd as the model pollutants of persistent organic pollutants and heavy metals, to study. the growth responses of plant and OCDF effects on phytoremediation of Cd. The results showed that during three months of planting the height and dry biomass of Mirabilis jalapa L. decreased slightly when the Cd concentration was not higher than 200 mg x kg(-1), and the plant exhibited high tolerance to Cd and OCDF. Compared with the Cd single pollution, OCDF had no significant effect on the height and root biomass of Mirabilis jalapa L. When the concentration of Cd was 200 mg x kg(-1) and the concentration of OCDF was 500 microg x kg(-1), the shoot biomass was reduced by 22.19%. In other treatments, OCDF showed no significant inhibition to the shoot biomass of Mirabilis jalapa L., but increased the shoot biomass in some treatments. Compared with single Cd pollution, when the concentration of Cd was 200 mg x kg(-1) and the concentration of OCDF was 100 microg x kg(-1), the Cd accumulation of root was reduced by 34.44%. When the concentration of Cd was 400 mg x kg(-1) and the concentration of OCDF was 100 microg x kg(-1), the Cd accumulation in root and leaf was reduced by 7.93% and 18.09%, respectively. In other treatments, OCDF promoted the extraction and accumulation of Cd by root, stem and leaf of Mirabilis jalapa L. from soil to some degree. So using Mirabilis jalapa L. to remediate Cd from high Cd concentration and OCDF cocontaminated soil is feasible.

Ecological effects of combined pollution associated with e-waste recycling on the composition and diversity of soil microbial communities.

The crude processing of electronic waste (e-waste) has led to serious contamination in soils. While microorganisms may play a key role in remediation of the contaminated soils, the ecological effects of combined pollution (heavy metals, polychlorinated biphenyls, and polybrominated diphenyl ethers) on the composition and diversity of microbial communities remain unknown. In this study, a suite of e-waste contaminated soils were collected from Guiyu, China, and the indigenous microbial assemblages were profiled by 16S rRNA high-throughput sequencing and clone library analysis. Our data revealed significant differences in microbial taxonomic composition between the contaminated and the reference soils, with Proteobacteria, Acidobacteria, Bacteroidetes, and Firmicutes dominating the e-waste-affected communities. Genera previously identified as organic pollutants-degrading bacteria, such as Acinetobacter, Pseudomonas, and Alcanivorax, were frequently detected. Canonical correspondence analysis revealed that approximately 70% of the observed variation in microbial assemblages in the contaminated soils was explained by eight environmental variables (including soil physiochemical parameters and organic pollutants) together, among which moisture content, decabromodiphenyl ether (BDE-209), and copper were the major factors. These results provide the first detailed phylogenetic look at the microbial communities in e-waste contaminated soils, demonstrating that the complex combined pollution resulting from improper e-waste recycling may significantly alter soil microbiota.

[Characteristics of dissolved organic matter in A/DAT-IAT system for municipal wastewater treatment based on ecological safety].

To ensure the water-quality safety and harmlessness of effluent from municipal wastewater, based on the lab-scale improved SBR-A/DAT-IAT process, dissolved organic matter (DOM) in municipal wastewater, demand aeration tank (DAT) supernatant and final effluent were classified and separated by applying the ultrafiltration membranes, and indexes such as TOC, UV254, 3D-EEM and toxicity were measured, to find out the sources of the toxic substances. The results showed that the lab-scale A/DAT-IAT process performed well on each molecular-weight fraction of DOM. The main composition in the effluent was humic-like substance. Along the process, The DOM distribution presented a trend of shifting to high molecular weight. Meanwhile, the aromaticity of DOM in the fraction with relative molecular weight below 1 x 10(3) increased significantly, leading to the increase in the reactivity of effluent with chlorine, which then increased the risk of disinfection by-products. In the raw wastewater, the toxic effects were originated from the fraction with relative molecular weight below 1 x 10(3), although the toxic effects were still originated from the same fraction in the effluent, they came from the biological treatment itself instead of the raw wastewater. Based on the analysis of TOC, UV254, 3D-EEM and toxicity, the removal of low molecular-weight humic-like substance should be emphasized to achieve the effluent organic emissions standards and to control the risk of chlorination by-products and toxicity. Therefore, future studies should focus on the removal of this fraction of DOM by adjusting technological parameters or adding a targeted processing unit.

Biochar: an effective amendment for remediating contaminated soil.

Biochar is a carbon-rich material derived from incomplete combustion of biomass.Applying biochar as an amendment to treat contaminated soils is receiving increasing attention, and is a promising way to improve soil quality. Heavy metals are persistent and are not environmentally biodegradable. However, they can be stabilized in soil by adding biochar. Moreover, biochar is considered to be a predominant sorptive agent for organic pollutants, having a removal efficiency of about 1 order of magnitude higher than does soil/sediment organic matter or their precursor substances alone.When trying to stabilize organic and inorganic pollutants in soil, several features of biochar' s sorption capacity should be considered, viz., the nature of the pollutants to be remediated, how the biochar is prepared, and the complexity of the soil systemin which biochar may be used. In addition, a significant portion of the biochar or some of its components that are used to remediate soils do change over time through abiotic oxidation and microbial decomposition. This change process is commonly referred to as "aging:" Biochar "aging" in nature is inevitable, and aged biochar exhibits an effect that is totally different than non-aged biochar on stabilizing heavy metals and organic contaminants in soils.Studies that have been performed to date on the use of biochar to remediate contaminated soil are insufficient to allow its use for wide-scale field application.Therefore, considerable new data are necessary to expand both our understanding of how biochar performs in the field, and where it can be best used in the future for soil remediation. For example, how biochar and soil biota (microbial and faunal communities)interact in soils is still poorly understood. Moreover, studies are needed on how to best remove new species of heavy metals, and on how biochar aging affects sorption capacity are also needed.

[Polycyclic musks exposure affects gene expression of specific proteins in earthworm Eisenia fetida].

To investigate the changes in gene expression of earthworm specific proteins following long-term exposure to low-dose polycyclic musks in soil, the mRNA expression levels of the four representative protein-coding genes (HSP70, CRT, cyPA, TCTP) were examined in earthworm Eisenia fetida exposed to polycyclic musks using real-time quantitative PCR (RT-qPCR). The purpose of this study was to investigate mRNA expression profiles of test protein genes in response to sublethal galaxolide (HHCB) and tonalide (AHTN) for 28 d exposure. The analysis results of both sequence alignment and melting curves of RT-qPCR reactions showed that the selected primers were appropriately qualified for quantitative mRNA analysis. mRNA expressions of HSP70 gene were not significantly changed in Eisenia fetida exposed to low concentrations of AHTN (less than 30 microg x g(-1)) and HHCB (less than 50 microg x g(-1)). But HSP70 gene expressions were significantly down-regulated at concentrations of AHTN or HHCB equal to or greater than 30 or 50 microg x g(-1). However, up-regulation of CRT gene expressions was induced in response to all test concentrations of AHTN and HHCB. Both cyPA and TCTP gene expressions were not varied compared to control groups after 28 days of exposure. Overall, the results indicated that HSP70 and CRT genes expression patterns might be potential early molecular biomarkers for predicting the harmful exposure level and ecotoxicological effects of polycyclic musks contaminated soil.

[Antioxidant enzyme gene expression as molecular biomarkers of exposure to polycyclic musks].

The objective of this study was to investigate the molecular toxicological effects of low level synthetic musks exposure on the earthworm Eisenia fetida. The method of Sybr Green I real time quantitative PCR (RT-qPCR) for detecting gene expression level was established. SOD (superoxide dismutase) and CAT (catalase) mRNA expression levels were measured after 28 days. of AHTN and HHCB exposure. The analysis results of both sequence alignment and melting curve demonstrated that the selected primers were suitable for mRNA quantification. The liner correlation coefficients of SOD and CAT standard curves were 0.997 and 0.994, respectively, and the PCR amplification efficiencies were both close to 100%. Therefore, relative quantification method could be applied to analyze the gene expression levels. The significant elevation of malondialdehyde (MDA) levels indicated that the reactive oxygen species-induced cellular oxidative injury might be one of the main toxic effects of AHTN and HHCB. Besides, a significant positive correlation was observed between the up-regulation of SOD, CAT mRNA and the MDA levels, suggesting that possible changes in the transcript expression of antioxidant enzyme genes were associated with the oxidative stress. Furthermore, the dose-response correlation between SOD, CAT mRNA levels and the exposure concentrations was also found. The overall results indicated that SOD and CAT genes might be potential molecular biomarkers for the evaluation of the pollution stress and toxicological effects of synthetic musks in the environment.

[Degradation pathways and main degradation products of tetracycline antibiotics: research progress].

Tetracycline antibiotics (TCs) can produce a series of abiotic degradation reactions in the process of production and storage, and some of the degradation products have lower antibacterial activity but higher toxicity, as compared to the parent antibiotics. TCs can enter the environment via the disposal of livestock and poultry wastes, and then degrade in one or more ways according to the external conditions. Besides abiotic degradation, bio-degradation also happens. This paper reviewed the degradation pathways and main degradation products of TCs in different ecological environments, and discussed the future research directions, aimed to provide valuable reference for the ecological risk assessment of the antibiotics.

[Effects of soil HHCB and Cd contamination on the growth of wheat seedlings (Triticum aestivum) and the pollutants accumulation in plants].

Using outdoor pot-culture experiment,biomasses of wheat seedlings and accumulation of HHCB and/or Cd in parts of wheat seedlings cultured in alluvial soil and cinnamon soil were investigated. The biomasses of wheat seedlings in different treatments followed the order as single HHCB treatment > HHCB and Cd treatment > single Cd treatment. The accumulation of HHCB in wheat seedlings cultured in alluvial soil was more than that in cinnamon soil, and effect of Cd on accumulation of HHCB in wheat seedlings cultured in alluvial soil was different to that in cinnamon soil. In alluvial soil, the accumulation of HHCB in different parts of wheat seedlings followed the sequence that root > stem > leaf. Cd significantly induced the accumulation of HHCB in wheat roots, but inhibited that of HHCB in wheat stems and leaves, and the highest inhibition rate was 44.07%. In cinnamon soil, the accumulation of HHCB in different parts of wheat seedlings followed the sequence that root > leaf > stem. The effect of Cd on accumulation of HHCB in wheat roots was not significant, but the median and high concentrations of Cd induced accumulation of HHCB in wheat stems and leaves significantly, and the highest induction rate was 35.95%. Besides, the accumulation of Cd in alluvial soil was lower than that in cinnamon soil, and HHCB could significantly induce the accumulation of Cd in wheat seedlings cultured in two different soils. The increasing rates of Cd accumulation in roots, stems and leaves in alluvial soil were 30.84%, 61.82% and 61.82%, and those in cinnamon soil were 41.53%, 184.16% and 206.18%, respectively. It is indicated that HHCB in cinnamon soil induced more accumulation of Cd in wheat seedlings than that in alluvial soil.

[Ecotoxicological effects of tetracycline on the seedling development of Chinese white cabbage (Brassica rapa L. chinensis group.) in soil].

The ecotoxicological effects of tetracycline (TC) on the early growth and seedlings development of Chinese white cabbage were investigated using the pot-culture method. The results showed that the stem elongation of the cabbages was promoted, while the root elongation and fresh weight of the cabbages were inhibited by 1-100 mg/kg TC. After a 28-day exposure, the inhibition rate of root elongation was up to 36.0% and that of fresh weight was up to 34.6% stressed by 100 mg/kg TC. With the exposure time of TC prolonged, the content of chlorophyll in leaves of the cabbage seedlings stressed by 100 mg/kg TC was significantly lower than that treated by other concentrations of TC, with the inhibition rate of chlorophyll was 21.7% - 29.0%. After a 7-day exposure to TC, the content of soluble protein (SP) and malondialdehyde (MDA) in the cabbage seedlings changed insignificantly. With the exposure time of TC prolonged, the content of SP in the cabbage seedlings decreased significantly, while the content of MDA increased significantly. Moreover, the activity of SOD, POD and CAT in Chinese white cabbage seedlings was inhibited by 1-100 mg/kg TC. The inhibition rates of SOD, POD and CAT activity exposed to 100 mg/kg TC were 33.9% - 45.3%, 33.8% - 67.7% and 29.6% - 57.7%, respectively. It suggested that TC has ecotoxicological effects on Chinese white cabbage seedlings with a chronic exposure.

Molecular characterization of a serine protease Pro1 from Plasmodiophora brassicae that stimulates resting spore germination.

Clubroot, caused by Plasmodiophora brassicae, is one of the most serious diseases of cultivated cruciferous crops in the world. However, the basis for pathogenicity in P. brassicae is not well understood. In this study, a serine protease gene (PRO1) was cloned from P. brassicae and its molecular characteristics were investigated. Southern analysis and specific polymerase chain reaction (PCR) amplification indicated that PRO1 is a single-copy gene present in a broad range of P. brassicae pathotypes. Northern analysis revealed that the expression of PRO1 was induced during plant infection, and that the quantity of transcript fluctuated according to the stage of pathogenesis. Amino acid sequence analysis suggested that the encoded protein (Pro1) belongs to the S28 family of proteases, with a predicted signal peptide and a theoretical molecular mass of 49.4 kDa. The open reading frame (ORF) of PRO1 was transferred into Pichia pastoris and Pro1 was heterologously produced. Pro1 showed proteolytic activity on skimmed milk and N-succinyl-Ala-Ala-Phe-7-amido-4-methylcoumarin, and the activity could be inhibited by serine protease inhibitors and the chelating agent ethylenediaminetetraacetic acid. The optimal temperature of Pro1 was 25 degrees C, and it exhibited high activity at pH 6.0-6.4. These values coincide with the temperature and pH conditions favourable for P. brassicae resting spore germination in the field. When Pro1 was used to treat canola root exudates, it enhanced the stimulating effect of the root exudates on P. brassicae resting spore germination, indicating that Pro1 may play a role during clubroot pathogenesis by stimulating resting spore germination through its proteolytic activity.

Effects of soil polycyclic musk and cadmium on pollutant uptake and biochemical responses of wheat (Triticum aestivum).

The single and joint toxicological effects of AHTN and cadmium (Cd) on early developmental stages of wheat, including AHTN and Cd uptake, chlorophyll (CHL), malondialdehyde (MDA), superoxide dismutase (SOD), and peroxidase (POD) contents in the seedlings, were investigated. Uptake of AHTN or Cd by seedlings increased with an increase in the concentrations of AHTN and Cd in soil. The presence of Cd inhibited the uptake of AHTN in wheat seedlings, while the low concentration of AHTN could induce the uptake of Cd. The biosynthesis of CHL was significantly inhibited by single AHTN and joint stress with AHTN and Cd. The MDA contents in wheat leaves and roots were significantly affected by single and joint stress with AHTN and Cd. SOD and POD activities in leaves was significantly induced by AHTN and Cd. However, the effect of AHTN and Cd on SOD and POD activities in roots was insignificant. This might indicate that wheat leaves were more sensitive to the binary mixture than wheat roots.

[Effect of soil organic matter and cadmium (II) on adsorption and desorption of chlortetracycline in soil].

Chlortetracycline (CTC) has been widely used in veterinary medicines and disease treatment. Heavy metals and antibiotics often coexist in soil due to land application of animal wastes and other sources of inputs. On the basis of the OECD Guideline 106, the batch equilibrium experimental method was employed to investigate sorption and desorption processes of CTC in cinnamon soil with and without soil organic matter (SOM) and examine the effect of Cd2+ on these processes. Results showed that the Freundlich model was the best isotherm to describe the experimental data for adsorption and desorption of CTC in soil on single and combined pollution conditions. In these a single chlortetracycline pollution and chlortetracycline-Cd combined pollution conditions, removal of SOM could increase the CTC adsorption capacity (K(f)) and adsorption intensity (1/n). The apparent adsorption-desorption hysteresis was found in cinnamon soil with and without SOM. In single pollution condition, the removal of SOM could significantly increase HI in cinnamon soil from 0.81 to 1.06. In all cases of CTC combined with Cd desorption studies, it had been known that HI of CTC in soils with SOM (1.11) were higher than those without SOM (0.84). This study was provided available data and parameters to set a more complete model to predict environmental concentration of CTC and evaluation their environmental risk.

[Ecotoxicological effects of oxytetracycline on wheat (Triticum aestivum) based on seed germination and seedling development].

The ecotoxicological effects of oxytetracycline (OTC) on the germination of wheat (Triticum aestivum) seeds and the early development of wheat seedlings were investigated. The results showed that the elongation of wheat shoots and roots was significantly (p < 0.05) inhibited by OTC, and there was a good dose-response relationship between the OTC concentration and inhibition rates. According to the linear regression equation, EC50 of OTC for inhibiting wheat shoot and root elongation was 65.5 mg/L and 34.7 mg/L, respectively. However, the germination of wheat seeds was not inhibited by OTC. Moreover, after a 21-day exposure to 0.15-2.40 mg/L OTC, the content of chlorophyll (CHL) decreased by 35.6%-47.3%, and the content of soluble protein (SP) in the leaves and roots of wheat plants decreased significantly. After a 7-day exposure, the activity of SOD and POD in wheat was not changed significantly. With the prolongation of exposure time, the activity of SOD and POD in wheat leaves and roots decreased significantly, the inhibition rate of SOD activity in roots increased up to 72.3% after a 21-day exposure to 2.4 mg/L OTC, which indicated that the antioxidant defense systems were damaged. The results above suggested that the low concentration OTC had ecotoxicological effects on wheat seedlings after chronic exposure.

[Characteristics of cadmium tolerance and bioaccumulation of Bidens pilosa L. seedlings].

Bidens pilosa L. has been identified as a newly found Cd-hyperaccumulator. In the present study, the characteristics of its Cd tolerance (growth response and physiological and biochemical characteristics) and accumulation were examined. The results showed that low Cd treatments (< or =32 mg/kg) could enhance plant growth, the dry biomass of shoot and root increased by 32.4%-44.7% and 29.1%-57.6%, respectively, at Cd concentrations 8-32 mg/kg when compared with the control. The shoot dry biomass reached a maximum of 0.22 g/pot at a concentration 8 mg/kg of Cd. Meanwhile, under different Cd treatments, chlorophyll (Chl) and soluble protein contents in leaves slightly decreased, resulting in 23.3% and 41.5% reduction, respectively, compared with the control. The activities of superoxide dismutase (SOD) firstly decreased and then increased with increasing Cd concentration. Peroxidase (POD) activities and malondialdehyde (MDA) contents increased with increasing Cd concentration, with 1.2-6.6 and 1.1-1.5 times increase, respectively, relative to the control. However, the definite negative effects on the plant growth and characteristics of physiology and biochemistry were observed at higher Cd concentrations (50-100 mg/kg). In gradual experiments, the values of bioaccumulation and translocation were more than 1.0, furthermore, the concentration of Cd in shoots reached 119.1 mg/kg at the soil Cd level of 100 mg/kg, showing B. pilosa has the basic characteristics of a Cd-hyperaccumulator. The results above indicated that B. pilosa has strong capacity of Cd tolerance and accumulation, so it has potential and valuable application to phytoremediation of contaminated soils by Cd.

[Ecological safety regulation of A/DAT-IAT process for municipal wastewater treatment].

Four controlling parameters of A/DAT-IAT process for municipal wastewater treatment, i. e., operation period (T), external recycled rate (R1), internal recycled rate (R2), and mixed liquid suspended solid concentration (MLSS), were studied by orthogonal experiments, and the regular and ecotoxicological indicators of the effluents were examined. The results showed that the optimum conditions of regular indicators removal were T = 3 h, R1 = 20%, R2 = 150%, and MLSS = 5000 mg x L(-1), and the optimum conditions of ecotoxicological indicators removal were T = 3 h, R1 = 20%, R2 = 150%, and MLSS = 3000 mg x L(-1). The reason which caused the difference of the two optimum conditions might be that there were some non-biodegradable organic matters having certain ecological toxic effects and some organic matters whose ecological toxicity increased after hydrolysis and acidification. Adding flocculants and properly choosing controlling parameters were suggested to improve the regular and ecotoxicological indicators of the effluent.

[Effects of illumination and seed-soaking reagent on seed germination of Solanum nigrum].

To explore a rapid seed germination method for hyperaccumulator Solanum nigrum, a germination experiment with different illumination and seed-soaking treatments was conducted in constant temperature box and greenhouse, with filter as burgeon base. Under illumination, the germination rate was about 5 times high of that without illumination (P < 0.05), indicating that illumination was one of the prerequisites for the seed germination of S. nigrum. All test seed-soaking reagents could significantly improve the germination rate of S. nigrum (P < 0.05), with the best effect of H2O2. The seeds treated with H2O2 had the shortest germination time. The germination rate of seeds soaked but without cleaning was 2-3 times as high as that of seeds soaked and cleaned with water.

[Effects of antimicrobial drugs on soil microbial respiration].

The effects on soil microbial respiration of sulfonamides, tetracyclines, macrolides and so on were studied using the direct absorption method. The results show sulfamethazine, sulfamethoxazole, chlortetracycline, tetracycline, tylosin and trimethoprim inhibit soil respiration 34.33%, 34.43%, 2.71%, 3.08%, 7.13%, 38.08% respectively. Sulfamethoxazole and trimethoprim have the highest inhibition rates among all the antibiotics. In early incubation period (0-2 d), the concentrations above 10 mg x kg(-1) of sulfamethazine, sulfamethoxazole and trimethoprim remarkably decrease soil CO2 emission. The effects of these antibiotics vary with their concentrations too. Sulfamethoxazole and trimethoprim show good dose-response relationships. According to the standard of pesticide safety evaluation protocol, the six antibiotics pose a little risk to soil microbial environment.