Functional groups of marine ciliated protozoa and their relationships to water quality

Ciliated protozoa (ciliates) play important ecological roles in coastal waters, especially regarding their interaction with environmental parameters. In order to increase our knowledge and understanding on the functional structure of ciliate communities and their relationships to environmental conditions in marine ecosystems, a 12-month study was carried out in a semi-enclosed bay in northern China. Samples were collected biweekly at five sampling stations with differing levels of pollution/eutrophication, giving a total of 120 samples. Thirteen functional groups of ciliates (A–M) were defined based on their specific spatio-temporal distribution and relationships to physico-chemical parameters. Six of these groups (H–M) were the primary contributors to the ciliate communities in the polluted/eutrophic areas, whereas the other seven groups (A–G) dominated the communities in less polluted areas. Six groups (A, D, G, H, I and K) dominated during the warm seasons (summer and autumn), with the other seven (B, C, E, F, J, L and M) dominating in the cold seasons (spring and winter). Of these, groups B (mainly aloricate ciliates), I (aloricate ciliates) and L (mainly loricate tintinnids) were the primary contributors to the communities. It was also shown that aloricate ciliates and tintinnids represented different roles in structuring and functioning of the communities. The results suggest that the ciliate communities may be constructed by several functional groups in response to the environmental conditions. Thus, we conclude that these functional groups might be potentially useful bioindicators for bioassessment and conservation in marine habitats.     

Effect of silicate supplementation on the alleviation of arsenite toxicity in 93-11 (Oryza sativa L. indica)

Chronic exposure to arsenic (As) in rice has raised many health and environmental problems. As reported, great variation exists among different rice genotypes in As uptake, translocation, and accumulation. Under hydroponic culture, we find that the Chinese wild rice (Oryza rufipogon; acc. 104624) takes up the most arsenic among tested genotypes. Of the cultivated rice, the indica cv. 93-11 has the lowest arsenic translocation factor value but accumulates the maximum concentration of arsenic followed by Nipponbare, Minghui 86, and Zhonghua 11. Higher level of arsenite concentration (50 μM) can induce extensive photosynthesis and root growth inhibition, and cause severe oxidative stress. Interestingly, external silicate (Si) supplementation has significantly increased the net photosynthetic rate, and promoted root elongation, as well as strongly ameliorated the oxidative stress by increasing the activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and peroxidase in roots and/or leaves of 93-11 seedlings. Notably, 1.873 mM concentration of Si considerably decreases the total As uptake and As content in roots, but significantly increases the As translocation from roots to shoots. In contrast, Si supplementation with 1.0 mM concentration significantly increases the total As uptake and As concentrations in roots and shoots of 93-11 seedlings after 50 μM arsenite treatment for 6 days.     

广州市南沙区水生生态环境现状的调查研究

在广州市南沙区水域采集地表水和水生生物样品,对水质主要理化指标、叶绿素a含量和初级生产力以及水生生物(浮游植物和浮游动物)的种类、数量、多样性和均匀度指数等进行调查,综合评价了南沙区水域水生生态环境质量.结果表明,利用不同指标对南沙区水域进行评价获得的结果基本一致,介于贫营养化至中营养化状态之间,水生生态环境质量状况较好.     

Effect of chlorination and ultraviolet disinfection on tetA-mediated tetracycline resistance of Escherichia coli

Antibiotic-resistant bacteria are an emerging threat to public health during drinking water consumption and reclaimed water reuse. Several studies have shown that the proportions of antibiotic-resistant bacteria in waters may increase when exposed to low doses of UV light or chlorine. In this study, inactivation of tetracycline-resistant Escherichia coli and antibiotic-sensitive E. coli by UV disinfection and chlorination was compared to determine the tolerance of tetracycline-resistant E. coli to UV light and chlorine, and tetracycline resistance of a tetracycline-resistant E. coli population was studied under different doses of the disinfectants. Our results showed that relative to antibiotic-sensitive E. coli, tetracycline-resistant E. coli had the same tolerance to UV light and a potentially higher tolerance to chlorination. The mortality frequency distributions of tetracycline-resistant E. coli exposed to tetracycline were shifted by both chlorination and UV disinfection. When compared to the hemi-inhibitory concentrations (IC₅₀) of tetracycline-resistant E. coli with no exposure to UV or chlorination, the IC₅₀ of tetracycline-resistant E. coli treated with tetracycline was 40% lower when inactivation by UV light or chlorination reached 3-log but was 1.18 times greater when inactivation by chlorination reached 4.3-log. Chlorination applied to drinking water or reclaimed water treatment may increase the risk of selection for highly tetracycline-resistant E. coli.     

生物填料地下渗滤系统对生活污水的脱氮

将草甸棕壤、炉渣和活性污泥等基质按体积比13∶6∶1配制生物填料,研究了生物填料地下渗滤系统（subsurface wastewater infiltration system,SWIS）在不同的水力负荷和污染负荷条件下对校园生活污水的脱氮效果。场地实验结果表明,当BOD5负荷为12.0 g BOD5/（m2·d）,表面水力负荷为0.04-0.10 m3/（m2·d）时,SWIS对NH＋4-N和TN的平均去除率分别为92.4%和82.0%。当水力负荷为0.08 m3/（m2·d）,BOD5负荷9.3-16.8 g BOD5/（m2·d）时,SWIS对NH＋4-N和TN的平均去除率为92.7%和81.2%。SWIS中氧化还原电位（oxygen reduction potential,ORP）随进水水力负荷和BOD5负荷的增加而降低,脱氮效率下降。综合出水水质和处理效率,适宜的水力负荷和污染负荷分别为0.065 m3/（m2·d）和12.0 g BOD5/（m2·d）。在此条件下,SWIS的启动周期为25-30 d。出水水质均优于《城市污水再生利用-景观环境用水水质》（GB/T18921-2002）标准,且处理效果稳定,抗负荷冲击能力强。     

膜电解法在线再生酸性蚀刻液及回收铜新技术

采用极化曲线法研究了酸性蚀刻液阴、阳极电化学行为,并构建了离子膜电解反应体系,考察了在线再生酸性蚀刻液及回收铜的效果。结果表明,阳极氧化过程发生浓差极化,存在极限电流密度,Cu＋含量越高,极限电流密度越大;阴极还原分4步反应进行,存在极限电流密度;强化溶液传质可有效提高阴、阳极极限电流密度,有利于避免电解过程中析出氯气和氢气;在线实验表明,通过监控阳极液ORP,可避免析出氯气;分步降低电流电解有利于避免析出氢气,形成致密的金属铜块;在电流为9～24A范围内分4步电解23．5h可再生酸性蚀刻液23．5L,同时电沉积回收510g铜,纯度高达99．98％。阴极电流效率达到95．2％,吨铜电耗3251kWh。电解过程中无氯气和氢气析出,无废液排放,表明膜电解法在线再生酸性蚀刻液具有良好的应用前景。     

高碱度水库水混凝过程中残留铝控制

针对高碱度水库水源的某水厂残留铝超标问题,选取碱化度(B)与Alb含量不同的3种铝盐絮凝剂,研究不同投量与pH值下混凝效果与残留铝浓度水平。结果表明,碱化度和Alb含量显著影响混凝效果。DOC和浊度的去除率随着3种絮凝剂AlCl3(B=0)、PACl-1(B=1.2)、PACl-2(B=2.2)投量增大而升高。3种絮凝剂投量在1.5～2.0 mg/L(以铝计)范围内,总铝和溶解铝含量最低。对于该水厂自制的絮凝剂PACl-2,可通过降低絮凝剂碱化度,或将水的pH值降低至7～7.5之间,以此可以提高PACl-2混凝效果,而且可以降低出厂水残留铝浓度。考虑工程应用可行性,可优先考虑调整絮凝剂生产工艺。     

粉煤灰负载铁离子催化氧化活性黄染料废水

以粉煤灰为载体,制备铁/粉煤灰负载型催化剂,并利用该催化剂催化H2O2氧化降解活性黄染料废水,探讨了H2O2投加量、催化剂投加量、染料初始浓度和初始pH值等因素对染料废水COD去除率和脱色率的影响。结果表明,当染料废水COD初始浓度为200 mg/L,初始pH值为1.7,投加0.5 g/100 mL催化剂及加入1.0 mL浓度为1.13 mol/L的H2O2溶液时,处理效果最好,此时染料废水的COD去除率和脱色率分别达到63%和99%,并且废水的可生化性得到很大的提高。利用该负载催化剂能够有效地减少活性黄染料废水中Fe3+的残留量。     

利用污泥熟肥作为高含水率污泥堆肥调理剂

采用静态强制通风好氧堆肥的方法,以木屑作为对比,考察了利用污泥熟肥作为调理剂对污泥堆肥过程的影响。结果表明,与以木屑作为调理剂的污泥堆体(对照组)相比,以污泥熟肥作为调理剂的污泥堆体(实验组)升温快,高温阶段(>50℃)持续时间长达10 d,满足粪便无害化卫生标准的要求,而对照组仅持续了2 d;实验组腐熟的堆肥含水率从60%降到39%,下降了21%,pH维持在7.5～8.5范围内,微生物活性较强,而对照组含水率仅下降15%,pH始终低于7.5;实验组种子发芽指数(GI)在第14天就回升到80%以上,基本上去除了植物毒性,而对照组GI在第22天才回升到50%。总体而言,污泥熟肥能显著改善堆肥中微生物的微环境,促进有机物的降解,缩短堆肥腐熟时间,是一种优质的调理剂。