Biological treatment of fish processing wastewater: A case study from Sfax City (Southeastern Tunisia)

The present work presents a study of the biological treatment of fish processing wastewater at salt concentration of 55 g/L. Wastewater was treated by both continuous stirred-tank reactor (CSTR) and membrane bioreactor (MBR) during 50 and 100 days, respectively. These biological processes involved salt-tolerant bacteria from natural hypersaline environments at different organic loading rates (OLRs). The phylogenetic analysis of the corresponding excised DGGE bands has demonstrated that the taxonomic affiliation of the most dominant species includes Halomonadaceae and Flavobacteriaceae families of the Proteobacteria (Gamma-proteobacteria class) and the Bacteroidetes phyla, respectively. The results of MBR were better than those of CSTR in the removal of total organic carbon with efficiencies from 97.9% to 98.6%. Nevertheless, salinity with increasing OLR aggravates fouling that requires more cleaning for a membrane in MBR while leads to deterioration of sludge settleability and effluent quality in CSTR.     

It's a dirty job but someone has to do it: The role of marine benthic macrofauna in organic matter turnover and nutrient recycling to the water column

Benthic macrofaunal populations through their feeding, bioturbation, burrow construction and sediment irrigation activities have profound influences on organic matter inputs to marine sediments (biodeposition) and on the vertical distribution of deposited organic matter within the sediment. These effects in turn influence the rates and pathways of organic matter mineralisation, and element cycles. Similarly, bioturbation, burrow construction and burrow irrigation are major determinants of sediment-water column fluxes of oxygen and nutrients.

In this review, I discuss the influences of the different benthic macrofaunal feeding (functional) groups on mineralisation processes and sediment-water column fluxes of particulate and dissolved nutrients. How these effects influence diagenic processes, the balance between aerobic and anaerobic processes, and the redox status of the surficial sediments. Finally, I discuss some of the limitations of the predominantly laboratory techniques which have been used to study “macrofaunal effects” and how this hinders the inclusion of the effects in quantitative sediment biogeochemical models.     

Sensitivity to biologically relevant odours may exceed the sum of component thresholds

Summary In four fruit-eating bats sniff-rate analysis revealed the threshold value for natural banana odour to be 1 × 10^–4 vol% of head-space while the threshold values for its major components were found to be 3–6 orders of magnitude higher; even the total of molecules present at the threshold dilution of banana odour was 2 orders of magnitude below the lowest threshold values obtained for single components. Thus, the responsiveness of the bats to threshold concentration of natural banana odour is discussed as an example of synergism of stimuli.     

生物炭对土壤水肥热效应的影响试验研究

本文通过野外大田小区试验以番茄（Lycopersicon esculentum Mill）为供试作物,通过在土壤中施加不同含量生物炭（Biochar）研究生物炭对土壤含水率、有机碳、速效养分含量和土壤温度的影响,从而寻求一个较为合适的施用量,为生物炭在内蒙古地区的大面积推广提供科学的理论依据。试验共设5个处理,3个重复：不施加生物炭（CK）,生物炭使用量分别为10 t·hm^-2（A）,20 t·hm^-2（B）,40 t·hm^-2（C）,60 t·hm^-2（D）,在各生育期取土样测定土壤含水率、有机碳、速效养分含量,并在各生育期连续3天测定土壤地表温度。试验结果表明：不同处理下土壤含水率随生物炭施用量增加呈先增加后减小的趋势,且均高于对照组,其中施炭量为40 t·hm^-2处理的土壤含水率增幅最明显,0～10 cm土层各生育期土壤含水率较对照组最大增幅分别为20.8%、13.7%、21.8%,10～20 cm土层各生育期土壤含水率较对照组最大增幅分别为33.9%、17.1%、21.3%;不同处理下土壤温度随着生物炭施用量的增加而升高,两者具有显著的正相关关系,各生育期各处理土壤地表温度较对照组最大增幅分别为58.1%、31.3%、55.8%;不同处理土壤有机碳含量随着生物炭施用量的增加而增大,番茄各生育期各处理土壤有机碳含量较对照组最大增幅分别为80.9%、62.7%、63.9%;不同处理土壤中碱解氮、速效钾、速效磷含量均随生物炭施用量的增加而呈现先增大后减小的趋势,且均大于对照组,各生育期各处理土壤碱解氮较对照组最大增幅分别为92.7%、45.7%、106.5%,速效磷最大增幅分别为120.1%、39.3%、250.4%,速效钾最大增幅分别为86.2%、118.5%、203.4%。综上所述,生物炭对于砂壤土具有保水、保肥、保温的特性,对于提高土壤水肥利用效率,增加土壤有机碳具有重要的作用,而且通过试验验证40 t·hm^-2的施?     

Testicular DNA synthesis inhibition—an in vivo system for the detection of mutagenic and carcinogenic chemicals

By binding covalently to DNA chemical mutagens and carcinogens inhibit replication, which can be measured as a decrease in thymidine incorporation into DNA. This DNA synthesis inhibition (DSI) has been determined in testicular cells of mice for a large number of compounds and has been found to correlate very well with their known mutagenic and carcinogenic properties.

Not only could this test give a qualitative answer about potential carcinogenicity or mutagenicity, but, with regard to its in vivo characteristics, could furthermore give an indication of the carcinogenic and mutagenic potency and thus be of use in the risk evaluation of chemical substances; the relationship between the DNA synthesis inhibition and the underlying alkylation of guanine ‐0⁶ by different methylating agents is demonstrated.

As toxic effects decrease thymidine incorporation, too, means are discussed for distinguishing between “true”;, mutagenic, and “false”;, cytotoxic, DNA synthesis inhibition.

In conclusion, the implications of including the DSI‐test in a battery of mutagenicity tests are outlined.     

Organic farmers in islands: Agricultural management and attitude towards the environment

SUMMARY

This study explores differences among organic farmers who live in islands and have isolated small-size operations. The relationships between farmers' characteristics and attitudes and farm management were interpreted by studying how they manage their land, their attitudes towards the environment and alternative farming systems, and their involvement in organic farming. The research was carried out using questionnaires addressed to organic farmers on the island of Thassos. Nonlinear canonical correlation was applied for data analysis. This information could contribute to adjustment of policy decisions for on-farm diversification. Agricultural policy makers should approach organic farmers in northern Thassos (productive irrigated olive orchards with gentle slopes) by enacting standards to reduce the cost of alternative plant protection methods and promoting their products in order to maintain and expand organic farming. They should also approach organic farmers in southern Thassos (less productive, dry cultivated olive orchards with steep slopes, overgrazed and often abandoned) by providing them with the necessary information and appropriate agricultural know-how to effectively manage their farms. Organic farmers with stable off-farm income are more aware of environmental values and consider that they risk less than others in order to gain the benefits of alternative farming systems. However, they should attend training programmes to achieve economic success to allow them to continue farming organically.     

Inorganic and methyl-mercury speciation in sediments of the Swarzędzkie Lake

Sediment samples were analysed for mercury and methylmercury content in different parts of the bottom sediment of Swarz ?dzkie Lake, which were influenced by different external pollution sources. The results of determination with two methods of mineralization using two separate media (HNO₃/H₂O₂ and HF) were compared. The accuracy of the studied methods was analysed using certified reference material IAEA 405 of river sediment. The recovery of mercury was satisfactory and ranged from 97.5 to 98.8%. Methylmercury compounds in the studied sediments were found in limited concentrations. Their concentrations ranged from 0.26 to 58.1 μg kg^?1, i.e. 1.0–7.4% of the total mercury content. The depth profile displayed high values of both total and methylmercury content at a depth of 10–20 cm, related to the heavy pollution of the lake in the 1980s. Canonical analysis displayed the relationship of both total mercury and methylmercury concentrations with organic matter and phosphorus content in bottom sediments.     

我国水环境有机物分析前处理技术

介绍了我国水环境有机物分析中常用的前处理技术,包括液液萃取、树脂吸附、固相萃取、固相微萃取、液膜萃取、半透膜被动采样、顶空、吹扫-捕集等,归纳了各种方法的原理、应用及优缺点,并对环境中有机污染物前处理技术的发展方向进行了展望。     

室内空气有机污染的研究现状

主要讨论了室内空气中有机物污染的研究现状。重点介绍了室内空气中多环芳烃 (PAHs)、挥发性有机物(VOCs)、醛类化合物等的污染状况及来源。简要叙述了室内空气污染的影响因素及对人体的健康风险评价。     

大体积进样-气相色谱法测定水中多种痕量有机磷农药

建立了大体积进样气相色谱-火焰光度法检测水中多种痕量有机磷农药的方法.重点研究了程序升温汽化(PTV)进样条件的选择,通过对分流排空量、吹扫时间、PIV起始温度等PTV参数的选择,优化了测试条件,提高了检测灵敏度.水中9种有机磷农药的线性良好,10ml水样中三乙基偶磷硫酯的检出限为0.01μg/L,硫磷嗪、致螟磷、甲拌磷、乐果、乙拌磷、甲基对硫磷、对硫磷和氨磺磷的检出限可达0.001μg/L.水中添加多种有机磷农药准确度精密度试验,平均回收率为85.8%～108%,相对标准差在3.3%～11.4%之间.与常规方法相比,该方法前处理简单快速、分析成本低.灵敏度、准确度和精密度均符合地表水检测质量的要求,适用于水环境中多种农药残留的快速检测.