Aphanizomenon gracile (Nostocales), a cylindrospermopsin-producing cyanobacterium in Polish lakes

The cyanobacterial cytotoxin cylindrospermopsin (CYN) has become increasingly common in fresh waters worldwide. It was originally isolated from Cylindrospermopsis raciborskii in Australia; however, in European waters, its occurrence is associated with other cyanobacterial species belonging to the genera Aphanizomenon and Anabaena. Moreover, cylindrospermopsin-producing strains of widely distributed C. raciborskii have not yet been observed in European waters. The aims of this work were to assess the occurrence of CYN in lakes of western Poland and to identify the CYN producers. The ELISA tests, high-performance liquid chromatography (HPLC)-DAD, and HPLC-mass spectrometry (MS)/MS were conducted to assess the occurrence of CYN in 36 lakes. The cyrJ, cyrA, and pks genes were amplified to identify toxigenic genotypes of cyanobacteria that are capable of producing CYN. The toxicity and toxigenicity of the C. raciborskii and Aphanizomenon gracile strains isolated from the studied lakes were examined. Overall, CYN was detected in 13 lakes using HPLC-MS/MS, and its concentrations varied from trace levels to 3.0 μg?L^?1. CYN was widely observed in lakes of western Poland during the whole summer under different environmental conditions. Mineral forms of nutrients and temperature were related to CYN production. The molecular studies confirmed the presence of toxigenic cyanobacterial populations in all of the samples where CYN was detected. The toxicity and toxigenicity analyses of isolated cyanobacteria strains revealed that A. gracile was the major producer of CYN.     

Recycling — an environmentally friendly and income generating activity towards sustainable solid waste management. Case study — Dar es Salaam City, Tanzania

Traditionally solid waste management has evolved as mainly the removal of municipal wastes by hauling them out of the city boundaries and dumping them ‘there’. This is in conformity with the ‘out of sight out of mind’ philosophy. However, with the ever increasing tonnage of refuse due to the expansion of urban centers, which implies increased collection, transportation and disposal costs, recycling is currently accepted as a sustainable approach to solid waste management. This paper reports on the findings of a study, conducted in the city of Dar es Salaam between the years 1993 and 1995, on the scavenging activities and recycling trends of some selected items in Dar es Salaam. Apart from the discussions on existing solid waste generation rates (2000 tonnes/day), composition (60% being organic/or vegetable matter) and their management in Dar es Salaam, the paper also presents data obtained through a survey of Vingunguti dump site and other waste collection centers. It was established that there are currently about 600 solid waste scavengers in Dar es Salaam, approximately 109 of whom operate at Vingunguti dump site and others at 14 different collection centers. Many of them opted for scavenging due to unemployment. The study findings indicate that their average monthly income exceeded the official minimum wage (at the time of study) enabling them to support their families. This demonstrates the potential of recycling to generate gainful employment with implied lower crime rates among the unemployed. Recycling activities in the city were observed to be not only a critical source of raw materials for small-scale industries, in the absence of which they would cease to operate, but also a widely accepted environmentally friendly technology for solid waste management. Out of 294 tonnes of studied waste materials (paper, metal, plastic, glass and textiles) only 4 tonnes are recovered and recycled. The remaining 290 tonnes/day of recyclable material are left to pollute the environment or are collected and transported for final disposal and, therefore, unnecessarily contribute to the shortening of the life span of the dump site. Finally, the paper gives some recommendations for improved recycling activity so as to make it an important means of reducing the overall volume of waste materials to be transported and deposited in the dump site and at the same time provide a potential opportunity for employment for unskilled workers.     

Pollution and Self-Cleansing of an Urban River in a Developing Country: A Case Study in Dar es Salaam, Tanzania

Pollution and self-purification trends of an urban river namely, Msimbazi River, in Dar es Salaam City, Tanzania, were investigated. Site investigations and water quality analyses were done. The river is polluted in terms of high organic and nutrient concentrations, low dissolved oxygen, and high counts of indicator organisms. Biochemical oxygen demand (BOD₅) concentrations were 27– 340 mg/L. Dissolved oxygen was found to be as low as 0.9 mg O₂/L. Bacteriological pollution increased with distance downstream of the river, a trend attributable to an increase in the catchment of pollution sources, which are on-site sanitation systems. Although the river has an appreciable self-purification capacity, the capacity is strained by persistent pollution overloads. The pollution plight of the river is attributable to its being flanked by expanding human habitats and vibrant industrial, institutional, and socio-economic activities. Provision for pretreatment of discharges into the river is put forward as a remedial measure for the observed pollution. Matching nontechnical and techno-social remedial measures are also recommended. These include sensitization of polluters on merits of environmental protection practices such as cleaner production and strict enforcement of environmental protection laws.     

Recycling inorganic domestic solid wastes: results from a pilot study in Dar es Salaam City, Tanzania

Solid waste recycling and recovery approach can be a sustainable and effective waste management system in many growing cities of the least developed countries. In the course of achieving proper solid waste management, a lot of efforts in these countries have, however, been focused more on collection and disposal and ignored waste recycling which can result into income generation, employment creation and reduction of the waste quantities that will finally require disposal in the existing municipal landfills or disposal sites. This paper reports the findings of a study on solid waste recycling in a selected semi-planned settlement in Dar es Salaam City, Tanzania. The objective of the study was to describe the existing solid waste management in the study area with a view to identifying the waste generation rates, types of the wastes and determine the amount of waste from the settlement that can be recycled for the purpose of income generation and reduction of the total amount of waste to be disposed of. Findings from this study revealed that waste generation rate in the study area was 0.36 kg per person per day, and that out of the 14 600 kg of recyclable waste generated per year, 8030 kg or 55% can be recycled and generate a per capita income of Tsh 834 000 for waste recyclists which is more than twice the official minimum annual wage (Tsh 360 000) in Tanzania at the time of the study. The study also revealed that effective waste recycling in the study area would result in the reduction of the total waste that need to be transported for final disposal by 11%.     

Suitability of oil bioremediation in an Artic soil using surplus heating from an incineration facility

A 168-day period field study, carried out in Sisimiut, Greenland, assessed the potential to enhance soil remediation with the surplus heating from an incineration facility. This approach searches a feasible ex situ remediation process that could be extended throughout the year with low costs. Individual and synergistic effects of biostimulation were also tested, in parallel. An interim evaluation at the end of the first 42 days showed that biostimulation and active heating, as separate treatments, enhanced petroleum hydrocarbon (PHC) removal compared to natural attenuation. The coupling of both technologies was even more effective, corroborating the benefits of both techniques in a remediation strategy. However, between day 42 and day 168, there was an opposite remediation trend with all treatments suggesting a stabilization except for natural attenuation, where PHC values continued to decrease. This enforces the “self-purification” capacity of the system, even at low temperatures. Coupling biostimulation with active heating was the best approach for PHC removal, namely for a short period of time (42 days). The proposed remediation scheme can be considered a reliable option for faster PHC removal with low maintenance and using “waste heating” from an incineration facility.     

Estrogenicity profile and estrogenic compounds determined in river sediments by chemical analysis, ELISA and yeast assays

An effects-directed strategy was applied to bed sediments of a polluted tributary in order to isolate and identify the major estrogenic chemicals it discharges into the River Po, the principal Italian watercourse. Sediment extract was concentrated by solid phase extraction and then fractioned into 10 fractions by reversed phase high performance liquid chromatography (RP-HPLC). Estrogenic activity of whole extract and fractions were determined using a recombinant yeast assay containing the human estrogen receptor (YES). The 10 fractions and whole extract were analysed for target compounds, e.g. estrone (E1), 17beta-estradiol (E2), estriol (E3), 4-nonylphenol (NP), 4-tert-octylphenol (t-OP), bisphenol A (BPA), using both liquid chromatography-tandem mass spectrometry (LC-MS/MS) and non-competitive enzyme-linked immunosorbent assays (ELISA). The YES assay determined high estrogenic activity in whole sediment (15.6 ng/g EE2 equivalents), and positive results for fractions nr 1, 2, 6, 7 and 8. E1, E3 and NP were the main estrogenic chemicals, however, other unidentified compounds contributed to sediment estrogenicity, particularly for polar fractions nr 1 and 2. A GC-MS screening performed in scan mode identified other potential contributors such as phthalates (DBP, BBP), and OP isomers. A next sampling campaign extended to other tributaries and receiving stretches of the River Po confirmed E1, E3 and NP as major estrogenic chemicals potentially threatening other sites of the main river. In general, target compound ELISAs have been shown to be suitable tools for a rapid screening of wide areas or large numbers of environmental samples for estrogenic risk. The potential for interferences suggests however to use cautiously the concentration values obtained from some of the immunoassays.     

The dependence of the beta coefficient of REA system with dynamic deadband on atmospheric conditions

We simulated the REA system with dynamic deadband to study numerical value and the effect of atmospheric conditions on the empirical constant beta which relates vertical flux to concentration difference between updrafts and downdrafts. We found that the value of beta depends only weakly on the friction velocity and atmospheric stability. In agreement with previous studies, the median value obtained for a system with dynamic deadband proportional to 0.5 times the running mean of the standard deviation of vertical wind speed was beta=0.42+/-0.03. For a single half-hour measurement one has to consider the large uncertainty of +/-0.2. According to our study, the dynamic deadband enables the use of a constant value of beta in flux calculation.     

A multivariate analysis of beta diversity across organisms and environments

We examined variability in hierarchical beta diversity across ecosystems, geographical gradients, and organism groups using multivariate spatial mixed modeling analysis of two independent data sets. The larger data set comprised reported ratios of regional species richness (RSR) to local species richness (LSR) and the second data set consisted of RSR:LSR ratios derived from nested species-area relationships. There was a negative, albeit relatively weak, relationship between beta diversity and latitude. We found only relatively subtle differences in beta diversity among the realms, yet beta diversity was lower in marine systems than in terrestrial or freshwater realms. Beta diversity varied significantly among organisms' major characteristics such as body mass, trophic position, and dispersal type in the larger data set. Organisms that disperse via seeds had highest beta diversity, and passively dispersed organisms showed the lowest beta diversity. Furthermore, autotrophs had lower beta diversity than organisms higher up the food web; omnivores and carnivores had consistently higher beta diversity. This is evidence that beta diversity is simultaneously controlled by extrinsic factors related to geography and environment, and by intrinsic factors related to organism characteristics.     

Mass,energy and material balances of SRF production process. Part 1: SRF produced from commercial and industrial waste

This paper presents the mass, energy and material balances of a solid recovered fuel (SRF) production process. The SRF is produced from commercial and industrial waste (C&IW) through mechanical treatment (MT). In this work various streams of material produced in SRF production process are analyzed for their proximate and ultimate analysis. Based on this analysis and composition of process streams their mass, energy and material balances are established for SRF production process. Here mass balance describes the overall mass flow of input waste material in the various output streams, whereas material balance describes the mass flow of components of input waste stream (such as paper and cardboard, wood, plastic (soft), plastic (hard), textile and rubber) in the various output streams of SRF production process. A commercial scale experimental campaign was conducted on an MT waste sorting plant to produce SRF from C&IW. All the process streams (input and output) produced in this MT plant were sampled and treated according to the CEN standard methods for SRF: EN 15442, EN 15443. The results from the mass balance of SRF production process showed that of the total input C&IW material to MT waste sorting plant, 62% was recovered in the form of SRF, 4% as ferrous metal, 1% as non-ferrous metal and 21% was sorted out as reject material, 11.6% as fine fraction, and 0.4% as heavy fraction. The energy flow balance in various process streams of this SRF production process showed that of the total input energy content of C&IW to MT plant, 75% energy was recovered in the form of SRF, 20% belonged to the reject material stream and rest 5% belonged with the streams of fine fraction and heavy fraction. In the material balances, mass fractions of plastic (soft), plastic (hard), paper and cardboard and wood recovered in the SRF stream were 88%, 70%, 72% and 60% respectively of their input masses to MT plant. A high mass fraction of plastic (PVC), rubber material and non-combustibles (such as stone/rock and glass particles), was found in the reject material stream.