Urban tinkering

Cities are currently experiencing serious, multifaceted impacts from global environmental change, especially climate change, and the degree to which they will need to cope with and adapt to such challenges will continue to increase. A complex systems approach inspired by evolutionary theory can inform strategies for policies and interventions to deal with growing urban vulnerabilities. Such an approach would guide the design of new (and redesign of existing) urban structures, while promoting innovative integration of grey, green and blue infrastructure in service of environmental and health objectives. Moreover, it would contribute to more flexible, effective policies for urban management and the use of urban space. Four decades ago, in a seminal paper in Science, the French evolutionary biologist and philosopher Francois Jacob noted that evolution differs significantly in its characteristic modes of action from processes that are designed and engineered de novo (Jacob in Science 196(4295):1161–1166, 1977). He labeled the evolutionary process “tinkering”, recognizing its foundation in the modification and molding of existing traits and forms, with occasional dramatic shifts in function in the context of changing conditions. This contrasts greatly with conventional engineering and design approaches that apply tailor-made materials and tools to achieve well-defined functions that are specified a priori. We here propose that urban tinkering is the application of evolutionary thinking to urban design, engineering, ecological restoration, management and governance. We define urban tinkering as:

A mode of operation, encompassing policy, planning and management processes, that seeks to transform the use of existing and design of new urban systems in ways that diversify their functions, anticipate new uses and enhance adaptability, to better meet the social, economic and ecological needs of cities under conditions of deep uncertainty about the future.

This approach has the potential to substantially complement and augment conventional urban development, replacing predictability, linearity and monofunctional design with anticipation of uncertainty and non-linearity and design for multiple, potentially shifting functions. Urban tinkering can function by promoting a diversity of small-scale urban experiments that, in aggregate, lead to large-scale often playful innovative solutions to the problems of sustainable development. Moreover, the tinkering approach is naturally suited to exploring multi-functional uses and approaches (e.g., bricolage) for new and existing urban structures and policies through collaborative engagement and analysis. It is thus well worth exploring as a means of delivering co-benefits for environment and human health and wellbeing. Indeed, urban tinkering has close ties to systems approaches, which often are recognized as critical to sustainable development. We believe this concept can help forge much-closer, much-needed ties among engineers, architects, evolutionary ecologists, health specialists, and numerous other urban stakeholders in developing innovative, widely beneficial solutions for society and contribute to successful implementation of SDG11 and the New Urban Agenda.

     

Effect of thiobencarb and pretilachlor on microorganisms in relation to mineralization of C and N in the Gangetic alluvial soil of West Bengal

An experiment was conducted under laboratory conditions to investigate the effect of two pre-emergence herbicides, viz., thiobencarb (at 1.5 and 4.5 kg active ingredient (a.i.) ha^?1) and pretilachlor (at 0.5 and 1.5 kg a.i. ha^?1), on the growth and multiplication of some microorganisms (bacteria, actinomycetes and fungi) in relation to transformations and availability of C and N in the Gangetic alluvial soil (Typic Haplustept) of West Bengal, India. Application of both the herbicides, in general, significantly increased microbial biomass, resulting in greater retention, mineralization and availability of oxidizable organic C and N in soil, and the stimulations were more pronounced when the herbicides were applied at their lower concentrations (recommended field application rates), more so with thiobencarb, as compared to pretilachlor. Compared to untreated control soil, the application of thiobencarb at lower concentration increased the proliferation of total bacteria, actinomycetes and fungi by 57.3, 36.6 and 55.2 %, respectively, and released the highest amount (40.2 %) of soluble NO₃ ^? in soil, while pretilachlor at field application rate induced the growth and multiplication of bacteria and fungi by 58.3 and 17.6 %, respectively. Irrespective of the concentrations, the stimulations were at par for both the herbicides towards the retention of oxidizable organic C, total N and exchangeable NH₄ ⁺ in soil.     

GIS-based statistical model for the prediction of flood hazard susceptibility

At present, flood is the most significant environmental problem in the entire world. In this work, flood susceptibility (FS) analysis has been done in the Dwarkeswar River basin of Bengal basin, India. Fourteen flood causative factors extracted from different datasets like DEM, satellite images, geology, soil and rainfall data have been considered to predict FS. Three heuristic models and one statistical model fuzzy Logic (FL), frequency ratio (FR), multi-criteria decision analysis (MCDA) and logistic regression (LR) have been used. The validating datasets are used to validate these models. The result shows that 68.71%, 68.7%, 60.56% and 48.51% area of the basin is under the moderate to very high FS by the MCDA, FR, FL and LR, respectively. The ROC curve with AUC analysis has shown that the accuracy level of the LR model (AUC?=?0.916) is very much successful to predict the flood. The rest of the models like FL, MCDA and FR (AUC?=?0.893, 0.857 and 0.835, respectively) have lesser accuracy than the LR model. The elevation was the most dominating factor with coefficient value of 19.078 in preparation of the FS according to the LR model. The outcome of this study can be implemented by local and state authority to minimize the flood hazard.

     

Co-composting of alkaline tissue digester effluent with yard trimmings

Alkaline digestion of animal carcasses is gaining popularity as a method of disposing of animals because of its very effective pathogen control and general ease of operation. Once completed, the resulting high-strength effluent can be released into the municipal sewer systems. In some cases where the municipal system is unable to handle this high-strength wastewater, alternate methods of treatment are required. Co-composting with a low-moisture substrate such as yard trimmings can be an effective option. This paper reports the results of absorption tests to determine the amount of digester effluent (from the Tissue Digestortrade mark process) that can be added to yard waste before leachate production begins. In addition, a low dosage of liquid effluent was added to yard trimmings and composted in laboratory bioreactors. Results show that leachate production begins when 0.6L-effluent is added per kg-unamended yard waste at an original moisture content of 55.6%. The amount of leachate produced increases exponentially following the empirical equation: leachate in mL/kg=0.145 e(6.007Effluent dosage in L/kg) (valid in the effluent addition range of 0-1.2L/kg). Composting of yard waste with effluent showed that the initial pH did not inhibit microbial activity up to 9.39 pH. Variability was high and there was no statistically significant difference in dry matter degradation between treatments (measured range was 1.3-6.0% of initial dry matter). Final compost had nitrogen and phosphorus concentrations of approximately 1% and 0.1%, respectively. The potassium concentration increased with increasing effluent addition and was 1.84% in the 0.2-L/kg treatment. All regulated heavy metals were several-fold below US EPA limits.     

Concentrations of chlorinated and brominated contaminants and their metabolites in serum of harbour seals and harbour porpoises

Harbour seals (Phoca vitulina) and harbour porpoises (Phocoena phocoena) are top predators in the North Sea and consequently accumulate a variety of pollutants in their tissues. Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and their hydroxylated metabolites (HO-PCBs and HO-PBDEs) were measured in serum of wild harbour seals (n = 47) and captive harbour porpoises (n = 21). Both species exhibit long life spans and do not have extreme situations, such as complete fasting during periods of lactation, in their annual cycles. For PCBs, concentrations in adult males were slightly higher than in juveniles and lowest in juvenile females. For PBDEs, juveniles have higher levels than adult males and females, probably as a consequence of lactational transfer. However, differences between these age–gender groups were not statistical significant, indicating that individual variation was limited within each species, even without knowing the feeding status of the animals. Body condition, particularly emaciation, has a major influence on the levels of chlorinated and brominated contaminants in serum. Profiles of PCBs were CB 153 > CB 138 > CB 187 > CB 180 and CB 153 > CB 138 > CB 149 > CB 187 > CB 180 for harbour seals and porpoises respectively. For PBDEs, BDE 47 was the predominant congener followed by BDE 100 and 99 in both species. In harbour seals, concentrations of sum PCBs (median: 39,200 pg/ml) were more than 200 times higher than levels of sum PBDEs (median: 130 pg/ml) and almost 10 times higher than concentrations of sum HO-PCBs (4350 pg/ml). In harbour porpoises, concentrations of sum PCBs (median: 24,300 pg/ml) were about 20 times higher than concentrations of PBDEs (median: 1300 pg/ml). HO-PCBs were detected in only 4 harbour porpoises and this at very low concentrations. Naturally-produced MeO-PBDEs were only found in harbour porpoises at concentrations ranging from 120 to 810 pg/ml. HO-PBDEs were not found in any species. In general, harbour seals accumulate less compounds and have mostly lower concentrations than harbour porpoises possibly as a result of a better developed metabolism.     

Inter-species differences for polychlorinated biphenyls and polybrominated diphenyl ethers in marine top predators from the Southern North Sea: Part 1. Accumulation patterns in harbour seals and harbour porpoises

Harbour porpoises (Phocoena phocoena) and harbour seals (Phoca vitulina) are two representative top predator species of the North Sea ecosystem. The median values of sum of 21 polychlorinated biphenyl (PCB) congeners and sum of 10 polybrominated diphenyl ether (PBDE) congeners were 23.1 μg/g lipid weight (lw) and 0.33 μg/g lw in blubber of harbour seals (n = 28) and 12.4 μg/g lw and 0.76 μg/g lw in blubber of harbour porpoises (n = 35), respectively. For both species, the highest PCB concentrations were observed in adult males indicating bioaccumulation. On the contrary, the highest PBDE concentrations were measured in juveniles, likely due to better-developed metabolic capacities with age in adults. A higher contribution of lower chlorinated and non-persistent congeners, such as CB 52, CB 95, CB 101, and CB 149, together with higher contributions of other PBDE congeners than BDE 47, indicated that harbour porpoises are unable to metabolize these compounds. Harbour seals showed a higher ability to metabolize PCBs and PBDEs.     

Studies on pigments,proteins and photosynthetic rates in some mangroves and mangrove associates from Bhitarkanika,Orissa

Pigment contents, proteins and net photosynthesis were investigated in fully developed leaf of 1-year-old seedlings of six mangroves (Bruguiera gymnorrhiza, Rhizophora apiculata) and mangrove associates (Caesalpinia bonduc, Cerbera manghas, Derris heterophylla, Thespesia populnea), collected from Bhitarkanika, located on the east coast of India. Large variations in the photosynthetic rates (P_N) among the six species were observed, ranging from 10.16 µmol CO₂ m^-2 s^-1 in C. bonduc to 15.28 µmol CO₂ m^-2 s^-1 in R. apiculata. The total leaf protein content ranged from 12.09 mg g^-1 dry wt in T. populnea to 51.89 mg g^-1 dry wt in B. gymnorrhiza. The chlorophyll a/b ratio was typically about 3.0 in all the studied species, except C. bonduc (2.8). Photosynthetic rates and chl a/b ratio in the leaves were found to be correlated. Analysis of chlorophyll and xanthophyll spectra suggested: (1) variations in different forms and amounts of carotenes as well as xanthophylls and (2) the presence of high amounts of near-UV-absorbing substances in leaves, particularly in the two mangroves (B. gymnorrhiza, R. apiculata) and a mangrove associate (T. populnea), which appears to be an adaptive feature. Estimation of the chl a/b ratios in isolated thylakoids yielded a low value of 1.8 for R. apiculata and >2.6 for other species. The total protein/chlorophyll ratios in thylakoids varied considerably from 3.14 (D. heterophylla) to 10.88 (T. populnea) among the mangrove associates and from 16.09 to 18.88 between the members of the Rhizophoraceae. The chlorophyll/carotenoid ratios in thylakoids of the six species were more or less similar. The absorption spectra for washed thylakoids of C. manghas and D. heterophylla exhibited absorption characteristics typical for C₃-plant thylakoids. However, thylakoids isolated from R. apiculata, B. gymnorrhiza, C. bonduc and T. populnea exhibited an unusual increase in absorption in the blue region (380-410 nm) of the absorption spectrum. The presence of high-absorbing (in the short-wavelength, near-UV region) pigments appears to be closely associated with the thylakoids in R. apiculata and T. populnea. Our results, therefore, suggest a wide range of variation, not only in protein and pigment contents of photosynthetic tissues, but also in the spectral characteristics and composition of the pigments in mangrove species. An understanding of the nature of these pigments in mangroves and their associates, under their natural conditions and especially in relation to eco-physiological adaptations, is necessary, not only in relation to conservation, but also to allow propagation under different salinity conditions.     

Assessment of heavy metal status and identification of source in soils under intensive vegetable growing areas of Brahmaputra valley,North East India

Environmental Monitoring and Assessment - Evaporation is an important meteorological variable that has a great impact on water resources. In the current research, climatology data, and seasonal...     

Microplastics pollution in Bangladesh: current scenario and future research perspective

ABSTRACT

Microplastics are emerging environmental pollutants that have gained tremendous scientific interest in recent years. These micropollutants are omnipresent both in the terrestrial and aquatic environments posing a deleterious threat to the ecosystem and biodiversity. So, it is important to develop a deep understanding of the environmental fate and potential adverse impacts of microplastics on the aquatic and terrestrial environments. By critically reviewing the previously published scientific literature, the present synthesis briefly outlines the characteristics, occurrence and potential toxic effects of microplastics on terrestrial and aquatic biota. The article also focuses on some innovative approaches for sustainable remediation of macroplastics as well as microplastics. Since the concept of microplastics pollution has yet in its infancy in Bangladesh, this synthesis provides an overview of the current scenario of microplastics pollution and some future research recommendations in the context of Bangladesh which might be helpful to the novice researchers of this field.