Cleaning symbiosis in an obligate goby–shrimp association

Shrimps from the genus Alpheidae had never been considered as a cleaner organism. In the present study, we demonstrate for the first time, Alpheus rapax engaging in cleaning symbiosis with its gobiid fish associate Myersina macrostoma. Within 450 min of observation time, 9 instances totalling 546 s of cleaning behaviour were recorded. Cleaning behaviour was always preceded by physical contact between the shrimps and their goby associates. The shrimps initiated all cleaning incidents, but these were always terminated by the gobies. Cleaning sessions were observed to occur mostly in the tail region (60.8 %) and followed by the head region (26.2 %). In one instance, a shrimp was observed to clean the gills of its goby associate. The gobies appear to exert some control as to where they were being cleaned by repositioning themselves during a cleaning session.     

Chitosan and chemically modified chitosan beads for acid dyes sorption

The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan were comparatively higher than chitosan-EGDE for both acid dyes. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.     

Recyling manganese-rich electrolytic residues: a review

Environmental Chemistry Letters - Huge amounts of manganese-rich solid residues are yearly produced worldwide by industrial electrolysis, calling for advanced methods of recycling in the context of...     

Food additives for the synthesis of metal nanoparticles: a review

Environmental Chemistry Letters - Metal nanoparticles have found applications in many fields such as molecular diagnostics, electronic devices and environmental remediation. Nonetheless,...     

Incorporation of sewage sludge in clay brick and its characterization.

This study reports the use of sewage sludge generated from sewage treatment plant (STP) as raw material in a clay brick-making process. The physico-chemical and mineralogical characterization of the sewage sludge and clay were carried out in order to identify the major technological constraints and to define the sludge pretreatment requirements if necessary. Moreover, the effects on processing conditions and/or on changes of typical final characteristics are also evaluated. Bricks were produced with sewage sludge additions ranging from 10 to 40% by dry weight. The texture and finishing of the surface of sludge-amended clay bricks were rather poor. As for the physical and chemical properties, bricks with a sludge content of up to 40 wt.% were capable of meeting the relevant technical standards. However, bricks with more than 30 wt.% sludge addition are not recommended for use since they are brittle and easily broken even when handled gently. A tendency for a general degradation of brick properties with sludge additions was observed due to its refractory nature. Therefore, sludge bricks of this nature are only suitable for use as common bricks, which are normally not exposed to view, because of poor surface finishing.     

Long-range migratory travel of a green turtle tracked by satellite: evidence for navigational ability in the open sea

A female of Chelonia mydas was tracked by satellite in the South China Sea in 1993 from the nesting beach to the resident foraging grounds more than 600 km away. The final leg of the journey, 475 km long, directly pinpointed the goal, with the turtle maintaining a constant speed and direction both night and day. This provides clues about the navigational mechanism used.     

HYDROLOGIC SIMULATION OF THE LITTLE WASHITA RIVER EXPERIMENTAL WATERSHED USING SWAT1

ABSTRACT: Precipitation and streamflow data from three nested subwatersheds within the Little Washita River Experimental Watershed (LWREW) in southwestern Oklahoma were used to evaluate the capabilities of the Soil and Water Assessment Tool (SWAT) to predict streamflow under varying climatic conditions. Eight years of precipitation and streamflow data were used to calibrate parameters in the model, and 15 years of data were used for model validation. SWAT was calibrated on the smallest and largest sub‐watersheds for a wetter than average period of record. The model was then validated on a third subwatershed for a range in climatic conditions that included dry, average, and wet periods. Calibration of the model involved a multistep approach. A preliminary calibration was conducted to estimate model parameters so that measured versus simulated yearly and monthly runoff were in agreement for the respective calibration periods. Model parameters were then fine tuned based on a visual inspection of daily hydrographs and flow frequency curves. Calibration on a daily basis resulted in higher baseflows and lower peak runoff rates than were obtained in the preliminary calibration. Test results show that once the model was calibrated for wet climatic conditions, it did a good job in predicting streamflow responses over wet, average, and dry climatic conditions selected for model validation. Monthly coefficients of efficiencies were 0.65, 0.86, and 0.45 for the dry, average, and wet validation periods, respectively. Results of this investigation indicate that once calibrated, SWAT is capable of providing adequate simulations for hydrologic investigations related to the impact of climate variations on water resources of the LWREW.     

Estimation of biomass distribution in Peninsular Malaysia and in the islands of Sumatra, Java and Borneo based on multi-resolution remote sensing land cover analysis

In this study we used high resolution (20 m) land cover maps to derive detailed information on land cover structure within the classes of a regional medium resolution (500 m) land cover map. This enabled improved biomass estimation for the medium resolution land cover classes. Although our results suggested that land cover maps based merely on medium resolution remote sensing data can be used to monitor the extent of forest cover, they also showed that these maps alone are not sufficient to produce reliable regional estimates on above ground biomass in insular Southeast Asia. A quarter of the study area was covered by sub-pixel size (500 m) mosaic of various land cover types containing 14% of biomass. In total, non-forest areas covered over 60% of the study area and included 43% of biomass. In these areas, highly fragmented within class land cover structure was shown to significantly affect biomass estimates. Therefore we conclude that forest/land cover monitoring based merely on medium resolution remote sensing data can no longer be used to sufficiently quantify carbon fluxes connected to land cover changes in insular Southeast Asia, but multi-resolution approaches are needed to perform this task.     

Status of Peatland Degradation and Development in Sumatra and Kalimantan

Peatlands cover around 13 Mha in Sumatra and Kalimantan, Indonesia. Human activities have rapidly increased in the peatland ecosystems during the last two decades, invariably degrading them and making them vulnerable to fires. This causes high carbon emissions that contribute to global climate change. For this article, we used 94 high resolution (10-20 m) satellite images to map the status of peatland degradation and development in Sumatra and Kalimantan using visual image interpretation. The results reveal that less than 4% of the peatland areas remain covered by pristine peatswamp forests (PSFs), while 37% are covered by PSFs with varying degree of degradation. Furthermore, over 20% is considered to be unmanaged degraded landscape, occupied by ferns, shrubs and secondary growth. This alarming extent of degradation makes peatlands vulnerable to accelerated peat decomposition and catastrophic fire episodes that will have global consequences. With on-going degradation and development the existence of the entire tropical peatland ecosystem in this region is in great danger.     

Single-Plant Biocomposite from Ricinus Communis: Preparation, Properties and Environmental Performance

A single-plant biobased composite material was prepared from fibre and matrix constituents produced from the castor plant, ricinus communis. It is shown that the mechanical properties of the castor plant fibres are comparable to those of other bast fibres and that the stiffness and strength characteristics of the castor fibre/polyamide 11 biocomposite compare well with those of other natural fibre composites. By using a biobased thermoplastic matrix material the reliance on non-renewable feedstock sources is reduced and end-of-lifetime recyclability is improved. The analysis of the environmental performance of the new castor plant composite suggests that the biobased material has great potential as a sustainable alternative replacing glass fibre-reinforced plastics.