The effect of management systems and ecosystem types on bark regeneration in Himatanthus drasticus (Apocynaceae): recommendations for sustainable harvesting

Bark and exudates are widely commercialized non-timber forest products. However, the ecological impacts of the harvesting of these products have seldom been studied. The aim of this study is to investigate the relationship of tree resilience to harvesting intensity in Himatanthus drasticus, a tree that is highly exploited in the Brazilian savanna (Cerrado) for its medicinal latex. Although the traded product is the latex, the traditional harvesting systems involve the removal of the bark of the trees to allow exploitation. A 3-year experiment was conducted in two different Cerrado ecosystems (open savanna and savanna woodland). Trees were debarked at four debarking intensities to simulate the effects of traditional management systems. Measurements of bark growth were taken every 6 months, and quantitative and qualitative indexes of bark regeneration were obtained. The mortality of the debarked trees was low and could not be related to the intensity of harvesting. No signs of attack by fungi or insects were recorded. Compared with other species exploited for bark, H. drasticus is very resilient to harvesting; however, bark regeneration is relatively slow. In both analyzed ecosystems, the regeneration indexes showed higher values in the controls than in the treatments, indicating that 3 years is not sufficient for total recovery of the rhytidome. Bark regeneration occurred primarily by sheet growth and was more rapid in open savanna than in savanna woodland. No differences in the rate of bark recovery were found among management treatments. Based on the results, sustainable harvesting guidelines are suggested for the species.     

Alien Flora of Indian Himalayan State of Himachal Pradesh

Recognizing the array of effects that invasive alien species have, documenting their status from biodiversity rich regions has been much emphasized. Lack of such studies is a major limitation that hampers proper management of alien species. The present paper, therefore, documents the alien flora of the Indian Himalayan state of Himachal Pradesh (HP) based on data obtained from literature and herbarium records. The alien flora of HP comprises of 497 species belonging to 85 families. Majority of them belong to family Asteraceae (59 species), followed by Poaceae (47 species) and Fabaceae (43 species). Amongst the genera, Ipomoea (9 species), Eucalyptus and Euphorbia (7 species each) are the most predominant. Herbs constitute the majority (i.e., 73 %) of alien species and a large percentage of them (i.e., 22.94 %) have South America as their native region. Further, of the total alien species, 248 are intentional introductions and majority (31 % species) have been introduced for ornamental purposes. It was revealed that 34 % species have naturalized while 29 % species have become invasive. Today, in addition to human-disturbed landscapes, alien species have also been reported from dense forests. Himalaya being a biodiversity hotspot and HP being a bio-rich Himalayan state, it is hoped that this inventory and assessment of alien flora will help in designing informed management and monitoring strategies against problematic plant invasions in the state.     

Planted floating bed performance in treatment of eutrophic river water

The objective of the study was to treat eutrophic river water using floating beds and to identify ideal plant species for design of floating beds. Four parallel pilot-scale units were established and vegetated with Canna indica (U1), Accords calamus (U2), Cyperus alternifolius (U3), and Vetiveria zizanioides (U4), respectively, to treat eutrophic river water. The floating bed was made of polyethylene foam, and plants were vegetated on it. Results suggest that the floating bed is a viable alternative for treating eutrophic river water, especially for inhibiting algae growth. When the influent chemical oxygen demand (COD) varied from 6.53 to 18.45 mg/L, total nitrogen (TN) from 6.82 to 12.25 mg/L, total phosphorus (TP) from 0.65 to 1.64 mg/L, and Chla from 6.22 to 66.46 g/m³, the removal of COD, TN, TP, and Chla was 15.3 %–38.4 %, 25.4 %–48.4 %, 16.1 %–42.1 %, and 29.9 %–88.1 %, respectively. Ranked by removal performance, U1 was best, followed by U2, U3, and U4. In the floating bed, more than 60 % TN and TP were removed by sedimentation; plant uptake was quantitatively of low importance with an average removal of 20.2 % of TN and 29.4 % of TP removed. The loss of TN (TP) was of the least importance. Compared with the other three, U1 exhibited better dissolved oxygen (DO) gradient distributions, higher DO levels, higher hydraulic efficiency, and a higher percentage of nutrient removal attributable to plant uptake; in addition, plant development and the volume of nutrient storage in the C. indica tissues outperformed the other three species. C. indica thus could be selected when designing floating beds for the Three Gorges Reservoir region of P. R. China.     

Management of invasive populations of the freshwater crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Decapoda,Cambaridae): test of a population-control method and proposal of a standard monitoring approach

Invasive species are one of the main threats to biodiversity. When an alien species is introduced into a new environment, fast identification and definition of management strategies may avoid or minimize impacts. When an invasive species is already established, the most adopted approaches are population control and monitoring. In order to perform such strategies, assessment of characteristics of the invasive population is imperative. This study tested a new method of population size estimation and monitoring in an invasive population of crayfish Procambarus clarkii in a conservation area in the Atlantic Rain Forest (Southeastern Brazil). The population dynamics was studied for 1 year to examine the efficacy of the selected method and to evaluate if the population is stable. Later, the effect of periodical removal of animals on the population size was tested. The method of population estimation used in this study proved to be very effective. We recommend using it to monitor invasive populations of P. clarkii. The population size varied discretely over the year with variable but low growth rate, indicating that the population is already established which introduce a notable threat to native species. The continuous removal of specimens proved to be inefficient since the growth rate was higher after the removal. One intensive removal event might be more effective than a continuous moderate removal as the one applied in this study.     

Intra-monsoonal variation of zooplankton population in the Sundarbans Estuarine System,India

The present study was conducted during July 2013 (early phase of monsoon or EM) and September 2013 (later phase of monsoon or LM) to ascertain the intra-monsoonal variation on zooplankton, by selecting 15 study stations in the river Saptamukhi, one of the main estuaries in the Sundarbans Estuarine System (SES). In 2013, SES experienced an unusually high monsoonal rainfall also exacerbated by cloud burst event at Himalayan region (upper stretches of SES) which tremendously increased the river runoff. The present work was aimed to decipher the effect of this unusual precipitation during the monsoon season on zooplankton assemblages along with different hydrological parameters. The abundance of zooplankton was recorded as lower during EM compared to LM. Altogether, 56 zooplankton taxa were identified with copepods forming the predominant population. Thirty-three copepod species were reported with 25 calanoid species forming the bulk of the biomass followed by 5 and 3 species of cyclopoids and harpacticoid, respectively. A combination of multivariate cluster analysis, biotic indices, and canonical correspondence analysis revealed noticeable alterations in the zooplankton community structure across the spatio-temporal scale. Furthermore, significant intra-monsoonal changes in zooplankton population correlated with several hydrological parameters were clearly noticed. Paracalanus parvus, Bestiolina similis and Oithona similis were observed to be the most dominant copepod species in both sampling periods. The result of the present study provides new insight on estuarine zooplankton community after unusual rainfall during monsoon season, and provides further evidence to support the conservation and management of the SES ecosystem.     

Relationships among varying sampling distance and the IBI in warmwater,headwater streams of the Eastern Corn Belt Plain

Single-pass electrofishing was used to define the most efficient sampling distance to assess stream condition using the index of biotic integrity (IBI) methodology in headwater (<36 km² drainage area), warmwater streams in the Eastern Corn Belt Plain ecoregion. Based on wetted widths (1–3.3 m) of sampled reaches, we defined effort based on increased area (range 50–555 m²). Sampled area necessary to capture a representative fish assemblage increased until 167-m² distance, which is equivalent to a minimum sampling distance of one habitat cycle. No significant difference in metric actual observed value response was found with increasing habitat cycle. Increased effort is required in smaller streams widths (≤1 m) to achieve the recommended sample area. The effect of rare fish on the IBI was tested using a modified Walford method. A significant decrease in IBI score was observed when 10 % of the rare data were removed. The presence of rare fish did not influence individual IBI metrics or scores for either the increased effort or reduced effort calibrations until greater than 3 % of the data was removed for number of species, 15 % removal of data for number of minnow species, and 5 % removal of data for catch per unit effort (CPUE). Increased effort did not affect any metric or IBI score, while reduced effort influenced the number of darter, madtom, and sculpin species and catch per unit effort metric scores but did not affect IBI score.     

Analysis of selected biomonitors to evaluate the suitability for their complementary use in monitoring trace element atmospheric deposition

The biomonitoring properties of oak tree bark compared with the epiphytic moss Hypnum cupressiforme and the influence of the tree bark, as its growth substrate, on the content of heavy metals in moss were investigated. Samples of the epiphytic moss H. cupressiforme and oak tree bark (Quercus spp.) were collected in Eastern Romania at a total of 44 sampling sites. Parallel moss and bark samples were collected from the same sides of the trunk circumference. V, Cr, Ni, Cu, Zn, As, Mo, Cd, In, Tl, Sn, Pb, and Bi were determined by ICP-MS. Principal component analysis was used to identify possible sources of metals in bark and moss. Six factors explaining 87 % of the total variance in the data set were chosen. The main factors represent long-range atmospheric transport of elements (Zn, Cd, (Pb), Bi, (Mo), (Tl)), local emissions from industrial sources (As, Cr, Ni, V), road traffic (Pb, Zn) and agricultural activities (Cu, (Zn)). The element concentrations in moss and bark samples are of the same order of magnitude. For almost all the elements, higher concentrations were obtained in moss. Significant correlations between concentrations in moss and bark samples were obtained for 7 of the 13 elements: V, Ni, Cu, Zn, Cd, In, and Bi, all typical anthropogenic pollutants. The use of tree bark for monitoring purposes might be an alternative in areas where there is a scarcity of mosses.     

Large-scale carbon stock assessment of woody vegetation in tropical dry deciduous forest of Sathanur reserve forest,Eastern Ghats,India

Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research, especially in the Eastern Ghats. Therefore, the present study was aimed to quantify the carbon storage in woody vegetation (trees and lianas) on large scale (30, 1 ha plots) in the dry deciduous forest of Sathanur reserve forest of Eastern Ghats. Biomass of adult (≥10 cm DBH) trees was estimated by species-specific allometric equations using diameter and wood density of species whereas in juvenile tree population and lianas, their respective general allometric equations were used to estimate the biomass. The fractional value 0.4453 was used to convert dry biomass into carbon in woody vegetation of tropical dry forest. The mean aboveground biomass value of juvenile tree population was 1.86 Mg/ha. The aboveground biomass of adult trees ranged from 64.81 to 624.96 Mg/ha with a mean of 245.90 Mg/ha. The mean aboveground biomass value of lianas was 7.98 Mg/ha. The total biomass of woody vegetation (adult trees + juvenile population of trees + lianas) ranged from 85.02 to 723.46 Mg/ha, with a mean value of 295.04 Mg/ha. Total carbon accumulated in woody vegetation in tropical dry deciduous forest ranged from 37.86 to 322.16 Mg/ha with a mean value of 131.38 Mg/ha. Adult trees accumulated 94.81% of woody biomass carbon followed by lianas (3.99%) and juvenile population of trees (1.20%). Albizia amara has the greatest biomass and carbon stock (58.31%) among trees except for two plots (24 and 25) where Chloroxylon swietenia contributed more to biomass and carbon stock. Similarly, Albizia amara (52.4%) showed greater carbon storage in juvenile population of trees followed by Chloroxylon swietenia (21.9%). Pterolobium hexapetalum (38.86%) showed a greater accumulation of carbon in liana species followed by Combretum albidum (33.04%). Even though, all the study plots are located within 10 km radius, they show a significant spatial variation among them in terms of biomass and carbon stocks which could be attributed to variation in anthropogenic pressures among the plots as well as to changes in tree density across landscapes. Total basal area of woody vegetation showed a significant positive (R ² = 0.978; P = 0.000) relationship with carbon storage while juvenile tree basal area showed the negative relationship (R ² = 0.4804; P = 0.000) with woody carbon storage. The present study generates a large-scale baseline data of dry deciduous forest carbon stock, which would facilitate carbon stock assessment at a national level as well as to understand its contribution on a global scale.     

Seasonal variations in species composition,abundance, biomass and production rate of tintinnids (Ciliata: Protozoa) along the Hooghly (Ganges) River Estuary,India: a multivariate approach

The study is the first documentation of seasonal variations in species composition, abundance and diversity of tintinnid (Ciliata: Protozoa), in relation to water quality parameters along the stretch of the Hooghly (Ganges) River Estuary (HRE), eastern coastal part of India. A total of 26 species (22 agglomerated and 4 non-agglomerated) belonging to 8 genera has been identified from 8 study sites where Tintinnopsis (17 species) represented the most dominant genera, contributing up to 65 % of total tintinnid community followed by Tintinnidium (2 species), Leprotintinnus (2 species) and Dadayiella, Favella, Metacylis, Eutintinnus and Helicostomella (each with solitary species). The maximum (1,666 ind.?l^?1) and minimum (62 ind.?l^?1) abundance of tintinnids was recorded during post-monsoon and monsoon, respectively. A distinct seasonal dynamics in terms of biomass (0.005–2.465 μg C l^?1) and daily production rate (0.04–3.13 μg C l^?1 day^?1) was also noticed, accounting highest value during pre-monsoon. Chlorophyll a and nitrate were found to be potential causative factors for the seasonal variations of tintinnids as revealed by a stepwise multiple regression model. The result of ANOVA showed a significant variation between species abundance and months (F?=?2.36, P?≤?0.05). k-dominance curves were plotted to determine the comparison of tintinnid dominance between the investigated stations. Based on a principal component analysis (PCA), three main groups were delineated with tintinnid ciliates and environmental parameters. The changes in lorica morphology in terms of temperature and salinity, recorded for three dominant species, provided information on the ecological characteristics of the species assemblage in this estuarine system.     

Impact of collection on bark regeneration from <Emphasis Type="Italic">Stryphnodendron rotundifolium</Emphasis> Mart. in northeastern Brazil

The growing commercial demand for products with medicinal use has caused overexploitation of several plant species worldwide. To prevent the decline of these populations, the collection of these resources should be done in a sustainable way considering the time of its replacement in natural stocks. This study was designed to identify the relationship between different intensities of extraction of bark from the trunk of Stryphnodendron rotundifolium Mart. and its regeneration speed. For this, we selected two areas of Cerrado in the Northeast of Brazil, where a monitoring experiment with duration of 24 months was performed. This experiment consisted in simulating different extractive damage to assess the regeneration of bark. In each area, we selected 20 individuals, among which four treatments with five repetitions were implemented. The data showed that in both study areas, the trees regenerated their shells faster when subjected to higher collection intensities. However, this regeneration was not related to variations in rainfall in the environment.     

Phytoremediation of phenol using Polygonum orientale,including optimized conditions

Removing phenol from wastewater has become a major challenge of international concern. Phytoremediation is a novel and eco-friendly method and is attracting an increasing amount of attention for treating phenol in wastewater. We studied the ability of Polygonum orientale, which is frequently present around water bodies and in wetlands in China, to phytoremediate phenol. We determined the inhibition concentration for phenol on P. orientale using emergency toxicology experiments and morphological observations. Isothermal and kinetic models were created to assess the adsorption process involved in phenol removal. Comparison tests in sterile conditions demonstrated that metabolic removal was the main way in which the phenol concentrations were decreased, and removal by adsorption played a smaller role. An orthogonal test was performed to determine the optimum conditions under which P. orientale will remove phenol, and these were found to be an initial phenol concentration of 5 mg L^?1, 100 % natural light, and a 13-day treatment time. These results provide a theoretical basis for increasing our understanding of the mechanisms involved in the removal of phenol by P. orientale and will help in developing its application in the greening of urban areas to provide both phytoremediation and esthetic landscaping.     

Mercury levels in myliobatid stingrays (Batoidea) from the Gulf of California: tissue distribution and health risk assessment

With the aim of knowing Hg distribution in selected tissues of myliobatid stingrays and assessing health risk to Mexican population, Hg concentration was determined in the muscle and liver of four ray species. Total Hg levels were determined by cold vapor atomic absorption spectrophotometry. With respect to the muscle, devil rays (Mobula spp.) showed lower Hg levels (<0.22 μg g^?1) than Rhinoptera steindachneri (0.37?±?0.25 μg g^-1 wet weight). In the case of the liver, the highest Hg concentration was found in Mobula japanica (0.22?±?0.01 μg g^?1). Hg levels in the muscle and liver varied according to the species; in some case, the liver accumulated more Hg than the muscle and the opposite pattern in other cases. R. steindachneri showed a significant difference between both tissues. No significant differences of Hg levels between males and females and between juveniles and adult specimens of R. steindachneri were found. Positive correlation between Hg concentrations and disc width and total weight was not significant for R. steindachneri (Rs?<?0.36, p?>?0.05). Batoids showed Hg values below the Mexican (NOM-027-SSA1-1993) limits (1.0 μg g^?1) in fishes for human consumption. The species with the highest potential of Hg transfer to human population is R. steindachneri; however, an adult (70 kg) could consume approximately 943 g per week without representing a health risk. Nevertheless, further and continuous monitoring is needed since batoids support an important fishery in Mexican waters, being a food resource and income to coastal communities.     

Compositing climate change vulnerability of a Mediterranean region using spatiotemporally dynamic proxies for ecological and socioeconomic impacts and stabilities

The study presents a new methodology to quantify spatiotemporal dynamics of climate change vulnerability at a regional scale adopting a new conceptual model of vulnerability as a function of climate change impacts, ecological stability, and socioeconomic stability. Spatiotemporal trends of equally weighted proxy variables for the three vulnerability components were generated to develop a composite climate change vulnerability index (CCVI) for a Mediterranean region of Turkey combining Landsat time series data, digital elevation model (DEM)-derived data, ordinary kriging, and geographical information system. Climate change impact was based on spatiotemporal trends of August land surface temperature (LST) between 1987 and 2016. Ecological stability was based on DEM, slope, aspect, and spatiotemporal trends of normalized difference vegetation index (NDVI), while socioeconomic stability was quantified as a function of spatiotemporal trends of land cover, population density, per capita gross domestic product, and illiteracy. The zones ranked on the five classes of no-to-extreme vulnerability were identified where highly and moderately vulnerable lands covered 0.02% (12 km²) and 11.8% (6374 km²) of the study region, respectively, mostly occurring in the interior central part. The adoption of this composite CCVI approach is expected to lead to spatiotemporally dynamic policy recommendations towards sustainability and tailor preventive and mitigative measures to locally specific characteristics of coupled ecological–socioeconomic systems.     

Live diatoms as indicators of urban stormwater runoff

Diatom bioassessment of streams/rivers does not distinguish between live (cells with intact chloroplasts) and dead (empty cells) individuals, even though most diatom samples collected from the field will be composed of a mixture of both. This study aimed to evaluate whether percentage of live diatoms (PLD), live diatom density and chlorophyll a, and diatom species compositions can be used as indicators of hydrologic disturbance in an urban stream. We deployed artificial substrates on a monthly basis and collected periphyton samples weekly over the course of one calendar year (n = 182) in three tributaries of urbanized Ruddiman Creek (Michigan, USA). We also collected samples before and after six major storm events (>0.5 cm rain). We found no temporal patterns in PLD (Mann-Kendall test p > 0.05) or species composition (non-metric multidimensional scaling (NMDS) ordination), which may be explained by a diatom composition already tolerant to frequent disturbance. There was no difference in PLD before and after storm events, which might partially be explained by their disturbance resistance due to different assemblage ages (1, 2, and 4 weeks old) before the storms. High flow had differential effects on diatom species; loosely attached Navicula and Nitzschia species were more easily removed compared to stalk-forming Gomphonema parvulum. The most important environmental variable that was found to affect live diatom density and chlorophyll was stream width, which has an indirect effect (as a measure of discharge) on periphyton assemblages. In conclusion, PLD was found to be unsuitable metric for assessing stormwater runoff in urban streams where periphyton may not have enough time to form mature communities.     

Removal of mercury(II) ions in aqueous solution using the peel biomass of <Emphasis Type="Italic">Pachira aquatica</Emphasis> Aubl: kinetics and adsorption equilibrium studies

Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g^?1 at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.     

Assessment of chlorine tolerance profile of <Emphasis Type="BoldItalic">Citrobacter</Emphasis> species recovered from wastewater treatment plants in Eastern Cape,South Africa

This present study assessed the chlorine tolerance of some Citrobacter species recovered from secondary effluents from the clarifiers of two wastewater treatment plants in the Eastern Cape, South Africa. The bacterial survival, chlorine lethal dose and inactivation kinetics at lethal doses were examined. Inactivation of the test bacteria (n = 20) at the recommended dose of 0.5 mg/l for 30 min exposure showed a progressive reduction in bacterial population from 4 to 5 log reduction and residuals ranged between 0.12 and 0.46 mg/l. The bactericidal activity of chlorine increased at higher dosages with a substantial reduction in viability of the bacteria and complete inactivation of the bacterial population at a lethal dose of 0.75 and 1.0 mg/l in 30 min. For the inactivation kinetics, bactericidal activity of chlorine increased with time showing a 3.67–5.4 log reduction in 10 min, 4.0–5.6 log reduction in 20 min and above 6.3 log reductions to complete sterilization of bacterial population over 30 min for all the entire test Citrobacter isolates used in this study. Furthermore, there was a strong correlation (R ² > 0.84) between bacteria inactivation and increase in contact time. This study appears to have provided support for laboratory evidence of bacterial tolerance to chlorine disinfection at current recommended dose (0.5 mg/l for 30 min), and chlorine concentration between 0.75 and 1.0 mg/l was found to have a better disinfecting capacity to check tolerance of Citrobacter species.     

The use of a natural coagulant (Opuntia ficus-indica) in the removal for organic materials of textile effluents

The goal of this study was to investigate the activity of the coagulant extracted from the cactus Opuntia ficus-indica (OFI) in the process of coagulation/flocculation of textile effluents. Preliminary tests of a kaolinite suspension achieved maximum turbidity removal of 95 % using an NaCl extraction solution. Optimization assays were conducted with actual effluents using the response surface methodology (RSM) based on the Box–Behnken experimental design. The responses of the variables FeCl₃, dosage, cactus dosage, and pH in the removal of COD and turbidity from both effluents were investigated. The optimum conditions determined for jeans washing laundry effluent were the following: FeCl₃ 160 mg L^?1, cactus dosage 2.60 mg L^?1, and pH 5.0. For the fabric dyeing effluent, the optimum conditions were the following: FeCl₃ 640 mg L^?1, cactus dosage 160 mg L^?1, and pH 6.0. Investigation of the effects of the storage time and temperature of the cactus O. ficus-indica showed that coagulation efficiency was not significantly affected for storage at room temperature for up to 4 days.     

Blood levels of cadmium and lead in residents near abandoned metal mine areas in Korea

We analyzed national data on blood lead levels (BLL) and blood cadmium levels (BCL) in residents living near 38 abandoned metal mining areas (n?=?5,682, 18–96 years old) in Korea that were collected by the first Health Effect Surveillance for Residents in Abandoned Metal mines (HESRAM) from 2008 to 2011. The geometric mean BCL and BLL were 1.60 μg/L (95 % CI?=?1.57–1.62 μg/L) and 2.87 μg/dL (95 % CI?=?2.84–2.90 μg/dL), respectively, notably higher than levels in the general population in Korea and other countries. We found significantly higher BLL and BCL levels in people living within 2 km of an abandoned metal mine (n?=?3,165, BCL?=?1.87 μg/L, BLL?=?2.91 μg/dL) compared to people living more than 2 km away (n?=?2,517, BCL?=?1.31 μg/L, BLL?=?2.82 μg/dL; P?<?0.0001) and to the general population values reported in the literature.     

Seasonal dynamic and in situ division rates of the dominant Dinophysis species in Punic harbors of Carthage (Gulf of Tunis, South Mediterranean)

This study investigates spatio-temporal variations of in situ division rate (μ) of two species of the genus Dinophysis. Based on a postmitotic index approach, estimates of μ from net-haul samples were compared during five daily cell cycles studies in three stations of the Punic harbors of Carthage (Gulf of Tunis). To study the annual cycle of Dinophysis spp., weekly sampling were carried out from March 2008 to June 2010. In addition, sampling over 24 h was conducted on three-cycle studies in late spring and two-cycle studies in autumn, seasons characterized by Dinophysis proliferations. We recorded important abundances of Dinophysis sacculus stein (2.25?×?10⁴ cells/l, June 2008) and Dinophysis cf. acuminata (3?×?10⁴ cells/l, June 2009). Cellular division was phased in D. sacculus stein and D. cf. acuminata, but the division time, required for the population cohorts to pass from one phase to another, and values of estimated division rates varied between seasons and stations for the same species. D. cf. acuminata exhibit moderate (0.22 day^?1) to high (0.68 day^?1) value of μ. In contrast, D. sacculus shows very low μ values (0.02–0.17 day^?1) in autumn season to moderate values (0.21–0.35 day^?1) in late spring. The results presented here confirm that the postmitotic index approach allowed estimated of μ at low field depths and concentrations (10²–10³ cells/l).     

The potential of different bio adsorbents for removing phenol from its aqueous solution

The use of natural resources for the removal of phenol and phenolic compounds is being looked upon by researchers in preference to other prevailing methods. In the present study, different biosorbents, brown algae (Padina pavonia), fresh water macrophyta (Ceratophyllum demersum), and black tea residue, were tested as adsorbent for the removal of phenol from aqueous solutions. The optimum conditions for maximum adsorption in terms of concentration of the adsorbate and pH were identified. The results show that the initial concentration increases as the removal of phenol increases in C. demersum; in the case of the other two adsorbents, the initial concentration increases as the removal of phenol decreases, especially for an initial concentration lower than 100 and 1,000 μg/L for P. pavonia and black tea residue, respectively. Maximum percentage removal of phenol by each adsorbent is 77, 50.8, and 29 % for C. demersum, P. pavonia, and black tea residue, respectively. Also, the biosorption capacity was strongly influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH of around 6–10. The first biosorbent (black tea residue) displays the maximum adsorption capacity at a pH of 10 with a percentage sorption capacity of 84 %; P. pavonia revealed a greater adsorption percentage at pH?10, reaching 30 %, while for C. demersum, the removal of phenol increases with the increase in initial pH up to 6.0 and decreases drastically with further increase in initial pH. The Freundlich, Langmuir, and Brauner–Emmet–Teller adsorption models were applied to describe the equilibrium isotherms. The results reveal that the equilibrium data for all phenol adsorbents fitted the Freundlich model which seemed to be the best-fitting model for the experimental results with similar values of coefficient of determination.