Characteristics of residual organochlorine pesticides in soils under different land-use types on a coastal plain of the Yellow River Delta

The residual levels of organochlorine pesticides (OCPs) were examined in soils covering five types of land use along a salinity gradient on the Yellow River Delta. The most prominent OCPs were dichlorodiphenyltrichloroethane (∑DDT, arithmetic mean = 5.11 μg kg^?1), hexachlorocyclohexane (∑HCH, 1.69 μg kg^?1) and ∑endosulfan (10.4 μg kg^?1). The spatial variability of OCPs composition shifted from γ-HCH and o,p′-DDT dominated pesticides in coastal soils to p,p′-DDE dominated pesticides in inland soils. In different land-use types, the percentages of β-HCH and p,p′-DDE are characterized by more recalcitrant components in decreasing order of vegetable fields, cereal fields, cotton fields, wetlands and tidal flats with increasing soil salinity. However, the less recalcitrant components, γ-HCH and o,p′-DDT, showed an opposite trend. Endosulfan sulfate predominated in all land-use types. Residual levels of β-HCH were affected by soil organic matter. The correlations between γ-HCH and clay content and between p,p′-DDE, o,p′-DDT and salinity might associate with the influence of sediment cotransport by the Yellow River and the density of anthropogenic activities in coastal region. Depth distribution of the OCPs in typical soil profiles also implied that local historical usage and sediment transport by the Yellow River both affected the OCPs residual in this region.     

Examining the potential impacts of sea level rise on coastal wetlands in north-eastern NSW,Australia

The coastal wetlands of north-eastern New South Wales (NSW) Australia are increasingly being affected by anthropogenic factors such as urbanisation, residential development and agricultural development. However, little is known about their vulnerability to sea level rise as a result of climate change. The aim of this research is to predict the potential impact of sea level rise (SLR) on the coastal wetland communities. Sea Level Affecting Marshes Model (SLAMM) was used to predict the potential impacts of sea level rise. Geographic Information System (GIS) was used for mapping and analysis. It was found that a meter rise in sea level could decrease coastal wetlands such as Inland fresh marshes from about 225.67 km² in February 2009 to about 168.04 km² by the end of the century in north-eastern NSW, Australia. The outcomes from this research can contribute to enhancing wetland conservation and management in NSW.     

Soil characteristics and their potential thresholds associated with <Emphasis Type="Italic">Scirpus mariqueter</Emphasis> distribution on a reclaimed wetland coast

We studied various soil characteristics associated with Scirpus mariqueter growth and spatial heterogeneity in the Shanghai Nanhui Dongtan wetlands. In September and October 2015, 12 soil characteristics (soil organic carbon, total phosphorus, total nitrogen, nitrate, nitrite, ammonia, orthophosphate, pH, moisture content, particle size, salinity, and tidal elevation) were analyzed from 101 soil samples. The key factors affecting S. mariqueter spatial distribution were determined using canonical correspondence analysis and curve-fitting analysis. Results showed that vegetation indices of height, cover, density, and biomass were positively correlated (P?<?0.05) with tidal flat elevation. S. mariqueter was mainly distributed at tidal flat elevations of 2.0–3.4 m. Plant coverage and density were positively correlated (P?<?0.05) with total nitrogen and soil salinity. Based on the curve-fitting and independent samples t-test analyses, thresholds of total nitrogen, conductivity, and tidal flat elevation of soil were 0.5475 g/kg, 0.8368 μS/cm, and 2.75 m, respectively. This study provides critical data for future coastal wetland remediation worldwide.     

Impact of logging activities in a tropical mangrove on ecosystem diversity and sediment heavy metal concentrations

Productivity of mangrove ecosystems is compromised by anthropogenic activities including over-exploitation of wood. This study set out to understand how different wood harvesting regimes have affected the biodiversity of a tropical ecosystem and to identify relationships between the heavy metal concentrations in the mangrove sediments and tree felling. Soil samples were collected and plant diversity studies carried out on seven sites in the mangrove. Physico-chemical, chemical and mineralogical analyses were done on soil samples and plant population structure, species richness, evenness and diversity index at these sites were calculated. Results showed that soils across sites were characteristically clayey and acidic, with high organic matter content. Minerals identified included quartz, gibbsite, goethite, hematite and kaolinite. Heavy metal concentrations were higher in Sites 6 and 7 with a longer history of anthropogenic activity. There were strong negative correlations between the duration of logging and NO₃-N (r = ?0.838, p = 0.019), total N (r = ?0.837, p = 0.019), NH₄ ⁺-N (r = ?0.844, p = 0.017), Mg = (?0.789, p = 0.035), K (r = ?0.819, p = 0.024), and Na (r = ?0.988, p = 0.002). Sites which had experienced logging for longer periods (sites 3, 6, and 7) had lower nutrient content and lower values for species richness and diversity index. Logging in mangrove ecosystems could alter soil characteristics, decreasing plant diversity and abundance. Logging dynamics around mangrove ecosystems should be considered in the wider strategy for management and conservation of similar mangrove ecosystems.     

Impacts of vineyard area dynamics on soil erosion in a Mediterranean catchment (1950-2011)

The Mediterranean basin has undergone widespread land cover change. Urbanization of coastal areas, land abandonment of steeper slopes, and agricultural intensification in alluvial plains are recurrent themes. The objective of this study was to examine how vineyard land cover changes have affected agricultural soil erosion in a 50 year period (1950–2011). The study area covers a 235 km² catchment located near the Gulf of St Tropez. Aerial photographs were used to map land cover in 1950, 1982, 2003 and 2011, and the RUSLE soil erosion model was run to estimate soil erosion.

Between 1950 and 2011, vineyard went from about 2,426 ha to 1,561 ha. Mean soil erosion increased as vineyard slopes became steeper (11.8 T ha^?1, 13.2 T ha^?1, 14.4 T ha^?1 and 13.5 T ha^?1 for 1950, 1982, 2003 and 2011). Total erosion decreased after 1982: 28,621 T y^?1 in 1950, 29,030 T y^?1 in 1982, 22,848 T y^?1 in 2003, and 21,074 T y^?1 in 2011. Total soil loss in 2011 is about 75% of values in 1950–1982, so impacts on water pollution and channel dredging have evolved positively over time.     

Environmental impact of CO<Subscript>2</Subscript>, Rn,Hg degassing from the rupture zones produced by Wenchuan <Emphasis Type="Italic">M</Emphasis><Subscript>s</Subscript> 8.0 earthquake in western Sichuan,China

The concentrations and flux of CO₂, ²²²Radon (Rn), and gaseous elemental mercury (Hg) in soil gas were investigated based on the field measurements in June 2010 at ten sites along the seismic rupture zones produced by the May 12, 2008, Wenchuan M _s 8.0 earthquake in order to assess the environmental impact of degassing of CO₂, Rn and Hg. Soil gas concentrations of 344 sampling points were obtained. Seventy measurements of CO₂, Rn and Hg flux by the static accumulation chamber method were performed. The results of risk assessment of CO₂, Rn and Hg concentration in soil gas showed that (1) the concentration of CO₂ in the epicenter of Wenchuan M _s 8.0 earthquake and north end of seismic ruptures had low risk of asphyxia; (2) the concentrations of Rn in the north segment of seismic ruptures had high levels of radon, Maximum was up to level 4, according to Chinese code (GB 50325-2001); (3) the average geoaccumulation index I _geo of soil Hg denoted the lack of soil contamination, and maximum values classified the soil gas as moderately to strongly polluted in the epicenter. The investigation of soil gas CO₂, Rn and Hg degassing rate indicated that (1) the CO₂ in soil gas was characterized by a mean \(\updelta^{13}C_{CO2}\) of ?20.4 ‰ and by a mean CO₂ flux of 88.1 g m^?2 day^?1, which were in the range of the typical values for biologic CO₂ degassing. The maximum of soil CO₂ flux reached values of 399 g m^?2 day^?1 in the epicenter; (2) the soil Rn had higher exhalation in the north segment of seismic ruptures, the maximum reached value of 1976 m Bq m^?2 s^?1; (3) the soil Hg flux was lower, ranging from ?2.5 to 18.7 n g m^?2 h^?1 and increased from south to north. The mean flux over the all profiles was 4.2 n g m^?2 h^?1. The total output of CO₂ and Hg degassing estimated along seismic ruptures for a survey area of 18.17 km² were approximately 0.57 Mt year^?1 and 688.19 g year^?1. It is recommended that land-use planners should incorporate soil gas and/or gas flux measurements in the environmental assessment of areas of possible risk. A survey of all houses along seismic ruptures is advised as structural measures to prevent the ingress of soil gases, including CO₂ and Rn, were needed in some houses.     

Influence of physico-chemical properties of soil clay fractions on the retention of dissolved organic carbon

This study investigated the effects of surface functional groups, cation exchange capacity (CEC), surface charge, sesquioxides and specific surface area (SSA) of three soil clay fractions (SCFs) (kaolinite–illite, smectite and allophane) on the retention of dissolved organic carbon (DOC) in soils. Physico-chemical properties of the SCFs before and after removing native carbon and/or sesquioxides were characterised, and the DOC adsorption–desorption tests were conducted by a batch method. Native organic carbon (OC)/sesquioxide removal treatments led to a small change in the CEC values of kaolinite–illite, but significant changes in those of smectite and allophane. The net negative surface charge increased in all samples with an increase in pH indicating their variable charge characteristics. The removal of native OC resulted in a slight increase in the net positive charge on soil clay surfaces, while sesquioxide removal increased the negative charge. Changes in the functional groups on the SCF surfaces contributed to the changes in CEC and zeta potential values. There was a strong relationship (R ² = 0.93, p < 0.05) between the Langmuir maximum DOC adsorption capacity (Q _max) and SSA. The Q _max value also showed a moderately strong relationship (R ² = 0.55, p < 0.05) with zeta potential (at pH 7). Q _max was only poorly correlated with CEC and native OC content. Therefore, along with SSA, the surface charge and functional groups of SCFs played the key role in determining the adsorption affinity and hence retention of DOC in soils.     

Seasonal changes in biomass,growth rates and production of subantarctic calanoid copepods in the Bay of Morbihan,Kerguelen Islands

The present study addresses the ecology of two dominant copepod species in the Bay of Morbihan, Kerguelen Archipelago. The biomass of the herbivore Drepanopus pectinatus (from 2 mg m^?3 in winter up to 500 mg m^?3 in summer) is tightly coupled to seasonal changes in chlorophyll a concentration in the region, whereas the biomass of the predatory euchaetiid Paraeuchaeta antarctica increases during two distinct periods over the year: 250 mg m^?3 in early summer, with the recruitment of the annual generation, and 100 mg m^?3 in autumn, with the deposition of lipids as energy reserves in C5 stages and adults. The juvenile growth rates predicted by temperature-dependent models (0.09 day^?1) closely approximate those observed in D. pectinatusin summer, but are much greater than those observed in P. antarctica (from 0.001 to 0.04 day^?1 depending on developmental stages). This difference can be explained by the reproductive strategies and trophic positions of the two species and may also result from the dependence of larval growth on energy reserves in P. antarctica. The production rates are five- and tenfold greater in juvenile stages than in adults, respectively, for D. pectinatus and P. antarctica. The secondary production by D. pectinatusis insufficient to support P. antarcticaduring winter, when the predatory species probably shifts to alternate prey. In summer the predation by P. antarctica accounts for only a minor part of the mortality estimated for D. pectinatus (from 20% to 60% depending on the examined station). At two of the three stations examined in the Bay of Morbihan, the production of P. antarctica could potentially support the dietary requirements of planktivorous seabirds in the region (~2,000 kg prey day^?1 for common diving petrels, Pelecanoides urinatrix, and ~90 kg prey day^?1 for rockhopper penguins, Eudyptes chysocome filholi).     

HCHs and DDTs in Yellow River of Henan section—a typical agricultural area in China: levels,distributions and risks

The levels, potential sources and ecological risks of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Yellow River of Henan section, a typical agricultural area in China, were investigated. Surface water samples and suspended particulate matters (SPMs) were collected from 23 sites during two seasons. In wet season, the residues of ∑HCHs (α-HCH, β-HCH, γ-HCH and δ-HCH) and ∑DDTs (p,p′-DDT, o,p′-DDT, p,p′-DDE, p,p′-DDD) ranged from 41.7 to 290 and 4.42 to 269 ng/L in surface water, while those varied from 0.86 to 157 and 1.79 to 96.1 ng/g dw in SPM, respectively. Moreover, in surface water, the levels of HCHs and DDTs in wet season were much higher than those in dry season. The reverse was true for residues of HCHs and DDTs in SPM. Compared with the large rivers in other regions, the levels of HCHs and DDTs in the studied area ranked at high levels and the residual concentrations might cause adverse biological risk, especially for ∑HCHs during wet season. Distributions of HCHs and DDTs delineated that the input of tributaries made a significant effect on the residue of HCHs and DDTs in the mainstream. ∑HCHs in surface water were consist of 26.7 % α-HCH, 30.0 % β-HCH, 37.9 % γ-HCH and 5.45 % δ-HCH and those in SPM contained 5.16 % α-HCH, 22.1 % β-HCH, 60.5 % γ-HCH and 12.2 % δ-HCH on average. Combined with ratios of α-HCH/γ-HCH in surface water (0.70) and in SPM (0.09), the results strongly indicated that lindane was recently used or discharged in the studied area. The mean percentage of DDTs′ isomers were 28.7 % p,p′-DDT, 29.8 % o,p′-DDT, 28.1 % p,p′-DDE and 13.4 % p,p′-DDD in surface water, while those were 12.5 % p,p′-DDT, 31.8 % o,p′-DDT, 30.5 % p,p′-DDE and 25.1 % p,p′-DDD in SPM. The ratios of (DDE + DDD)/∑DDTs and o,p′-DDT/p,p′-DDT revealed that the DDTs in the studied area mainly derived from long-term weathering of technical DDTs residue and the input of dicofol.     

Awareness of sea-level response under climate change on the coast of Ghana

In response to climate change, coastal communities are expected to experience increasing coastal impacts of sea-level rise (SLR). Strategies formulated and implemented to curb these impacts can thus be more effective if scientific findings on the response to climate change and SLR impacts on coastal communities are taken into consideration and not based merely on the need for coastal protection due to physical coastal erosion. There is also the need to determine the level of awareness of sea-level rise and responses in coastal communities to improve adaptation planning. This study assesses the impact of future erosion on the coastal land cover of Ghana. This assessment estimates approximately 2.66 km², 2.77 km², and 3.24 km² of coastal settlements, 2.10 km², 2.20 km² and 2.58 km² of lagoons, 1.39 km², 1.46 km² and 1.71 km² of wetlands to be at risk of inundation by the year 2050 based on coastal erosion estimates for the 2.6, 4.5 and 8.5 Representative Concentration Pathways (RCPs) used in the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC). This study also assesses the level of awareness of respondents to SLR on the coast of Ghana and explores the availability and level of integration of scientific knowledge of SLR into coastal adaptation strategies in Ghana. Assessment of the awareness of SLR responses to the changing climate in Ghana is made through semi-structured interviews at national, municipal/district and coastal community scales. Although settlements may be inundated based on the coastal erosion estimates, coastal dwellers interviewed cherish their proximity to the sea and are determined to maintain their occupancy close to the sea as spatial location influences their source of livelihood (fishing). Respondents lack knowledge/understanding of SLR, as the majority of household interviewees attributed the rise or fall in sea level to God. Respondents from Ngiresia alleged that the ongoing coastal sea defence project in their community has led to increased malaria cases.     

Kinetic and mechanism studies of the adsorption of lead onto waste cow bone powder (WCBP) surfaces

This study examines the adsorption isotherms, kinetics and mechanisms of Pb²⁺ sorption onto waste cow bone powder (WCBP) surfaces. The concentrations of Pb²⁺ in the study range from 10 to 90 mg/L. Although the sorption data follow the Langmuir and Freundlich isotherm, a detailed examination reveals that surface sorption or complexation and co-precipitation are the most important mechanisms, along with possibly ion exchange and solid diffusion also contributing to the overall sorption process. The co-precipitation of Pb²⁺ with the calcium hydroxyapatite (Ca-HAP) is implied by significant changes in Ca²⁺ and PO₄ ^3? concentrations during the metal sorption processes. The Pb²⁺ sorption onto the WCBP surface by metal complexation with surface functional groups such as ≡ POH. The major metal surface species are likely to be ≡ POPb⁺. The sorption isotherm results indicated that Pb²⁺ sorption onto the Langmuir and Freundlich constant q _max and K _F is 9.52 and 8.18 mg g^?1, respectively. Sorption kinetics results indicated that Pb²⁺ sorption onto WCBP was pseudo-second-order rate constants K ₂ was 1.12 g mg^?1 h^?1. The main mechanism is adsorption or surface complexation (≡POPb⁺: 61.6%), co-precipitation or ion exchange [Ca_3.93 Pb_1.07 (PO₄)₃ (OH): 21.4%] and other precipitation [Pb 50 mg L^?1 and natural pH: 17%). Sorption isotherms showed that WCBP has a much higher Pb²⁺ removal rate in an aqueous solution; the greater capability of WCBP to remove aqueous Pb²⁺ indicates its potential as another promising way to remediate Pb²⁺-contaminated media.     

Ecotoxicological risks of the abandoned F–Ba–Pb–Zn mining area of Osor (Spain)

Due to its potential toxic properties, metal mobilization is of major concern in areas surrounding Pb–Zn mines. In the present study, metal contents and toxicity of soils, aqueous extracts from soils and mine drainage waters from an abandoned F–Ba–Pb–Zn mining area in Osor (Girona, NE Spain) were evaluated through chemical extractions and ecotoxicity bioassays. Toxicity assessment in the terrestrial compartment included lethal and sublethal endpoints on earthworms Eisenia fetida, arthropods Folsomia candida and several plant species, whereas aquatic tests involved bacteria Vibrio fischeri, microalgae Raphidocelis subcapitata and crustaceans Daphnia magna. Total concentrations of Ba (250–5110 mg kg^?1), Pb (940 to >5000 mg kg^?1) and Zn (2370–11,300 mg kg^?1) in soils exceeded intervention values to protect human health. Risks for the aquatic compartment were identified in the release of drainage waters and in the potential leaching and runoff of metals from contaminated soils, with Cd (1.98–9.15 µg L^?1), Pb (2.11–326 µg L^?1) and Zn (280–2900 µg L^?1) concentrations in filtered water samples surpassing US EPA Water Quality Criteria (2016a, b). Terrestrial ecotoxicity tests were in accordance with metal quantifications and identified the most polluted soil as the most toxic. Avoidance and reproduction tests with earthworms showed the highest sensitivity to metal contamination. Aquatic bioassays performed in aqueous extracts from soils confirmed the results from terrestrial tests and also detected toxic effects caused by the mine drainage waters. Algal growth inhibition was the most sensitive aquatic endpoint. In view of the results, the application of a containment or remediative procedure in the area is encouraged.     

Biochar-based constructed wetlands to treat reverse osmosis rejected concentrates in chronic kidney disease endemic areas in Sri Lanka

The objectives were to investigate the potential remedial measures for reverse osmosis (RO) rejected water through constructed wetlands (CWs) with low-cost materials in the media established in chronic kidney disease of unknown etiology (CKDu) prevalent area in Sri Lanka. A pilot-scale surface and subsurface water CWs were established at the Medawachchiya community-based RO water supply unit. Locally available soil, calicut tile and biochar were used in proportions of 81, 16.5 and 2.5% (w/w), respectively, as filter materials in the subsurface. Vetiver grass and Scirpus grossus were selected for subsurface wetland while water lettuce and water hyacinth were chosen for free water surface CWs. Results showed that the CKDu sensitive parameters; total dissolved solids, hardness, total alkalinity and fluoride were reduced considerably (20–85%) and most met desirable levels of stipulated ambient standards. Biochar seemed to play a major role in removing fluoride from the system which may be due to the existing and adsorbed K⁺, Ca⁺², Mg⁺², etc. on the biochar surface via chemisorption. The least reduction was observed for alkalinity. This study indicated potential purification of aforesaid ions in water which are considerably present in RO rejection. Therefore, the invented bio-geo constructed wetland can be considered as a sustainable, economical and effective option for reducing high concentrations of CKDu sensitive parameters in RO rejected water before discharging into the inland waters.     

Home range of immature green turtles tracked at an offshore tropical reef using automated passive acoustic technology

Seventeen immature green turtles Chelonia mydas were tracked concurrently by automated ultrasonic receivers at a coral reef off North-Eastern Australia (September–December 2010, 16.4°S, 145.6°E). The majority (n = 11) were tracked for the entire 100-day study, the remainder for 23–85 days. Detection data aggregated at 30-min intervals produced median 6.5–35 daily locations for individual turtles. Home range areas (95 % utilisation distribution) were ≤1 km², $ {\bar{\text{x}}} $  ± SD = 0.74 km² ± 0.159. To the best of our knowledge, these are the first home range estimates for C. mydas foraging at offshore tropical reefs. The findings are important for conservation in revealing near-continuous presence of the same individuals within a small geographic area. Time between detections was very short (median <3 min) demonstrating passive ultrasonic technology can track multiple turtles in a foraging environment with higher temporal resolution than typically achieved by satellite tracking.     

Comparative degradation rates of chitinous exoskeletons from deep-sea environments

Hydrothermal vent environments, particularly those associated with the vestimentiferan Riftia pachyptila, are believed to be among the highest chitin-producing systems. In order to elucidate the chitin cycle in these environments, we estimate the in situ chitin degradation rates of tube-worm exoskeletons. Our in situ experiments show that the tubes of Riftia are highly stable structures. Comparative measurements of the degradation rates of Riftia tubes and crab shells immersed at deep-sea vents show that the tubes would be degraded within 2.5 years, whereas the time for the total degradation of the vent crab (Bythograea thermydron) carapaces would not exceed 36 days. The importance of the microbial participation in this degradation was estimated for Riftia tubes. Based on previous work, we calculated chitin production by a population of Riftia tubes of about 750 g m^-2 year^-1 (763). From our in situ experiments, we estimated a microbial chitinolysis rate of about 500 g m^-2 year^-1 (496) (65% of the chitin produced).Exoskeletons containing β-chitin appear more stable in natural environments than those containing α-chitin and would thus be less available as carbon and nitrogen sources. In contrast, isolated β-chitin was hydrolysed faster than α-chitin during in vitro degradation experiments; for instance, Riftia β-chitin was degraded about 3- to 4-fold faster than Bythograea α-chitin. A stabilization process by disulfide bonds of the proteins-chitin link, rather than the crystalline form of the chitin (α/β), accounts for the resistance of Riftia tubes to enzymatic attacks.     

Differences in the species- and size-composition of fish assemblages in three distinct seagrass habitats with differing plant and meadow structure

Fish faunas were sampled seasonally using a large and a small beam trawl in three seagrass habitats comprising predominantly Amphibolis griffithii or Posidonia sinuosa or Posidonia coriacea, which differ in seagrass and meadow structure. Amphibolis griffithii and P. sinuosa both produce a relatively dense leaf canopy, but the former exhibits a distinct architecture, with the leaf canopy overlying relatively open spaces surrounding woody stems, compared to the uniformly dense blade-like leaves of P. sinuosa which emerge directly from the sediment. In comparison, P. coriacea provides a landscape of patchy seagrass amongst areas of bare sand. Since the latter seagrass habitat contains large areas of sand, fish were also sampled in adjacent unvegetated areas. The number of species and density of fish were greater (P<0.05) in P. sinuosa than in either A. griffithii or P. coriacea. The mean number of species caught using the large trawl ranged from 16 to 24 in the first of these habitats compared to 14–21 and 9–15 in the last two habitats, respectively, and the mean densities ranged between 78 and 291 fish 1000 m^?2 in P. sinuosa compared to 31–59 fish 1000 m^?2 in A. griffithii and 31–59 fish 1000 m^?2 in P. coriacea. The biomass of fish was greater (P<0.05) in both P. sinuosa and A. griffithii than in P. coriacea (4.2–5.3 kg and 3.3–6.2 kg versus 0.7–1.9 kg 1000 m^?2, respectively). Furthermore, the size-structure of fish differed among these habitats, where the median weight of fish was 72.1 g in A. griffithii, compared to 7.5 g and 19.8 g in P. sinuosa and P. coriacea, respectively. Ordination and ANOSIM demonstrated that the species-composition differed markedly among the three seagrass habitats (P<0.001), suggesting that fish species display a distinct preference for particular seagrasses characterised by different architecture. Differences in species-composition among the seagrass habitats partly reflected the size-composition of fish in each habitat. The open space below the canopy of A. griffthii is likely to allow larger fish to occupy this habitat, whereas only small fish would be able to penetrate the dense foliage of P. sinuosa. Differences in species- and size-composition of fish among these habitats may be the result of settlement-sized larvae discriminating between particular seagrass and meadow structures, or fish being subject to different levels of predation and/or accessibility to food or space. The species-composition in P. coriacea was highly dispersed and did not differ from that of unvegetated areas. While several species were associated with both P. coriacea and bare-sand habitats, some species did display a high affinity with the seagrass P. coriacea. This may reflect an association with the sparse and narrower leaves of this seagrass or with the patchy occurrence of the seagrass Heterozostera tasmanica, which commonly occurs as an understorey in this habitat.     

In vitro mass multiplication of screw pines (<Emphasis Type="Italic">Pandanus</Emphasis> spp.) - an important costal bio- resource

An efficient in vitro mass multiplication protocol was developed for selected species of screw pine (Pandanus fascicularis Lam., P. furcatus Roxb.). The protocol could be successfully used for large scale production of planting materials leading to cultivation and making bio-fences or green belts in coastal areas, wetlands for protection and preventing soil erosion. This will facilitate the replenishment of the bio resource and also provide good breeding space for various fauna associated with it. For developing the tissue culture protocol, shoot tips and tillers from the mature plants were used as the explants. Surface sterilization with 0.1 % mercuric chloride for 1 min. Yielded good fraction (65 %) of contamination free explants. Explants inoculated in MS solid medium supplemented with 6-benzylaminopurine (BAP, 2.5 mg/l) and indole-3-acetic acid (IAA, 0.5 mg/l), induced 2–3 shoot buds in 5 weeks. These buds either individually or along with the explant portion, sub-cultured to fresh media containing the same hormonal combinations, resulted induction of 5–6 shoot buds in 4 weeks. Repeated subcultures of shoot buds in the same medium produced 8–10 shoot buds in every 4 weeks. Shoot elongation was achieved (~ 3 cm) by transferring the shoot clusters or individual shoots to basal medium, and the elongated shoots were rooted in vitro or ex vitro. Root induction in shoots (87.4 %) was achieved in MS medium supplemented with 0.1 mg/l indole-3-butyric acid (IBA). Rooted shoots were established in paper/polythene cups filled with fine sand, which subsequently recorded 85 % establishment under the shade-net house with proper irrigation. Plants grown in poly-bags were later successfully established in different field conditions and recorded 100 % survival.     

Effect of diet and paralarval development on digestive enzyme activity in the cephalopod <Emphasis Type="Italic">Robsonella</Emphasis><Emphasis Type="Italic">fontaniana</Emphasis>

This study aims at establishing the maturation of the digestive system in Robsonella fontaniana by means of measuring the digestive enzyme activity in paralarvae after hatching. Different groups of newly hatched paralarvae were fed with Artemia sp. (FA), Lithodes santolla zoea (FL) or were starved to serve as negative control (ST), the experimental period lasted 27 days after hatching (DAH). The semi-quantitative assay api^® ZYM (bioMérieux, France) was used to identify the pool of digestive enzymes present in paralarvae prior to selecting the specific enzymes acid phosphatase, total protease, trypsin and chymotrypsin for analysis. Mortality and larval protein content were also measured during the experiment. The survival of R. fontaniana hatchlings differed depending on the quality of the diet offered (ST < FA < FL), the same trend was observed with respect to paralarval protein content. Total protease and acid phosphatase activities were not related to either time of development or diet (P < 0.05). However, the activity of trypsin and chymotrypsin after DAH 10 was dependent on diet (P < 0.05). Paralarvae fed with Lithodes zoea (FL) performed better than paralarvae in the other two groups, exhibiting lower mortality, higher protein content and the highest proteolytic activity for trypsin and chymotrypsin. The results indicate that Lithodes-larvae are a better diet for R. fontaniana paralarvae than Artemia sp.     

Evaluation of rare earth elements in groundwater of Lagos and Ogun States,Southwest Nigeria

Rare earth elements in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare earth elements (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365–488 (69.5 ± 117)] µg L^?1 than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14–232 (22.6 ± 41.1)] µg L^?1. Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO₃ ^2? (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.     

Combination system of full-scale constructed wetlands and wetland paddy fields to remove nitrogen and phosphorus from rural unregulated non-point sources

Constructed wetlands (CWs) have been used effectively to remove nitrogen (N) and phosphorus (P) from non-point sources. Effluents of some CWs were, however, still with high N and P concentrations and remained to be pollution sources. Widely distributed paddy fields can be exploited to alleviate this concern. We were the first to investigate a combination system of three-level CWs with wetland paddy fields in a full scale to remove N and P from rural unregulated non-point sources. The removal efficiencies (REs) of CWs reached 57.3 % (37.4–75.1 %) for N and 76.3 % (62.0–98.4 %) for P. The CWs retained about 1,278 kg N ha^?1 year^?1 and 121 kg P ha^?1 year^?1. There was a notable seasonal change in REs of N and P, and the REs were different in different processing components of CWs. The removal rates of wetland paddy fields adopt “zero-drainage” water management according to local rainfall forecast and physiological water demand of crop growth reached 93.2 kg N ha^?1 year^?1 and 5.4 kg P ha^?1 year^?1. The rice season had higher potential in removing N and P than that in the wheat season. The whole combined system (0.56 ha CWs and 5.5 ha wetland paddy fields) removed 1,790 kg N year^?1 and 151 kg P year^?1, which were higher than those from CWs functioned alone. However, another 4.7-ha paddy fields were needed to fully remove the N and P in the effluents of CWs. The combination of CWs and paddy fields proved to be a more efficient nutrient removal system.