Growth of Marine Microalgae in Landfill Leachate and Their Ability as Pollutants Removal.

Leachate from landfill contains concentrated nutrients that may enter the terrestrial and aquatic environment, including nearby coastal areas. The nutrient contaminants eventually bring harm to marine organisms, including microalgae. This study was performed to investigate the growth of two green microalgal species, i.e. Chlorella sp. and Nannochloropsis sp. in diluted landfill leachate. Besides, the ability of nutrient removal by these microalgal was also explored from the changes of chemical oxygen demand (COD) and nutrients content. The initial and final concentrations of COD, NH3-N, and PO4 3- in the diluted leachate (5%, 10% and 15%) were measured and the growth patterns of these species were determined by counting the cell numbers for 12 days. Comparison of these microalgae showed that the growth rate of Nannochloropsis was significantly higher compared to Chlorella in all leachate concentrations. Leachate at 5% enhanced the growth of both microalgae, while leachates at 10% and 15% decreased their growth as early as at the beginning of the test. It is apparent that the less concentrated leachate discharged into seawater would not pose any toxicity to the environment and would not bear adverse effect to microalgae yet could promote their growth. This study also revealed that the microalgae could remediate leachate pollution by its ability of nutrient removal; thus, leading to the potential application in wastewater bioremediation, including industrial waste and palm oil mill effluent.

Larut lesapan dari tapak pelupusan mengandungi bahan pencemar atau nutrien berkepekatan tinggi yang boleh mencemarkan persekitaran daratan dan akuatik, termasuk kawasan pantai berdekatan. Pada masa ini, pencemaran larut lesapan di kawasan pantai membawa satu kebimbangan yang serius. Bahan pencemar ini boleh membahayakan organisma marin termasuk mikroalga. Kajian ini melaporkan pertumbuhan dua spesis mikroalgal hijau, iaitu Chlorella sp. dan Nannochloropsis sp. di dalam larut lesapan yang telah dicairkan. Perubahan permintaan oksigen kimia (COD) dan kandungan nutrien, iaitu amonia-nitrogen (NH3-N) dan fosfat (PO4 3−) juga dipantau. Corak pertumbuhan mikroalga telah dikenal pasti selepas dikultur di dalam larut lesapan yang telah dicairkan dengan kepekatan 5%, 10% dan 15% selama 12 hari. Bacaan awal COD, NH3-N, dan PO4 3− sebelum kajian dan bacaan akhir COD selepas kajian diukur. Dari segi kepekatan, larut lesapan pada 5% meningkatkan pertumbuhan, sementara larut lesapan pada 10% dan 15% menurunkan pertumbuhan kedua-dua spesis mikroalga seawal permulaan ujian. Perbandingan dari segi spesis mikroalga pula menunjukkan bahawa kadar pertumbuhan Nannochloropsis jauh lebih tinggi berbanding Chlorella dalam semua kepekatan larut lesapan yang diuji. Walau bagaimanapun, dalam larut lesapan berkepekatan 5%, Chlorella menunjukkan keupayaan untuk menyah nutrien berlebihan dengan lebih cekap berbanding Nannochloropsis. Secara keseluruhan, kajian ini memberi gambaran bahawa larut lesapan yang berkepekatan rendah di dalam air laut tidak akan menimbulkan kesan buruk kepada alam sekitar dan mikroalga, tetapi sebaliknya dapat meningkatkan pertumbuhan mikroalga tersebut. Kajian ini juga mendedahkan bahawa mikroalga boleh membantu dalam mengurangkan pencemaran oleh larut lesapan disebabkan keupayaannya dalam menyingkirkan lebihan nutrien. Oleh itu, kajian ini merintis kepada potensi penggunaan mikroalga di dalam bidang bioremediasi air sisa, termasuklah untuk sisa industri dan air kumbahan dari kilang minyak sawit.

Assessment of heavy metal pollution in surface sediments of the Bayan Lepas area, Penang, Malaysia.

This study aimed to evaluate the spatial and temporal distribution of heavy metals (Cd, Cr, Cu, Co, Fe, Pb, Ni, V, and Zn) in the sediments of Bayan Lepas Free Industrial Zone of Penang, Malaysia. Ten sampling stations were selected and sediment samples were collected during low tide (2012-2013). Metals were analyzed and the spatial distribution of metals were evaluated based on GIS mapping. According to interim sediment quality guidelines (ISQG), metal contents ranged from below low level to above high level at different stations. Based on the geoaccumulation index (Igeo) of sediment, sampling stations were categorized from unpolluted to strongly polluted. The enrichment factor (EF) of metals in the sediment varied between no enrichment to extremely high enrichment. The potential ecological risk index (RI) indicated Bayan Lepas FIZ was at low risk.

Biosorption of copper and zinc by immobilised and free algal biomass, and the effects of metal biosorption on the growth and cellular structure of Chlorella sp. and Chlamydomonas sp. isolated from rivers in Penang, Malaysia.

In this study, the biosorption of copper and zinc ions by Chlorella sp. and Chlamydomonas sp. isolated from local environments in Malaysia was investigated in a batch system and by microscopic analyses. Under optimal biosorption conditions, the biosorption capacity of Chlorella sp. for copper and zinc ions was 33.4 and 28.5 mg/g, respectively, after 6 hr of biosorption in an immobilised system. Batch experiments showed that the biosorption capacity of algal biomass immobilised in the form of sodium alginate beads was higher than that of the free biomass. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed that copper and zinc were mainly sorbed at the cell surface during biosorption. Exposure to 5 mg/L of copper and zinc affected both the chlorophyll content and cell count of the algal cells after the first 12 hr of contact time.

Monitoring of Water Quality and Microalgae Species Composition of Penaeus monodon Ponds in Pulau Pinang, Malaysia.

Many reports have revealed that the abundance of microalgae in shrimp ponds vary with changes in environmental factors such as light, temperature, pH, salinity and nutrient level throughout a shrimp culture period. In this study, shrimp cultivation period was divided into three stages (initial = week 0-5, mid = week 6-10 and final = week 11-15). Physical and chemical parameters throughout the cultivation period were studied and species composition of microalgae was monitored. Physical parameters were found to fluctuate widely with light intensity ranging between 182.23-1278 µmol photon m(-2)s(-1), temperature between 29.56°C -31.59°C, dissolved oxygen (DO) between 4.56-8.21 mg/l, pH between 7.65-8.49 and salinity between 20‰-30‰. Ammonium (NH4 (+)-N), nitrite (NO2 (-)-N), nitrate (NO3 (-)-N), and orthophosphate (PO4 (3-)-P) concentrations in the pond at all cultivation stages ranged from 0.017 to 0.38 mg/l, 0.24 to 2.12 mg/l, 0.06 to 0.98 mg/l and 0.16 to 1.93 mg/l respectively. Statistical test (ANOVA) showed that there were no significant difference (p<0.05) in nutrients concentrations among the cultivation stages. All nutrients concentrations however were still in the tolerable level and safe for shrimp culture. The chlorophyll a contents were found to range from 5.03±2.17 to 32.61±0.35 µg/l throughout the cultivation period. A total of 19 microalgae species were found in the shrimp pond, with diatoms contributing up to 72% of the species followed by Chlorophyta (11%) and Cyanophyta (11%). However, weekly species abundance varied through the study period. At the initial stage, when there were no shrimps in the pond, Anabaena spp. and Oscillatoria spp. (Cyanophyta) were the dominant species, followed by Chlorella sp. and Dunaliella sp. (Chlorophyta). When shrimps were introduced into the pond, Amphora sp., Navicula sp. Gyrosigma sp. and Nitzschia sp. (diatoms) started to exist. At the middle and towards the final stage of the shrimp culture period diatoms were the dominant species. The Chlorophyta (Chlorella sp.) domination took place only twice, which was at week 2 and 13. The absence of some of the coastal water microalgae species in the shrimp pond was most likely due to the fact that they could not tolerate the physicochemical factors of harsh environment. In this study, Cylindrotheca closterium was regarded as the most tolerant species among the microalgae due to its ability to exist for 6 weeks out of the 15 weeks of cultivation.

Disposable E-Tongue for the Assessment of Water Quality in Fish Tanks.

A disposable screen-printed e-tongue based on sensor array and pattern recognition that is suitable for the assessment of water quality in fish tanks is described. The characteristics of sensors fabricated using two kinds of sensing materials, namely (i) lipids (referred to as Type 1), and (ii) alternative electroactive materials comprising liquid ion-exchangers and macrocyclic compounds (Type 2) were evaluated for their performance stability, sensitivity and reproducibility. The Type 2 e-tongue was found to have better sensing performance in terms of sensitivity and reproducibility and was thus used for application studies. By using a pattern recognition tool i.e. principal component analysis (PCA), the e-tongue was able to discriminate the changes in the water quality in tilapia and catfish tanks monitored over eight days. E-tongues coupled with partial least squares (PLS) was used for the quantitative analysis of nitrate and ammonium ions in catfish tank water and good agreement were found with the ion-chromatography method (relative error, ±1.04- 4.10 %).

Photosynthetic gas exchange under emersed conditions in eulittoral and normally submersed members of the Fucales and the Laminariales: interpretation in relation to C isotope ratio and N and water use efficiency.

Ten species of brown macroalgae (five eulittoral and one submersed species of the Fucales; four submersed species of the Laminariales) from a rocky shore at Arbroath, Scotland, were examined for characteristics of emersed photosynthesis in relation to the partial pressure of CO2 and O2. The five eulittoral species of the Fucaceae were approaching CO2 saturation for light-saturated photosynthesis at normal air levels of CO2 (35 Pa) in 21 kPa O2. The normally submersed algae are further from CO2 saturation under these conditions, especially in the case of the four members of the Laminariales. The rate of net photosynthesis in the Fucaceae is O2-independent in the range 2-21 kPa O2 over the entire range of CO2 partial pressure tested (compensation up to 95 Pa). For the other five algae tested, net photosynthesis is slightly inhibited by O2 at 21 kPa relative to 2 kPa over the entire range of CO2 partial pressures tested (compensation up to 95 Pa). CO2 compensation partial pressures are low (<0.5 Pa) for the Fucaceae and independent of O2 in the range 2-42 kPa. For the other five algae, the CO2 compensation partial pressure are higher, and increased with O2 partial pressure in the range 2-42 kPa. These gas exchange data show that the Fucaceae exhibit more C4-like characteristics of their photosynthetic physiology than do the other five species tested, although even the Laminariales and Halidrys siliquosa are not classic C3 plants in their photosynthetic physiology. These data suggest that, in emersed conditions as well as in the previously reported work on submersed photosynthesis, a "CO2 concentrating mechanism" is operating which, by energized transmembrane transport of inorganic C, accumulates CO2 at the site of RUBISCO and, at least in part, suppresses the oxygenase activity. Work with added extracellular carbonic anhydrase (CA), and with a relatively membrane-impermeant inhibitor of the native extracellular CA activity (acetazolamide), suggests that, in emersed conditions as well as in the previously reported work on algae submersed in seawater at pH 8, HCO inf3sup- is the major inorganic C species entering the cell. At optimal hydration, the rate of emersed photosynthesis in air is not less than the rate of photosynthesis when submersed in seawater, at least for the Fucaceae. δ13C ratios of organic C for the Fucaceae are slightly more negative than is the case for the other five algae; these data are consitent with substantial (half or more of the entering inorganic C) leakage of CO2 from the accumulated pool, and with some contribution of atmospheric CO2 to the organic C gain by the eulittoral algae. The predicted increase in N use efficiency of photosynthesis in the Fucaceae, with their more strongly developed CO2 concentrating mechanism, is consistent with data on emersed, but not submersed, photosynthesis for the algae collected from the wild and thus at a poorly defined N status. The more C4-like gas exchange charateristics of photosynthesis in the eulittoral Fucaceae may be important in increasing the water use efficiency of emersed photosynthesis from the limited capital of water available for transpiration by a haptophyte.

Exogenous inorganic carbon sources for photosynthesis in seawater by members of the Fucales and the Laminariales (Phaeophyta): ecological and taxonomic implications.

Characteristics of inorganic carbon assimilation by photosynthesis in seawater were investigated in six species of the Fucales (five Fucaceae, one Cystoseiraceae) and four species of the Laminariales (three Laminariaceae, one Alariaceae) from Arbroath, Scotland. All of the algae tested could photosynthesise faster at high external pH values than the uncatalysed conversion of HCO 3- to CO2 can occur, i.e. can "use" external HCO 3- . They all had detectable extracellular carbonic anhydrase activity, suggesting that HCO 3- use could involve catalysis of external CO2 production, a view supported to some extent by experiments with an inhibitor of carbonic anhydrase. All of the algae tested had CO2 compensation concentrations at pH 8 which were lower than would be expected from diffusive entry of CO2 supplying RUBISCO as the initial carboxylase, consistent with the operation of energized entry of HCO 3- and / or CO2 acting as a "CO2 concentrating mechanism". Quantitative differences among the algae examined were noted with respect to characteristics of inorganic C assimilation. The most obvious distinction was between the eulittoral Fucaceae, which are emersed for part of, or most of, the tidal cycle, and the other three families (Cystoseiraceae, Laminariaceae, Alariaceae) whose representatives are essentially continually submersed. The Fucaceae examined are able to photosynthesise at high pH values, and have lower CO2 compensation concentrations, and lower K1/2 values for inorganic C use in photosynthesis, at pH 8, than the other algae tested. Furthermore, the Fucaceae are essentially saturated with inorganic C for photosynthesis at the normal seawater concentration at pH 8 and 10°C. These characteristics are consistent with the dominant role of a "CO2 concentrating mechanism" in CO2 acquisition by these plants. Other species tested have characteristcs which suggest a less effective HCO 3- use and "CO2 concentrating mechanism", with the Laminariaceae being the least effective; unlike the Fucaceae, photosynthesis by these algae is not saturated with inorganic C in normal seawater. Taxonomic and ecological implications of these results are considered in relation to related data in the literature.