High Total Phosphorus Research Articles

Spatial variation of phosphorus fractionation in the coral reef sediments of Lakshadweep Archipelago, Indian Ocean

ABSTRACTSurface sediments were collected from the shore and lagoons of Kavaratti, Kadamat and Agatti islands of Lakshadweep Archipelago during May 2015 and analysed for the spatial distribution of the micronutrient element, phosphorus. Phosphorus was separated by sequential extraction procedure into five fractions – exchangeable (Ex-P), iron bound, (Fe-P), calcium bound (Ca-P), organic and residual fractions (OP) and total phosphorus (TP). The average relative contribution of each P species to TP was: OP > Ca –P > Ex – P > Fe – P. The high concentration of organic and residual phosphorus (87–96%) compared to inorganic phosphorus is particularly evident at stations characterised by higher total phosphorus concentrations. Among the three forms of IP in the sediments, Ca-P was dominant at all stations. The OC/OP ratio ranged from 3 to 163 in the sediments, suggesting that the organic matter in sediments had been subjected to degradation. Hence, the major contribution towards organic and residual phosphorus form is from the residual fraction comprising biologically resistant or non-available phosphorus form composed of refractory materials. The concentration of phosphorus reported in the present study is higher than that of the earlier studies in Lakshadweep, indicating a terrestrial and anthropogenic influence on the sediment.

The effect of Phragmites australis and Eichhornia crassipes in the removal of high total phosphorus concentrations from water

In order to evaluate the accumulation of high phosphorus and the distribution on macrophytes part, the experiment was conducted by arranged vegetated and unvegetated treatment in a greenhouse experiment. Reactor containing 5L of phosphorus solution (50 or 500 mg/L), 4 kg of sediment and plants (Phragmites australis or Eichhornia crassipes) were prepared. The studied concentrations tried to stimulate an accumulation of Total Phosphorus (TP) in plants. Water were sampled every 5 days during 30 days of experiments while sediment and plant samples (roots, submerged leaves and aerial leaves) were collected at the beginning and at end of this study. Relative growth rate (RGR) of plants was determined considering initial and final plant height. As results, more than 60% of TP was removed by P. australis and E. crassipes from the water. Both P. australis and E. crassipes has great capability to accumulated TP in their tissues, submerged part of leaves accumulated highest TP than other part, due to directly contact with water. RGR was positive suggested both plant able to tolerance TP in high concentration. P. australis was accumulated higher TP than E. crassipes. Therefore P. australis is suitable for phytoremediation practice, being capable to tolerate high TP concentration.

Three new Fragilaria species (Bacillariophyta) from low-conductivity mountain freshwaters (Alps and Apennines)

More or less needle-shaped species of Fragilaria s.s. are difficult to identify. Here we contribute to the taxonomy of this difficult group by describing three species new to science from very low conductivity mountain freshwater environments. Two of the new species resemble taxa established by Kützing in the early 19th century: F. rumpens and F. vaucheriae. Fragilaria spinaspeciosa sp. nov., from a seepage (helocrenic spring) in the northern Apennines, is superficially similar to F. rumpens, but has a lower stria density. Fragilaria tridentina sp. nov. is distinguished from F. gracilis by its smaller length-to-breadth ratio and more closely spaced areolae. Fragilaria vaucheriaeraetica sp. nov. is distinguished from F. vaucheriae and F. microvaucheriae by its outline and denser striae. These last three species also have distinctly different ecologies. Fragilaria vaucheriaeraetica sp. nov. is found in very low conductivity, very low nitrate, ultra-oligotrophic waters, while F. vaucheriae and F. microvaucheriae are found in medium conductivity, high total phosphorus, and relatively high nitrate streams. Accurate species identification and knowledge of each species’ ecological preferences are critically important if diatoms are to be used effectively as indicators of environmental impact and climate change. Weakly buffered, low alkalinity, low nutrient and low conductivity mountain freshwater habitats are sensitive to human disturbance and biotopes for many rare (Red List) diatoms. As such, they serve as valuable early warning systems for detecting the effects of climate change and other human activities.

Total phosphorus analyses: is the convenience of automated inline-UV digestion robust enough for freshwater nutrient monitoring?

Child AW, Moore BC. 2019. Total phosphorus analyses: is the convenience of automated inline-UV digestion robust enough for freshwater nutrient monitoring? Lake Reserve Manage. 35:140–147Phosphorus (P) is an essential and often growth-limiting nutrient in aquatic ecosystems. Excessive P in aquatic ecosystems can result in accelerated eutrophication and is a prime cause of “impaired” water quality listing under the Clean Water Act. Total phosphorus (TP) is a commonly used metric for predicting productivity and assessing nutrient enrichment in aquatic ecosystems. Accurate and precise TP data are essential for aquatic resource managers and scientists. Inline-ultraviolet (inline-UV) and persulfate digestions are both approved methods for estimating TP within water samples, and literature on their relative digestion efficiencies is available. However, the available literature to date has only evaluated relatively high TP concentrations, >90 µg P/L, considerably higher than critical trophic concentrations for natural lakes and streams. We compared inline-UV digestion with the more common autoclave persulfate digestion, analyzing TP from 32 freshwater sites in northern Idaho and eastern Washington. Sites were chosen to represent common ranges of TP (5 to 350 µg P/L) found in surface waters throughout the world. Both digestions performed adequately on third-party reference materials used for laboratory accreditation requirements. The linear model comparing logarithmic transformations of TP estimates from both digestion methods were correlated (p < 0.001, R2 = 0.8110), and suggested inline-UV digestion may not accurately estimate low-level TP concentrations in natural waters. Our results indicate that inline-UV digestion results are overall not comparable to autoclave digestion (absolute mean difference 16 µg/L or 22%, p < 0.001); lake managers should be aware that TP method selection can significantly alter data interpretation for nutrient monitoring plans.

Ecology and Diversity of Plankton in Kotmale Reservoir, Sri Lanka

Present study investigated the relationship between plankton communities and environmental variables in five different locations of the Kotmale Reservoir during the period of June 2008 to May 2011. A total of 123 plankton species were recorded with 85 species of phytoplankton and 38 species of zooplankton. The relative abundance data indicate that Aulacoseira granulata (31.06%), Botryococcus braunii (12.34%) and Microcystis sp. (11.93%) were the dominant phytoplankton species while Acanthocystis turfacea (52.22%) was the dominant zooplankton species. Staurastrum cingulum was the dominant species in sites where the immediate catchment is covered with reservation forest with no significant inflow streams. Aulacoseira granulata, Fragellaria capucina and Navicula sp. were abundant in locations where the highest total phosphorus (TP) values were recorded. The main inflow streams, Puna Oya and Pundalu Oya appear to bring nutrient rich waters from its catchment with dense tea estates, agricultural lands, industries and villages. Microcystis sp. was abundant in locations where the highest values for TP, dissolved phosphorus (DP), ammonia, conductivity and turbidity were recorded. Botryococcus braunii was dominant in the location where Puna Oya reaches the reservoir. Staurastrumlepta canthum was abundant in the location located closer to the dam where the water body mostly contains limnetic characteristics. Among the zooplankton, cladocera species were abundant in sites where Staurastrum cingulum was identified. Rotifers and ciliate protozoans were identified closer to the dam and at the sites with high dominance of Microcystis sp. Accordingly, it was apparent that the distribution and abundance of these plankton species depend on the prevailing environmental conditions which ultimately show their ability to use as environmental indicators.

Drastic reduction of sludge in wastewater treatment plants: co-digestion of sewage sludge and aqueous waste in a thermophilic membrane reactor

ABSTRACT Sewage sludge and aqueous wastes are usually treated in separate facilities. Both may pose specific issues, mainly related to the uncertainty of the recovery/disposal route and costs, for the sludge, and to the extremely variable quantitative and qualitative properties, for the aqueous waste. In the present work, the co-digestion of thickened sludge and aqueous wastes in a Thermophilic Aerobic Membrane Reactor (TAMR) was studied in order to allow the almost complete reduction of sludge directly in wastewater treatment plants (WWTPs). Different conditions (aerobic and alternate aeration) were tested in a pilot plant, at the semi-industrial scale. The TAMR plant was operated at 48°C with constant organic load rate (5 kgCOD m−3 d−1) and hydraulic retention time (5 days). The main results obtained are the following: (I) high overall COD (78–97%) and total phosphorus (>60%) removal rate under both the studied aeration conditions; (II) increase of ammonia concentration due to the effective ammonification of organic nitrogen; (III) low specific sludge production (0.04) in the thermophilic reactor.

Spatial variability and temporal dynamics of cyanobacteria blooms and water quality parameters in Missisquoi Bay (Lake Champlain)

Abstract Cyanobacteria bloom events have been associated with eutrophication processes, along with hydrologic and climate factors. Missisquoi Bay is a portion of Lake Champlain (USA–Canada) that is highly eutrophic and prone to cyanobacteria blooms and cyanotoxins. This study assessed the spatial–temporal influence of nutrients, turbidity and temperature in cyanobacteria distributions during a bloom event in the summer of 2006. Correlations, generalized linear models (GLMs), geostatistics and local indications of spatial association (LISA) autocorrelation analysis tested the influence of nutrient and non-nutrient explanatory variables in cyanobacteria biovolume. Total phosphorus exhibited a high direct correlation with cyanobacteria biovolume. The best performing GLMs included total phosphorus, total nitrogen, Secchi depth (as turbidity) and temperature as explanatory variables of cyanobacteria biovolume. Variogram analysis of those variables resulted in a better understanding of the underlying spatial variation process of the cyanobacteria bloom event. The LISA test revealed a moderate but stable autocorrelation between cyanobacteria biovolume and total phosphorus from 180 to 1,000 m of weight distance, suggesting the possibility of up-scaling the current results to coarse-resolution satellite imagery for more frequent monitoring of bloom events. The LISA test also revealed the spatial–temporal dynamic (movement of cyanobacteria scums) of high cyanobacteria blooms with high total phosphorus concentration.

Diatom assemblages (Bacillariophyta) in six tropical reservoirs from southeast Brazil: species composition and spatial and temporal variation patterns

Abstract Aim Relationships between species composition and variation patterns in diatom assemblages over six tropical reservoirs located in Southeast Brazil were explored. Methods Surface-sediment and phytoplankton diatom assemblages were determined and Canonical Correspondence Analysis was used to verify the set of environmental variables that best explain the species composition variation among sites. Results A total of 28 diatom taxa representing 20 genera were identified using light and scanning electron microscopy. Information on their ecological preferences was also provided. Humidophila biscutella is reported for the first time in Brazil whereas Sellaphora sassiana and Humidophila brekkaensis are reported for the first time in São Paulo State. Three groups of potential water quality indicators were delineated: the first suggests oligotrophic conditions, the second is related to cold waters with low luminosity in a mixing regime, and the third is a small group of tolerant species occurring in water with high conductivity, pH and total phosphorus conditions. Conclusion present study provided the first insight into the general diatom communities over six tropical reservoirs in Southeast Brazil and provided information on their ecology and distribution aiming bioassessment. The potential of water quality indicator diatom groups here outlined are in line with those reported in the literature and reinforce the importance of PEJU for the maintenance of ecological quality of reservoirs and reference conditions for the Metropolitan Region of São Paulo water sources.

Quantifying Phosphorus Sources and Sinks in the Gaoping River-Sea System in Southwestern Taiwan

This study aims to quantify sources and sinks of phosphorus (P) in the small mountainous river (SMR)-sea system in southwestern Taiwan. The Gaoping River (GP) exported total phosphorus (TP) at 1.08 × 109 mol year−1 into the GP coastal sea, corresponding to a global highest TP yield of 3.28 × 105 mol km−2 year−1 from the watershed during the study period. The river water TP comprised of 98.2% particulate P (PP) and 1.8% dissolved P. The PP was associated mainly with 10–63 μm particles and comprised 92.5% particulate inorganic P (PIP) and 7.5% particulate organic P (POP). The river flux of TP (or TP yield) was primarily determined by the sediment load which in turn was driven by river discharge varying with local climate variability. In the GP coastal sea, sedimentation rates decreased gradually with water depth, ranging from 0.032 to 1.62 g cm−2 year−1, and the highest rates were located on both sides of the GP Canyon, likely the result of typhoon impacts. The burial fluxes of the PP ranged from 0.02 to 0.84 mg cm−2 year−1, comprising approximately 88% PIP and 12% POP. The total deposition rates of sediment and PP were approximately 6.6 × 106 t year−1 and 4227 t year−1, respectively, in the study area, if integrated over an area of 3045 km2, with a maximum water depth of 1500 m. The burial efficiency of PP in the GP coastal sea ranged from 44 to 95%, which decreased generally with sampling location depth. A budget model showed that the imbalance of P sources (1.08 × 109 mol P year−1) and sinks (1.36 × 108 mol P year−1) implies about 90% of river inputs being recycled or exported out of the study area. The SMR margin that is associated with the canyon may act as an efficient conduit in transporting TP across the narrow margin into deep oceans.

Effects of light intensity on biomass, carbohydrate and fatty acid compositions of three different mixed consortia from natural ecological water bodies

This study investigated the effect of light intensity on three various microalga consortia collected from natural ecological water bodies (named A, B and C) towards their fatty acid profiling and fractions, carbohydrate and protein production at different light intensities of 100, 200 and 300 μmol m−2 s−1. The results indicating that increasing light intensity positively correlated with the lipid production than carbohydrate and protein. Irrespective to the solids (Total and Volatile Solid) content, lipids and carbohydrate has varied significantly. Consortia C showed higher productivity toward lipids, whereas consortia A and B accumulated more carbohydrate and protein, respectively. The microscopic images revealed the breakdown of cells during the increase in light intensity, in spite, the similar algal species were observed in all consortia experimented. Principal component analysis (PCA) revealed that low light intensity aid relatively in high protein, Total Nitrogen and Total Phosphorus, meanwhile high intensity attributed carbohydrates and unsaturated fatty acids (USFA) contents.

Time series trend analysis and prediction of water quality in a managed canal system, Florida (USA)

Water quality in the Everglades canal system discharging into the St. Lucie Estuary in south Florida is greatly influenced by anthropogenic activities. We analyzed the water quality parameters trend from 1979 to 2014 using seasonal trend decomposition and LOESS of four canals (C23, C24, C25, and C44). We also predicted the value of total nitrogen (TN) and total Phosphorus (TP) and turbidity from 2016 to 2020 using exponential smoothing and additive Holt-winters method. The main goals of this paper were to reveal long-term changes trends in water quality and identify the emphasis of management in the near future. We found that the change range of water quality parameters was different, but change rules were similar. The mean of DO at each station was in the range of 5.0∼6.3 mg l-1, and the colour was in the range of 5 ∼ 400PCU. The highest specific conductivity was 2250 μS cm-1 in C24 and the lowest was 125 μS cm-1 in C44, and the minimum turbidity was only 0.4 NTU at C25 and the maximum value was 90.3 NTU at C44. The mean value of TN at each station was C24>C44 >C23>C25, and TP was C24>C23>C44>C25. Nutrient export exhibited an upward trend for TN from all the basins and downward trend was present for TP. Water quality was influenced by rainstorm and non-point source pollution. Our predictions showed that TN and TP concentrations in C23 canal were higher than other three canals every month and turbidity of C44 canal was higher than other three canals. Therefore, improved best management practices should be implemented on land that have high TN and TP concentrations in runoff and leachate flowing into the C23 canal.

Biogeographical Patterns of Species Richness and Abundance Distribution in Stream Diatoms Are Driven by Climate and Water Chemistry.

In this intercontinental study of stream diatoms, we asked three important but still unresolved ecological questions: (1) What factors drive the biogeography of species richness and species abundance distribution (SAD)? (2) Are climate-related hypotheses, which have dominated the research on the latitudinal and altitudinal diversity gradients, adequate in explaining spatial biotic variability? and (3) Is the SAD response to the environment independent of richness? We tested a number of climatic theories and hypotheses (i.e., the species-energy theory, the metabolic theory, the energy variability hypothesis, and the climatic tolerance hypothesis) but found no support for any of these concepts, as the relationships of richness with explanatory variables were nonexistent, weak, or unexpected. Instead, we demonstrated that diatom richness and SAD evenness generally increased with temperature seasonality and at mid- to high total phosphorus concentrations. The spatial patterns of diatom richness and the SAD-mainly longitudinal in the United States but latitudinal in Finland-were defined primarily by the covariance of climate and water chemistry with space. The SAD was not entirely controlled by richness, emphasizing its utility for ecological research. Thus, we found support for the operation of both climate and water chemistry mechanisms in structuring diatom communities, which underscores their complex response to the environment and the necessity for novel predictive frameworks.

An evaluation of high frequency turbidity as a proxy for riverine total phosphorus concentrations

Surface water eutrophication resulting from excessive phosphorus (P) inputs is one of today's most challenging environmental issues. Riverine total phosphorus (TP) concentrations have high temporal variability, which complicates flux estimation. We evaluated the usefulness of high frequency in-situ turbidity measurements as a proxy for TP in Sävjaån, a river draining a mixed land use catchment (722 km2) in central Sweden. Turbidity was monitored every 10th–15th minute during 6 consecutive years (2012–2017). Linear regression showed a good relationship between high frequency turbidity and TP (r2 = 0.64) and could hence be used for comparison of flux estimation methods. Predictive power of the turbidity-TP relationship was not improved by adding seasons, hydrograph rising/falling limb or high/low stream discharge to the model which argues for a single transfer function relating turbidity and TP. Both TP and turbidity were log-normally distributed. However, flux estimates were sensitive to data transformation; predicted TP concentrations and fluxes based on log-transformed data were biased towards lower concentrations and fluxes compared to non-transformed data. In five of six years grab sample and high frequency estimated TP fluxes were similar (grab sample estimates −10% to +13% P transport compared to high frequency flux estimates). The exception was in 2013, when a 50-year spring flood occurred, and the grab sample estimated flux was 56% larger than that estimated from high frequency data. Thus, the flux comparisons were mostly affected by stream discharge, which underlines the importance of capturing high discharge episodes with, e.g. in situ sensors. While uncertainties regarding the use of turbidity as a proxy for TP remain, it is clear that credible water chemistry data can be obtained with current high frequency sensors. We conclude that high frequency data can be used to better understand catchment response to external pressures and gain insights into water quality that will be missed with grab sampling.

Systematic deviations from linear size spectra of lake fish communities are correlated with predator–prey interactions and lake‐use intensity

Size structure of organisms at logarithmic scale (i.e. size spectrum) can often be described by a linear function with a negative slope; however, substantial deviations from linearity have often been found in natural systems. Theoretical studies suggest that greater nonlinearity in community size spectrum is associated with high predator–prey size ratios but low predator–prey abundance ratios; however, empirical evaluation of the effects of predator–prey interactions on nonlinear structures remains scarce. Here, we aim to empirically explore the pattern of the size‐specific residuals (i.e. deviations from the linear regression between the logarithmic fish abundance and the logarithmic mean fish size) by using size spectra of fish communities in 74 German lakes. We found that nonlinearity was strong in lakes with high predator–prey abundance ratios but at low predator–prey size ratios. More specifically, our results suggest that only large predators, even if occurring in low abundances, can control the density of prey fishes in a broad range of size classes in a community and thus promote linearity in the size spectrum. In turn, the lack of large predator fishes may cause high abundances of fish in intermediate size classes, resulting in nonlinear size spectra in these lakes. Moreover, these lakes were characterized by a more intense human use including high fishing pressure and high total phosphorus concentrations, which have negative impacts on the abundance of large, predatory fish. Our findings indicate that nonlinear size spectra may reflect dynamical processes potentially caused by predator–prey interactions. This opens a new perspective in the research on size spectrum, and can be relevant to further quantify the efficiency of energy transfer in aquatic food webs.

Phosphorus Contents Re-visited After 40 Years in Muddy and Sandy Sediments of a Temperate Lagoon System

Worldwide, coastal water bodies suffer from anthropogenically elevated nutrient inputs, which led to eutrophication. Sediments in eutrophic systems are assumed to be an important internal nutrient source. The total phosphorus (TP) concentration (mg g-1 dry mass) is widely used as a proxy for the sediment nutrient load. 2-D distribution maps of TP concentrations are used for management plans, where areas of high TP values are marked in red. However, the sediment density is lowered at increasing water content, which can lead to different TP stocks per g m-2. The aim of this study was, to do a re-evaluation of TP concentrations and stocks in the model ecosystem of the Dars-Zingst Bodden chain, a typical lagoon system of the southern Baltic Sea. Sediment cores were taken at eight stations along transects from shallow to deeper parts of the lagoon. Samples were analyzed for TP, water and organic content, as well as density. This data set was compared to results from a sediment survey during the time of highest nutrient inputs (40 years ago) at the same sampling stations. TP concentrations from 40 years ago and today were in the same range. The highest TP concentrations (up to 0.6 mg TP g-1 dry mass) were found in the deeper basins and lowest concentrations in the shallow areas of the lagoon (down to 0.05 mg TP g-1 dry mass). However, normalization over dry bulk density reversed some results. The highest TP stocks (up to 5 g TP m-2) were then found in the shallow areas and lowest stocks (down to 0.2 g TP m-2) in the deeper parts of the lagoon. Some stations did not exhibit any differences of TP at all, even after including the dry bulk density. These findings suggest that there seems to be no up-, or downward trend in nutrient concentrations of sediments even after 25 years of reduced external nutrient inputs. Furthermore, TP stocks point to possible diffuse P entry pathways that counteract external nutrient reductions. These findings can have an impact on possible countermeasures for ecosystems rehabilitation, like sediment removal or nutrient reductions in the adjacent land.

Phytoplankton response to climate changes and anthropogenic activities recorded by sedimentary pigments in a shallow eutrophied lake

Studies that address the potential effects of climate and anthropogenic activities on lacustrine phytoplankton succession are scarce in the shallow lakes. In the present work, the succession of phytoplankton community inferred from sedimentary pigments has been investigated; the impacts of climate and anthropogenic activities on the succession have been evaluated by the generalized additive models (GAMs) in a shallow eutrophied lake, Lake Chaohu, located eastern China. The results show that phytoplankton succession can be divided into two periods: pre-1960s and post 1960s. The mean values of ββ‑Car and Chl a increased after the 1960s at both sites sampled, from 0.013 to 0.359, and 0.013 to 1.382 μg g−1, respectively (site C4), and from 0.015 to 0.530, and 0.010 to 0.921 μg g−1, respectively (site C14), reflecting significant increases of primary productivity since the 1960s. The percentage of diatoms and dinoflagellates preserved in sediments decreased from ~90% to ~15% since the 1960s, while cyanobacteria and green algae increased from ~5% to ~35%, respectively, reflecting the shift of the lake phytoplankton community. This succession was related to construction of the Chaohu Dam in 1963, increasing discharges of anthropogenic N and P into the Lake, and a generally warming environment as reflected by increasing average air temperatures. The results of GAMs showed aquatic total phosphorus (TP) concentration is the dominant contributor to phytoplankton community change, explaining 42.74%, 40.27%, 40.77% and 72.28% of the variance of total algae, cyanobacteria, green algae, and diatoms and dinoflagellates, respectively. The positive impacts of increasing TP concentrations on abundances of total algae, cyanobacteria, and green algae were observed during periods of relatively high TP concentrations since the mid-1970s. The positive responses of total algae, cyanobacteria, green algae and diatoms and dinoflagellates to increasing average air temperatures were observed since the mid-1990s, showing that a generally warmer environment facilitated algae proliferation.

Evaluating the effect of diffuse and point source nutrient transfers on water quality in the Kombolcha River Basin, an industrializing Ethiopian catchment

AbstractMany catchments in sub‐Saharan Africa are subject to multiple pressures, and addressing only point sources from industry does not resolve more widespread diffuse pollution from sediment and nutrient loads. This paper reports on a preliminary study of nutrient transfers into rivers in two catchments in the industrializing city of Kombolcha, North Central Ethiopia. Sampling of rivers and industrial effluents was done over two sampling periods in the wet season of 2013 and 2014. Catchments boundaries and land use map were generated from remote sensing and ground data. Higher total nitrogen (TN) concentrations were found from sub‐catchments with largest agricultural land use, whereas highest total phosphorus (TP) was associated with sub‐catchments with hilly landscapes and forest lands. Emissions from brewery and meat processing were rich in nutrients (median TN: 21–44 mg L−1; TP: 20–58 mg L−1) but contributed on average only 10% (range 4–80%) of the TN and 13% (range 3–25%) of the TP loads. Nutrient concentrations in the rivers exceeded environmental quality standards for aquatic life protection, irrigation, and livestock water supply. In Ethiopia, more than 85% of farmers operate on less than 2 ha of land, with concomitant pressure for more intensive farming. Land is exclusively owned by the State, reducing a sense of land stewardship. As the City of Kombolcha moves to agricultural intensification and increased industrialization, attention is needed to fill gaps in monitoring of nutrient pollution in rivers and use information to reconcile development with land use and its degradation.

Dynamics in the effects of the species–area relationship versus local environmental factors in bomb crater ponds

The species–area relationship (SAR) is a well-investigated subject raising questions nonetheless. We hypothesized that SAR can be modified by naturally extreme conditions (high pH, conductivity, and total phosphorus) in a small spatial scale. A bombing range was chosen as a sampling location with a densely scattered cluster of bomb crater ponds, which vary in size and in extremity to study the hypothesis. Macroinvertebrate communities from 25 bomb crater ponds were sampled, along with the macrophyte community, while pH, conductivity, total phosphorus, and area were also registered. A decision tree was used to separate extreme from normal ponds based on their chemical characteristics. SAR was found to be the dominant driving force, increasing species richness in the extreme ponds. However, in the normal ponds, the small island effect was observed. The macroinvertebrate communities and macrophyte community types are congruent in normal ponds. Our findings imply that rules in ecology cannot be handled rigidly and there are dynamics existing between the factors that influence the composition of a macroinvertebrate community that cannot be ignored at habitat restorations.

Sedimentary polycyclic aromatic hydrocarbons record recent anthropogenic activities near high-elevation Lake Sayram, northwest China

Mountain lakes are sensitive to natural perturbations and human activities. Profiles of anthropogenic polycyclic aromatic hydrocarbons (PAHs) in lake sediments serve as a natural archive from which human impacts on lakes can be reconstructed. Two parallel sediment cores (34 cm long) were extracted from Lake Sayram in the Tianshan Mountains of arid northwest China and dated using 210Pb and 137Cs. PAHs in the sediments were used to infer the past ∼150 years of anthropogenic impact on the lake. Results showed that PAH concentrations in the lake sediments were generally low, but nevertheless reflect some human activity. Benzo(ghi)perylene (BghiP) and indeno(1, 2, 3-cd)pyrene (IcdP) are typical markers of vehicular traffic, so significant correlations between PAH (especially BghiP and IcdP) and metal concentrations suggest that PAHs in sediments are effective proxies for anthropogenic activities. Furthermore, constrained cluster analysis revealed that the vertical profile of PAHs was characterized by three periods that correspond to changes in human activities. Prior to the 1960s, low PAH concentrations in the sediments generally indicate that the lake was virtually unaffected by human impact. BghiP and IcdP concentrations, however, displayed a minor peak in the 1950s, possibly reflecting transport from a remote polluted region via prevailing westerly winds. From the 1960s through the 1990s, relatively high values of PAHs, especially high molecular weight (HMW) PAHs BghiP and IcdP, and heavy metal enrichment factors (EFs), were related to increasing anthropogenic activities. After the 1990s, maxima of PAHs, HMW PAHs, BghiP, IcdP, EFs, together with highest total phosphorus (TP) and total organic carbon (TOC) values, reflect intensive human-related impact on the lake. The coincidence of limnological changes and local socio-economic development suggest that sedimentary PAHs record recent anthropogenic impact on Lake Sayram.

Nutrient Level of a Young Tropical Hydroelectric Dam Reservoir in Sarawak, Malaysia

Monitoring the nutrient level of a reservoir is crucial as excess nutrients can lead to hypoxia and fish kills in the reservoir. Hence, this study was carried out to examine the nutrient level of the Bakun reservoir, which is a newly built hydroelectric reservoir in Sarawak, Malaysia. Water samples were taken at five stations in the reservoir at three different depths (surface layer, 10 m, and 20 m) in November 2013. The present study demonstrated that Bakun reservoir contained low nitrite-nitrogen (≈ 0.005 mg/L) and nitrate-nitrogen (≈ 0.005 mg/L) concentrations but high five-day biochemical oxygen demand (≈ 4.73 mg/L) and organic Kjeldahl nitrogen (≈ 0.16 mg/L) concentrations indicating that organic pollution occurred in the reservoir. On the other hand, a mean total phosphorus concentration of 98.3 μg/L in the Bakun reservoir complied with the 200 μg/L standard value of Class II according to National Water Quality Standards in Malaysia. The nutrient level in the Bakun reservoir differed according to sampling stations and depths. Samplings stations located at Murum River downstream of the Murum dam construction site showed peak value of turbidity (182 FNU) and organic Kjeldahl nitrogen (0.45 mg/L) particularly at deeper water column. Batang Balui and Linau River were observed with higher five-day biochemical oxygen demand (&gt; 6 mg/L) compared to other stations. Station near to the Bakun hydroelectric dam contained relatively high nitrite-nitrogen and total phosphorus concentrations but low nitrate-nitrogen and organic Kjeldahl nitrogen concentrations. Anthropogenic activities such as floating house and Murum dam construction have influenced the nutrients level in the reservoir.&#x0D; Keywords : Bakun hydroelectric reservoir, dam construction, nitrogen, phosphorus, turbidity