Inter-laboratory study to improve the quality of the analysis of nutrients in rainwater chemistry

This paper describes the results of an inter-laboratory study conducted for the analysis of nutrients (nitrate, ammonium, phosphate, total nitrogen (TN), and total phosphorus (TP)) in natural rainwater. For this purpose, rainwater samples were collected and aggregated in Singapore and homogenized. These samples were immediately filtered through 0.45 μm membrane filters and autoclaved for 15 min at 80 °C in order to stabilize the nutrients. The homogeneity and the stability of nutrients were rigorously tested for a period of three months initially. Upon ensuring the homogeneity and stability, the samples were distributed to 15 different laboratories from various countries around the world (Australia, Brazil, India, Mauritius, Singapore, Slovenia, Spain, Taiwan, and USA). Almost all laboratories have reported the analytical results for nitrate whereas only 8 of the 15 laboratories reported results for other nutrients such as ammonium, phosphate, TN, and TP. The discrepancy was mainly due to the presence of these nutrients in low concentration levels (particularly ammonium ion and phosphate). Not all the laboratories were equipped with analytical capabilities to conduct the analysis of nutrients in low concentration levels. Further, the uncertainty associated with the analysis of TN and TP restricted the number of laboratories that could report their analytical data on nutrients. All 14 laboratories reported nitrate-nitrogen results which were in good agreement with each other (0.68 ± 0.07 mg l^?1). Similarly, the results of TN and TP were also comparable among at least 8 laboratories. This inter-laboratory study on the analysis of nutrients in natural rainwater, conducted for the first time, provided an opportunity to the participating laboratories to assess and improve their laboratory performance, thereby, improving the quality of their analytical data.     

Anti-barnacle biofouling coatings for the protection of marine vessels: synthesis and progress

Environmental Science and Pollution Research - Marine biofouling has gnawed both mobile and non-mobile marine structures since time immemorial, leading to the deterioration of designed operational...     

Heat stress alters serum lipid metabolism of Chinese indigenous broiler chickens-a lipidomics study

Environmental Science and Pollution Research - Heat stress (HS) by high-temperature environment reduced the production performance of poultry and caused losses to the breeding industry. The present...     

Biochemical constituents and bioaccumulation as biomarkers in the green mussel Perna viridis with reference to silver and chromium toxicity

The sublethal effect of silver and chromium on some biochemical constituents was studied in the green mussel Perna viridis. The results revealed an overall reduction in total protein, total DNA, total RNA, glycogen, protein bound sugars and total lipid in the gill, hepatopancreas, and ovary of the mussels exposed to metals individually and in combination when compared with control. It was apparent that mussels exposed to mixtures of metals exhibited highly significant (P?P?P?相似文献   

Particulate emissions from a stationary engine fueled with ultra-low-sulfur diesel and waste-cooking-oil-derived biodiesel

Stationary diesel engines, especially diesel generators, are increasingly being used in both developing countries and developed countries because of increased power demand. Emissions from such engines can have adverse effects on the environment and public health. In this study, particulate emissions from a domestic stationary diesel generator running on ultra-low-sulfur diesel (ULSD) and biodiesel derived from waste cooking oil were characterized for different load conditions. Results indicated a reduction in particulate matter (PM) mass and number emissions while switching diesel to biodiesel. With increase in engine load, it was observed that particle mass increased, although total particle counts decreased for all the fuels. The reduction in total number concentration at higher loads was, however, dependent on percentage of biodiesel in the diesel-biodiesel blend. For pure biodiesel (B100), the reduction in PM emissions for full load compared to idle mode was around 9%, whereas for ULSD the reduction was 26%. A large fraction of ultrafine particles (UFPs) was found in the emissions from biodiesel compared to ULSD. Nearly 90% of total particle concentration in biodiesel emissions comprised ultrafine particles. Particle peak diameter shifted from a smaller to a lower diameter with increase in biodiesel percentage in the fuel mixture.     

A study of gas/particle partitioning of SVOCs in the tropical atmosphere of Southeast Asia

Gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were collected at a tropical site in Southeast Asia over 12-h periods during November and December 2006 to determine their gas/particle distributions by analyzing integrated quartz filter and polyurethane foam samples. Gas/particle partitioning coefficients, K_p, were calculated, and their relationship with the subcooled liquid vapor pressure p_L^o for both PAHs and PCBs was investigated. The regressions of log K_p vs. log p_L^o for most of samples gave high correlations for both PAHs and PCBs and the slopes were statistically shallower than ?1, but they were relatively steeper than those obtained in temperate zones of the Northern Hemisphere. By comparison, the particle-bound fraction of low molecular weight (LMW) PAHs was underestimated by both Junge-Pankow adsorption and K_OA (octanol–air partition coefficient) absorption models, while the predicted values agree relatively better with those observed ones for high molecular weight (HMW) PAHs. In addition, the adsorption onto the soot phase (elemental carbon) predicted accurately the gas/particle partitioning of PAHs, especially for LMW compounds. On the other hand, the K_OA absorption model using the measured organic matter fraction (f_OM) value fitted the PCB data much better than the adsorption model did, indicating the sorption of nonpolar compounds to aerosols might be dominated by absorption into organic matters in this area.     

Removal of cyanotoxins from surface water resources using reusable molecularly imprinted polymer adsorbents

Introduction

Microcystins (MCs; cyclic heptapeptides) are produced by freshwater cyanobacteria and cause public health concern in potable water supplies. There are more than 60 types of MCs identified to date, of which MC-LR is the most common found worldwide. For MC-LR, the WHO has established a threshold value of 1???g?L^?1 for drinking water. The present MCs removal methods such as coagulation, flocculation, adsorption, and filtration showed low efficiency for removing dissolved MC fraction from surface waters to the stipulated limit prescribed by WHO based on MC health impacts. The search for cost-effective and efficient removal method is still warranted for remediation of dissolved MC-LR-contaminated water resources.

Materials and methods

Molecularly imprinted polymer (MIP) adsorbent has been prepared using non-covalent imprinting approach. Using MC-LR as a template, itaconic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross-linking monomer, a MIP has been synthesized. Computer simulations were used to design effective binding sites for MC-LR binding in aqueous solutions. Batch binding adsorption assay was followed to determine binding capacity of MIP under the influence of environmental parameters such as total dissolved solids and pH.

Results and discussion

The adsorptive removal of MC-LR from lake water has been investigated using MIPs. The MIP showed excellent adsorption potential toward MC-LR in aqueous solutions with a binding capacity of 3.64???g?mg^?1 which is about 60% and 70% more than the commercially used powdered activated carbon (PAC) and resin XAD, respectively. Environmental parameters such as total organic carbon (represented as chemical oxygen demand (COD)) and total dissolved solids (TDS) showed no significant interference up to 300?mg?L^?1 for MC-LR removal from lake water samples. It was found that the binding sites on PAC and XAD have more affinity toward COD and TDS than the MC-LR. Further, the adsorption capacity of the MIP was evaluated rigorously by its repeated contact with fresh lake water, and it was found that the adsorption capacity of the MIP did not change even after seven adsorption/desorption cycles. The contaminated water of MC-LR (1.0???g?L^?1) of 3,640?L could be treated by 1?g of MIP with an estimated cost of US $1.5.

Conclusions

The adsorption capacity of the MIP is 40% more than commercially used PAC and resins and also the polymer showed reusable potential which is one of the important criteria in selection of cyanotoxins remediation methods.     

Three-dimensional printing of molluscan shell inspired architectures via fused deposition modeling

Environmental Science and Pollution Research - Nature always astonishes us with its marvelous creations which act as a model for acquiring a solution to complex human problems, this practice of...