Polybrominated diphenyl ethers (PBDEs) in sediment and bivalves from Korean coastal waters

Concentrations of polybrominated diphenyl ethers (PBDEs) were determined in sediment and bivalves collected from 25 coastal locations in Korea. Twenty major PBDE congeners were found in all sediment and bivalve samples. SigmaPBDE20 concentrations ranged from 0.45 to 494 ng/g, dry weight (average 27.8 ng/g dry weight) in sediments, and from 0.38 to 9.19 ng/g, wet weight (average 2.94 ng/g wet weight) in bivalves. The highest concentrations were found at locations near industrial complexes and large harbors, suggesting that human activities contribute to PBDEs contamination in Korean coastal environment. PBDE concentrations measured in our study, excluding BDE congener 209 (deca-BDE), in sediment and bivalves were lower than those reported from other countries; whereas BDE 209 concentrations were comparable to or higher than those reported from other countries. The predominant PBDE congener in sediments and bivalves was deca-BDE, which accounted for >90% and >60% of the total PBDE concentrations in sediment and bivalves, respectively. This is consistent with high consumption of deca-BDE for the flame-retardant market in Korea. Significant correlations existed among BDEs 28, 47, 99, 100, 153 and 154 in sediments and bivalves; however, BDEs 183 and 209 showed little correlation compared with less highly brominated congeners.     

Levels and distribution of polybrominated diphenyl ethers in plant, shellfish and sediment samples from Laizhou Bay in China

Polybrominated diphenyl ethers (PBDEs) are potentially harmful and persistent environmental pollutants. PBDEs concentrations are reported in plant, shellfish and sediment samples collected from Chinese Laizhou Bay. The summation operator(11)PBDE concentrations in plant and shellfish samples from Laizhou Bay were in the range of 70-5900ngg(-1) and 230-720ngg(-1) lipid, respectively. The summation operator(11)PBDEs concentrations in river sediment intervals samples ranged from 1.3 to 1800ng g(-1) dry weight. Pearson correlation analyses were performed on concentrations of PBDEs congeners of different sediment sample intervals. There were significant positive correlations for BDE 28 and BDE 100 (r=0.945, p<0.01), BDE 47 and BDE 99 (r=0.879, p<0.01), BDE 153 and BDE 154 (r=0.934, p<0.01), nona-BDEs and BDE 209 (r>0.934, p<0.01). BDE 209 was the predominant congener in all analyzed samples, consistent with the fact that deca-BDE technical mixtures are the dominant PBDEs product in Laizhou Bay. Data showed that PBDEs should be considered as an increasing pollution problem in the Laizhou Bay region.     

Levels and distributions of polybrominated diphenyl ethers,hexabromocyclododecane, and tetrabromobisphenol A in sediments from Taihu Lake,China

The concentrations and distribution of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA) were investigated in 28 sediment samples collected from Taihu Lake, Eastern China. The results showed that all three classes of compounds were detected in 28 sediment samples but that PBDEs were the main contaminants in the study area. The total PBDE concentrations ranged from 3.77 to 347 ng/g dry weight (dw) with a mean value of 72.8 ng/g dw, whereas the concentrations ranged from 0.168 to 2.66 and from 0.012 to 1.30 ng/g dw for HBCD and TBBPA, respectively. In all of the sediment samples, BDE-209 was the predominant congener, accounting for 95.9 to 98.6 % of the total PBDEs, which indicated that commercial mixtures of deca-BDEs were the main sources of PBDE contamination. Higher concentrations of PBDEs were found in samples collected from Meiliang Bay and Gonghu Bay near the inflow river, which suggested that inflow runoff might play an important role in the PBDE levels in Taihu Lake sediments.     

Congener-specific accumulation and environmental risk assessment of polybrominated diphenyl ethers in diverse Korean sewage sludge types

Industrial, domestic wastewater, and livestock sludge samples were collected from 23 wastewater treatment plants in Korea and analyzed for polybrominated diphenyl ethers (PBDEs). The concentrations of Σ₁₉PBDE ranged from 4.01 to 10,400 ng/g dry weight. The average Σ₁₉PBDE concentrations in industrial, domestic wastewater, and livestock sludge were 1,560?±?3,610, 402?±?148, and 27.6?±?50.4 ng/g dry weight, respectively. The composition of PBDEs differed according to the type of sludge. Among the PBDE congeners, BDE 209 was dominant in all sludge samples. After BDE 209, relatively high levels were found for BDE 28 and 47 from industrial sludge, BDE 47 and 99 from domestic wastewater sludge, and BDE 206, 207, and 208 from livestock sludge. Using hierarchical cluster analysis, sludges were divided into three groups according to PBDE congener composition. A risk assessment of PBDEs in sludge used for soil amendment was carried out. Preliminary results indicated that the potential risk of soil exposed to PBDEs in sludge was relatively low.     

Polybrominated diphenyl ethers in surface sediments from principal watersheds of Shanghai, China: levels, distribution, influencing factors, and risk assessment

Fourteen and 17 sediment samples were collected from three main rivers of Shanghai in July and November, respectively. Eight polybrominated diphenyl ether (PBDE) congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, and BDE-209) were detected in these samples to clarify the pollution status in the metropolis. Instrumental analyses showed that the concentrations of ∑₈PBDEs ranged from 10.97 to 64.05 ng/g dry weight (dw), with an average value of 29.71 ng/g dw. BDE-209 was the predominant congener accounting for more than 97 % of total PBDEs, followed by BDE-47 and BDE-99. Remarkable spatial and seasonal distributions of PBDE concentrations were observed, suggesting that local sources, seasonal climates, and hydrologic conditions might be the influencing factors. Moderate correlations (r ²?=?0.28–0.51, p?<?0.05) were found between total organic carbon and PBDEs, which indicated that organic carbon content influenced the distributions of PBDEs in sediment of Shanghai at some extent. Hazard quotients revealed PBDEs posed no potential risk to benthic organisms in the study area at present.     

Distribution of polybrominated diphenyl ethers in the surface sediments of the Taihu Lake, China

Twenty-eight sediment samples were collected from the Taihu Lake and analyzed to acquire information about the levels, distribution, possible sources, time trend and inventory of polybrominated diphenyl ethers (PBDEs) in the Taihu Lake. Our results showed that the most abundant BDE congeners in surface sediments were BDE-47, 99 and 209, with a median value of 0.124, 0.279, and 22.72 ng(gdw)(-1), respectively. The levels of BDE-209 in our samples were much higher relative to those of the other BDE congeners and made up more than 80% of the PBDEs levels in almost all samples. Disregarding BDE-209, among the seven PBDEs (BDE-28, 47, 99, 100, 153, 154, 183) more concerned, the most abundant ones were BDE-47 and 99, which contributed 44.65% (ranged from 29.02% to 73.11%), 24.24% (ranged from 2.27% to 39.66%) to ∑(7)PBDEs, respectively. The correlation between PBDE and TOC was poor, indicating that PBDEs concentrations in sediments of the Taihu Lake were controlled not only by TOC contents, but also by a combined effect of transport, mixing, depositional mechanisms associated with PBDEs, uncontaminated sediments, or fresh input of PBDEs. As expected, the time trend of PBDEs concentration in surface sediment from Taihu Lake were increasing, and the inventory of ∑(25)PBDEs and BDE-209 were estimated to be 3668 kg and 26296 kg.     

Tributyltin distribution and producing androgenic activity in water,sediment, and fish muscle

This study investigated the concentrations of Tributyltin (TBT) in water, sediment, and fish muscle samples taken from Kaohsiung Harbor and Kaoping River estuary, Taiwan. TBT concentrations in water and sediment samples ranged from less than 18.5 to 34.1 ng Sn L^?1 and from 2.44 to 29.7 ng Sn g^?1 weight per weight (w/w), respectively. Concentrations in the TBT‐contaminated fish muscle samples ranged from 10.8 to 79.6 ng Sn g^?1 w/w. The TBT concentrations in fish muscle were higher than those in water and sediment samples. The fish muscle/water TBT bioconcentration factor (BCF) ranged from 590 to 3363 L kg^?1. Additionally, the water samples were assessed for androgenic activity with an MCF7‐AR1 human breast cancer cell line. The androgenic activity ranged from 0.94 to 3.1 ng‐dihydrotestosterone per litre water (ng‐DHT L^?1). Higher concentrations of TBT in water and sediment samples occurred in the dry season, but the androgenic activity had higher values in the rainy season.     

Distribution of polychlorinated biphenyls and polybrominated diphenyl ethers in birds of prey from Switzerland

Polychlorinated biphenyls (PCBs) and the structurally related polybrominated diphenyl ethers (PBDEs) have been associated with chronic neurotoxicity involving reduced motor activity and impaired attentiveness. Such neurobehavioral effects indicate that the central nervous system may represent an important target organ for the action of these persistent contaminants in wildlife. As a consequence, the brain of different terrestrial and aquatic birds collected in Switzerland was analysed for PCBs and PBDEs. In parallel, the same contaminants were examined in the accompanying adipose tissue. After clean-up by means of glass columns containing acidified silica, deactivated alumina and anhydrous sodium sulphate, the samples were analysed by high resolution gas chromatography/tandem mass spectrometry (HRGC-MS/MS). Median PCB concentrations in the brain (sum of PCB 28, PCB 52, PCB 101, PCB 118, PCB 138, PCB 153 and PCB 180) ranged between 13 ng g(-1) wet weight (ww) in blackbirds (Turdus merula) and 428 ng g(-1) ww in sparrow hawks (Accipiter nisus). Median PBDE concentrations in the brain (sum of BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, BDE 154 and BDE 183) ranged from below the decision limit in buzzards (Buteo buteo) and blackbirds, to 14 ng g(-1) ww in sparrow hawks. After correction for the respective lipid content, higher PCB or PBDE concentrations in brain compared to adipose tissue, were found in three sparrow hawks, four buzzards and in all investigated blackbirds. These results suggest that a deficit in the neuroprotective function of the blood-brain barrier may cause unexpected levels of PCBs and PBDEs in the central nervous system.     

Aliphatic Hydrocarbons Distribution in Sediment Cores of Select Creeks in Delta State,Nigeria

The spatial and seasonal changes in the distribution, composition, and concentrations of aliphatic hydrocarbons were investigated in sediment cores of Ubeji, Ifie, and Egbokodo Creeks in the Niger Delta, Nigeria. A total of 222 sediment core samples were collected during the wet season (August 2010) and the dry season (January 2011). The samples were dried, soxhlet extracted, fractionated and analyzed for aliphatic hydrocarbons by using a gas chromatograph with flame ionization detector (GC-FID). The concentrations of aliphatic hydrocarbons ranged from 37 to 286,894 μg/kg (wet season) and from 30 to 11,773 μg/kg (dry season). The concentrations of n-alkanes for a number of stations in this study are comparable to sites with high anthropogenic activities in the Niger Delta. The carbon preference index (CPI) and the pristane/phytane ratios showed that the major source of hydrocarbon pollution in the sediment core was from petrogenic origin.     

Occurrence of polybrominated diphenyl ethers (PBDEs) and 2,2’,4,4’,5,5’-hexabromobiphenyl (BB-153) in water samples from the Diep River, Cape Town, South Africa

Until recently, studies reporting the concentrations of polybrominated diphenyl ethers (PBDEs) as well as polybrominated biphenyls (PBBs) are generally scarce in the literature. Consequently, this study was aimed to investigate the occurrence and concentrations of certain PBDE congeners (BDE 28, 47, 100, 99, 154, 153, 183 and 209) and BB 153 in river water samples collected bi-monthly from the Diep River. The routine analyses of the target compounds were performed using a high-capillary GC–microelectron capture detection, while their structural elucidation was assessed using GC-TOF-MS technique. The overall mean concentrations of the sum of the eight PBDE congeners were 2.60, 4.83 and 4.29 ng/L for the upstream, point of discharge and downstream sampling points, respectively. Similarly, the overall mean concentrations of BB 153 were 0.25, 4.85 and 1.56 ng/L for the upstream, point of discharge and downstream sampling points, respectively. BDE 47 was the dominant congener found in these samples contributing between 19 and 26 % to the total PBDEs across the sampling points. The statistical analyses performed on the results obtained showed that all the congeners, except BDE 209 in certain instances, had strong positive correlations with one another, thus suggesting that these contaminants could be emanating from the same source. In this study, potential sources of these pollutants other than WWTP discharges into the investigated river were also identified. However, the relatively high concentrations of the target compounds found at the point of discharge sampling point coupled with the large volume of treated effluent being discharged suggested that the contributions from this source could be very significant over time.     

Occurrence and concentrations of polybrominated diphenyl ethers in sewage sludge from three wastewater treatment plants in Kuwait

Polybrominated diphenyl ether (PBDE) concentrations were measured in sewage sludge samples collected from three wastewater treatment plants in Kuwait over a six month period. PBDEs were detected in all samples analyzed and there were significant differences between the three wastewater treatment plants. The mean (and range) of summation PBDEs concentrations measured are as follows: Jahra 52.5 ng g(-1) (5.7-169.5 ng g(-1)); Reqqa, 144 ng g(-1) (32-296 ng g(-1)); Umm Haylaman, 377 ng g(-1) (23-1599 ng g(-1)). The differences in concentrations of the sum of penta congeners were consistently different at the three treatment plants with values increasing in the order: Jahra相似文献   

Polybrominated diphenyl ethers in sediments of the Daliao River Estuary, China: levels, distribution and their influencing factors

The concentrations, compositional profiles, possible sources of polybrominated diphenyl ethers (PBDEs) in sediments of the Daliao River Estuary as well as the factors influencing the distribution of PBDEs were investigated. The total concentrations of PBDEs ranged from 0.13 to 1.98 ng g⁻¹ d.w. BDE209 was the dominating congener in all sediment samples, indicating the pollution of PBDEs in the Daliao River Estuary mainly came from the use of deca-BDE commercial mixtures. The intrusion of sea waters promoted the deposition of the colloid-associated PBDEs in the estuary. There were significantly negative correlations between PBDE concentration in sediment with pH value and salinity in the bottom water. The higher river flow in the flood season (summer) obviously accelerated the transport of PBDEs, and thereby increased the risk of PBDE contamination to the deep ocean. Moreover, a positive correlation between TOC and PBDE distributions was observed, suggesting that TOC regulated the distributions of PBDEs in sediments of Daliao River Estuary.     

Polybrominated diphenyl ethers in house dust in Singapore

The use of polybrominated diphenyl ethers (PBDEs) as flame retardants in Singapore is not strictly regulated; therefore these compounds can be readily found in furniture, electronic devices, and building materials. This study was the first of its kind to be conducted in Singapore to measure concentrations of PBDEs in house dust. Samples were collected from 31 homes in various locations across the island-state of Singapore, and a total eight PBDEs congeners were measured. PBDEs were detected in all 31 dust samples and the number of BDE congener detected per home ranged between 3 and 8. The most abundant BDE congeners found were BDE 47, 99 and 209, with a median value of 20 ng g(-1) dust, 24 ng g(-1) dust and 1000 ng g(-1) dust, respectively. BDE 209 contributed 88% to the median of all the congeners, and BDE 47 and 99 contributed 1.8% and 3.5%, respectively. Different congener profiles were observed between this and studies conducted elsewhere, which is consistent with the use of different commercial PBDE around the world. No significant correlations between PBDE dust levels and residential characteristics (number of TVs and computers, floor area or flooring material) were observed. The daily intake of PBDEs via the inhalation pathway was estimated. House dust may be regarded as the most important exposure route of PBDEs for children.     

Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Sediment Cores of Selected Creeks in Delta State,Nigeria

The spatial and seasonal distribution and concentrations of polycyclic aromatic hydrocarbons (PAHs) were investigated in core sediments of Ubeji, Ifie, and Egbokodo creeks in the Niger Delta, Nigeria. A total of 222 core sediment samples were collected during the wet season (August 2010) and the dry season (January 2011). The samples were dried, Soxhlet extracted, fractionated, and injected into a gas chromatograph with flame ionization detector (GC-FID). The concentrations of PAHs ranged from not detected to 2,654 μg/kg (wet season) and not detected to 3,513 μg/kg (dry season). In general, the concentrations of PAHs for a number of stations in this study are comparable to sites with high anthropogenic activities in the Niger Delta. The toxicity risk assessment based on the total BaP equivalent quotient of the seven carcinogenic PAHs (BaA, Chry, BbF, BkF, BaP, DBA, and Iper) was 97.416 μg/kg and did not exceed the method B cleanup level for benzo(a)pyrene (137 μg/kg), according to toxic equivalency factors, which implied that PAHs in sediments of the present study currently have minimal adverse effects. This study provided information on the concentrations and profiles of PAHs sediment cores, which is useful for source diagnosis, environmental quality management, contamination history, and environmental forensic studies.     

Polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in pike from Swedish waters with emphasis on temporal trends, 1967-2000

Temporal trends of five tetra- to hexabromodiphenyl ethers [BDE47, BDE99, BDE100, BDE153 and BDE154) and two methoxy-tetraBDEs [6-methoxy-2,2',4,4'- tetraBDE (6-MeO-BDE47) and 2'-methoxy-2,3',4,5'- tetraBDE (2'-MeO-BDE68)] in pike from Lake Bolmen for the years 1967-2000, are presented. All BDE congeners show increasing trends up to the mid-1980s (Sigma5PBDE from 60 to 1600 pg/g wet weight in 1989, i.e. a more than 25-fold increase), and then decrease or level off. The decreasing trends of PBDEs after the 1980s were considerably slower in the present study than was found in a study of an environmental matrix from the Baltic Proper covering the same time period. This difference suggests local sources near Lake Bolmen. The MeO-BDEs show initially decreasing concentrations, which for 6-MeO-BDE47 continues until the early 1990s. The concentrations of 6-MeO-BDE47 in herring from five locations along the Swedish coast increased from south to north in the Baltic Sea. No correlation between the concentrations of the BDE congeners and the MeO-BDEs was observed, indicating sources other than PBDEs for these compounds. The presence of MeO-BDEs in fish from lakes with different characteristics suggests a natural production not favoured by eutrophication, or dependent on sampling season and geographical location.     

Levels,congener profile and inventory of polychlorinated biphenyls in sediment from the Songhua River in the vicinity of cement plant,China: a case study

This study investigated the contamination levels, homologue, and congener profiles and evaluated the residue inventory of polychlorinated biphenyls (PCBs) in sediment of the Songhua River in the vicinity of cement plant. The total concentration of detected 35 PCB congeners ranged from 1.12 to 2.19 ng/g dry weight (dw) in sediment, with a mean value of 1.56 ng/g dw, and the concentration of PCBs decreased in the following order: the downstream?>?cement plant?>?upstream. The results of total organic carbon (TOC)-normalized PCB concentrations indicate that the sediments have low potential ecological risk in this area. The study results on homologue and congener of PCBs show that the emissions from cement production could be the major sources of PCBs in sediment, and the low-chlorinated PCBs will be exchanged among air, water, and sediment with increasing temperature during summer and flow to downstream with water during the wet season. The spatial density and total burden of PCBs in the surface sediments were 17.2 ng/cm² and 1.2 kg, respectively. To our knowledge, this study is the first to explore the pollution characteristics of unintentionally produced PCB emissions from cement industry by means of monitoring sediment samples.     

Levels, compositions, and inventory of polybrominated diphenyl ethers in sewage sludge of Guangdong Province, South China

Polybrominated diphenyl ethers (PBDEs) were measured in sewage sludge samples collected from major wastewater treatment plants in Guangdong Province, South China. Concentrations of ∑₃₉PBDE (all 39 compounds including tri- to hepta- PBDE congeners except for BDE-209) ranged from 3.6 to 428 ng/g dw with a mean value of 67.4 ng/g dw and a median value of 25.9 ng/g dw, and those of BDE-209 ranged from 9.9 to 5,010 ng/g dw (mean 1,024 ng/g dw and median 824 ng/g dw). The PBDE mixtures detected were mainly comprised of penta-, octa-, and deca-BDEs, with deca-BDE as the dominant constituent. The most abundant congeners, excluding BDE-209, were BDE-47, BDE-99, and BDE-183. Good correlations were found among the concentrations of BDE-47, BDE-99, BDE-100, BDE-138, and BDE-154 (r?>?0.8). However, poor correlations were found between the concentrations of BDE-209 and all other congeners (r?<?0.3). This fact suggests that most tri- to hepta-BDEs detected did not originate from decomposition of deca-BDE. The estimated annual emission of ∑_allPBDEs, ∑₃₉PBDEs, penta-BDE, octa-BDE, and deca-BDE to the Pearl River Delta environment (PRD), based on the sludge samples analyzed, amounts to 232, 20.2, 5.5, 1.7, and 212 kg per year, implicating sewage sludge as a significant source of PBDEs to the PRD environment.     

Organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in Singapore's coastal marine sediments

Persistent organic pollutants (POPs) are ubiquitous pollutants in the marine environment, particular in coastal areas affected by industry and shipping traffic. POPs are known for their recalcitrance and toxicity in the environment, and there is increasing concern over their global distribution and impact upon wildlife. Marine surface sediment samples taken within 6 km of the coastline of Singapore were analyzed to determine prevailing concentrations of organochlorine pesticides (OCPs), polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs). Total PCB concentrations varied widely from 1.4 to 329.6 ng/g (average 73.9 ng/g), where high concentrations were detected at sample locations closest to industrial areas with intensive shipping traffic. Total DDT concentrations ranged from 2.2 to 11.9 ng/g (average 6.7 ng/g) and were lower than the concentration range of 3.3-46.2 ng/g measured for total HCH (average 18.1 ng/g). Ratios of DDT/(DDE+DDD) in sediments do not indicate recent inputs of DDT into Singapore's marine environment, but high concentrations of alpha-HCH and gamma-HCH show evidence for the usage of HCHs in Southeast Asia. Peak concentrations of cis- and trans-Chlordane were 10 ng/g. Among the PBDE congeners BDE 47, 99, and 100 only BDE 47 could be detected at a range of 3.4-13.8 ng/g (average 6.2 ng/g). The levels of OCPs, PCBs and PBDEs were compared to available data for other countries in Asia, and indicated relatively moderate levels of contamination. Peak concentrations of PCBs, HCH isomers, Chlordane, Heptachlor, Heptachlor epoxide and Dieldrin have the potential to induce ecotoxicological impacts based on levels specified in the sediment quality standards of the USEPA and Canadian Council of Ministers of the Environment.     

Levels of polybrominated diphenyl ethers (PBDEs) in breast milk from Beijing, China

The levels of polybrominated diphenyl ethers (PBDEs) in breast milk from Beijing, China, were studied. The 6 predominant PBDEs congeners (BDE47, BDE99, BDE100, BDE153, BDE154 and BDE183) in 23 pooled breast milk samples from 205 mothers living in Beijing were measured. Mean and median of SigmaPBDEs concentrations in all samples were 1.12ngg(-1) lipid and 1.07ngg(-1) lipid, respectively. The Statistical difference in SigmaPBDEs concentrations was found between urban areas (1.22ngg(-1) lipid, n=14) and rural areas (0.97ngg(-1) lipid n=9). The sum of BDE47 and BDE153 accounted for more than 70% of SigmaPBDEs in most samples. The significant correlation was found between the SigmaPBDEs in pooled samples and average of consumption of food of animal origin in the pools in urban area. However, there was no correlation was found between the SigmaPBDEs in pooled samples and average of consumption of food of animal origin in the pools in rural area of Beijing. The current study showed that the level of PBDEs in breast milk from Beijing was lower than that from South China and some developed countries such as USA and Sweden.     

Olive tree, Olea europaea L., leaves as a bioindicator of atmospheric PCB contamination

Olive tree leaf samples were collected to investigate their possible use for biomonitoring of lipophilic toxic substances. The samples were analyzed for 28 polychlorinated biphenyls (PCB) congeners. Twelve congeners were detected in the samples. PCB-60, 77, 81, 89, 105, 114, and 153 were the most frequently detected congeners ranging from 32 % for PCB-52 to 97 % for PCB-81. Σ₁₂PCBs concentration varied from below detection limit to 248 ng/g wet weight in the sampling area, while the mean congener concentrations ranged from 0.06 ng/g (PCB-128?+?167) to 64.2 ng/g wet weight (PCB-60). Constructed concentration maps showed that olive tree leaves can be employed for the estimation of spatial distrubution of these congeners.