DISOLVED OXYGEN PERFORMANCE IN DEGRADATION OF TOTAL PETROLEUM HYDROCARBONS BY EX SITE ACTIVATED SLUDGE

Contamination of soil by the activities of exploration, production and disposal of oil waste into the environment causes serious damage to the environmental ecosystem, the target of processing by the activated sludge as a model for remediation of petroleum contaminated site. Optimization of oxygen supply becomes special attention in aerobic bioprocess for optimizing the growth of microorganisms to degrade total petroleum hydrocarbons. Thus, the study was focused on determining the performance of dissolved oxygen in degradation of total petroleum hydrocarbons by ex situ activated sludge. The research used biological methods (bioremediation), with the ratio of contaminated soil to water was 20:80%(w/v) and a soil size 40/50 mesh. The degradation process was carried out with 15% and 20% (v/v) activated sludge put into the bioreactor slurry with a capacity of 4 liters and stirring was 90 rpm at a temperature of 30oC as well as aeration and nutrient injection into the bioreactor. TPH analysis was measured by the gravimetric method. The results obtained showed that the performance of dissolved oxygen increased well in the bioreactor slurry at 15% (v/v) and 20% (v/v) activated sludge concentrations was 3.31–8.57 mg/L and 3.5–8.21 mg/L respectively, which had an impact on the level of TPH degradation, namely from 18,000 µg/g to 2870 µg/g and 18,000 µg/g to 1970 µg/g during the 49 days remediation period. In general, activated sludge shows good performance throughout the remediation period.

Stratification in the North Sea: response to different atmospheric forcing

<p>On-set of spring stratification is one of the physical factors that influence the productivity of the continental shelves. Atmospheric convective mixing determines the on-set of spring stratification. This is particularly important in seasonally stratified shelf seas, where stratification constrain nutrient injection to the water column. Higher productivity in stratified period relies on intermittent diapycnal mixing events. Thus, the on-set and intensity of stratification is important for the functioning of the shelf-sea ecosystem. In this study, we investigate on-set of stratification, and its relation with the atmospheric conditions as well as imprints of sub-mesoscale features. We use high resolution in-situ measurements from 10 glider deployments, spanning over 18 months in the central North Sea. Focusing on two consecutive winters, we present year to year variability in the timing and intensity of stratification. An early initiation of stratification is observed in 2018/2019, which is also intense compared to the previous year of 2017/2018. We find that reduced wind stress and net air-sea heat fluxes result in an early on-set of stratification in 2018/2019. In February 2019, intermittent increases in chlorophyll are observed, corresponding to a minimum in sea-to-air heat loss. Similarly, in 2019 an earlier spring bloom is observed. We investigate this period with NEMO model outputs at 7km resolution (AMM7) and show a similar response, emphasizing the influence of atmospheric variability on dynamics of the shelf-sea.   </p>

Low-Abundance Dietzia Inhabiting a Water-Flooding Oil Reservoir and the Application Potential for Oil Recovery

With the development of molecular ecology, increasing low-abundance microbial populations were detected in oil reservoirs. However, our knowledge about the oil recovery potential of these populations is lacking. In this study, the oil recovery potential of low-abundance Dietzia that accounts for less than 0.5% in microbial communities of a water-flooding oil reservoir was investigated. On the one hand, Dietzia sp. strain ZQ-4 was isolated from the water-flooding reservoir, and the oil recovery potential was evaluated from the perspective of metabolisms and oil-displacing test. On the other hand, the strain has alkane hydroxylase genes alkB and P450 CYP153 and can degrade hydrocarbons and produce surfactants. The core-flooding test indicated that displacing fluid with 2% ZQ-4 fermentation broth increased 18.82% oil displacement efficiency, and in situ fermentation of ZQ-4 increased 1.97% oil displacement efficiency. Furthermore, the responses of Dietzia in the reservoir accompanied by the nutrient stimulation process was investigated and showed that Dietzia in some oil production wells significantly increased in the initial phase of nutrient injection and sharply decreased along with the continuous nutrient injection. Overall, this study indicates that Dietzia sp. strain has application potential for enhancing oil recovery through an ex situ way, yet the ability of oil recovery in situ based on nutrient injection is limited.

Cephalic phase insulin secretion is KATP channel independent

Glucose-induced insulin secretion from pancreatic β-cells critically depends on the activity of ATP-sensitive K+channels (KATPchannel). We previously generated mice lackingKir6.2, the pore subunit of the β-cell KATPchannel (Kir6.2−/−), that show almost no insulin secretion in response to glucosein vitro. In this study, we compared insulin secretion by voluntary feeding (self-motivated, oral nutrient ingestion) and by forced feeding (intra-gastric nutrient injection via gavage) in wild-type (Kir6.2+/+) andKir6.2−/−mice. Underad libitumfeeding or during voluntary feeding of standard chow, blood glucose levels and plasma insulin levels were similar inKir6.2+/+andKir6.2−/−mice. By voluntary feeding of carbohydrate alone, insulin secretion was induced significantly inKir6.2−/−mice but was markedly attenuated compared with that inKir6.2+/+mice. On forced feeding of standard chow or carbohydrate alone, the insulin secretory response was markedly impaired or completely absent inKir6.2−/−mice. Pretreatment with a muscarine receptor antagonist, atropine methyl nitrate, which does not cross the blood–brain barrier, almost completely blocked insulin secretion induced by voluntary feeding of standard chow or carbohydrate inKir6.2−/−mice. Substantial glucose-induced insulin secretion was induced in the pancreas perfusion study ofKir6.2−/−mice only in the presence of carbamylcholine. These results suggest that a KATPchannel-independent mechanism mediated by the vagal nerve plays a critical role in insulin secretion in response to nutrientsin vivo.

In-stream uptake and retention of C, N and P in a supraglacial stream

Supraglacial streams form annually during the melt season, transporting dissolved solutes from the melting ice and snowpack to subglacial flow paths and the glacier terminus. Although nutrient and carbon processing has been documented in other supraglacial environments (cryoconite holes, snowpack), little work has examined the potential for in-stream nutrient retention in supraglacial streams. Here we carried out a solute nutrient injection experiment to quantify NH3+, PO43−and labile dissolved organic carbon (DOC) retention in a supraglacial stream. The experiment was performed on a 100 m stream reach on Mendenhall Glacier, an outlet glacier on the Juneau Icefield, southeastern Alaska, USA. The study stream contained two distinct reaches of equal length. The first reach had a lower velocity (0.04 ms−1) and contained abundant gravel sediment lining the ice–water interface, while the second reach was devoid of bedload sediment and had an order-of-magnitude higher velocity. At the end of the second reach, the stream emptied into a moulin, which is typical of supraglacial streams on this and other temperate glaciers. We found that N and P were transported largely conservatively, although NO3−increased along the reach, suggestive of nitrification. Labile DOC was retained slightly within the stream, although rates were low relative to the travel times observed within the supraglacial stream. Although our findings show that these streams have low processing rates, measurable in-stream nitrification and dissolved organic matter uptake within this biologically unfavorable environment suggests that supraglacial streams with longer residence times and abundant fine substrate have the potential to modify and retain nutrients during transport to the glacier terminus.