[Systematic Evaluation of Low-carbon Operation of Typical A2O Processes in Municipal Sewage Plant].

Under the "Carbon Peak, Carbon Neutral" goal, the systematic evaluation of the carbon emission equivalent (CO2eq) and its compositions of the typical A2O process has important guiding significance for the low-carbon operation of most municipal sewage plants in China. Based on the operational data on the first municipal sewage plant of Jiaozuo in 2020 and the methods presented in "2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, " a systematic evaluation of the CO2eq of the typical A2O process was established, including direct emissions that were built on the Arrhenius model introducing the water temperature factor and indirect emissions from the three aspects of electricity consumption, agent addition, and sludge transportation. The results showed that the daily emission intensities of CH4 and N2O were (115±56) kg·d-1 and (30±18) kg·d-1, respectively. Additionally, indirect carbon emissions from electricity consumption and agent addition accounted for 48.4% and 51.3% in the biochemical treatment section, respectively. In 2020, CO2eq amounts of total research plant and per unit sewage were 2.17×104 t and (0.63±0.07) kg·m-3, respectively. The magnitude of the proportion of different carbon emission compositions was as follows:sewage electricity (36.5%)>sewage agent (26.6%)>N2O direct (15.4%)>sludge agent (9.6%)>sludge electricity (6.7%)>CH4 direct (4.9%)>sludge transportation (0.3%). System import/export fluxes of carbon and nitrogen elements were calculated, followed by the carbon to nitrogen mass ratio in the sewage plant. Direct carbon emission characteristics of CH4 and N2O and their influencing factors were discussed, respectively. Based on the balance theory of carbon and nitrogen elements in the system, it is proposed that the selective introduction of industrial wastewater may become an important reference measure for the low-carbon operation of municipal sewage plants in the future.

[Relationship between groundwater quality index of physics and chemistry in riparian zone and water quality in river].

Riparian zone hydrology is dominated by shallow groundwater with complex interactions between groundwater and surface water. There are obvious relations of discharge and recharge between groundwater and surface water. Flood is an important hydrological incident that affects groundwater quality in riparian zone. By observing variations of physical and chemical groundwater indicators in riparian zone at the Kouma section of the Yellow River Wetland, especially those took place in the period of regulation for water and sediment at the Xiaolangdi Reservoir, relationship between the groundwater quality in riparian zone and the flood water quality in the river is studied. Results show that, affected by the river and pond water, the highest point of groundwater temperature is near the pond in spring, and near the river in winter; and regulation for water and sediment at the Xiaolangdi Reservoir also affects groundwater temperature in riparian zone, which reaches its maximum at 100 m far from the river bank. There exists a strong zone of nitrification area at 50 m from the river bank, and in this area, the groundwater pH value is lower by 0.2 to 0.4 unit than that of the other regions, with great annual varieties. The turbidity of groundwater is affected by irrigation, which is more obvious than other indicators of groundwater. The turbidity of groundwater and river water increase rapidly during the early phase of flood retreat, and slope stability of river bank is the initial impact of the soil erosion of river bank. Conductivity, chloride and sulfate data show that the range of 50-200 m in riparian wetland is a very important salt accumulation zone, and the width of salt accumulation zone changes with seasons, and this area is also a very important zone of sulfur reduction. The quality of groundwater at 200 m from the river bank is also significantly affected by floods. Physical and chemical indicators of water change strongly in this area. The result indicates that there is a very close relationship between groundwater and surface water, and it is the typical land and water ecotone between groundwater of riparian zone and the river. Rational protection for this region is critical for the conservation of water quality both in the river and groundwater.

[Relationship between groundwater level in riparian wetlands and water level in the river].

The development and degradation processes of riparian wetlands are significantly affected by river hydrological processes. By observing the variation of groundwater levels in riparian wetlands at the Kouma section of the Yellow River Wetland, especially that during the period of regulation for water and sediment at the Xiaolangdi Reservoir, relationship between groundwater level in riparian wetlands and flood water level in the river is studied. The results show that groundwater level in riparian wetlands is significantly affected by water level in the river investigated. There is a negative exponential relationship between groundwater level and the distance between wells and river. The correlation coefficient shows the maximum (R2 > 0.98) during the period of regulation for water and sediment. Affected by the cultivation system in the flooding area, distance between monitoring wells and river bank, water level in the river variation of groundwater level in the wetland changed greatly. In artificial wetland, which is far from the river, the inter-annual variation in groundwater levels show a " (see symbol)" shape, while in the farmland, which is close to the river, the inter-annual variation of groundwater levels show a big peak. The groundwater level 400 m from the river is affected by flood events obviously, that in the area which is less than 200 m from the river is significantly affected by flood events in the area which is especially less than that in the area that is less than 100 m from the river, the groundwater level is affected by flood events intensively. The result indicated that there was a very close relationship between groundwater and surface water, and it was the hydrological ecotone between groundwater of riparian wetlands and the river. It is very important that rational protection for this region (very important for the area which is less than 100 m from the river, important for the area that is between 100 m and 200 m from the river) is critical for the conservation of water quality in the river and groundwater quality.

Differentiation of mesenchymal stem cells into dopaminergic neuron-like cells in vitro.

OBJECTIVE: To explore the way to induce mesenchymal stem cells (MSCs) to differentiate into dopaminergic neurons in vitro. METHODS: MSCs were obtained from rat bone marrow, cultured and passaged. MSCs used in this experiment had multipotency, which was indirectly proved by being induced to differentiate into chondrocytes and adipocytes. MSCs were cultured in medium containing 0.5 mmol/L IBMX for 2 days. Then the medium was replaced with induction medium, which contained GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments. The surface markers of the differentiated neurons, such as NSE, nestin, MAP-2a, b and TH were detected by immunocytochemistry and Western blot after MSCs were cultured in induction medium for 7 days and 15 days. RESULTS: MSCs differentiated into neural progenitors and expressed nestin after MSCs were incubated with medium containing IBMX for 2 d. After the medium was replaced with induction medium containing many inducing agents, MSCs differentiated into neuron-like cells and dopaminergic neuron-like cells and expressed NSE, MAP-2a, b and TH. The percentage of NSE-positive cells, MAP-2a, b-positive cells and TH-positive cells was 30.032 +/- 2.489%, 41.580 +/- 5.101% and 34.958 +/- 5.534%, respectively after MSCs were induced in medium containing GDNF, IL-1beta, mesencephalic glial-cell-conditioned medium and flash-frozen mesencephalic membrane fragments for 15 days. CONCLUSION: MSCs can differentiate into dopaminergic neuron-like cells and are a new cell source for the treatment of neurodegeneration diseases and have a great potential for wide application.