System for Deep Sediment Flow Culture Simulating In-situ Water Pressure

It discloses a system for deep sediment flow culture simulating in-situ water pressure, comprising a flow culture apparatus, an inflow pressurizer and an outflow depressurizer, wherein the inflow pressurizer comprises a pressure tank, an air inlet pipe, a pressure regulating valve, a pressure-resistant container and a first support, wherein the pressure tank is connected with an air inlet of the pressure-resistant container through the air inlet pipe, the pressure regulating valve is arranged on the air inlet pipe, and the pressure-resistant container containing in-situ overlying water added with isotopes is placed on the first support, a water outlet of the pressure-resistant container being connected with a water inlet pipe of the flow culture apparatus; the outflow depressurizer comprises a porous medium pipe, a second support, a depressurized water outlet pipe and a water catcher.

This application claims priority to Chinese Patent Application Ser. No. CN202010848160.7 filed on 21 Aug. 2020.

TECHNICAL FIELD

The present invention relates to a laboratory culture apparatus, and in particular to a system for deep sediment flow culture simulating in-situ water pressure.

BACKGROUND

Nitrogen conversion flow culture of sediment is a water culture experiment in which in-situ overlying water added with isotopes is in a flowing state, and the nutrients, acidity and temperature of submerged sediment are kept at a stable level, which is of great significance for the simulation of nitrogen cycle processes in ecologically critical areas such as hyporheic zones of rivers and lakes, coastal dry and wet areas and hydro-fluctuation belt in reservoir areas. However, there is a big problem with existing flow culture technology, that is, the in-situ water pressure of deep sediment cannot be simulated, while water pressure is an important factor affecting nitrogen source input of sediment and release of reactant gases (N2and N2O), which has great influence on the quantification of nitrogen cycle rate. Therefore, existing flow culture technology can hardly be applied to the culture of sediment in high-dam deep reservoirs.

SUMMARY

Purpose: To address problems in the prior art, the present invention provides a system for deep sediment flow culture simulating in-situ water pressure.

Technical solution: The system for deep sediment flow culture simulating in-situ water pressure described herein comprises a flow culture apparatus and an inflow pressurizer and an outflow depressurizer each connected with the flow culture apparatus, wherein the inflow pressurizer comprises a pressure tank, an air inlet pipe, a pressure regulating valve, a pressure-resistant container and a first support, wherein the pressure tank is connected with an air inlet of the pressure-resistant container through the air inlet pipe, the pressure regulating valve is arranged on the air inlet pipe, and the pressure-resistant container containing in-situ overlying water added with isotopes is placed on the first support, a water outlet of the pressure-resistant container being connected with a water inlet pipe of the flow culture apparatus; the outflow depressurizer comprises a porous medium pipe, a second support, a depressurized water outlet pipe and a water catcher, wherein the porous medium pipe is filled with a porous medium material and placed on the second support, wherein an inlet of the porous medium pipe is connected with a water outlet pipe of the flow culture apparatus, and an outlet of the porous medium pipe is connected with one end of the depressurized water outlet pipe, the other end of the depressurized water outlet pipe extending into the water catcher.

Further, a pressure gauge and a pressure relief valve are arranged on the pressure-resistant container. The length, width and height of the pressure-resistant container are set as follows: length>twice the width, width>twice the height. The pressure in the pressure-resistant container is adjusted by the pressure regulating value to P during culture:

where h is a simulated water depth and P0is 1 standard atmospheric pressure.

Further, the porous medium material in the porous medium pipe is a material meeting the following condition:

permeability coefficient of the porous medium material

where q is a required flow rate of flow culture experiment, L is a length of the porous medium pipe, r is a radius of the porous medium pipe, and h is a simulated water depth.

Further, the inflow pressurizer, the flow culture apparatus and the outflow depressurizer are hermetically connected.

Beneficial effects: The present invention has significant advantages over the prior art in that the in-situ water pressure can be simulated for flow culture of deep sediment, and the outflow rate can be controlled through different media in the porous medium pipe.

DETAILED DESCRIPTION

The embodiment provides a system for deep sediment flow culture simulating in-situ water pressure. As shown inFIG. 1, the system comprises a flow culture apparatus, an inflow pressurizer and an outflow depressurizer which are hermetically connected. These apparatuses are described separately below.

The inflow pressurizer is configured to simulate in-situ water pressure, comprising a pressure tank1, an air inlet pipe2, a pressure regulating valve3, a pressure-resistant container4, a pressure gauge5, a pressure relief valve6and a first support8, wherein the pressure tank1is connected with an air inlet of the pressure-resistant container4through the air inlet pipe2, the pressure regulating valve3is arranged on the air inlet pipe2, and the pressure-resistant container4containing in-situ overlying water7added with isotopes is placed on the first support8, wherein a water outlet of the pressure-resistant container4is hermetically connected with a water inlet pipe10of the flow culture apparatus. The pressure tank1is filled with an inert gas, and the pressure-resistant container4is made of steel and is integrally sealed with the water outlet. Generally, about 20-30 L of water is required for a single flow culture. In order to reduce the impact of changes of water depth in the container on simulated intensity of pressure, the container is designed with a wide and flat structure, that is, the length, width and height are set as follows: length>twice the width, width>twice the height. In the embodiment, the length, width and height are 100 cm, 30 cm and 10 cm, respectively.

During culture, it is necessary to regulate the gas injected into the pressure-resistant container4from the pressure tank1by adjusting the pressure regulating valve3, and control the pressure of the pressure-resistant container4at P:

where h is a simulated water depth and P0is 1 standard atmospheric pressure.

(2) Flow Culture Apparatus

The flow culture apparatus is mainly configured for flow culture, comprising a water inlet pipe10, an inflow sampling valve11, a water outlet pipe12, an outflow sampling valve13, a flow culture pipe14, an in-situ sediment column15, a sealing rubber plug16and a thermostatic water bath pipe17, wherein the water inlet pipe10is hermetically connected with the water outlet of the pressure-resistant container4through a hermetical connecting device9, the inflow sampling valve11is located on the water inlet pipe10, and the outflow sampling valve13is located on the water outlet pipe12, both the water inlet pipe10and the water outlet pipe12are inserted into the flow culture pipe14, the in-situ sediment column15with the bottom sealed by the sealing rubber plug16is located in the flow culture pipe14, and the flow culture pipe14is placed in the thermostatic water bath pipe17. The water inlet pipe10, the water outlet pipe12and the flow culture pipe14are in integrated design and made of steel, the height and inner diameter of the flow culture pipe14are 30 cm and 9 cm respectively, and the inner diameter of both the water inlet pipe and the water outlet pipe is 5 mm. The principle of flow culture is the same as that in the prior art, and will not be repeated here.

The outflow depressurizer comprises a porous medium pipe18, a second support19, a depressurized water outlet pipe20and a water catcher21, wherein the porous medium pipe18is placed on the second support19, with its inlet being connected with the water outlet pipe12of the flow culture apparatus and kept at the same level, and its outlet being connected with one end of the depressurized water outlet pipe20, the other end of which extends into the water catcher21. The porous medium pipe18is made of steel and filled with a porous medium material, which enables outflow depressurization. The flow rate (q) of the flow culture experiment is generally controlled at 1 ml/min. Due to the large water head difference (i.e., −h) between inflow and outflow, the present invention uses a porous medium for depressurization. According to Darcy-Weisbach Formula, the flow velocity in the porous medium pipe is:

then permeability coefficient

where q is a required flow rate of flow culture experiment, L is a length of the porous medium pipe, r is a radius of the porous medium pipe, and h is a simulated water depth. It can be seen that the porous medium material meets the permeability coefficient k, and the selection of the porous medium material varies with the simulated water depth (h).

Experimental facilities, combined with isotope tracing and isotope pairing techniques, are used to calculate the denitrification rate and anammox rate of sediment.

In addition, the system can also measure the nutrient flux at a sediment-water interface under in-situ water pressure by measuring the nutrient concentration of sediment and water before and after culture, and measure the flux of gases such as greenhouse gas released from sediment or water under in-situ water pressure by measuring the concentration of the gases such as greenhouse gas in the water before and after culture.