王文林,劉 筱,韓宇捷,杜 薇,劉 波,曾杰亮,童 儀,高 巖,關(guān) 雷,范軍旗,李文靜,何 斐
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規(guī)?;i場(chǎng)機(jī)械通風(fēng)水沖糞式欄舍夏季氨日排放特征
王文林1,劉 筱2,韓宇捷2,杜 薇1,劉 波2※,曾杰亮2,童 儀2,高 巖2,關(guān) 雷2,范軍旗2,李文靜1,何 斐1
(1. 環(huán)境保護(hù)部南京環(huán)境科學(xué)研究所,南京 210042; 2. 南通大學(xué)地理科學(xué)學(xué)院,南通 226007)
選取長三角地區(qū)典型機(jī)械通風(fēng)水沖糞模式養(yǎng)豬場(chǎng),針對(duì)不同生長階段的肥豬欄舍和不同類型的母豬欄舍排放口氨排放進(jìn)行同時(shí)監(jiān)測(cè)(其中,育肥豬按質(zhì)量分保育(<24 kg)、育肥-Ⅰ(24~60 kg)、育肥-Ⅱ(60~120 kg)3個(gè)階段,母豬分為妊娠豬與分娩豬2種類型),估算各欄舍氨排放通量,分析各欄舍氨排放特征,探討各生長階段對(duì)氨排放貢獻(xiàn)。研究結(jié)果表明,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩欄舍氨質(zhì)量濃度分別為(0.97±0.40)、(3.37±0.70)、(5.45±2.30)、(2.19±1.06)、(1.44±0.48)mg/m3;各欄舍氨排放具有顯著的日變化過程,早晨氨排放呈波動(dòng)增大趨勢(shì),午后開始降低,至夜間保持低值排放;小時(shí)氨排放速率與溫度呈極顯著正相關(guān),與濕度呈顯著負(fù)相關(guān);各生長階段氨排放存在差異,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩欄舍日排放速率分別為0.85、6.53、8.20、10.39和13.86 g/(頭·d);保育、育肥-Ⅰ和育肥-Ⅱ階段對(duì)肥豬氨排放的貢獻(xiàn)率分別為3.64%、26.11%和70.25%,妊娠豬與分娩豬對(duì)母豬氨的貢獻(xiàn)率分別為75.32%和24.68%,母豬的氨排放速率是肥豬的1.87倍。
氨;排放控制;污染;規(guī)?;B(yǎng)豬場(chǎng);水沖糞
氨(NH3)是大氣中的堿性氣體,其與二氧化硫、氮氧化物迅速形成細(xì)顆粒物(PM2.5)[1-3],是重污染天氣二次無機(jī)顆粒物爆發(fā)式增長的重要前體物[4],對(duì)霧霾的形成和大氣污染有著重要影響。畜禽養(yǎng)殖是大氣氨的主要排放源,研究表明中國畜禽養(yǎng)殖氨排放量占總排放量54.06%。中國作為養(yǎng)豬大國,由于過于追求肉產(chǎn)量,在豬日糧中加入過高的蛋白質(zhì),導(dǎo)致糞便中產(chǎn)生過高的氨排放,中國養(yǎng)豬業(yè)氨排放總量遠(yuǎn)遠(yuǎn)高于歐美國家[5],其氨排放占畜禽養(yǎng)殖業(yè)氨排放量之首[6]。因此,開展典型規(guī)?;i場(chǎng)氨排放特征研究,進(jìn)而提出氨排放系數(shù),核算區(qū)域養(yǎng)豬的氨排放量,對(duì)于區(qū)域PM2.5粒子源解析,闡明典型農(nóng)業(yè)源氨排放污染現(xiàn)狀、控制大氣顆粒物污染、改善區(qū)域環(huán)境空氣質(zhì)量都有著非常重要的意義。
國外針對(duì)豬舍氨排放研究起步較早,開發(fā)了面向開放性欄舍的通風(fēng)量監(jiān)測(cè)方法[7-9],著重探討了欄舍的通風(fēng)方式對(duì)于氨排放的影響[10-11],分析了不同清糞方式下欄舍氨排放特征[12-14]。中國研究尚處于起步階段,國內(nèi)學(xué)者對(duì)開放性豬舍不同季節(jié)氨排放通量進(jìn)行了監(jiān)測(cè)與估算[15-16],初步探討了欄舍地板結(jié)構(gòu)對(duì)欄舍氨排放的影響[17]。對(duì)欄舍氨排放與溫度、濕度、通風(fēng)量等主要影響因子還缺乏系統(tǒng)研究。此外,分析同一時(shí)間段內(nèi)不同生長階段育肥豬以及母豬的氨排放特征,辨明各生長階段肥豬、不同類型母豬對(duì)氨排放貢獻(xiàn),為提出科學(xué)可靠的生豬氨排放系數(shù)提供科學(xué)依據(jù),對(duì)準(zhǔn)確測(cè)算區(qū)域養(yǎng)豬氨排放量具有重要意義。但是,目前還無針對(duì)同一時(shí)間內(nèi)不同生長階段肥豬與母豬的氨排放特征的系統(tǒng)研究,對(duì)于不同生長階段肥豬、不同類型母豬對(duì)氨排放貢獻(xiàn),以及肥豬與母豬氨排放之間的相互關(guān)系尚不清楚。
本研究選取典型規(guī)?;i場(chǎng),監(jiān)測(cè)不同生長階段肥豬與母豬欄舍氨排放濃度,核算不同生長階段育肥豬與母豬的排放速率,探究規(guī)?;B(yǎng)豬場(chǎng)欄舍氨排放特征,辨析氨排放重要影響因素,探討生長階段肥豬、不同類型母豬對(duì)氨排放貢獻(xiàn),以及肥豬與母豬氨排放之間的相互關(guān)系,以期為區(qū)域畜禽養(yǎng)殖氨排放核算提供技術(shù)支撐。
南通市2015年生豬、家禽畜禽養(yǎng)殖量在長三角16個(gè)城市中均位居首位。如皋市是南通下屬市縣中的養(yǎng)殖大市,位于長江中下游里下河流域,2015年底,如皋市全市全年生豬飼養(yǎng)量203.47萬頭,生豬存欄量68.56萬頭,家禽飼養(yǎng)量3 636.07萬羽,家禽存欄量1126.68萬羽、奶牛存欄量0.13萬頭,生豬、家禽和奶牛的規(guī)模養(yǎng)殖占比分別達(dá)90.21%、95.78%和91%[18]。
選取的豬場(chǎng)位于如皋市搬經(jīng)鎮(zhèn)嚴(yán)鮑村,該豬場(chǎng)為江蘇省畜牧生態(tài)健康養(yǎng)殖示范基地,母豬存欄600頭,肥豬年出欄15 000頭左右?,F(xiàn)占地面積7.56 hm2,建筑面積12 000 m2,養(yǎng)殖場(chǎng)平面圖見圖1。欄舍采用智能化母豬飼喂站、全自動(dòng)喂料線及全自動(dòng)化通風(fēng)、采暖系統(tǒng),地面為水泥實(shí)心地板,采用人工水沖糞;糞水通過地下管道集中到集糞池提升至沼氣發(fā)酵池進(jìn)行沼氣發(fā)電。沼液、沼渣返回農(nóng)田作有機(jī)肥料。欄舍為全封閉式,舍內(nèi)設(shè)有溫度探頭,進(jìn)行溫控,當(dāng)舍內(nèi)達(dá)到設(shè)定溫度以上時(shí),欄舍一側(cè)風(fēng)機(jī)排風(fēng)扇(窗)開啟,舍外新鮮空氣由欄舍另一側(cè)通風(fēng)窗(夏季開啟濕簾)進(jìn)入,此時(shí)舍內(nèi)廢氣由風(fēng)機(jī)排風(fēng)扇(窗)排出,當(dāng)舍內(nèi)溫度回落到設(shè)定溫度以下,風(fēng)機(jī)排風(fēng)扇(窗)關(guān)閉,不同季節(jié)開啟的排風(fēng)扇個(gè)數(shù)不同。排風(fēng)起到調(diào)節(jié)溫度及降低舍內(nèi)氨氣等其他氣體濃度的作用,養(yǎng)殖與欄舍概況見表1。
表1 研究豬場(chǎng)養(yǎng)殖與欄舍概況
在不同類型的欄舍進(jìn)風(fēng)口和出風(fēng)口設(shè)置采樣點(diǎn)(見圖1),其中進(jìn)風(fēng)口采樣點(diǎn)位于濕簾中心位置,出風(fēng)口采樣點(diǎn)位于每個(gè)開啟的排風(fēng)扇中心點(diǎn)偏上(經(jīng)前期監(jiān)測(cè)此位置能代表排風(fēng)口的平均速率),采樣點(diǎn)與窗口平面的水平距離為10 cm。同時(shí)設(shè)置背景采樣點(diǎn),在廠區(qū)內(nèi)常年盛行風(fēng)向上風(fēng)向的空曠地帶(半徑15 m內(nèi)無欄舍和糞污處理設(shè)施),采樣點(diǎn)高為1.5 m(圖1)。
圖1 養(yǎng)豬場(chǎng)平面與監(jiān)測(cè)點(diǎn)布設(shè)示意圖
運(yùn)用便攜式氨氣檢測(cè)儀(smart pro 10,監(jiān)測(cè)量程為0~100×10?6,分辨率為0.01×10?6,傳感器為瑞士MEMBRAPOR-CR50,檢測(cè)精度為±2%F·S)連續(xù)測(cè)定進(jìn)風(fēng)口、排放口、背景點(diǎn)氨濃度,連續(xù)監(jiān)測(cè)72 h,每分鐘記錄并存儲(chǔ)1次數(shù)據(jù),測(cè)定前氣體檢測(cè)儀用標(biāo)準(zhǔn)氣體進(jìn)行標(biāo)定校正。使用便攜氣象站(美國Kestrel 5000)同步測(cè)定排風(fēng)口排風(fēng)速率,每分鐘記錄并存儲(chǔ)1次數(shù)據(jù)。在各采樣點(diǎn)通過便攜式氣象站同步測(cè)定氣象要素(溫度、氣壓、濕度、風(fēng)速)每1分鐘記錄并存儲(chǔ)1次數(shù)據(jù)。監(jiān)測(cè)于2017年7月2日至4日開展,連續(xù)監(jiān)測(cè)3 d。
1.3.1 通風(fēng)量
式中V為每小時(shí)欄舍通風(fēng)量,m3/h;V為排風(fēng)口每小時(shí)平均排風(fēng)速率,m/s;為排風(fēng)口總面積,m2;為排風(fēng)口每小時(shí)累計(jì)排風(fēng)時(shí)長,min/h;為采樣點(diǎn)每小時(shí)平均溫度,K;0為標(biāo)準(zhǔn)狀況下氣體的溫度,273 K;為采樣點(diǎn)每小時(shí)平均氣壓,kPa;0為標(biāo)準(zhǔn)狀況下氣體的壓力,101.3 kPa。
1.3.2 氨排放量
式中a為每小時(shí)氨排放量,mg/h;in,out分別為進(jìn),排風(fēng)口氨氣小時(shí)平均濃度,mg/m3。
1.3.3 氨排放速率
式中為日排放速率,g/(頭·d);為欄舍中畜禽個(gè)體數(shù)。
監(jiān)測(cè)期間欄舍排風(fēng)口和背景監(jiān)測(cè)點(diǎn)氨平均排放濃度、平均通風(fēng)速率、平均溫度、平均濕度見表2。從溫度來看,各欄舍排風(fēng)口的平均溫度在26.2~27.4 ℃之間,要高于背景平均溫度的25.1 ℃,這主要與欄舍內(nèi)豬自身散熱有關(guān)。從濕度來看,除保育欄舍外其他欄舍濕度要高于背景值,其中,分娩、育肥-Ⅱ,妊娠欄舍排風(fēng)口平均濕度分別達(dá)到98.4%、93.93%和91.3%。濕度的升高主要受濕簾增濕和水沖清糞增濕的影響。各欄舍的通風(fēng)速率與所開啟的排風(fēng)扇大小、數(shù)量及通風(fēng)時(shí)間有關(guān),妊娠欄舍、育肥-Ⅱ欄舍由于所養(yǎng)豬只個(gè)體質(zhì)量大且數(shù)量多,降溫需求高,通風(fēng)速率大,平均通風(fēng)速率分別達(dá)到362.41和355.25 m3/min。
背景點(diǎn)氨平均質(zhì)量濃度為0.2mg/m3,各欄舍排放口氨平均排放質(zhì)量濃度在0.97~5.45 mg/m3之間,顯著高于背景值。從肥豬欄舍來看,育肥-Ⅱ欄舍排風(fēng)口氨平均排放質(zhì)量濃度最大,平均值為5.45mg/m3,最大值達(dá)到11.78 mg/m3;其次是育肥-Ⅰ欄舍,平均值為3.37 mg/m3,最大值達(dá)到4.72 mg/m3;保育欄舍排風(fēng)口氨排放平均質(zhì)量濃度最低,為0.97mg/m3,分別為育肥-Ⅱ和育肥-Ⅰ欄舍的17.8%和28.8%。從母豬欄舍來看,妊娠欄舍排風(fēng)口氨排放平均濃度要高于分娩欄舍,前者是后者的1.52倍。
表2 欄舍排風(fēng)口和背景點(diǎn)的氨平均濃度、通風(fēng)速率、平均溫度與平均濕度
通過分析各欄舍排放氨濃度日變化過程(見圖2)發(fā)現(xiàn),各欄舍排放口氨濃度存在明顯的日變化過程,大致表現(xiàn)為早晨氨濃度開始波動(dòng)上升,至午后開始波動(dòng)降低,夜間氨濃度保持低值且波動(dòng)不大。各欄舍排放口氨濃度最大值均出現(xiàn)在上午06:00~08:00左右,與該時(shí)段欄舍清糞以及豬晨起后的活動(dòng)有關(guān),育肥-Ⅱ欄舍由于養(yǎng)殖量和豬質(zhì)量較大,這一過程尤為明顯;最小值出現(xiàn)在夜間,這是由于夜間糞污人為擾動(dòng),同時(shí)豬自身活動(dòng)較少。育肥-Ⅱ欄舍由于養(yǎng)殖數(shù)量大,個(gè)體質(zhì)量大,全天排放口氨的濃度要高于其他欄舍,同時(shí)受清糞、飼喂擾動(dòng)后的波動(dòng)要大于其他欄舍。保育欄舍全天各時(shí)段排放口氨濃度要基本小于其他欄舍,這與舍內(nèi)所飼養(yǎng)豬的生長日齡較短、質(zhì)量輕、進(jìn)食量少有關(guān)。在母豬欄舍中,妊娠欄舍白天排放口氨濃度要高于分娩欄舍,妊娠欄舍母豬數(shù)量多有關(guān),而二者在夜間氨濃度差異不大。通過各欄舍氨排放濃度的相關(guān)性分析發(fā)現(xiàn),各欄舍排放口氨濃度相互呈極顯著正相關(guān)(見表3),表明各欄舍排放口氨濃度具有相似的日變化趨勢(shì)。
注:圖中數(shù)據(jù)為3日同時(shí)刻平均值。
表3 各欄舍排風(fēng)口每20 min氨濃度的相關(guān)關(guān)系(Pearson系數(shù))
注:**表示極顯著相關(guān)(<0.01)。
Note: ** indicates extremely significant correlation (<0.01).
2.2.1 小時(shí)排放速率
各欄舍每小時(shí)單位畜禽氨排放量(小時(shí)排放速率)日變化過程見圖3。由圖3可知,欄舍每小時(shí)單位畜禽氨排放量具有顯著的日變化過程,與欄舍氨排放濃度變化趨勢(shì)相似,即早晨氨排放開始波動(dòng)增大,午后開始降低,至夜間保持低值排放。白天受到清糞、飼喂活動(dòng)的擾動(dòng)以及豬自身活動(dòng)的影響,氨排放出現(xiàn)波動(dòng)峰值。其中,清糞過程對(duì)氨排放影響較大,肥豬各欄舍氨排放峰值均出現(xiàn)在清糞時(shí)間段(上午06:00-08:00)。保育、育肥-Ⅰ、育肥-Ⅱ每日最大小時(shí)氨排放速率平均值分別為77.4、349.2、715.9 mg/(h·頭),育肥-Ⅱ豬分別是育肥-Ⅰ豬、保育豬的2.05倍和9.25倍。夜間豬處于睡眠狀態(tài),基本無人為擾動(dòng),20:00至凌晨04:00保持低值排放,保育、育肥-Ⅰ、育肥-Ⅱ每日最小氨排放速率平均值分別為16.0、192.3、153.4 mg/(h·頭)。保育、育肥-Ⅰ、育肥-Ⅱ欄舍日均排放量別為253.70、1 174.69和2 789.07 g/d,育肥-Ⅱ欄舍分別是育肥-Ⅰ欄舍、保育欄舍2.37倍和10.99倍。母豬欄舍氨排放峰值均出現(xiàn)上午07:00時(shí),妊娠和分娩豬舍每日最大小時(shí)排放速率平均值分別為833.8和1 163.9 mg/(h·頭)。從排放總量上來看,妊娠和分娩欄舍日均排放量別為1 703.20和360.40 g/d。分娩欄舍要小于妊娠欄舍,主要是由于分娩欄舍僅有26頭母豬,新出生仔豬體質(zhì)量小,以飲用母乳為食,氨排放很少。
注:圖中數(shù)據(jù)為3日同時(shí)段釋放速率平均值。
2.2.2 日排放速率
根據(jù)各類型豬氨排放速率分別計(jì)算各類型豬的日排放速率。各生長階段肥豬的每天排放速率分別為0.85(保育)、6.53(育肥-Ⅰ)和8.20 g/(頭·d)(育肥-Ⅱ),隨著個(gè)體質(zhì)量增加排放量也逐漸增大,個(gè)體質(zhì)量由10 kg增加到85 kg,單位個(gè)體肥豬的氨日排放量相應(yīng)增大了8.64倍。妊娠豬和分娩豬的日排放速率分別為10.39和13.86 g/(頭·d),分娩豬是妊娠豬的1.33倍。
欄舍氨排放受多種因素的共同影響。豬舍內(nèi)糞、尿是舍內(nèi)氨的主要來源,豬只自身活動(dòng)也會(huì)產(chǎn)生一定量的氨[19-21]。豬糞便中的氨氮主要來源于飼料中蛋白質(zhì)在豬消化道中分解產(chǎn)生的氨基酸[22],飼料中的粗纖維比例也對(duì)糞便中氨排放存在影響[23-24]。此外,飼料進(jìn)食量會(huì)決定豬的糞尿排泄量。隨著個(gè)體生長,單位個(gè)體的進(jìn)食量也在增加,導(dǎo)致糞尿排泄量增多,進(jìn)而增加氨排放[25]。育肥-Ⅱ階段的肥豬以及母豬氨排放量較大與進(jìn)食量大有關(guān)(圖3)。清糞過程中導(dǎo)致的糞尿擾動(dòng)會(huì)增大氨釋放,在每天糞便清理時(shí)間造成糞尿翻動(dòng),飼喂時(shí)間欄舍內(nèi)豬的活動(dòng)強(qiáng)度增大,導(dǎo)致出現(xiàn)氨排放峰值(圖3)。
通過分析各欄舍排放口氨小時(shí)排放速率與溫度、濕度相關(guān)性發(fā)現(xiàn),氨排放速率與溫度呈極顯著正相關(guān)(圖4),與濕度呈顯著負(fù)相關(guān)(圖5),這與相關(guān)研究結(jié)果一致[26]。進(jìn)一步對(duì)欄舍氨小時(shí)排放速率與排風(fēng)口溫度、濕度的響應(yīng)關(guān)系進(jìn)行綜合分析,通過線性回歸分析發(fā)現(xiàn)欄舍氨排放日變化過程與排放口的溫度和濕度的日變化過程存在很好相關(guān)關(guān)系,即一定溫濕度范圍內(nèi),氨排放速率與溫、濕度響應(yīng)關(guān)系顯著,結(jié)果見表4。表明溫度、濕度是影響?zhàn)B殖場(chǎng)欄舍氨排放的重要因素,在溫度高、濕度低季節(jié)氨排放量會(huì)增大,反之則減小。這主要由于較高的溫度能提高脲酶活性,促進(jìn)糞便中含氮物質(zhì)分解釋放出氨[27],則在一定的通風(fēng)條件下欄舍會(huì)向環(huán)境中排放更多的氨。此外,由于氨的水溶性較大,濕度增大會(huì)降低空氣環(huán)境中氨濃度[27]清糞方式?jīng)Q定了糞、尿在舍內(nèi)的存積時(shí)間及混合程度,以及糞尿受擾動(dòng)的程度,進(jìn)而會(huì)影響欄舍氨排放[19,28]。水沖糞相比干清糞,糞便擾動(dòng)相對(duì)較小,加之水沖增加濕度,一定程度上會(huì)減少氨的排放。以育肥-Ⅱ階段為例,本研究獲得的日氨排放速率為8.20 g/(頭·d),相同豬只質(zhì)量、機(jī)械通風(fēng)、干清糞模式欄舍夏季氨排放速率為11.89 g/(頭·d)[6],水沖糞模式要比干清糞模式小31.03%(表5)。對(duì)比育肥-Ⅰ階段和妊娠豬相關(guān)研究結(jié)果發(fā)現(xiàn),本研究的水沖糞模式下的日氨排放速率相比于干清糞模式也具有相同的結(jié)果(表5)。水泡糞雖減少了清糞對(duì)糞尿的擾動(dòng),但糞尿在欄舍中存儲(chǔ)時(shí)間較長,糞尿會(huì)持續(xù)釋放氨進(jìn)而增加欄舍的釋放量。以分娩豬為例,本研究水沖糞模式的氨日排放速率為13.86 g/(頭·d),相比于水泡糞模式的19.26 g/(頭·d),為后者的71.96%。
圖4 氨排放速率與溫度相關(guān)關(guān)系
圖5 氨排放速率與濕度相關(guān)關(guān)系
表4 氨排放速率與溫度、濕度響應(yīng)關(guān)系
注:1為溫度,℃;2為濕度,%;為氨排放速率,mg·(h·頭)-1。
Note:1indicates temperature, ℃;2indicates humidity, %;indicates ammonia emission rate, mg·(h·頭)-1).
欄舍通風(fēng)方式?jīng)Q定了欄舍通風(fēng)量,對(duì)欄舍產(chǎn)生的氨氣等污染氣體排放量有直接作用[29-30]。此外,欄舍通風(fēng)方式會(huì)影響豬舍的溫度、濕度,進(jìn)而影響欄舍氨排放[31]。機(jī)械通風(fēng)欄舍通常根據(jù)舍內(nèi)溫度設(shè)定排風(fēng)扇開關(guān)頻率與排風(fēng)周期。由于夏季溫度較高,排風(fēng)扇盡量開啟以維持舍內(nèi)溫度不宜過高,因而夏季通風(fēng)量較大。從理論上講,夏季相同清糞模式下機(jī)械通風(fēng)欄舍相對(duì)于通量小的自然通風(fēng)欄舍的氨排放量有增大的風(fēng)險(xiǎn)。陳園等[6]研究的干清糞模式機(jī)械通風(fēng)欄舍的氨排放速率要大于相同清糞模式自然通風(fēng)欄舍[32]氨排放速率(表5)。一般機(jī)械通風(fēng)欄舍都配置濕簾,若運(yùn)行良好在通風(fēng)降溫的同時(shí)可最大程度的增大欄舍濕度,進(jìn)而通過降溫、增濕來減少空氣環(huán)境中的氨氣濃度。本研究采用濕簾降溫和機(jī)械通風(fēng)模式,并采用水沖糞方式會(huì)進(jìn)一步加大欄舍環(huán)境濕度,會(huì)減少欄舍內(nèi)氨的產(chǎn)生進(jìn)而會(huì)降低氨排放量。這可能是本研究氨排放速率小于通風(fēng)模式欄舍氨排放的主要原因。
表5 國內(nèi)外相關(guān)研究對(duì)比情況
根據(jù)肥豬的各生長階段的養(yǎng)殖周期天數(shù)(表1),根據(jù)各階段實(shí)測(cè)日排放速率核算出肥豬整個(gè)生長周期的氨排放量,進(jìn)而獲得肥豬氨日排放速率為5.94 g/(頭·d)。保育、育肥-Ⅰ和育肥-Ⅱ階段對(duì)肥豬氨排放的貢獻(xiàn)率分別為3.64%、26.11%和70.25%(圖6a)。同樣,根據(jù)妊娠豬和分娩豬養(yǎng)殖周期天數(shù)和實(shí)測(cè)氨日排放速率核算出母豬整體日排放速率為11.07 g/(頭·d),妊娠豬與分娩豬對(duì)母豬氨排放的貢獻(xiàn)率分別為75.32%和24.68%(圖6b)。母豬的排放速率是肥豬的1.87倍。
各生長階段肥豬與不同類型母豬由于進(jìn)食量、日?;顒?dòng)、糞尿排泄量等生理過程不同,導(dǎo)致氨排放量存在明顯差異。從生豬養(yǎng)殖實(shí)際來看,同一時(shí)間段內(nèi)各個(gè)生長階段的肥豬與母豬是同時(shí)進(jìn)行養(yǎng)殖。那么,準(zhǔn)確評(píng)估各生長階段肥豬、不同類型母豬對(duì)氨排放貢獻(xiàn)程度,對(duì)提出科學(xué)可靠的生豬氨排放系數(shù),進(jìn)而構(gòu)建高精度、動(dòng)態(tài)的區(qū)域生豬氨排放清單更有實(shí)際意義。應(yīng)結(jié)合日齡、糞及尿的排放量,開展全年為周期的系統(tǒng)研究。
a. 肥豬
a. Fattening pig
b. 母豬
1)各欄舍氨排放濃度存在顯著差異,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩欄舍氨質(zhì)量濃度分別為(0.97±0.40)、(3.37±0.70)、(5.45±2.30)、(2.19±1.06)和(1.44±0.48) mg/m3。
2)各欄舍氨排放具有顯著的日變化過程,早晨氨排放開始波動(dòng)增大,午后開始降低,至夜間保持低值排放;各欄舍受到清糞與豬只自身活動(dòng)影響在早晨06:00-08:00出現(xiàn)峰值,保育、育肥-Ⅰ、育肥-Ⅱ、妊娠和分娩欄舍每日最大小時(shí)氨排放速率分別為77.4、349.2、715.9、833.8和1 163.9 mg/(h·頭)。
3)飼喂、清糞等人為擾動(dòng)會(huì)增加欄舍的氨排放,小時(shí)氨排放速率與溫度呈極顯著正相關(guān),與濕度呈顯著負(fù)相關(guān)。
4)保育、育肥-Ⅰ、育肥-Ⅱ、妊娠、分娩欄舍日排放速率分別為0.85、6.53、8.20、10.39和13.86 g/(頭·d);經(jīng)核算肥豬和和母豬的氨日排放速率分別為5.94和11.07 g/(頭·d);保育、育肥-Ⅰ和育肥-Ⅱ階段對(duì)肥豬氨排放的貢獻(xiàn)率分別為3.64%、26.11%和70.25%;妊娠豬與分娩豬對(duì)母豬氨排放的貢獻(xiàn)率分別為75.32%和24.68%;母豬的氨排速率是育肥豬的1.87倍。
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Daily emission characteristics of ammonia from typical industrial pig farm with manure cleaning by rising water in summer
Wang Wenlin1, Liu Xiao2, Han Yujie2, Du Wei1, Liu Bo2※, Zeng Jieliang2, Tong Yi2, Gao Yan2, Guan Lei2, Fan Junqi2, Li Wenjing1, He Fei1
(1.210042; 2.226007,)
Ammonia (NH3), as the only reactive alkaline gas, plays a crucial role in the neutralization of atmospheric sulfuric or nitric acid to generate ammonium salts, thereby affecting the acidity of cloud water and aerosols. At present, the ammonia emissions which is the main component of fine particulate (particulate matter equal to or less than 2.5m in aerodynamic diameter; PM2.5), has become a global hot issue. Livestock and poultry breeding is the main emission source of ammonia, and the total amount of ammonia released by China's pig industry is much higher than that of Europe and North America. An in-depth study about ammonia emission from livestock sources may help policy-makers to develop emission reduction scheme and ease the haze. Generally, pig is considered to be the major contributor to ammonia emission. Therefore, in this study, we investigated NH3emissions from a pig farm in Yangtze River delta region which were equipped with typical mechanical ventilation system and manure collection system cleaning by rising water. It monitored the ammonia emissions from different houses at the same time which included different growth stages of the fattening pigs and sows (among them, the fattening pigs can be divided in three phases according to the weight, Nursery (<24 kg), and Fattening-I (24-60 kg) and Fattening-Ⅱ(60-120 kg).The sow can be divided into Gestation and Farrowing, and the ammonia emission flux was determined. Meanwhile, in this study, we analyzed the ammonia emission characteristics to explore the contribution of ammonia emissions in different growth stage. The results showed that the NH3concentrations of Nursery, Fattening-Ⅰ, Fattening-Ⅱ, Gestation and Farrowing were (0.97±0.4), (3.37±0.70) and (5.45±2.30), (2.19±1.06) and (1.44±0.48) mg/m3, respectively. The ammonia emission in each column had a significant daily change process. In the morning, the ammonia discharge were fluctuated and increased, then started to decrease in the afternoon, and the value kept low at night. The ammonia emission rate was significantly positively correlated with the temperature and was negatively correlated with the humidity. The daily NH3emissions rate of Nursery, Fattening-Ⅰ, Fattening-Ⅱ, Gestation and Farrowing were 0.85, 6.53, 8.20, 10.39 and 13.86 g/(pig·d). In fattening pigs, the contribution rate of Nursery, Fattening-Ⅰ, Fattening-Ⅱwere 3.64%, 26.11% and 70.25%. In sows, the contribution rate of Gestation and Farrowing was 75.32% and 24.68%. Artificial disturbance, such as feeding and defecation, increased the ammonia emission in the pig houses. The ammonia emission rate of sows was 1.87 times higher than fattening pigs. By monitoring the concentration of ammonia emission from fattened pigs and sows at different growth stages, we explored the characteristics of ammonia emission from large-scale pig farms, discriminated and analyzed the important influencing factors of ammonia emission, and discussed the contribution of fattened pigs and sows of different types to ammonia emission during growth stages to provide technical support for the accounting of ammonia emission in regional livestock and poultry breeding. These findings in this paper could be useful for estimation of ammonia emissions accurately and implementation of ammonia emission reduction measures in China.
ammonia; emission control; pollution; industrial pig farm; manure cleaning by rising water
2018-03-19
2018-07-03
大氣重污染成因與治理攻關(guān)項(xiàng)目(DQGG0208);環(huán)保公益性行業(yè)科研專項(xiàng)(201509038);環(huán)境保護(hù)部部門預(yù)算項(xiàng)目“畜禽養(yǎng)殖大氣氨排放污染控制工作指南”;江蘇省大學(xué)生創(chuàng)新訓(xùn)練計(jì)劃項(xiàng)目(201710304035Z、201710304078Y)聯(lián)合資助
王文林,副研究員,博士,主要研究方向?yàn)榱饔蛎嬖次廴究刂?。Email:wangwenlin_jjl@126.cn
劉 波,副教授,博士,主要從事環(huán)境面源污染過程與防治研究。Email:lb@ntu.edu.cn
10.11975/j.issn.1002-6819.2018.17.028
X552
A
1002-6819(2018)-17-0214-08
王文林,劉 筱,韓宇捷,杜 薇,劉 波,曾杰亮,童 儀,高 巖,關(guān) 雷,范軍旗,李文靜,何 斐. 規(guī)?;i場(chǎng)機(jī)械通風(fēng)水沖糞式欄舍夏季氨日排放特征[J]. 農(nóng)業(yè)工程學(xué)報(bào),2018,34(17):214-221. doi:10.11975/j.issn.1002-6819.2018.17.028 http://www.tcsae.org
Wang Wenlin, Liu Xiao, Han Yujie, Du Wei, Liu Bo, Zeng Jieliang, Tong Yi, Gao Yan, Guan Lei, Fan Junqi, Li Wenjing, He Fei. Daily emission characteristics of ammonia from typical industrial pig farm with manure cleaning by rising water in summer[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(17): 214-221. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.17.028 http://www.tcsae.org