Water quality in low‐elevation streams and rivers of New Zealand: Recent state and trends in contrasting land‐cover classes
Water quality in low‐elevation streams and rivers of New Zealand: Recent state and trends in contrasting land‐cover classes
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DOI：
10.1080/00288330.2004.9517243
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发表时间：
2004-06
影响因子：
1.6
通讯作者：
S. Larned;M. Scarsbrook;T. Snelder;N. Norton;B. Biggs
中科院分区：
文献类型：
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作者：
S. Larned;M. Scarsbrook;T. Snelder;N. Norton;B. Biggs
由于普遍的土地利用变化，新西兰的河流水质在低海拔集水区面临极大的破坏风险，但尚未在全国范围内对这些河流的状况进行评估。利用15个地区委员会和单位当局的地表水监测方案以及国家河流水质网的数据，评估了新西兰各地低海拔河流水质的近期状况(1998-2002年)和趋势(1996-2002年)。在国家一级和四个土地覆盖类别(原生森林、人工林、牧场和城市)内进行了评估。通过将大量的牧场细分为6个气候等级和7个河流目，进行了更精细的评估。在国家一级，粪便指示菌大肠杆菌、溶解无机氮和溶解活性磷的中位数超过了保护水生生态系统和人类健康的建议准则。不同土地覆盖类别的水质状况差异很大：田园和城市类别的大肠杆菌和溶解氮磷浓度比原生和人工林类别高2-7倍，而牧场和城市类别的水透明度中值比原生和人工林类别低40%-70%。田园类与城市类水质状况无统计学差异，人工林类水质状况与原生林类水质状况无统计学差异。低海拔河流的显著趋势仅限于四个参数：流量(在所有情况下都呈下降趋势)、温度、透明度和电导率(在所有情况下都呈上升趋势)。流动、温度和清晰度的趋势在全国范围内和在牧民阶层内都是明显的。这些趋势的幅度很小，对应于参数中值的≤变化为0.5%/年。
Abstract River water quality in New Zealand is at great risk of impairment in low elevation catchments because of pervasive land‐use changes, yet there has been no nationwide assessment of the state of these rivers. Data from the surface‐water monitoring programmes of 15 regional councils and unitary authorities, and the National River Water Quality Network were used to assess the recent state (1998–2002) and trends (1996–2002) in water quality in low‐elevation rivers across New Zealand. Assessments were made at the national level, and within four land‐cover classes (native forest, plantation forest, pastoral, and urban). Finer‐scaled assessments were made by subdividing the large number of pastoral sites into six climate classes, and seven stream orders. At the national level, median concentrations of the faecal indicator bacterium Escherichia coli, and dissolved inorganic nitrogen and dissolved reactive phosphorus exceeded guidelines recommended for the protection of aquatic ecosystems and human health. Water quality state varied widely within land‐cover classes: E. coli and dissolved nitrogen and phosphorus concentrations in the pastoral and urban classes were 2–7 times higher than in the native and plantation forest classes, and median water clarity in the pastoral and urban classes was 40–70% lower than in the native and plantation forest classes. Water quality state in the pastoral class was not statistically different from that of the urban class, and water quality state in the plantation forest class was not statistically different from that of the native forest class. Significant trends in low‐elevation rivers were limited to four parameters: flow (trending down in all instances), and temperature, clarity, and conductivity (trending up in all instances). The trends in flow, temperature, and clarity were apparent at the national scale, and within the pastoral class. The magnitudes of these trends were very low, corresponding to changes of ≤0.5%/ year in parameter medians.