Location: Southern Horticultural ResearchTitle: Comparative analysis of water quality between runoff entrance and middle of recycling irrigation reservoirs
|ZHANG, HAIBO - Virginia Polytechnic Institution & State University|
|RICHARDSON, PATRICIA - Virginia Polytechnic Institution & State University|
|BELAYNEH, BRUK - University Of Maryland|
|RISTVEY, ANDREW - University Of Maryland|
|LEA-COX, JOHN - University Of Maryland|
|HONG, CHUAN - Virginia Polytechnic Institution & State University|
Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2015
Publication Date: 7/14/2015
Citation: Zhang, H., Richardson, P.A., Belayneh, B.E., Ristvey, A., Lea-Cox, J., Copes, W.E., Hong, C. 2015. Comparative analysis of water quality between runoff entrance and middle of recycling irrigation reservoirs. Water. 7:3861-3877; doi:10.3390/w7073861. 2015.
Interpretive Summary: As containment ponds become a common part of the irrigation infrastructure for conserving and protecting increasingly scarce water resources in ornamental plant nurseries, better management protocols need to be developed. Differences in seven water quality measurements were compared between the points where irrigation runoff enters the pond and the middle of the pond in nurseries in Virginia and Maryland. Surface water temperature and oxidation-reduction potential were lower in the middle than at the entrance of the pond, while dissolved oxygen, pH and chlorophyll-a followed the opposite trend, and electrical conductivity, total dissolved solids and turbidity had only very small differences. The magnitude of the differences decreased with water depth, but increased during April to October when water separates into three horizontal stratification layers. The water quality differences that occurred in the ponds were small enough that monitoring at a single point would be sufficient to make water management decisions that affect disinfectant treatments and crop productivity. This is important when considering the cost of labor and equipment necessary for documenting water quality in agricultural production systems. This information will benefit agricultural businesses that draw irrigation water from shallow ponds, university extension specialists, crop advisers, and research scientists.
Technical Abstract: Recycling irrigation reservoirs (RIRs) are an emerging aquatic ecosystem of critical importance, for conserving and protecting increasingly scarce water resources. Here we compare water quality between runoff entrance and middle of four RIRs in nurseries in Virginia (VA) and Maryland (MD). Surface water temperature (T) and oxidation-reduction potential (ORP) were lower in the middle than at the entrance, while the trend was opposite for dissolved oxygen (DO), pH and chlorophyll a. The magnitude of these differences between the entrance and middle decreased with increasing depth. These differences were magnified by water stratification (from April to October). Minimum differences were observed for electrical conductivity (EC), total dissolved solids (TDS) and turbidity (TUR). Cluster analyses were performed on water quality difference data to evaluate whether the differences vary with respect to reservoirs. Two clusters were formed with one consisting primarily of VA reservoirs, while the other mostly consisting of MD reservoirs. Water quality in the middle and at the entrance of RIRs was most dynamic because of runoff inflow. The two-point water quality differences observed here, although statistically significant, do not appear enough to cause significant impact on crop health and productivity. These results indicate that monitoring at a single point is sufficient to obtain reliable water quality estimates in RIRs, to develop water quality management plans. This is important when considering the cost of labor and equipment necessary for documenting water quality in agricultural production systems. .